Page 10 - LN-NEURAL CONTROL & COORDINATION

The hypothalamus, that lies at the base of thalamus contains a number of

centres, which control body temperature, urge for eating and drinking. It also
contains several groups of neurosecretory cells, which secrete hormones called
hypothalamic hormones.
The inner parts of cerebral hemispheres and a group of associated deep
structures like amygdala, hippocampus, etc., form a complex structure (limbic
lobe or limbic system) that are involved in the regulation of sexual
behaviour,expression of emotional reactions, e.g„ excitement, pleasure,rage
and fear and motivation,

ii. Midbrain
The midbrain is located between the thalamus hypothalamus of the forebrain
and pons of the hindbrain. A canal called the cerebral aqueduct passes
through, the midbrain.
The dorsal portion of the midbrain mainly consists of two pairs (i.e., four) of
rounded swellings (lobes) called corpora quadrigemina.
iii. Hindbrain

The hindbrain consists of
(a) Pons consists of fibre tracts that interconnect different regions of the brain.
(b) Cerebellum is the second largest part of the human brain (means litde
cerebrum). It has very
convoluted surface in order to provide the additional space for many more
neurons.
(c) Medulla (oblongata) is connected to the spinal cord and contains centres,
which control respiration, cardiovascular reflexes and gastric secretions.

Note:
* Midbrain and hindbrain form the brain stem. It is the posterior part of the
brain that continues with the spinal cord.
* Out of the twelve pairs of cranial nerves (in higher vertebrates), ten pairs
come from the brain stem.
Spinal Cord

(i) It forms the posterior part of the CNS, running mid-dorsally in the neural
canal of the vertebral column. In an adult, the spinal cord is about 42-45 cm
long. Its diameter varies at different levels.
(ii) The spinal cord is formed of two types of nervous tissue, i.e., grey matter
and white matter.
(iii) The grey matter is surrounded by white matter, which consists of groups of
myelinated axons.
(iv) The spinal nerve tracts are divisible into two, ascending (conducting
sensory impulses towards brain) and descending (conducting motor impulses

from brain).