Page 185 - 86 human physiology part-2

Chapter 20

The cutaneous senses are touch, pressure, heat, cold and pain. Their purpose is to provide the
central nervous system with information about the external environment and its effect on the skin.

4. Explain how sweating helps maintain normal body temperature.

Eccrine sweat glands are coiled tubular glands derived from the outer layer of skin but extending
into the inner layer. The sweat glands are
controlled by sympathetic cholinergic nerves which are controlled by a centre in the
hypothalamus. The hypothalamus senses core
temperature directly, and also has input from temperature receptors in the skin and modifies the
sweat output, along with other thermoregulatory processes.

5. Explain where on the body hair has important functions, and describe these functions.

Hair on the scalp provides insulation from cold for the head.
The hair of eyelashes and eyebrows helps keep dust and perspiration out of the eyes.
Hair in our nostrils helps keep dust out of the nasal cavities.
Any other hair on our bodies no longer serves a function, but is an evolutionary remnant.

The Nervous System

1. The junction between one neuron and the next, or between a neuron and an effector is called:

• A ) A synapse
B ) A dendrite
C ) A neuotransmitter
D ) A ventricle
E ) None of the above

2. A fast excitatory synapses follows this order:

• A ) (1) neurotransmitter released (2) diffused across the synaptic cleft to a receptor protein
(3) binding of the transmitter opens pores in the ion channels and positive ions move in.
B ) (1) neurotransmitter released (2) diffused across the synaptic cleft to a receptor protein (3)
binding of the transmitter opens pores in the ion channels and negative ions move in.
C ) (1) neurotransmitter released (2) diffused across the synaptic cleft to a receptor amino acid (3)
binding of the transmitter opens pores in the ion channels and positive ions move in.
D ) (1) diffused across the synaptic cleft to a receptor protein (2) neurotransmitter released (3)
binding of the transmitter opens pores in the ion channels and positive ions move in.
E ) None of the above

3. Resting potential is

A ) excess positive ions accumulate inside the plasma membrane
B ) excess negative ions accumulate inside the plasma membrane
C ) excess positive ions accumulate outside the plasma membrane
D ) excess positive ions accumulate outside the plasma membrane
• E ) both b & d

400 | Human Physiology