Which of the following statement is wrong regarding conduction of nerve impulse?
In a resting neuron, the axonal membrane is more permeable to K+ ions and nearly impermeable to Na+ ions.
Fluid outside the axon has a high concentration of Na+ and low concentration of K+, in a resting neuron
Ionic gradients are maintained by Na-K pumps across the resting membrane, which transport 3 Na+ ions outwards for 2K+ ions into the cell.
Resting potential is the electrical potential difference across the resting membrane
Resting potential is the electrical potential difference across the resting membrane
E.
A neuron is polarized only when the outer surface of the axonal membrane possess a negative charge and its inner surface is positively charged.
In a resting nerve fibre, axoplasm contains a high concentration of K+ and negatively charged proteins and low concentration of Na+. In contrast, the fluid outside axon contains a low concentration of K+ and a high concentration of Na+ and thus forms a concentration gradient. This ionic gradient is maintained by Na+ – K+ pump. As a result, the outer surface of axonal membrane possesses a positive charge while its inner surface is negatively charged and therefore is polarised.
If drosal nerve of spinal cord is broken down then its effect is :
no impulse is transmitted
impulse is transmitted but slowly
impulse is trasmitted fast
no effect on impulse
Intercellular communication in multicellular organism occurs through :
digestive system only
respiratory system only
nervous system only
both nervous and endocrine system
Assertion : The imbalance in the concentration of Na+, K+ and proteins generates the resting potential.
Reason : To maintain the unequal distribution of Na+ and K+, the neurons use electrical energy.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both the assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both the assertion and reason are false.
A condition in which body's internal environment remains relatively constant within limits is called :
homeostasis
hemostasis
hematoma
haemopoiesis
If a stimulus, several times greater than the threshold stimulus is provided to a muscle fibre, it will
contract with a larger force
contract with a smaller force
contract with the same force
undergo tetany.
Which of the following part of a neuron is covered by fatty sheath ?
axon
cyton
dendrite
node of Ranvier
Tongue is under control of :
trigeminal nerve
facial nerve
automatic nervous system
glossopharyngeal nerve
The yellowish pigmented spot at the posterior pole of the human eye lateral to the blind spot is
crista
saccule
iris
meatus
meatus
