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    • Introduction to Physiology


      Physiology is the most fascinating and ancient branch of science. It is fascinating because, it unfolds the mystery of complicated functional aspects of individual organs in the body. It is ancient because, it exists ever since the origin of life. Even before knowing the language, culture and society, man knew about the hunger, thirst, pain and fear which are the basics of physiology. Physiology is defined as the study of functions of various systems and different organs of the body. Physiology is of different types namely, Human Physiology, Animal Physiology and Plant Physiology. Human Physiology and Animal Physiology are very much inter-related. Knowledge of Human Physiology is essential to understand the other allied subjects like Biochemistry, Pharmacology, Pathology, Medicine, etc. However, it is worthwhile to have a brief know ledge of anatomy of different systems and various organs to understand the principles of Human Physiology. The basic physiological functions include, provision of oxygen and nutrients, removal of metabolites and other waste products, maintenance of blood pressure and body temperature, hunger and thirst, locomotor functions, special sensory functions, reproduction and the higher intellectual functions like learning and memory. In the unicellular organisms, all the physiological functions are carried out by simple diffusion through the cell membrane. Because of the evolutionary and ecological changes over the years, individual system is developed for each function such as digestive system, cardiovascular system, respiratory system, excretory system, etc. Every system in the body is independent structurally and functionally yet, all the systems are interdependent. 

      Essentials of Medical PhysiologySixth Edition, K Sembulingam PhD and Prema Sembulingam PhD. JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD. New Delhi • Panama City • London • Dhaka • Kathmandu

      Human Physiology is usually studied under the following headings:
      • 1. Cell & Body Fluids Physiology
      • 2. Blood Physiology
      • 3. Nerves & Muscles Physiology
      • 4. Digestive System Physiology
      • 5. Renal Physiology and Excretion
      • 6. Endocrine & Reproductive System Physiology
      • 7. Cardiovascular System Physiology
      • 8. Respiratory System Physiology
      • .9. Central Nervous System Physiology
      • 10. Special Senses Physiology
      • 11. Skin Physiology & thermoregulation

    • Cell Physiology and Body Fluids


      Objectives after studying this chapter, you should be able to . . .

      1. Describe the structure and functions of the plasma membrane, glycocalyx, and ions channels.
      2. Expound the functions of cilia and flagella.
      3. Explain the means of cell-to-cell adhesion.
      4. Describe how the cells communicate with each other (signal transduction or cell signaling).
      5. Expound the ways by which cell regulates the intracellular [Ca2+] and [H+].
      6. Know the composition of extracellular and intracellular body fluids.
      7. Explain osmosis, osmolarity and osmotic pressure, and tonicity of the body fluids.
      8. Know the forces producing movement of substances between compartments.
      9. Describe the process of endocytosis and exocytosis.
      10. Describe the primary factors (Starling forces) that determine fluid movement through the capillary membrane and the formation of interstitial fluid and lymph.
      11.  Describe the intake versus output of water.

      Interesting facts about cell and cell membrane:

      • Scientists estimate that our bodies contain anywhere from 75 to 100 trillion cells, all work in perfect harmony.
      • A typical cell is 10 square micrometers in size and 1 nanogram in mass!
      • The cell membrane is ridiculously small. It’s so small, in fact, that you’d have to stack more than 10,000 cell membranes on top of each other to equal the thickness of a standard piece of the paper. Yet despite this small thickness, the total surface area of cell membrane in the average human body is incredibly large. There’s more than 27871 square meters of it in the human body, which is enough to fully cover 4 American football fields.
      • The amount of information that the cell membrane protects is incredible. It’s essentially like having your own HDD operating within every cell. What the cell membrane does, however, is protects these data and actually use this data library. It directs the information to go to different places in the body and it helps to keep people functional and healthy.
      • The of phospholipids of the membrane acts a lot like the insulation of a double-glazed window while helps to facilitate movement of specific selective substances and resisting molecules that shouldn’t be entering the cells


      Interesting facts about body fluids and water

      • Water is key to life. Humans can survive more than a month without food, but only a few days without water.
      • Transportation: Water transports glucose, oxygen, and fat to body tissues and waste products, such as carbon dioxide, and lactic acid away from body tissues.
      • Body temperature regulation: Your body produces enough heat in only thirty minutes to boil a half-gallon of water. The body wants to keep a constant temperature of approximately 37ºC. If the body temperature increases to >41ºC, cells will die.
      • To prevent overheating, the body regulates temperature by sweating. Water absorbs heat from the working muscles and dissipates this heat to circulating blood and ultimately through the skin and by sweat evaporation.
      • Digestion: Water is an important component of saliva, intestinal, and gastric juices, which help digest food.
      • Lubrication: Water is a good lubricator of joints, organs, and tissues.
      • Drinking too much water too quickly can lead to water intoxication. Water intoxication occurs when water dilutes the sodium level in the bloodstream and causes an imbalance of water in the brain. Water intoxication is most likely to occur during periods of intense athletic performance.
      • Pure water (solely hydrogen and oxygen atoms) has a neutral pH of 7, which is neither acidic nor basic. Water dissolves more substances than any other liquid
      • Wherever it travels, water carries chemicals, minerals, and nutrients with it.
      • By the time a person feels thirsty, his or her body has lost over 1 percent of its total water amount.

    • Blood Physiology


      Objectives after studying this chapter, you should be able to . .

      1. Describe the blood components and hemopoiesis.
      2. Describe red blood cell, its function, and explain the mechanism for regulation of its production.
      3. Expound the plasma proteins and their functions.
      4. Understand the composition, types, forms, synthesis, destruction and abnormalities of Hb.
      5. Characterize the types of anemia.
      6. Explain the types, functions, and the formation of white blood cells.
      7. Describe the types of immunity and the development of the immune system.
      8. Understand the inflammatory process.
      9. Expound blood types, blood incompatibility, and transfusion reaction.
      10.  Understand platelets and their functions.
      11. Describe hemostasis & fibrinolytic activity.

      Amazing facts about blood

      • The human body manufactures 17 million red blood cells per second. If stress precipitates a need the body can produce up to 7 times that amount. (That’s up to 119 million red blood cells per second).
      • Cows have 800 (and possibly more) blood types.
      • George Washington was bled to death by doctors, who were treating him for a cold. Bloodletting was a common medical practice in those times in order to remove “dirty blood,” when in reality it only weakens the patient. Half or more of his blood was removed within a few hours.
      • There is about 0.2 milligrams of gold in our bodies, most of which is in our blood. However, you would need to bleed 40,000 people dry just to collect enough blood to make an 8-gram souvenir.
      • Mosquitoes prefer blood type O to any other.
      • A 2014 study published in the journal Neurology found those with blood type AB were twice as likely to experience memory problems as those with type O blood.
      • All blood isn’t red. Crabs have blue blood. Earthworms and leeches have green blood. Many invertebrates, such as starfish, have clear or yellowish blood.

    • Nerves & Muscles Physiology


      Objectives after studying this chapter, you should be able to . . .

      1. Explain the genesis of resting membrane potential.
      2. Describe the action potential of nerve, skeletal, cardiac, and smooth muscle fibers.
      3. Expound the effect of extracellular fluid ion concentrations on the cell membrane potential.
      4. Explain the mechanism of propagation of the action potential.
      5. Describe rhythmicity of certain excitable tissues.
      6. Expound the nerve fiber morphology, its myelination, and the nerve fiber classification.
      7. Explain the synaptic transmission and neurotransmitters.
      8. Expound transmission of impulses from nerves to skeletal muscle fibers: The neuromuscular junction.
      9. Describe the histological appearance of the skeletal muscle fiber.
      10.  Explain the mechanism of muscle contraction.
      11.  Describe the source of energy for the muscle.
      12.  Characterize types of muscle contraction.
      13.  Expound different events-related to muscle contraction such as skeletal muscle tone, muscle fatigue, muscle hypertrophy, muscle atrophy, the staircase effect, and Relationship between muscle length and tension.
      14.  Describe the types of smooth muscles, and the mechanism of smooth muscle contraction.
      15.  Explain the difference between smooth, skeletal, and cardiac muscles.


      Interesting facts……..:

      The strength of the electrostatic field (E) is directly related to the potential difference (Δϕ, otherwise known as voltage) divided by the distance (d) between the poles.
      E = – Δϕ/d
      So, in a lightning storm, the electrical field would be measured as the difference in voltage of the earth and the clouds, divided by the distance between them. Lightning is produced when the electrostatic force (E) is around 3 million volts per meter!
      We know that the voltage across a neuron’s membrane is 0.07 volts and the average thickness of the membrane is 5 nanometers.
      ENeuron = -(0.07 volts) / (5×10-9 meters)
      ENeuron = 14 million volts per meter!  That’s more than four times the electrostatic force required to produce lightning during a thunderstorm! (see figure)..

      • If the soma of a neuron was the size of a tennis ball, how long would motor axon be? A mile long and the diameter of a garden hose.
      • What if we lined up all the neurons in our body? How long would that line stretch?
      • Let's assume that one neuron is about 10 microns long. Remember, this is just an example, because neurons come in all different sizes. So, if we line up 100 billion neurons which are 10 microns long...
      •              100,000,000,000 neurons x 10 microns = 1,000 km
      • The neurons in your brain make enough electricity to illuminate a 25-watt light bulb.
      • Average number of neurons in the human brain = 100 billion, more than stars in the Milky Way.
      • After the age of 35, human brain will start losing about 7,000 brain cells a day. The cells will never be replaced.
      • There are around 650 skeletal muscles in the human body.
      • If muscle strength is regarded as the ability to use force on something then the jaw muscle (masseter) is the strongest in the body. The strongest muscles in relation to the job they have to do is the external muscles of the eye which are large and about 100 times stronger than they need to be in relation to the small size and weight of the eyeball.
      • It takes 17 muscles in the face for us to smile and 43 muscles to frown.
      • If all of the muscles in the body could all pull in one direction, it would create a force of 25 tons!
      • Muscles make up about 40% of total body weight.
      • The smallest muscles, like the smallest bones, are found in the middle ear, some of these are the tensor tympani (connected to the ear drum) and the Stapedius.



    • Digestive System Physiology


      Objectives after studying this chapter, you should be able to . . .
      1. Describe the gross and microscopic anatomy and the basic functions of the digestive system.
      2. Describe the composition and functions of saliva, and explain how salivation is regulated.
      3. Describe the mechanisms of chewing and swallowing.
      4. Explain how gastric secretion and stomach motility are regulated.
      5. Explain the mechanism of vomiting.
      6. Describe the role of the gallbladder and state the role of bile in digestion and describe how its entry into the small intestine is regulated.
      7. Describe how entry of pancreatic juice into the small intestine is regulated and state the role of pancreatic juice in digestion.
      8. List the major functions of the large and small intestine.
      9. Describe the regulation of defecation.
      10. List the enzymes involved in chemical digestion; name the foodstuffs on which they act.
      11. List the end products of protein, fat, carbohydrate, and nucleic acid digestion.
      12. Describe the process of absorption of breakdown products of foodstuffs that occurs in the small intestine.

      13. Describe the main functions of liver.


      Interesting facts about digestive system

      • Every day 11.5 liters of digested food, liquids and digestive juices flow through the digestive system, but only 100 mls is lost in feces.
      • The length of your entire digestive system from mouth to anus is approximately 30 feet long.
      • Muscles of the digestive system contract in waves to move the food down distally. This means that food would get to a person's stomach, even if persons were standing on their head.
      • An adult's stomach can hold approximately 1.5 liters of material.
      • Laundry detergents take cues from the digestive system. Laundry detergents often contain several different classes of enzymes, including proteases, amylases and lipases. The human digestive system also contains such enzymes. The digestive system also employs these types of enzymes to break down food. Proteases break down proteins, amylases break down carbohydrates and lipases break down fats. For example, your saliva contains both amylases and lipases, and your stomach and small intestine use proteases.
      • The small intestine is about 22 feet (7 meters) long, and about an inch (2.5 centimeters) in diameter. Based on these measurements, you'd expect the surface area of the small intestine to be about 6 square feet (0.6 square m) — but it's actually around 2,700 square feet (250 square m), or about the size of a tennis court. That's because the small intestine has three features that increase its surface area. This is because the walls of the intestine have folds, and also contain structures called villi, which are fingerlike projections of absorptive tissue. What's more, the villi are covered with microscopic projections called microvilli. All of these features help the small intestine to better absorb food.
      • Physicians treated peptic ulcers incorrectly for nearly a century. Peptic ulcers are painful sores on the lining of the esophagus, stomach or small intestine, and they affect approximately 50 million Americans each year, according to a 2007 study in the journal American Family Physician. Physicians long thought that stress and spicy food caused people to develop the sores — an explanation that seemed to make sense, given that ulcer patients often complain about burning pain after eating spicy food. So for almost 100 years, doctors prescribed a treatment involving rest and a bland diet. In 1982, Australian researchers Barry Marshall and Robin Warren discovered that the real culprit behind ulcers is the bacterium Helicobacter pylori, which burrows into the stomach's mucosal lining. Thanks to this finding, doctors have come up with a better treatment for ulcers: antibiotics. This discovery earned Marshall and Warren the Nobel Prize in Physiology or Medicine in 2005.
      • Your GI system plays host 400-500 species of bacteria.
      • An adult female’s small intestine is longer than the average adult males.
      • Hydrochloric acid, produced by the stomach, can dissolve metal but has no effect on plastic.
      • Estimates of how much saliva our bodies produce each day range from 1 to 3 liters.




    • Respiratory System Physiology


      Objectives after studying this chapter, you should be able to . . .

      1. Explain the anatomical and physiological classification of the respiratory system.
      2. Describe the functions of pleura.
      3. Expound the processes of inspiration and expiration.
      4. Define the general classification of lung disorders.
      5. Identify the role of surfactant in respiratory physiology.
      6. Explain the compliance of the lung and the work of breathing.
      7. Describe the pulmonary volumes and capacities and their measurement.
      8. Identify the dead space.
      9. Expound the respiratory passageways resistance.
      10. Explain nervous and humeral control over the airway smooth muscles.
      11. Describe the respiratory unit, respiratory membrane, and the factors that affect rate of gas diffusion through the respiratory membrane.
      12. Identify ventilation – perfusion ratio of the lungs and its regulation.
      13. Describe the transport of oxygen and carbon dioxide in the blood and body fluids.
      14. Expound O2-Hb dissociation curve and its importance in loading and unloading of oxygen by the blood.
      15. Explain the brainstem respiratory center control over respiration.
      16. Describe the factors that regulate respiration through modulation of the activity of respiratory center.
      17. Expound the pulmonary blood flow.
      18. Define hypoxia and its types.
      19. Define hypercapnia.
      20. Describe specific ventilatory patterns.


      Amazing Respiratory Facts !

      • The right lung is slightly larger than the left. 

      • Every day about 10,000 L of air is inspired into the airways and the lungs.

      • The highest recorded "sneeze speed" is 165 km per hour.

      • The surface area of the lungs is roughly the same size as a tennis court.

      • The capillaries in the lungs would extend 1,600 kilometers if placed end to end.

      • Beathing: It is the first activity in life; unconsciously controlled; and one of the vital sign of life. Necessary because all cells need O2 & produce CO2. Brain anoxia is fatal if continue more than two minutes.

      • The total surface area of the respiratory membrane is estimated to be about 100 square meters, over which a quantity of blood of about 60-140 ml only (the quantity of blood in the capillaries if the lung at any given instant) is spread, creating a film 10 µ (or approximately one red cell diameter which explain the rapidity of respiratory exchange of gases). In addition, the diameter of the pulmonary capillaries is about 8 microns which is about the same diameter of RBC, therefore, RBC as it pass through these capillaries are in fact in close contact with the endothelial membrane. This also help in making the gas exchange rapid because the gases can pass directly from RBC to the alveoli without passing through significant plasma.



    • Cardiovascular System Physiology


      Objectives after studying this chapter, you should be able to . . .

      1. Explore anatomical and physiological considerations of cardiovascular system, comparison the structures and pathways of the pulmonary and systemic circulations, comparison in the structure of an artery and vein, and explain how the structure of each type of vessel relates to its function. Describe the structure of capillaries and explain the physiological significance of this structure.
      2. Explain the operation of the heart valves. Explain the origin of the heart sounds and state when in the cardiac cycle these sounds are produced.
      3. Name the functional blood supply of the heart. Define ischemia and discuss the possible causes of myocardial ischemia.
      4. Explore the cardiac muscle cells metabolism.
      5. Describe action potential of atrial and ventricular cardiac muscles, the structures and pathways of electrical impulse conduction in the heart, the electrical activity in the sinoatrial node and explain why this tissue functions as the heart’s normal pacemaker.
      6. Relate the time involved in the production of an action potential to the time involved in the contraction of myocardial cells and explain the significance of this relationship.
      7. Describe the medullary control of the cardiovascular system
      8. Explore the role of exercise, epinephrine, various ions, and autonomic nervous system in control on heart rate.
      9. Explain what information can be gained from an electrocardiogram (ECG), the Leads of the ECG, meaning of the QRS-T complex of an ECG record, vectors and mean electrical axis. Describe some common arrhythmias that can be detected with an ECG.
      10. Describe the cardiac cycle, describe the pressure changes that occur in the ventricles during the cardiac cycle and relate these changes to the action of the valves and the flow of blood. Define systole, diastole, stroke volume.
      11. Explain Cardiac Output and Its control.
      12. Define heart sounds, and murmur.
      13. Explain Blood Flow, Blood Pressure, and Resistance and factors affect them
      14. Define blood pressure, and list factors affecting and/or determining blood pressure.
      15. Define and explain Circulatory shock.
      16. Define autoregulation and local regulation of blood flow (perfusion).
      17. Discuss the unique features of the arterial circulation of the brain, fetus, skin, skeletal muscles, lungs, heart, and hepatic portal circulation.
      18. Name the fetal vascular modifications, or “fetal shunts,” and describe their function before birth.
      19. Describe the circulatory changes that occur during exercise, during change in body position, cardiovascular changes during pregnancy.


      Amazing Facts about CVS!
      • The heart beats around 3 billion times in the averages person's life.
      • It takes about 20 seconds for a red blood cell to circle the whole body.
      • Red blood cells make approximately 250,000 round trips of the body before returning to the bone marrow, where they were born, to die.
      • Red blood cells may live for about 4 months circulating throughout the body, feeding the 60 trillion other body cells.
      • On average your heart will pump one to seven gallons of blood a minute. That’s as much as 2,000 gallons a day. There’s 365 days in a year so that’s 730,000 gallons of blood a year! When you’re 80 years old your heart will have pumped 58,400,000 gallons of blood.
      • If you’ve ever wondered how big your heart is just make a fist.
      • The circulatory system is extremely long. If you were to lay out all of the arteries, capillaries and veins in one adult, end-to-end, they would stretch about 60,000 miles (100,000 kilometers). What's more, the capillaries, which are the smallest of the blood vessels, would make up about 80 percent of this length. By comparison, the circumference of the Earth is about 25,000 miles (40,000 km). That means a person's blood vessels could wrap around the planet approximately 2.5 times!
      • Capillaries are tiny, averaging about 8 microns (1/3000 inch) in diameter, or about a tenth of the diameter of a human hair. Red blood cells are about the same size as the capillaries through which they travel, so these cells must move in single-file lines. Some capillaries, however, are slightly smaller in diameter than blood cells, forcing the cells to distort their shapes to pass through.
      • In a particularly memorable scene in the 1984 film, "Indiana Jones and the Temple of Doom," a man rips out another man's still-beating heart. While easily removing a person's heart with your bare hand is the stuff of science fiction, the heart actually can still beat after being removed from the body. This eerie pulsing occurs because the heart generates its own electrical impulses, which cause it to beat. As long as the heart continues to receive oxygen, it will keep going, even if separated from the rest of the body.
      • The earliest known writings on the circulatory system appear in the Ebers Papyrus, an Egyptian medical document dating to the 16th century B.C. The papyrus is believed to describe a physiological connection between the heart and the arteries, stating that after a person breathes air into the lungs, the air enters the heart and then flows into the arteries. (The work makes no mention of the role of red blood cells). Interestingly, the ancient Egyptians were cardiocentric — they believed the heart, rather than the brain, was the source of emotions, wisdom and memory, among other things. In fact, during the mummification process, Egyptians carefully removed and stored the heart and other organs, but ripped out the brain through the nose and discarded it.
      • The end of a relationship really can "break your heart". A condition called stress cardiomyopathy entails a sudden, temporary weakening of the muscle of the heart (the myocardium). This results in symptoms akin to those of a heart attack, including chest pain, shortness of breath and arm aches. The condition is also commonly known as "broken heart syndrome" because it can be caused by an emotionally stressful event, such as the death of a loved one or a divorce, breakup or physical separation from a loved one.
      • A good hearty laugh where your belly hurts and tears run down your eyes is actually great for heart health. It can send 20 percent more blood flowing through your body. This is because when you laugh, the lining of your blood vessels relax and expand. Laughter also helps reduce stress. So watch a funny movie and get a good laugh for a healthy heart!

    • Autonomic Nervous System Physiology


      Objectives after studying this chapter, you should be able to . . .

      1. Describe the anatomical organization of the parasympathetic and sympathetic nervous system.
      2. List the different types of adrenergic and cholinergic receptors.
      3. Tabulate the receptor-mediated biological effects of different adrenergic receptors in different organs.


    • Central Nervous System (CNS) Physiology


      Objectives after studying this chapter, you should be able to . . .

      1. Describe the basic structural and organizational characteristics of the nervous system.
      2. Discuss the structure and functions of the spinal cord.
      3. Discuss the significance of neuronal pools, and describe the major patterns of interaction among neurons within and among these pools and the inhibitory mechanisms within the CNS.
      4. Identify the receptors for the general senses, and describe how they function.
      5. Identify the major sensory pathways, and explain how it is possible to distinguish among sensations that originate in different areas of the body.
      6. Describe the higher interpretation of sensory signals by the cerebral cortex in Primary sensory areas, Sensory association areas, and Wernicke's area.
      7. Describe the components, processes, and functions of the somatic motor pathways, and the levels of information processing involved in motor control.      
      8. Describe the steps in a neural reflex, and classify the types of reflexes.
      9. Explain how higher centers control and modify reflex responses.
      10. Identify the main components of the medulla oblongata, pons, the midbrain, the diencephalon, the limbic system, thalamus, hypothalamus, basal ganglia, cerebrum, and the cerebellum, and specify the functions of each.
      11. Explain postural reflexes.
      12. Discuss the origin and significance of the major types of brain waves seen in an electroencephalogram.
      13. Define and discuss emotion, memory, Language and Speech, and sleep.
      14. Explain how the brain is protected and supported, and discuss the formation, circulation, and function of cerebrospinal fluid.


      Our Central Nervous System ... Fun Facts!

      • The human brain is the only organ in the human body that lacks nerves despite the fact that it acts as the central command for the central nervous system. This simply implies that, the human brain feels no pain.
      • The human brain consumes the largest portion of the total energy that is generated in the human body. To be precise, the brain consumes 20% of that energy despite the fact that it only represents only 2% of the total body weight. The energy is vital for maintaining healthy brain cells and fueling nerve impulses. The energy consumed by the brain which is approximately 25 watts is sufficient enough to illuminate a light bulb.
      • The human brain is regarded as the fattest organ in the human body. About 60% of the human brain is comprised of fat which is the highest concentration of fat that is present in a single organ in a healthy human being. Furthermore, 75% of the total brain mass is comprised of water which regulates various functions in the brain.
      •  The neocortex is the portion of the human brain that is responsible for language and consciousness. It makes up approximately 76% of the human brain and making it the largest when compared to that in other animals.
      • There are millions of nerve cells in the human body. This number even exceeds the number of stars in the Milky Way.
      • The human brain alone consists of about a 100 billion neurons. If all these neurons were to be lined up, it would form a 600 mile long line.
      • In humans, the right side of the brain controls the left side of the body, while the left side of the brain controls the right side.
      • In a child developing inside the womb, neurons grow at the rate of 250,000 neurons per minute.
      • By the time of its birth, the baby's brain consists of around 10 million nerve cells.
      • The weight of the brain in average adult males is 1375 grams, while in females it is 1275 grams. - This does not mean men are smarter, just to make that clear. A man's brain has 6.5 times more gray matter compared to women, but a woman's brain has 10 times more white matter compared to men.
      • And as we grow older, the brain loses a gram each year.
      • The nervous system is very quick; it can transmit impulses at a tremendous speed of 1-130 meters per second.
      • There are 43 different pairs nerves which connect the central nervous system to every part of our body. Twelve of these nerve pairs are connected to the brain, while the remaining 31 are connected to the spinal cord, which is why it's so important to get your back checked out.
      • If the soma of a spinal motor neuron were the size of a tennis hall, its dendrites would form a huge bushy mass that could fill a 30-seat classroom from floor to ceiling. Its axon would be up to a mile long but a little narrower than a garden hose. This is quite a point to ponder. The neuron must assemble molecules in its "tennis ball" soma and deliver them through its "mile-long garden hose" to the end of the axon. In a process called axonal transport, neurons em-ploy motor proteins that can carry organelles and macromolecules as they crawl along the cytoskeleton of the nerve fiber to distant destinations in the cell.

        Terminology:

      • Ganglia are a group of cells bodies in the peripheral nervous system are known as ganglia. Even though the term ganglia is associated with peripheral nervous system, there are special multiple subcortical nuclei called basal ganglia in the brain.
      • Nuclei (centers) are the clusters of neuron cells bodies found in the central nervous system.
      • The axon pathways arising from ganglia are called nerves of the peripheral nervous system and that arising from nuclei are called tracts of the central nervous system.

       


    • Endocrine Physiology


      After studying this chapter, you should be able to:
      1. Classify hormones into their major chemical categories.
      2. Describe the synthesis, storage, hormone receptors, regulation of secretion, mechanism of Action of Hormones of hormones.
      3. Describe how the hypothalamus of the brain controls the endocrine system.
      4. Name the endocrine glands and state where they are located and the hormones secreted by each .
      5. List the major hormones and their effects on the body.
      6. Understand the role of hormone-binding proteins.
      7. Understand the feedback control mechanisms of hormone secretion.
      8. Explain the effects of secretion, degradation, and excretion on plasma hormone concentrations.
      9. State the functions of oxytocin and explain the stimulus for secretion of each.
      10. State the functions of the hormones of the anterior pituitary gland, and state the stimulus for secretion of each.
      11. State the synthesis, release, transport, regulation of secretion, functions of thyroxine and T3, and describe the stimulus for their secretion.
      12. Give examples of the clinical application of excess or deficiet of thyroid hormones.
      13. State the structure, mechanism of secretion, Mechanism of action, function, regulation of secretion of insulin
      14. Pathophysiology of diabetes mellitus
      15. Explain how calcitonin and parathyroid hormone work as antagonists.
      16. Explain how glucagon and insulin work as antagonists.
      17. Explain somatostatin action and regulation of secretion
      18. Describe adrenal glands histologically, type of secretions.
      19. State the functions of epinephrine and norepinephrine, regulation of adrenal medullary secretion, and explain their relationship to the sympathetic division of the autonomic nervous system.
      20. Describe the effects of Dopamine release.
      21. Describe the Calcium metabolism and bone physiology including the role of 1-25 Dihydroxycholecalciferol, Parathyroid hormone (PTH), and Calcitonin.
      22. State the functions of aldosterone and cortisol, and describe the stimulus for secretion of each.
      23. Explain Vasopressin Effects, its control of secretion, and an example of clonical application.
      24. State Growth Hormone (GH) and Somatomedins effects and stimulus of their release.
      25. Describe the factors that affect the Growth.
      26. State the function and control of secretion of melanocyte stimulating hormone.
      27. Expound the the Male reproductive system and its hormones including Gametogenesis and ejaculation, The Sertoli cells secretion, Spermatogenesis and the factors affect it, Semen composition, secretion, Erection & Ejaculation.
      28. Expound the function and control of secretion of prolactin.
      29. Describe the Female reproductive system including Control of ovarian functions, Ovarian (menstrual) cycle, Uterine cycle.  
      30. State the functions of estrogen, progesterone, testosterone, and inhibin and state the stimulus for secretion of each.
      31. Explain some aspects about Contraception, Puberty, Menopause, Menstrual abnormalities, Pregnancy, and Parturition.
      32. Explore the Hormones secreted from placenta and their functions.
      33. Expound Development of breasts and lactation.
      34. Explain how the steroid hormones are believed to exert their effects.

      Fun Facts of the Endocrine System!!

      • We must be thankful to the pineal gland for our sweet sleep. It secretes melatonin which regulates our sleep.
        There are 30 hormones in the human body.
      • Traditional Chinese healers practiced endocrinology more than 2,000 years ago.
      • The term "hormone" is only about a century old.
      • Not all hormones come from the endocrine system.
      • Diabetes was once diagnosed by tasting urine.
      • Alcohol has widespread effects on the endocrine system.
      • An early endocrinologist attempted hormone replacement therapy on himself.
      • Stress kicks the endocrine system into high gear.
      • Plants produce hormones without an endocrine system.

    • Renal & Urinary System Physiology


      Objectives after studying this chapter, you should be able to . . .

      1. Describe the different regions of the nephron tubules and the location of the tubules in the kidney.
      2. Describe the structural and functional relationships between the nephron tubules and their associated blood vessels.
      3. Describe the composition of glomerular ultrafiltrate and explain how it is produced.
      4. Explain how the proximal convoluted tubule reabsorbs salt and water.
      5. Describe active transport and osmosis in the loop of Henle and explain how these processes produce a countercurrent multiplier system.
      6. Explain how the vasa recta function in countercurrent exchange.
      7. Describe the role of antidiuretic hormone (ADH) in regulating the final urine volume.
      8. Describe the mechanisms of glucose reabsorption and define the terms transport maximum and renal plasma threshold.
      9. Define the term renal plasma clearance and explain why the clearance of inulin is equal to the glomerular filtration rate.
      10. Explain how the clearance of different molecules is determined and how the processes of reabsorption and secretion affect the clearance measurement.
      11. Describe the mechanism of Na+ reabsorption in the distal tubule and explain why this reabsorption occurs together with the secretion of K+.
      12. Describe the effects of aldosterone on the cortical portion of the collecting duct and explain how aldosterone secretion is regulated.
      13. Explain how activation of the renin-angiotensin-aldosterone system results in the stimulation of aldosterone secretion.
      14. Explain how the interaction between plasma K+ and H+ concentrations affects the tubular secretion of these ions.
      15. Describe the role of the kidneys in the regulation of acid-base balance.

      16. Describe the different mechanisms by which substances can act as diuretics and explain why some diuretics cause excessive loss of K+.


      Our Urinary System.......Fun Facts!
      • The blood flow in kidneys is higher than the blood flow in heart, liver and brain. Though the kidneys weigh on 0.5% of the entire body weight, they actually receive more arterial blood compared to other organs in body. Almost 25% of the blood pumped by the heart goes to the kidneys.
      • In case of adults, kidneys form only 0.5% of the entire body weight.
      • Exactly half of one single kidney is capable of doing the job that is performed by two kidneys together.
      • In a single hour, kidneys receive around 120 pints of blood. Kidneys cleanse about 1.3 litres of blood every minute to produce about the same quantity of urine per day. Kidneys filter blood approximately 400 times a day!. Each day 50 gallons of blood are filtered all the way through 140 miles of tubes and millions of filters inside the kidneys.
      • The first successful human kidney transplant was performed in 1954. The NHS now performs around 3,000 kidney transplants a year.
      • There are 13 mentions of kidneys in the King James Bible but none for the singular ‘kidney’. The only mention of kidneys in Shakespeare is in The Merry Wives Of Windsor when Falstaff refers to someone as “a man of my kidney”.

    • Special Senses


      Objectives after studying this chapter, you should be able to . . .

      1. Identify the internal and accessory structures of the eye, and explain the functions of each.
      2. Explain the principles of optics, the eye & light refraction.
      3. Explain eye accommodation, the near point of vision, emmetropia, and errors of refraction.
      4. Describe the microscopic details of retina, visual receptors.
      5. Explain color, the mechanism of dark & light adaptation and color vision.
      6. Describe how light stimulates the production of nerve impulses, and trace the visual pathways to their destinations in the brain.
      7. Explain vision-related events (the fields of vision, pupillary light reflex and accommodation reflex).
      8. Describe the structures of the external, middle, and internal ear, explain their roles in equilibrium and hearing, and trace the pathways for equilibrium and hearing to their destinations in the brain.
      9. Describe the sensory organs of smell, trace the olfactory pathways to their destinations in the brain, and explain the physiological basis of olfactory discrimination.
      10. Describe the sensory organs of taste, trace the gustatory pathways to their destinations in the brain, and explain the physiological basis of gustatory discrimination.
      Fun Facts about ..... special Senses
      • The average blink lasts for about 1/10th of a second. You blink about 12 times every minute.
      • Eyes heal quickly. With proper care, it only takes about 48 hours for the eye to repair a corneal scratch.
      • Seeing is such a big part of everyday life that it requires about half of the brain to get involved.
      • Newborns don’t produce tears. They make crying sounds, but the tears don’t start flowing until they are about 4-13 weeks old.
      • The cells in your eye come in different shapes. Rod-shaped cells allow you to see shapes, and cone-shaped cells allow you to see color.
      • Your eyes are about 1 inch across and weigh about 0.25 ounce.
      • Some people are born with two differently colored eyes. This condition is heterochromia. Even if no one in the past few generations of your family had blue or green eyes, these recessive traits can still appear in later generations.
      • Each of your eyes has a small blind spot in the back of the retina where the optic nerve attaches. You don’t notice the hole in your vision because your eyes work together to fill in each other’s blind spot.
      • Out of all the muscles in your body, the muscles that control your eyes are the most active.
      • It’s a myth that liars make less eye contact. In fact, a well-practiced liar will try to overcompensate as an attempt to “prove” they are telling the truth, by making too much eye contact and holding a gaze.
      • It’s impossible to sneeze with your eyes open. Your eyes and nose are connected by cranial nerves, so the stimulation from a sneeze travels up one nerve to the brain, then down another nerve to the eyelids, typically prompting a blink.
      • While a fingerprint has 40 unique characteristics, an iris has 256. This is why retinal scans are increasingly being used for security purposes. A retinal scanner uses infrared light to map the unique pattern of blood vessels on a person’s retina. This pattern is so intricate that even identical twins do not have the same configuration.
      • People can detect at least one trillion distinct scents
      • Women have a better sense of smell than men
      • Dogs have nearly 44 times more scent cells than humans.
      • Loss of smell may signal future illnesses. “Decreased sense of smell may be an early sign of Alzheimer’s or Parkinson’s disease,”
      • Each human has their own distinct odor.
      • Decline in smell may predict death within five years. A recent study published in the journal PLOS ONE found that a decreased ability to identify scents may predict death within five years. The study looked at more than 3,000 Americans aged 57 to 85, and found that people unable to identify scents like rose, orange, and peppermint were more than three times as likely to die in the next five years.


    • Acid-Base Balance Physiology

      Objectives after studying this chapter, you should be able to . . .

      1. Explain the influence of the hydrogen ion (H+ ) on body fluids.
      2. Identify the pH ranges for acidosis and alkalosis.
      3. Discuss the three regulatory mechanisms for pH control and how the regulatory mechanisms can maintain acid-base balance.
      4. Identify metabolic acidosis and alkalosis and respiratory acidosis and alkalosis through use of arterial blood gases.
      5. Explain how various clinical conditions can cause metabolic acidosis and alkalosis and respiratory acidosis and alkalosis.
      6. Identify clinical symptoms of metabolic acidosis and alkalosis and respiratory acidosis and alkalosis.
      7. Discuss the body’s defense action and the clinical management for acid-base balance and be able to apply this information to various clinical situations.
      8. Explain the health interventions for patients in metabolic and respiratory acidosis and alkalosis states.


    • Skin, Body Temperature, & Regulation of body fluids


      The Busy Bees: The bees maintain a temperature between 25 and 35°C in the beehive. This is how they do it. When the beehive gets cold, the bees go buzzing. They move their wings so rapidly that their body temperature rises. To reduce the loss of heat, they huddle close to each other. They also cover the ‘cells’ containing the larvae to protect them from cold. When the beehive gets hot, some bees go out and bring water in their proboscis. They spray it in the hive while their friends who stayed in the hive move their wings to create currents of air to hasten evaporation of the water. How very similar to our desert coolers in which the pump sprays water and the fan hastens its evaporation!

      Objectives after studying this chapter, you should be able to . . .

      1. Understand how the human body regulates temperature.
      2. Explore ways in which the human body self-regulates to maintain homeostasis.