Exam from october Flashcards
Compare the absorptive and the postabsorptive phase in terms of biochemical and hormonal changes that take place in those phases.
Increased insulin levels.
Increased glycogenesis, converting glucose to glycogen.
Increased lipogenesis which is converting glucose to adipose tissue.
Increased glycolysis, converting the glucose to ATP
Biochemical changes during the postabsorptive phase:
Increased glycogenolysis: The liver breaks down stored glycogen into glucose and releases it into the bloodstream.
Increased lipolysis: When glucose levels are low, the body switches to using stored fats as an energy source. Hormones such as glucagon promote the breakdown of stored fats into fatty acids, which can be used by cells for energy.
Increased gluconeogenesis: Gluconeogenesis is the process by which the liver synthesizes glucose from non-carbohydrate sources, such as amino acids and fatty acids.
Increased ketone body production: When fatty acids are metabolized in the liver, they produce ketone bodies, which can be used by the brain as an energy source during prolonged fasting or starvation.
What is the relevance of evaporative water cooling for human physiology? How does the mechanism work and in which conditions it is used?
When we need to cool down quickly such as under exercise and high temperatures. The mechanism is based on when we sweat the water will use our body heat to evaporate which lowers the bodies temperature.
Explain the mechanism of ventilation-perfusion matching in the lungs.
There are local control mechanisms to match ventilation perfusion in the lungs. The capillary’s surrounding the alveoli’s can constrict or relax to provide blood to best ventilating alveoli’s. Also the bhroncioles, pulmonary arteries and systemic arteries can constrict and relax in response to pO2 and pCO2.
Explain the concept of alveolar ventilation. How is that different from minute ventilation?
In summary, alveolar ventilation specifically refers to the volume of fresh air that reaches the alveoli for gas exchange, while minute ventilation represents the total volume of air moved in and out of the lungs per minute, including both fresh air and dead space ventilation.
Intracellular calcium ions play a key role in muscular contraction, for instance in vasoconstriction. Briefly describe how the sympathetic system may trigger vasoconstriction. Your answer should include critical steps such as involved transmitters, receptors, and key intracellular events.
Activation of sympathetic nerve fibers: Sympathetic nerve fibers release the neurotransmitter norepinephrine into the bloodstream, which binds to alpha-1 adrenergic receptors on the smooth muscle cells of the blood vessels.
Activation of G-protein coupled receptors: Alpha-1 adrenergic receptors are G-protein coupled receptors, which activate intracellular signaling pathways when they bind to norepinephrine. The activation of these receptors leads to the activation of the Gq protein.
Activation of phospholipase C: The Gq protein activates the enzyme phospholipase C.
Release of intracellular calcium ions: It binds to receptors on the sarcoplasmic reticulum (SR) of the smooth muscle cells, triggering the release of stored calcium ions into the cytoplasm. This leads to an increase in intracellular calcium levels.
Activation of myosin light chain kinase: Calcium ions bind to calmodulin, which activates the enzyme myosin light chain kinase (MLCK). MLCK phosphorylates the myosin light chain (MLC) in the smooth muscle cells, which initiates the process of cross-bridge cycling and ultimately leads to vasoconstriction.
The renin-angiotensin-aldosterone system (RAAS) is initiated by secretion of renin from juxtaglomerular cells in the kidneys.
a) What effect does RAAS have on systemic blood pressure?
The Renin-Angiotensin-Aldosterone System (RAAS) plays an important role in regulating systemic blood pressure. The RAAS is a complex hormonal system that is activated when blood pressure drops, causing the kidneys to release the enzyme renin. Renin acts on a protein called angiotensinogen, which is produced by the liver, to produce angiotensin I. Angiotensin I is then converted into angiotensin II by an enzyme called angiotensin-converting enzyme (ACE), which is primarily found in the lungs.
Angiotensin II is a potent vasoconstrictor, meaning that it causes the blood vessels to narrow, which increases blood pressure. It also stimulates the release of aldosterone from the adrenal glands, which causes the kidneys to retain sodium and water, leading to an increase in blood volume and further increasing blood pressure.
b) Through what mechanism does RAAS affect systemic blood pressure?
Angiotensin II is a potent vasoconstrictor, meaning that it causes the blood vessels to narrow, leading to an increase in blood pressure. It also stimulates the release of aldosterone from the adrenal glands, which causes the kidneys to retain sodium and water, leading to an increase in blood volume and further increasing blood pressure.
What stimuli induce secretion of renin by juxtaglomerular cells?
Juxtaglomerular cells are specialized cells located in the walls of the afferent arterioles that supply blood to the glomeruli in the kidneys. These cells are responsible for producing and secreting the enzyme renin in response to certain stimuli.
The secretion of renin by juxtaglomerular cells is stimulated by several factors, including:
Decreased blood pressure or blood volume: When blood pressure or blood volume decreases, it triggers a reflex response that activates the juxtaglomerular cells to secrete renin.
Sympathetic nervous system activation: The sympathetic nervous system, which is responsible for the body’s “fight or flight” response, can also stimulate the release of renin from the juxtaglomerular cells.
Decreased sodium chloride concentration in the distal tubule: Juxtaglomerular cells are sensitive to the concentration of sodium chloride in the distal tubule of the kidney. If the concentration of sodium chloride is too low, it can trigger the release of renin.
Prostaglandins: Certain prostaglandins, which are hormones produced in response to inflammation and injury, can also stimulate the release of renin.
Overall, the secretion of renin by juxtaglomerular cells is a complex process that is regulated by multiple factors in response to changes in the body’s needs.
Which of the following statement/s in relation to oxygen transport and hemoglobin is/are TRUE?
Statement 1. Reduced blood pH reduces the total amount of oxygen bound to hemoglobin at high partial pressures (pO2 > 150 mmHg)
Statement 2. Anemia reduces oxygen transport by shifting the oxygen dissociation curve to the right
Statement 3. Carbon monoxide reduces oxygen transport by outcompeting oxygen in the binding to the heme group
Statement 4. Increased concentrations of 2,3-DPG increase hemoglobin affinity for oxygen
Statement 5. Hemoglobin oxygen saturation is always highest in pulmonary veins
A) Only 1 and 3 are TRUE
B) Only 2 and 5 are TRUE
C) Only 3 and 5 are TRUE
D) Only 1, 2 and 4 are TRUE
E) Only 2, 4 and 5 are TRUE
The TRUE statements in relation to oxygen transport and hemoglobin are:
Statement 2. Anemia reduces oxygen transport by shifting the oxygen dissociation curve to the right
Statement 3. Carbon monoxide reduces oxygen transport by outcompeting oxygen in the binding to the heme group
Statement 5. Hemoglobin oxygen saturation is always highest in pulmonary veins.
Therefore, the correct answer is C) Only 3 and 5 are TRUE.
Statement 1 is false as reduced blood pH shifts the oxygen dissociation curve to the right, causing hemoglobin to release oxygen more readily at any given partial pressure of oxygen. Statement 4 is also false, as increased concentrations of 2,3-DPG (2,3-diphosphoglycerate) decrease hemoglobin affinity for oxygen.
do question 6
Which one of the following is NOT regarded as part of primary hemostasis?
A) Vasoconstriction
B) Platelet recruitment
C) Granule secretion
D) Von Willebrand factor signaling
E) Fibrinolysis
The answer is E) Fibrinolysis.
Primary hemostasis involves the initial response to vascular injury, which includes vasoconstriction, platelet recruitment, and granule secretion. Von Willebrand factor (VWF) signaling is also an important part of primary hemostasis, as VWF helps platelets adhere to the injured vessel wall.
Fibrinolysis, on the other hand, is part of secondary hemostasis, which involves the formation of a fibrin clot to stabilize the platelet plug. Fibrinolysis is the process by which the clot is broken down once the injury has healed, and is not considered part of primary hemostasis.
Which is the main enzyme/factor of the coagulation cascade that work as both procoagulant and anticoagulant?
A) Factor II
B) Factor VII
C) Factor VIII
D) Factor IX
E) Factor XI
A
Severe vomiting can result in metabolic alkalosis. Which compensatory mechanisms are involved in restoring pH?
Mechanism 1. Reduced ventilation
Mechanism 2. Reabsorption of H+
Mechanism 3. Increased ventilation
Mechanism 4. Reabsorption of HCO3-
Mechanism 5. Excretion of HCO3-
A) Only mechanisms 2 and 3
B) Only mechanisms 1 and 2
C) Only mechanisms 3 and 5
D) Only mechanisms 1, 2 and 5
E) Only mechanisms 2, 3 and 4
B
Urine concentration depends on the differential permeability to ions and water of the different parts of the nephron, and this is partly regulated by hormones. Which one of the alternatives below is/are TRUE?
Alternative 1. The permeability of the proximal tubule to water is hormonally regulated by anti-diuretic hormone
Alternative 2. The permeability of the proximal tubule to Na+ is hormonally regulated by aldosterone
Alternative 3. The permeability of the descending loop of Henle to water is hormonally regulated by antidiuretic hormone
Alternative 4. The permeability of the distal tubule to Na+ is hormonally regulated by aldosterone
Alternative 5. The permeability of the collecting duct to water is hormonally regulated by anti-diuretic hormone
A) Only alternatives 1 and 4 are TRUE
B) Only alternatives 2 and 5 TRUE
C) Only alternatives 4 and 5 are TRUE
D) Only alternatives 1, 3 and 4 are TRUE
E) Only alternatives 1, 3 and 5 are TRUE
ADH, antidiuretic hormone stimulate reabsorption of water through upregulation of Aquaporins in late distal tubule and collecting duct as response to low blood pressure. Aldosterone upregulates Na+ -channels in distal tubule and collecting duct.
Therefore C is correct, 4 and 5 is right.
Consider the complex regulation of respiration by the autonomic nervous system. Which of the following alternatives is NOT true?
A) Locally released acetylcholine regulates bronchial constriction by acting on cholinergic receptors.
B) Locally released non-cholinergic mediators can functionally counteract the effect of acetylcholine in regulating bronchial constriction.
C) Locally released norepinephrine regulates bronchial constriction by acting on cholinergic receptors.
D) Circulating epinephrine can contribute to regulating bronchial constriction.
E) Respiratory muscle afferents are involved in regulating the ventilation rate.
The following statement is NOT true:
C) Locally released norepinephrine regulates bronchial constriction by acting on cholinergic receptors.
Norepinephrine does not act on cholinergic receptors to regulate bronchial constriction. Instead, it acts on beta-2 adrenergic receptors to cause bronchodilation. Acetylcholine, on the other hand, acts on muscarinic receptors to cause bronchoconstriction.
