Which of the following part of a neuron is covered by fatty sheath ?

• axon

• cyton

• dendrite

• node of Ranvier

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

A condition in which body's internal environment remains relatively constant within limits is called :

• homeostasis

• hemostasis

• hematoma

• haemopoiesis

Intercellular communication in multicellular organism occurs through :

• digestive system only

• respiratory system only

• nervous system only

• both nervous and endocrine system

Tongue is under control of :

• trigeminal nerve

• facial nerve

• automatic nervous system

• glossopharyngeal nerve

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.

177.

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.

Sella Turcica is found

• in bones

• in joints

• nearby pituitary

• nearby thyroid

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

The yellowish pigmented spot at the posterior pole of the human eye lateral to the blind spot is

• crista

• saccule

• iris

• meatus

• meatus