Present inside the body and stimulated by internal stimuli as those present in viscera, muscles, tendons, joints, and ligaments which are known as proprioceptors.

2) According to the type of stimuli or the energy to which the receptor is sensitive:

a. Thermoreceptors:

Which are stimulated by thermal changes.

b. Chemoreceptors:

Which are stimulated by chemicals as taste receptors in the tongue, and smell receptors in the membrane lining the nose.

c. Photoreceptors:

Which are stimulated by light and present in the retina of eye. There are two types of these receptors are present; the rods which are stimulated by dim light, and cones which are stimulated by bright light and colours.

d. Mechanoreceptors:

Which are stimulated by mechanical changes, such as touch, and pressure receptors in the skin, and receptors for hearing and equilibrium in the ear.

Revision VII

ٍٍٍSensitivity in Livings.

1. Give the scientific term that represents each of the following:

A. Two main functions for sensitivity in livings. (----------------------------------------)

B. Two types of stimuli to which sensitivity systems can pick up and respond to. (------------------------------------------------)

C. The movement in which the leaflets of Mimosa hang downwards and fold their upper surfaces at night. (------------------------------------)

D. One of the main Auxins present in plants. (--------------------------------)

E. The response of plant parts to the external stimulus of gravity. (-----------------------)

F. The response of plant parts to the external stimulus of light. (-----------------------)

G. The response of plant parts to the external stimulus of humidity. (---------------------)

H. The two systems that organize the functions of different body organs and control the relation between Man and his environment. (----------------------------------------)

I. The link between the nervous system and the endocrine glands system. (--------------)

J. The structures that receive information in the form of external and internal stimuli. (-----------------------------------------------------)

K. The unit of structure of the nervous system. (-------------------------------------)

L. The system that includes the brain and the spinal cord. (---------------------------)

M. The system That includes the cranial nerves and the spinal nerves. (------------------)

N. The system that controls the involuntary muscles and the glands. (---------------------)

O. The system that its nerve fibres originate from the thoracic and lumbar region (segments) of the spinal cord. (------------------------------------------)

P. The system that its nerve fibres originate from the brain and the sacral region of the spinal cord. (-------------------------------------)

Q. The response of the nerve cell to the stimulus which includes a state of depolarization followed by repolarization. (-----------------------------------------)

R. The period during which, the membrane of the nerve cell regains its physiological properties to be ready to respond to new stimulus. (----------------------------------)

2. Give reasons for:

A. Leaflets of Mimosa plant hang downwards and fold their upper surfaces.

b. The plant stem is +ve phototropic.

c. The plant root is –ve phototropic.

d. The plant stem is –ve geotropic.

e. The plant root is +ve geotropic.

g. The plant root is +ve hydrotropic.

H. Neurons cannot divide.

I. Dendrites are very important structures in the nerve cells.

j. The conduction rate of nerve impulses through myelinated axons is rapid.

K. The nerve cell membrane is said to be polarized at rest.

L. Polarization of the nerve cell membrane at rest.

M. The speed of propagation of the nerve impulse along a nerve fibre depends on its diameter.

N. Stimulation of the nerve obeys the all or none law.

3. Draw a labeled diagram to represent:

Date: 2015-12-17; view: 855