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.
C.
contract with the same force
A muscle fibre would contract only when it receives stimulation of certain intensity called threshold stimulus. Response of a muscle fibre to a stimulus is not proportional to its intensity. It is absent when the intensity is subliminal. Muscle fibre contracts to the maximum whether the stimulus has threshold value or supraliminal value.
The yellowish pigmented spot at the posterior pole of the human eye lateral to the blind spot is
crista
saccule
iris
meatus
meatus
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.
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
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
Which of the following part of a neuron is covered by fatty sheath ?
axon
cyton
dendrite
node of Ranvier
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
A condition in which body's internal environment remains relatively constant within limits is called :
homeostasis
hemostasis
hematoma
haemopoiesis
