MDS PREP
What hormone is secreted by the kidneys that stimulates red blood cell production?
1) Renin
2) Erythropoietin
3) Aldosterone
4) Cortisol
Erythropoietin is the hormone secreted by the kidneys that stimulates red blood cell production in response to low oxygen levels in the blood.
MEAN CIRCULATING FILLING PRESSURE IS?
1. DIFFERENCE BETWEEN CENTRAL VENOUS PRESSURE AND CENTRAL ARTERIAL PRESSURE
2. MEAN ATRIAL PRESSURE
3. ARTERIALPRESSURE TAKEN JUST AT THE POINT WHEN HEART STOPS BEATING
4. DIFFERENCE BETWEEN SYSTEMIC AND PULMONARY ARTERIAL PRESSURE
Physiology
Answer: 3
Mean Circulating Filling Pressure (MCFP) is a concept used in cardiovascular physiology to describe the average pressure in the large veins and the right atrium when the heart is not actively pumping (i.e., during diastole or when the heart is stopped). It reflects the pressure that fills the heart and is influenced by the volume of blood in the circulatory system and the compliance of the vascular system.
What is the role of the acrosome in sperm?
1) Provides energy for sperm motility
2) Contains enzymes that help in the penetration of the ovum
3) Protects the sperm DNA
4) Involved in the fertilization process by fusing with the egg membrane
Physiology
Answer: 2
The acrosome is a cap-like structure located on the head of a spermatozoon. It contains lysosome-like organelles rich in enzymes that are essential for penetrating the egg's outer layers during fertilization.
What is the role of intrinsic factor in vitamin B12 absorption?
1) It protects vitamin B12 from gastric digestion
2) It facilitates binding of vitamin B12 to intestinal receptors
3) It synthesizes vitamin B12 in the gastrointestinal tract
4) It increases the production of gastric acid
Physiology
Answer: 2
Intrinsic factor binds to vitamin B12 and protects it from digestion, allowing it to be absorbed in the ileum.
Diabetic insipidus is due to the lack of
1 Insulin
2 Angiotensin.
3 Aldosterone.
4 A.D.H.
Physiology
Answer: 4
Diabetic insipidus is due to the lack of 4. A.D.H. (Antidiuretic hormone).
Explanation:
Diabetic insipidus (DI) is a condition characterized by the production of large
volumes of dilute urine due to the lack of the antidiuretic hormone (ADH) or the
body's inability to respond to it. It is different from diabetes mellitus, which
involves problems with insulin and blood sugar regulation.
1. Insulin: Insulin is a hormone produced by the pancreas that plays a critical
role in regulating blood sugar levels. A deficiency or resistance to insulin
leads to diabetes mellitus, not diabetic insipidus. Diabetes mellitus is
characterized by hyperglycemia (high blood sugar) and increased thirst and urine
production due to the inability of the kidneys to reabsorb glucose properly.
2. Angiotensin: Angiotensin is a hormone system that plays a role in the
regulation of blood pressure and fluid balance. It is involved in the
renin-angiotensin-aldosterone system (RAAS). While it is crucial for maintaining
blood pressure, it is not directly related to the pathophysiology of diabetic
insipidus.
3. Aldosterone: Aldosterone is a mineralocorticoid hormone produced by the
adrenal glands. It helps regulate sodium and potassium levels in the body, which
in turn affects fluid and blood volume. While it is essential for electrolyte
and fluid balance, it does not cause diabetic insipidus when lacking.
4. Antidiuretic hormone (ADH): ADH is a hormone produced by the hypothalamus and
stored in the posterior pituitary gland. It acts on the kidneys to increase
water reabsorption, which leads to the production of concentrated urine. In
diabetic insipidus, there is either a deficiency of ADH or the kidneys fail to
respond to it adequately. This results in the kidneys being unable to reabsorb
enough water, leading to the production of large volumes of dilute urine and
increased thirst.
There are two main types of diabetic insipidus: central and nephrogenic. Central
DI occurs when the pituitary gland does not produce enough ADH, while
nephrogenic DI results from the kidneys' inability to respond to ADH. Both types
lead to an imbalance in water regulation and can cause symptoms such as polyuria
(excessive urine production), polydipsia (excessive thirst), and dehydration if
not managed properly.
To treat diabetic insipidus, the underlying cause must be addressed. If it is
central DI, synthetic ADH (desmopressin) is administered to replace the missing
hormone. If it is nephrogenic DI, the treatment focuses on addressing the
kidney's response to ADH and managing symptoms such as maintaining fluid intake
and sometimes medications to reduce urine output.
What is the role of intrinsic factor in vitamin B12 absorption?
1) It protects vitamin B12 from gastric digestion
2) It facilitates binding of vitamin B12 to intestinal receptors
3) It synthesizes vitamin B12 in the gastrointestinal tract
4) It increases the production of gastric acid
Intrinsic factor facilitates the binding of vitamin B12 to intestinal receptors, which is essential for its absorption in the ileum.
Which of the following statements about the neuronal circuit of the cerebellum is true?
1) Climbing fibers originate from the cerebral cortex and terminate on purkinje cells.
2) Mossy fibers establish excitatory synapses with interneurons in the molecular layer.
3) Stellate and basket cells are stimulated by inhibitory inputs from purkinje cells.
4) Golgi cells are inhibited by mossy fiber inputs.
E. All of the above.
Mossy fibers originate from various sources in the brain and spinal cord and terminate on granule cells in the granular layer of the cerebellum. The axons of granule cells, called parallel fibers, stimulate the purkinje cells and also synapse with interneurons such as stellate and basket cells in the molecular layer and Golgi cells in the granular layer. Climbing fibers originate from the inferior olivary nuclei and synapse directly on purkinje cells. The statement that stellate and basket cells are stimulated by inhibitory inputs from purkinje cells is incorrect; they are stimulated by parallel fibers and inhibit purkinje cells. Golgi cells are also stimulated by mossy fibers and help in the regulation of the overall output of the cerebellum.
What is the primary mechanism responsible for the reclamation of bile acids in the enterohepatic circulation?
1) Active transport in the ileum
2) Facilitated diffusion in the colon
3) Passive diffusion in the small intestine
4) Bacterial synthesis in the liver
Physiology
Answer: 1
Bile acids are actively reabsorbed in the ileum, primarily by the sodium-dependent bile acid transporter (ASBT), and returned to the liver.