All courses · elective
Physiology
A 3000-level course in human and mammalian physiology for biology majors and premedical students. It takes each organ system the way physiologists study it, with numbers and with the classic and modern experiments that settled how it works: body fluids and control, muscle, the heart and circulation, breathing, the kidney and acid-base balance, the endocrine glands, digestion, lymphoid organs and skin, reproduction, and exercise as the whole body at work. Every lesson has a worked problem, a simulation and original MCAT-style questions. The first look at each system, compared across animals, is in Organismal Biology.
10 units · 30 lessons
Unit 1 · The internal environment and its control
- Unit 1: The internal environment and its control Body Water and Its Compartments✓ done In the textbook model, retain a litre of solute-free water and about two-thirds ends up inside your cells; retain a litre of isotonic saline and none does. Why?
- Unit 1: The internal environment and its control Endocrine Axes and How to Test Them✓ done Delay sleep and, in young adults, the night's big growth hormone surge is delayed with it. What can one blood sample tell you?
Unit 2 · Muscle
- Unit 2: Muscle Skeletal Muscle: Length, Load and Speed✓ done A muscle lifting nothing and a muscle holding a load it cannot move both do zero external work. Where is the power?
- Unit 2: Muscle Smooth Muscle and the Myogenic Response✓ done Raise the pressure inside a small artery and it narrows against the stretch instead of simply widening. What is the muscle sensing?
Unit 3 · The heart and circulation
- Unit 3: The heart and circulation Cardiac Action Potentials and the ECG✓ done A ventricular cell stays depolarised for about a fifth of a second. Why can't your heart cramp into a sustained contraction the way a skeletal muscle can?
- Unit 3: The heart and circulation The Cardiac Cycle and Pressure-Volume Loops✓ done Plot ventricular pressure against volume and every heartbeat draws a loop. Which corner moves when the arteries tighten?
- Unit 3: The heart and circulation Cardiac Output and Venous Return✓ done The heart cannot pump out more blood than flows back in. So what sets cardiac output: the heart, or the veins?
- Unit 3: The heart and circulation Resistance, Compliance and Local Blood Flow✓ done In the muscle of an anesthetized cat, only about 15 percent of arterial pressure is spent crossing the capillary bed. So where does the rest go?
- Unit 3: The heart and circulation Capillary Exchange, Lymph and Edema✓ done Adults born with almost no plasma albumin usually have only mild swelling. Why does the textbook Starling balance not flood their tissues?
- Unit 3: The heart and circulation Regulating Arterial Pressure✓ done Cut the nerves that sense arterial pressure in a dog and the mean pressure is little changed after the first days. So what sets the level?
- Unit 3: The heart and circulation Blood Cells, Hematocrit and Clotting✓ done An endurance athlete can have a lower hematocrit than an untrained friend and more red cells. How?
Unit 4 · Breathing
- Unit 4: Breathing Lung Mechanics and Surfactant✓ done Fill an excised lung with saline instead of air and it takes far less pressure to inflate. What was the air adding?
- Unit 4: Breathing Ventilation, Perfusion and Gas Exchange✓ done The mean alveolar oxygen partial pressure is not sampled in a person. It is calculated as an ideal value. Here is the arithmetic, and what it tells you that a blood sample cannot.
- Unit 4: Breathing Control of Breathing, Altitude and Diving✓ done Hold your breath and the urge that finally defeats you comes mostly from rising carbon dioxide rather than from falling oxygen. Why is the controller built that way?
Unit 5 · Kidney, fluids and acid-base
- Unit 5: Kidney, fluids and acid-base Glomerular Filtration and Renal Blood Flow✓ done Squeeze the arteriole that drains the glomerulus and filtration can rise or fall. Which, and why?
- Unit 5: Kidney, fluids and acid-base Tubular Transport, Segment by Segment✓ done What can a missing transporter tell you that a urine sample cannot?
- Unit 5: Kidney, fluids and acid-base Water, Sodium and Potassium Balance✓ done A litre of water can lower plasma sodium concentration without changing total body sodium by a single millimole.
- Unit 5: Kidney, fluids and acid-base Acid-Base Balance✓ done Plasma carries more than a hundred thousand bicarbonate ions for every free hydrogen ion. What keeps that ratio of buffer to acid so steady?
Unit 6 · Endocrine systems
- Unit 6: Endocrine systems The Thyroid and Metabolic Rate✓ done A person with no thyroid who takes only T4 still has T3 in the blood. Where does it come from?
- Unit 6: Endocrine systems The Adrenal Cortex and Medulla✓ done The kidney's aldosterone receptor binds cortisol just as tightly, and plasma carries far more cortisol. So why does aldosterone run sodium transport?
- Unit 6: Endocrine systems Insulin, Glucagon and Blood Glucose✓ done Why can oral glucose evoke more insulin than the same blood glucose reached intravenously?
- Unit 6: Endocrine systems Calcium, Phosphate and Bone✓ done Your kidneys filter about ten grams of calcium a day and you lose about a fifth of a gram in urine. What sets that last fraction?
Unit 7 · Digestion and absorption
- Unit 7: Digestion and absorption Gut Motility, Secretion and Gut Hormones✓ done Mice that lack one chloride channel are born with intact pacemaker cells in their gut and no electrical slow waves. What does that channel do?
- Unit 7: Digestion and absorption Absorption, the Liver and Enterohepatic Circulation✓ done Nine to eleven litres enter your gut lumen each day and a couple of hundred grams of stool leave. Which transporters decide the difference?
Unit 8 · Defense, skin and temperature
- Unit 8: Defense, skin and temperature Lymphoid Organs and Immune Traffic✓ done Drain a rat's thoracic duct for a few days and its lymph runs short of lymphocytes. Where were they coming from?
- Unit 8: Defense, skin and temperature Skin, Sweat and Human Thermoregulation✓ done A gram of sweat that evaporates carries off about 2.4 kJ of heat. A gram that drips carries off almost none.
Unit 9 · Reproduction
- Unit 9: Reproduction Sexual Differentiation and the Testis✓ done An AMH-null male mouse can make sperm and retain a uterus. Which testicular signals have separated?
- Unit 9: Reproduction The Ovarian Cycle and Fertility✓ done In one 1984 study, single progesterone samples from normally cycling women in the mid-to-late luteal phase ranged from 2.3 to 40.1 ng per mL. What does one sample tell you?
- Unit 9: Reproduction Pregnancy, Birth and Lactation✓ done Maternal cardiac output rises about 40 percent in pregnancy, yet mean arterial pressure falls only slightly. What absorbs the extra flow?