MDS PREP
What is the main function of the cephalic phase of gastric secretion?
1) To secrete digestive enzymes
2) To increase gastric motility
3) To increase gastric acidity
4) To initiate the secretion of gastrin
E) To prepare the stomach for food intake
The cephalic phase of gastric secretion is initiated by the sight, smell, thought, or taste of food and prepares the stomach for the arrival of food by increasing gastric secretion, gastric motility, and salivation. It does not directly increase gastric acidity but does contribute to the overall digestive process.
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.
The epithelial cells of the villi in the small intestine are responsible for:
1) Secreting gastric acid
2) Synthesizing bile
3) Final stage of digestion and nutrient absorption
4) All of the above
The epithelial cells of the villi in the small intestine contain various digestive enzymes and microvilli that increase the surface area for nutrient absorption. These cells are crucial for the final stages of digesting carbohydrates and proteins, as well as for the absorption of nutrients.
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 transport maximum for phosphate reabsorption in the kidneys?
1) 0.10 mM/min
2) 0.50 mM/min
3) 1.00 mM/min
4) 2.00 mM/min
The transport maximum for phosphate reabsorption in the kidneys is approximately 0.50 mM/min, indicating the maximum amount that can be reabsorbed before excretion occurs.
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 primary mechanism by which the pancreas regulates the activity of its own enzymes in the small intestine?
1) By secreting specific enzyme inhibitors
2) By controlling the pH of pancreatic juice
3) By altering the concentration of bile salts
4) Through the action of the sphincter of Oddi
E) By regulating the flow of pancreatic juice into the intestine
The pancreas secretes specific enzyme inhibitors, such as trypsin inhibitor, to prevent the premature activation of pancreatic enzymes in the pancreas itself. These inhibitors are degraded in the duodenum when the enzymes encounter the higher pH, allowing the enzymes to become active and participate in the digestion of food. Additionally, the presence of food in the intestine triggers the release of secretin, which stimulates the pancreas to secrete bicarbonate to neutralize acidic chyme and create an optimal environment for enzyme activity.
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.