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.
What type of aphasia results from a lesion in Broca’s area?
1) Sensory aphasia
2) Motor aphasia
3) Global aphasia
4) Conduction aphasia
E. Wernicke’s aphasia
A lesion in Broca's area leads to motor aphasia, also known as Broca's aphasia or expressive aphasia. This type of aphasia is characterized by difficulty in producing speech, particularly with grammatical errors and reduced vocabulary. Understanding of language is usually preserved, but the ability to form coherent sentences is impaired.
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.
What is the primary action of endorphins on the body?
1) Inhibition of pain
2) Stimulation of growth
3) Regulation of mood and emotions
4) Increased blood pressure
E. Regulation of sleep-wake cycle
Endorphins, particularly ?-endorphin, are opioid peptides that act as natural painkillers. They are released during stress and pain and bind to opioid receptors in the brain and spinal cord to inhibit the transmission of pain signals. While they do have secondary effects on mood and stress response, their primary function is pain inhibition.
Which of the following is a characteristic of the absolute refractory period during an action potential?
1) The membrane is fully depolarized.
2) The membrane is fully repolarized.
3) The membrane is inexcitable regardless of the strength of the stimulus.
4) The membrane is hyperpolarized.
E. The membrane is depolarized.
The absolute refractory period occurs during the initial phase of repolarization after an action potential. During this period, the membrane is inactivated and cannot be depolarized to generate another action potential, regardless of the stimulus strength. This ensures that action potentials are unidirectional and do not propagate backward along the axon.
What is the primary function of the epididymis in the male reproductive system?
1) Storage and maturation of sperm
2) Secretion of androgens
3) Formation of the spermatozoa
4) Fusion of gametes during fertilization
Physiology
Answer: 1
The epididymis is a coiled tubular structure located behind the testis. Its primary function is to store and mature sperm cells, making them fully motile and capable of fertilization.
What happens to the osmolarity of tubular fluid as it ascends the Loop of Henle?
1) It becomes hypertonic
2) It remains isotonic
3) It becomes hypotonic
4) It fluctuates significantly
As tubular fluid ascends the Loop of Henle, its osmolarity becomes hypotonic due to the reabsorption of sodium and chloride without water.
What is the function of the middle piece in a sperm cell?
1) It produces the enzymes needed for sperm maturation
2) It contains the mitochondria for energy production
3) It is responsible for the sperm's ability to penetrate the egg
4) It is involved in the process of fertilization
The middle piece of a sperm cell contains mitochondria, which provide the energy needed for sperm motility and movement towards the egg.