Q-131. Rods & Cones are differ in all except
a) Light Sensitivity
d) Signal Transduction
Answer: Signal Transduction
The mechanism of signal transduction or photo-transduction is almost similar in both rods and cones,
Rods and cones differ in structure, photochemical molecules, sensitivity, retinal distribution, synaptic connection and function.
Q-132. Somatomedin mediates
c) Glucose taken up by cells
d) Deposition of chondroitin sulfate
Answer: Deposition of chondroitin sulfate
The effect of growth hormone on growth, cartilage and protein metabolism depend on an interaction between growth hormones and somatomedins.
Somatomedins are polypeptide growth factors secreted by liver and other tissues.
Somatomedin mediates the incorporation of sulfate into cartilage and collagen formation.
Type of Somatomedins:
Somatomedin C or Insulin Like Growth Factor-I: Skeletal and cartilage growth
Insulin Like Growth Factor-II: Growth during fetal development
Q-133. Muscle spindle detects
a) Muscle Length
b) Muscles tension
c) Muscle stretch
Answer: Muscle Length
Muscle spindles are specialized sensory organs and detect muscle length and rate of changes in muscle length.
Golgi Tendon Organ-Detect muscle tension and rate of change in muscle tension.
Q-134. High affinity of fetal Hb for O2 due to:
a) Decreases 2, 3 DPG
b) Reduced pH
c) Increase releases of CO2
d) Oxygen dissociation curve is shifted to right
Answer: Decreases 2, 3 DPG
Fetal hemoglobin’s affinity for oxygen is substantially greater than that of adult hemoglobin.
This greater affinity for oxygen is explained by the lack of fetal hemoglobin’s interaction with 2, 3-bisphosphoglycerate (2, 3-BPG or 2, 3-DPG).
In adult red blood cells, this substance decreases the affinity of hemoglobin for oxygen.
2, 3-BPG is also present in fetal red blood cells, but interacts less efficiently with fetal hemoglobin than adult hemoglobin, due to a change in a single amino acid found in the 2, 3-BPG ‘binding pocket’: from Histidine to serine.
This change results in 2, 3-BPG binding less well to fetal Hb, and as a result, oxygen will bind to it with higher affinity than adult hemoglobin.
Q-135. Estrogens action on carbohydrate metabolism
a) Increase uptake of glucose through increase in insulin sensitivity
b) Glycolysis increase
c) Increasing central adipose deposition
d) Worsening of NIDDM
Answer: Increase uptake of glucose through increase in insulin sensitivity
Insulin resistance is prevalent in healthy postmenopausal women.
A moderate dose of estrogen appears to increase insulin sensitivity but higher doses may attenuate this benefit and progestins may cause a decrease in insulin sensitivity.
Longer duration of estrogen use among postmenopausal women may relate to an increased risk of type 2 diabetes.
Q-136. Capacitance of sperm takes place in:
a) Seminiferous tubules
c) Vas deference
Capacitation of sperm:
Once ejaculated into the female, the spermatozoa move up the uterus to isthmus of uterine tubes, where they slow down and undergoes Capacitation.
This further maturation process involves two components: increasing motility of the spermatozoa and facilitating their preparation for the acrosome reaction.
The roll of Capacitation appears to be facilitatory rather than obligatory.
From the isthmuses the capacitated spermatozoa move rapidly to the tubal ampulla, where fertilization takes place.
Q-137. Not done by insulin
a) Glycogen synthesis
The actions of insulin on cells include:
Increased amino acid/ Glucose uptake
Increased potassium uptake
Increased glycogen synthesis
Increased lipid synthesis
Increased esterification of fatty acids
Q-138. True about spinocerebellar tract is:
b) Smoothens and coordinates movement
c) Learning induced by change in vestibulo-ocular reflex
d) Planning and programming
Answer: Smoothens and coordinates movement
The spinocerebellar tracts relay information about limb position and movement to the cerebellum.
To do this effectively, proprioceptive information from muscles, tendons, and joints, and exteroceptive information from skin receptors are integrated to allow for a complete picture of the body in motion.
There are several different pathways to the cerebellum. The major ones are the posterior spinocerebellar tract, which carries information from the lower limb, and the cuneocerebellar tract, which is the upper limb equivalent of the posterior spinocerebellar tract.
Two other pathways play a smaller role in the control of movement: the anterior spinocerebellar tract integrates proprioceptive information from the lower limb with descending input, and the rostral spinocerebellar tract integrates information from the upper limb with descending input.
Together, these four tracts convey a complete picture of the body in motion to the cerebellum, where that information is then used to fine-tune and adjust movement as well as to facilitate motor learning.
Lesions of the spinocerebellar tracts lead to ataxias, or loss of muscle coordination, due to a loss of proprioceptive input to the cerebellum.
Q-139. Maximum potassium ions secretion is seen in
b) Gastric secretion
c) Jejunal secretion
d) Colonic secretion
Enteric fluid potassium content:
Gastric secretion-9 mEq/L
Pancreas- 5-10 mEq/L
Small intestine-5 mEq/L
Colonic secretion-100 mEq/L
Salivary Glands- 1.5 L
Stomach- 2.5 L
Bile- 0.5 L
Pancreas- 1.5 L
Intestine- + 1 L
The accumulation of K+ in the colon is partially offset by H±k+ ATPase in the luminal membrane of cells in the distal colon, with resulting active transport of K+ into the cell.
Q-140. Cortical representation of body in the cerebrum is
The various parts of body are represented in the pre-central gyrus (Primary motor cortex) and post-central gyrus (Primary somatosensory area) with the feet at top of gyrus and face at bottom.
These areas are not in proportion to their size in the body with the lips, face and hands occupying relatively larger area.