During the propagation of a nerve impulse, the action potential results from the movement of :

K⁺ ions from extracellular fluid to intracellular fluid
Na⁺ ions from intracellular fluid to extracellular fluid
K⁺ ions from intracellular fluid to extracellular fluid
Na⁺ ions from extracellular fluid to intracellular fluid

Solution

During propagation of nerve impulse, Na⁺ enters inside so (+ve) change is formed inside the membrane. K⁺ ions come out.

Which of the following pair(s) is/are correct?

Semicircular canal - Balancing
Cochlea - Hearing
Utriculus & sacculus - Balancing & hearing
All of the above

Given below is a diagrammatic cross section of a single loop of human cochlea:

Which one of the following options correctly represents the names of three different parts?

B: Tectorial membrane,
C: Perilymph,
D: Secretory cells
C: Endolymph,
D: Sensory hair cells,
A: Serum
D: Sensory hair cells,
A: Endolymph,
B: Tectorial membrane
A: Perilymph,
B: Tectorial membrane,
C: Endolymph

Which one of the following pairs of structures distinguishes a nerve cell from other types of cells?

Vacuoles and fibres
Flagellum and medullary sheath
Nucleus and mitochondria
Perikaryon and dendrites.

Solution

The cytoplasm immediately surrounding the nucleus is loaded with protein synthetic machinery and is called perikaryon, dendrites are usually shorter, tapering and much branched processes which may be one to several. These two are only present in nerve cells.

Which of the following is an example of negative feedback loop in humans?

Secretion of tears after falling of sand particles into the eye.
Salivation of mouth at the sight of delicious food
Secretion of sweat glands and constriction of skin blood vessels when it is too hot
Constriction of skin blood vessels and contraction of skeletal muscles when it is too cold

Solution

When the set point of hypothalamus is disturbed by high temperature, it stimulates vasodilation and sweating while in low temperature there is vasoconstriction and shivering.

During the transmission of nerve impulse through a nerve fibre, the potential on the inner side of the plasma membrane has which type of electric change?

First positive, then negative and continue to be positive
First negative, then positive and continue to be positive.
First positive, then negative and again back to positive
First negative, then positive and again back to negative

Solution

Once the events of depolarization have occurred, a nerve impulse or spike is initiated. Action potential is another name of nerve impulse. It lasts about 1 msec (millisecond).The stimulated, negatively charged point on the outside of the membrane sends out an electrical current to the positive point (still polarized adjacent to it). This local current causes the adjacent inner part of the membrane to reverse its potential from –70 mV to +30 mV. The reversal repeats itself over and over until the nerve impulse is conducted through the length of the neuron.

One of the examples of the action of the autonomous nervous system is

swallowing of food
pupillary reflex
peristalsis of the intestine
knee-jerk response

Solution

Autonomic nervous system regulates and coordinates involuntary activities like heart beat, homeostasis, body temperature, breathing, gut peristalsis and secretion of glands. Human intestine shows movements during food digestion called peristalsis.

In a man, abducens nerve is injured. Which one of the following functions will be affected?

Movement of the eye ball
Movement of the tongue
Swallowing
Movement of the neck

Solution

Abducens nerve is the sixth cranial nerve. It supplies the extraocular muscle (superior oblique) of eyeball, therefore controls movement of the eyeball.

Four healthy people in their twenties got involved in injuries resulting in damage and death of a few cells of the following. Which of the cells are least likely to be replaced by new cells?

Liver cells
Neurons
Malpighian layer of the skin
Osteocytes

Solution

The neurons are cells specialised to conduct an electrochemical current. Neuron cells do not have the capability of division.

Afferent nerve fibres carry impulses from

Effector organs to central nervous system
Receptors to central nervous system
Central nervous system to muscles
Central nervous system to receptors

Solution

Nerve impulse carry through afferent nerve fibres from receptors to central nervous system.

UnAttempted

0

Attempted

0

Correct

0

Wrong

0

Complete