MDS PREP
The primary regulators of gastric emptying are:
1) Vagal reflexes
2) Intestinal hormones
3) Local neural reflexes
4) All of the above
Gastric emptying is regulated by a combination of vagal reflexes, intestinal hormones such as secretin and cholecystokinin, and local neural reflexes known as the enterogastric reflex. These mechanisms work in concert to modulate the rate of emptying based on the needs of the body.
What is the effect of epinephrine on the bronchial smooth muscles during the fight-or-flight response?
1) Constriction (bronchoconstriction)
2) Dilatation (bronchodilatation)
3) No effect
4) Spasm
Answer: 2) Dilatation (bronchodilatation)Explanation: Epinephrine acts on beta-2 adrenergic receptors in the bronchial smooth muscles, leading to their relaxation and dilatation of the bronchioles. This allows for increased airflow and oxygenation of the lungs, which is essential during the fight-or-flight response.
What is the function of the hypothalamus in the regulation of spermatogenesis?
1) It produces gonadotropin-releasing hormone (GnRH) which stimulates the release of LH and FSH from the pituitary
2) It produces androgens such as testosterone
3) It directly controls the maturation of spermatids
4) It has no role in spermatogenesis
Physiology
Answer: 1
The hypothalamus produces GnRH, which stimulates the anterior pituitary to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH is essential for the maturation of spermatogonia into primary spermatocytes, while LH acts on Leydig cells to produce testosterone, which is critical for the later stages of spermatogenesis and sperm maturation.
What is the main difference between endopeptidases and exopeptidases?
1) Endopeptidases cleave internal peptide bonds, while exopeptidases act on the terminal peptide bonds.
2) Endopeptidases are inactive in the stomach, whereas exopeptidases are active in the stomach.
3) Endopeptidases are exclusively found in the pancreas, whereas exopeptidases are exclusively found in the intestinal mucosa.
4) Endopeptidases are exclusively activated by enterokinase, whereas exopeptidases are activated by other enzymes.
E) Endopeptidases are inhibited by acidic pH, while exopeptidases function best at acidic pH.
Endopeptidases, also known as endoproteinases, are enzymes that hydrolyze peptide bonds within the polypeptide chain, breaking down proteins into smaller peptides. Examples include pepsin, trypsin, and chymotrypsin. In contrast, exopeptidases, or exoproteinases, cleave peptide bonds at the ends of the polypeptide chain, either at the N-terminal (aminopeptidases) or C-terminal (carboxypeptidases). These enzymes are involved in the final steps of protein digestion and the degradation of small peptides into individual amino acids.
What is the primary function of vitamin D in the body?
1) Blood clotting
2) Bone formation and maintenance
3) Vision
4) Immune system function
The primary function of vitamin D in the body is bone formation and maintenance, as it helps regulate calcium and phosphate levels.
What is the primary visual area of the occipital lobe also known as?
1) Brodmann area 17
2) V1
3) Calcarine cortex
4) Striate cortex
The primary visual area is Brodmann area 17, which is located in the occipital lobe's medial side of the calcarine sulcus. It is also commonly referred to as the striate cortex due to the distinctive myelinated strip, the stria of Gennari.
What is the primary function of the neck in a sperm cell?
1) It connects the head and tail of the sperm
2) It produces the sperm's energy for movement
3) It is responsible for the fertilization process
4) It contains the cell's genetic material
Physiology
Answer: 1
The neck of the sperm cell is a small structure that connects the head, which contains the nucleus with the chromosomes, to the tail, which is responsible for the sperm's movement.
Which hormone is primarily responsible for the conversion of 7-dehydrocholesterol to cholecalciferol in the skin?
1) Parathyroid hormone (PTH)
2) Vitamin D
3) Ultraviolet B (UV2) light
4) 25-hydroxyvitamin D3
Physiology
Answer: 3
The conversion of 7-dehydrocholesterol to cholecalciferol (vitamin D3) in the skin is initiated by the action of UVB light from sunlight, not by any specific hormone.