Tag: biology

• The fish heart contains both oxygenate and deoxygenated blood as it has one atrium and one ventricle.
• Closure of A-V valves produces the first heart sound.
• The vascular connection between the digestive tract and the liver is called the hepatic portal system.
• Purkinje fibres are nerve fibres present in the heart wall.

• The medulla oblongata of the brain controls cardiac activities.
• The action of sympathetic nerve fibres increases the heart rate, while that of the parasympathetic nerve fibres decrease it.
• Sensory fibres extend from the receptors present in the walls of the aortic arch, carotid sinuses and vena cava to the cardiovascular centre in the medulla oblongata.

Cardiac activity could be moderated by the autonomous neural system. The action of sympathetic nerve fibres increases the heart rate and the stroke volume, while that of the parasympathetic nerve fibres decrease these.

Thus, the correct answer is 'The sympathetic system stimulates heart rate and stroke volume.'

An electroencephalogram (EEG) is a test that detects electrical activity in the brain using small, flat metal discs (electrodes) attached to scalp. 

Evoked potential studies measure electrical activity in the brain in response to stimulation of sight, sound, or touch. Stimuli delivered to the brain through each of these senses evoke minute electrical signals. These signals travel along the nerves and through the spinal cord to specific regions of the brain and are picked up by electrodes, amplified, and displayed for a doctor to interpret. Evoked potentials studies involve three major tests that measure response to visual, auditory, and electrical stimuli. Evoked potential studies may be used to assess hearing or sight, especially in infants and children, to diagnose disorders of the optic nerve, and to detect tumors or other problems affecting the brain and spinal cord. The tests may also be performed to assess brain function during a coma.

A SQUID (superconducting quantum interference device) is a very sensitive magnetometer used to measure extremely subtle magnetic fields, based on superconducting loops containing Josephson junctions. SQUIDs are sensitive enough to measure fields as low as 5 aT (51018 T) within a few days of averaged measurements. Magnetoencephalography (MEG), uses measurements from an array of SQUIDs to make inferences about neural activity inside brains. Because SQUIDs can operate at acquisition rates much higher than the highest temporal frequency of interest in the signals emitted by the brain (kHz), MEG achieves good temporal resolution.

Reserpine is an indole alkaloid, antipsychotic and antihypertensive drug that has been used for the control of high blood pressure.
Rustom Jal Vakil was the first to pioneer the use of resperine to control hypertension.
Thus, the correct answer is option (A), 'Jal Vakil'.

$\beta$-wave or $\eta$ rhythm is the term used to designate the frequency range of human brain activity between 12.5 and 30 Hz.
Thus, the correct answer is option C.