CBSE Questions for Class 11 Medical Biology Chemical Coordination And Integration Quiz 7 - MCQExams.com

Correct option: D.

Explanation:

· It is a sphenoid bone called Sella turcica. Latin for the term “Turkish saddle” is shaped like a saddle.

· Sella turcica: it means Turkish saddle and the reason Turkish saddle looks different from the western saddle is that the Turkish saddle is meant for comfort not for roping that means it's very deep.

· In the sella front part is followed by a flat part, this is called the planum sphenoid alley, there's a bulge right before the flat part which looks tuber-like, this is the tuberculum sella and then the back part which is the dorsal part is the dorsum sella and then that slopes on down to the clivus what lives in a sella is the pituitary gland.

Hence, Sella turcica is a depression in the skull which lodges the pituitary gland.

• Angiotensin is a polypeptide that narrow blood vessels and thus regulates arterial pressure. 
• Angiotensin not only constricts blood vessels all over the body in order to increase systemic blood pressure, but it also works in the kidneys in order to maintain blood pressure in the glomerulus(glomerular pressure) so that the glomerular filtration rate stays normal even in the condition when blood pressure is low. Hence, angiotensin increases glomerular pressure.

• Angiotensinogen is a precursor protein made in the liver for a hormone called angiotensin I. 
• And renin catalyzes a reaction that converts the angiotensinogen protein into angiotensin I, which is a precursor hormone that is converted to an active hormone called angiotensin II by an enzyme known as an angiotensin-converting enzyme in the lungs. Hence, Angiotensinogen is converted to angiotensin by renin.

$$\textbf{Correct option:D}$$ 

$$\textbf{Solution:}$$

$$\textbf{Option (A)}$$

$$\bullet$$ Renin is an enzyme secreted from the juxtaglomerular kidney cells ,it is  essential for the regulation of blood pressure and fluid balance.

$$\textbf{Option (B)}$$

$$\bullet$$ Oxytocin promotes the contraction of uterine muscle and helps inducing labour at the later stages of pregnancy .Oxytocin also contracts  myoepithelial cells of the lactating breast ,bringing milk from the alveoli to mammary ducts.  

$$\textbf{Option (C)}$$

$$\bullet$$ It promotes reabsorption of water from distal convoluted tubules and collecting ducts of nephrons in the kidneys which results in the excretion of hypertonic urine and maintain the fluid contents in the body.

$$\bullet$$ Contraction of involuntary muscles in the walls of the intestine,gall bladder and blood vessels and urinary bladder which creates a pressure effect that is controlled by vasopressin/ADH. 

$$\textbf{Option (D)}$$

$$\bullet$$ Anti Natriuretic factor is secreted from heart cells in response to increased deoxygenated blood so it dilates the blood vessels (vasodilation) and thus, decreases the blood pressure.

$$\bullet$$ It  inhibits the secretion of renin from the juxtaglomerular apparatus of the kidney which results in decreased reabsorption of NaCl from collecting duct and reduced secretion of aldosterone(sodium homeostasis) from adrenal cortex.

$$\textbf{Hence, the correct option is (D)}$$

• Renin, also known as an angiotensinogenase, is an aspartic protease protein.
• This enzyme is secreted by the kidneys that participate in the body's renin–angiotensin–aldosterone system (RAAS)  that mediates the volume of extracellular fluid (blood plasma, lymph and interstitial fluid), and arterial vasoconstriction. 
• Thus, it regulates the body's mean arterial blood pressure. Hence, renin is not secreted by the liver.

$$\textbf{Correct option:D}$$ 

$$\textbf{Solution:}$$

$$\textbf{Option (A)}$$

$$\bullet$$ Gastrin is a gastrointestinal tract hormone secreted from the mucosa of the pyloric region in the stomach that stimulates secretion of hydrochloric acid and pepsinogen.

$$\textbf{Option (B)}$$

$$\bullet$$ Secretin is a gastrointestinal tract hormone, it is secreted from intestinal mucosa of duodenum and jejunum which promotes the release of enzymes and bicarbonates from the exocrine parts of pancreas ,decreases secretions and movements of the stomach but promotes bile secretion from gallbladder.

$$\textbf{Option (C)}$$

$$\bullet$$ Estradiol is the principal estrogens that promotes development of secondary sexual characters , uterine epithelium and mammary glands.

$$\textbf{Option (D)}$$

$$\bullet$$ Erythropoietin,a glycoprotein, is secreted from the kidney cells when there is a shortage of oxygen in the circulation. It stimulates the production of RBCs from bone marrow.

$$\textbf{Hence, the correct option is (D)}$$

• Adenohypophysis : It is formed of two lobes:

1. Anterior lobe - It secretes growth hormone, follicle stimulating hormone, luteinizing hormone, prolactin, adrenocorticotropic hormone and thyroid stimulating hormone.
2. Intermediate lobe (or median lobe) - It secretes melanocyte stimulating hormone.

• Neurohypophysis: It is formed of posterior lobe and secretes oxytocin and vasopressin.

• Membrane bound receptors : These are present on the cell membrane of target cells.
• Intracellular receptors: These are present inside the target cell.