MDS PREP
The first sensation of bladder filling occurs at approximately:
1) 150 ml
2) 250 ml
3) 450 ml
4) 750 ml
The first sensation of bladder filling, known as the first sensation of urgency, typically occurs when the bladder is about one-quarter full, which is around 150 ml. This is the point where an individual begins to become aware of the need to urinate.
What is the primary neurotransmitter responsible for the contraction of the pupillary sphincter muscle?
1) Acetylcholine
2) Norepinephrine
3) Epinephrine
4) GABA
Answer: 1) AcetylcholineExplanation: The pupillary sphincter muscle is innervated by the parasympathetic nervous system, which uses acetylcholine as its primary neurotransmitter. Contraction of this muscle leads to pupil constriction, or miosis, which occurs in low-light conditions or when focusing on near objects.
MCQ: The first sensation of bladder filling occurs at approximately:
1) 150 ml
2) 250 ml
3) 450 ml
4) 750 ml
The first sensation of bladder filling occurs at approximately 150 ml, signaling the need to void.
What is the normal plasma concentration of glucose that does not lead to its excretion in the urine?
1) 100 mg/100 ml
2) 180 mg/100 ml
3) 200 mg/100 ml
4) 250 mg/100 ml
Physiology
Answer: 1
In a healthy individual, glucose is completely reabsorbed when the plasma concentration is 100 mg/100 ml or less.
What is the primary function of the macula densa?
1) Filtration of blood
2) Regulation of glomerular filtration rate
3) Secretion of renin
4) Reabsorption of glucose
The primary function of the macula densa is to regulate glomerular filtration rate by sensing sodium chloride concentration in the tubular fluid.
Which of the following substances does NOT directly depolarize taste cells during the sensation of bitter taste?
1) Increased intracellular calcium (Ca+) concentration
2) Activation of amiloride-sensitive Na+ channels
3) Closure of K+ channels
4) Release of neuronal glutamic acid
Bitter taste is mediated by the activation of bitter receptors, which are G protein-coupled and result in an increase in intracellular Ca+2 and subsequent neurotransmitter release, not by the activation of sodium channels as seen in salty taste transduction.
In which part of the male reproductive system does spermatogenesis occur?
1) Seminal vesicles
2) Epididymis
3) Prostate gland
4) Seminiferous tubules
Physiology
Answer: 4
Spermatogenesis is the process of sperm cell development. It takes place in the seminiferous tubules within the testes. These tubules are lined with spermatogonia, which mature into primary spermatocytes, then secondary spermatocytes, and finally into spermatids, which mature into spermatozoa.
What is the role of the corpus luteum in the second half of the menstrual cycle?
1) It secretes FSH
2) It secretes LH
3) It secretes estrogen and progesterone
4) It secretes inhibin
Physiology
Answer: 3
The corpus luteum, which forms after ovulation, secretes estrogen and progesterone. These hormones are essential for preparing the endometrium for potential implantation and supporting early pregnancy.