Intro to Physiology Flashcards
Levels of Physiology
Patient, Organ and cell
What does physiology provide medicine with (except pathophysiology)?
Not the cure but why the cure fails to work and why it may work
Pathophysiology example
Type 1 Diabetes: autoimmune destruction of beta cells of pancreas. Insufficient insulin as less beta cells to secrete it. Hyperglycaemia after meals so kindey cannot reabsorb glucose in urine. So excess fluid lost in urine as water potential of urine lowered. Loss of glucose from body in urine so weight loss, hunger, thirst and fatigue.
Example of pressure in medicine
physiological
When thoracic wall expands, negative pressure created in pleural space due to fluid tension of fluid layer so visceral pleura (and so the lungs) follows, creating negative pressure in lungs
Example of pressure in medicine (non-physiological)
Pneumothorax. Air gets into pleural space. So no fluid tension so visceral pleura does not expand. Air expands in the space so lung collapses and visceral pleura follows
Example of force in medicine (physiological)
Starling’s Law: the more you fill the heart’s ventricles, the more blood it pumps out and with greater force due to stretching of cells.
Example of force in medicine (non-physiological)
Dilated Cardiomyopathy: The heart chambers expand and weaken so ventricles cannot generate much force as it is not stretched by entrance of fluid so cannot pump as much blood
Example of electricity in medicine
ECG measures electrical field given off by all heart muscle cells acting in synchrony (each time heart beats, cells give a signal)
What feature on an ECG reveals if someone is having an acute myocardial infarct?
ST elevation
Where is stomach acid made? Where is it secreted from the cell?
Parietal cells lining gastric epithelium. Secreted into lumen of stomach from apical side of cell
Which reaction is involved in making acid in the body? Quote the reaction. What catalyses it?
Carbonic Anhydrase Reaction. H20 + CO2 => H2CO3=>H+ + HCO3- Catalysed by carbonic anhydrase
What is the pH of cell contents in relation to the rest of the bodily fluids?
Cell contents are slightly more acidic. Rest of bodily fluids tend to be slightly alkaline at 7.3.
What conditions change the direction of carbonic anhydrase reaction?
It goes forward if CO2 concentration is high and goes backwards if CO2 concentration is low e.g. in lungs
What is the importance of acids and bases created in the body?
They are secreted throughout the digestive tract and bases are important in salivary glands and pancreas.
Why is it hard for H+ to cross cell membrane? Significance of carbonic anhydrase in movement of H+ across cell membrane
H+ is charged. CO2 is uncharged and easily crosses membrane so react acid (H+) with HCO3- to make CO2. CO2 crosses membrane down gradient and reacts with water (using CA enzyme) on other side to make H+. So H+ has crossed.
