MDS PREP
What is the primary role of sleep spindles during sleep?
1 ) To facilitate memory consolidation
2) To maintain muscle tone
3) To regulate body temperature
4) To initiate REM sleep
Sleep spindles are associated with the transition from stage 1 to stage 2 NREM sleep and are thought to play a role in memory consolidation and the integration of new information.
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 is the most common cause of vitamin D deficiency?
1) Inadequate sunlight exposure
2) Poor dietary intake of vitamin D
3) Impaired liver function
4) Impaired kidney function
Inadequate sunlight exposure is the most common cause of vitamin D deficiency, as sunlight is necessary for the skin to produce vitamin D.
What is the primary function of the gastric inhibitory polypeptide (GIP)?
1) Stimulating gastric acid secretion
2) Inhibiting gastric acid secretion
3) Stimulating insulin secretion
4) Inhibiting insulin secretion
E) Stimulating gastric emptying
GIP is released from the K cells of the duodenum and jejunum in response to the presence of nutrients, particularly glucose and fat. Its primary function is to stimulate insulin secretion from the pancreatic beta cells, which helps regulate postprandial blood glucose levels. It also inhibits gastric acid secretion and gastric emptying.
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.
Angiotensin I is formed by the action of which enzyme on Angiotensinogen?
1) Renin
2) ACE
3) Aldosterone
4) Erythropoietin
Angiotensin I is formed by the action of renin on Angiotensinogen, which is produced by the liver and released into the bloodstream.
The decreased CO2 concentration the airways causes
1. Dilation of airways
2. Constriction of airways
3. No effect on airway
4. Complete obliteration of airway.
Physiology
Answer: 2
The decreased CO2 concentration in the airways can cause bronchoconstriction,
which is the constriction of the airways. This is the correct answer among the
options provided. Here is the detailed explanation:
CO2 (carbon dioxide) is an important regulator of bronchial tone. It acts
primarily through the chemoreceptors located in the carotid body and the
medullary centers of the brain, which respond to changes in the partial pressure
of CO2 in the arterial blood (PaCO2). When the concentration of CO2 in the
airways decreases, it leads to a reduction in the PaCO2. This drop in PaCO2 is
detected by the central nervous system, which then responds to maintain
homeostasis.
The body normally adjusts the diameter of the airways to ensure proper gas
exchange and ventilation. When PaCO2 levels decrease, the respiratory center in
the brain perceives this as an increase in pH (alkalosis), which can be
detrimental to the body's overall homeostasis. To counteract this, the
respiratory center initiates a reflex that can lead to bronchoconstriction. This
reflex is known as the Hering-Breuer reflex. The vagus nerve, which innervates
the airway smooth muscles, is activated by the increase in pH, causing the
release of acetylcholine and other bronchoconstrictive substances. This, in
turn, results in the contraction of the smooth muscles surrounding the
bronchioles, leading to a narrowing of the airway diameter.
Therefore, the correct answer is 2. Constriction of airways.
This response is essential in the regulation of respiration and maintaining the
optimal pH balance in the body. It is part of the body's complex system to
ensure that oxygen and carbon dioxide are properly exchanged in the lungs and
that the blood remains at a slightly alkaline pH level. However, in individuals
with certain respiratory conditions such as asthma or chronic obstructive
pulmonary disease (COPD), bronchoconstriction can exacerbate their symptoms and
potentially lead to respiratory distress.
What is the primary mechanism of the fight-or-flight response in the regulation of glycogenolysis?
1) Activation of glycogen phosphorylase by epinephrine
2) Inhibition of glycogen synthase by cortisol
3) Stimulation of glucose-6-phosphatase by thyroid hormones
4) Activation of hexokinase by norepinephrine
Answer: 1) Activation of glycogen phosphorylase by epinephrineExplanation: Epinephrine acts on the beta-adrenergic receptors of liver and muscle cells, which activate protein kinase. This kinase then phosphorylates and activates glycogen phosphorylase, an enzyme that breaks down glycogen into glucose-1-phosphate, which is rapidly converted to glucose-6-phosphate for use in glycolysis or for release into the bloodstream to maintain glucose levels during stress.