CIE Categories Archives: 11. Coordination and response

11. Coordination and response

11.1 The Nervous System.

1 .The nervous system of a mammal consists:

  • The central nervous system (CNS) comprising the brain and the spinal cord.
  • Te peripheral nervous system (PNS) comprising the cranial nerves, spinal nerves and sense organs.

2 . A neurone is a nerve cell. A nerve fibre is a long protoplasmic extensions of the cell body of a neurone. It serves to transmit impulses.

3 . A nerve is a collection of nerve fibres.

4 . Neurones:Sensory

1 ) Sensory neurones:

  • It is a receptor neurone,
  • It transmits impulses from the sense organ (receptor) to the CNS.

2 ) Motor neurone:

  • It is an effector neurone.
  • It transmits impulses from the CNS to the effectors.

3 ) Relay neurone:

  • It connects sensory neurones to motor neurones.

5 . A synapse is a junction between two neurones. A dendron transmits impulses towards the cell body of a neurone. An axon transmits impulses away from the cell body of a neurone.

6 . Structure and functions of the human brain:

Fig.11.1 The structure of the human brain.

7 . Reflex actions involve messages being transmitted from the sensory neurone to the motor neurone without involving the conscious part of the brain.

8 . A reflex arc is the shortest pathway by which impulses travel from the receptor to the effector in a reflex action.

11.2 The Eye.
1 . Structure and functions of the eye:

Fig.11.2 Structure of the eye.

2 . Accommodation is the ability to change the curvature of the lens, so that light rays continue to be focused on the retina.

11.3 Hormones.

1 . Hormones are chemical substances produced by a gland, carried by the blood, to the target organ(s), and produce a response, and destroyed in the liver.

2 . Since hormones are proteins, therefore they are affected by pH and temperature.

3 . The pituitary gland plays an important role as a “controller”. It secretes a number of hormones, each of which controls the activity of a particular gland, hence the pituitary gland is sometimes referred to as the “master gland”.

4 . Location of endocrine gland:

5 . The islets of Langerhans are the special group of cells in the pancreas which secrete the hormone insulin into the bloodstream.

6 . Adrenaline:

7 . Insulin:

11.4 Diabetes Mellitus.

1 . Signs of diabetes mellitus:

  • A persistently high blood glucose level and glucose in the urine after a meal are signs of diabetes mellitus.

2 . Treatment:

3 . An insulin-dependent person is a person who needs daily injections of insulin.

4 . An insulin-independent person is a person who doesn’t usually require any injections of insulin.

Type 1 diabetes (Juvenile-onset diabetes=early-onset diabetes=insulindependent diabetes)

Type 2 diabetes (Adult-onset diabetes=late-onset diabetes=insulin-dependent diabetes)


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