The Nectary schools

Date : 23rd September 2024

Week: 3

Class: SS3

Subject: Biology

Topic: Nervous coordination

Sub topics: meaning of coordination, organisation of Nervous system, Central Nervous system, the
Brain(structure and functions),spinal cord.

Spelling drills

Nervous coordination

Co-ordination is the process by which different parts of an organism work together for proper
effectiveness.

The nervous system is a complex network of specialized cells, tissues, and organs that coordinate and
regulate various functions in the body. All metabolic processes in the body of an organism do not
functions individually but are all closely linked and dependent on each other for effective functioning.
The two communication systems that bring about this co-ordination are:

(I) The endocrine system ( hormones)

(ii) The Nervous system.

Both the nervous system and endocrine systems work together very closely to bring about coordination
of body activities.

Organization of the nervous system

The nervous system is organized into two main components: The central nervous system (CNS) and the
peripheral nervous system (PNS).

Central Nervous System (CNS)

The central nervous system (CNS) is a crucial part of the nervous system and consists of two main
components: the brain and the spinal cord.
 i. The Brain

The brain is the command center of the nervous system and is responsible for processing sensory
information, thoughts, emotions, and coordinating various body functions. The brain is the most highly
specialized organ it is protected by the skull or cranium. The brain is made up of three main parts. These
are(a) forebrain (b) midbrain (c) hindbrain.

(a) The forebrain is the largest and most complex division of the brain, responsible for various higher-
level functions. It is made up of two main parts. These are cerebrum and olfactory lobes and made up of
two minor parts called thalami and hypothalami.

The main parts of forebrain

 Cerebrum : the cerebrum is the largest part of the brain and it is made up of hemisphereswhich
are the right and left hemispheres.the cerebral hemispheres are partially separated from each
other by a deep furrow known as median fissure. They are protected by a band of fibres called
corpus collosum. The outer part of the cerebrum is known as cerebral cortex or grey matter.
Their functions is to controls all voluntary actions e.g movement of legs,arms, speech e.t.c.

Cerebral Cortex

1. Outer layer of the cerebrum

2. Divided into four lobes:

- Frontal lobe (decision-making, motor control)

- Parietal lobe (sensory processing, spatial awareness)

- Temporal lobe (memory, language processing)

- Occipital lobe (vision processing

 Olfactory lobes: they are located anteriorly at the fore Brain.they are pair of small structure.
Their functions is to receive sensory impulses of smell.
 Thalami : Thalami ( thalamus) are two ovoid structures attached to the back of the forebrain.
Their Thalamus helps in experiencing sensation and it sends or passes impulses to the cerebral
cortex and vice versa
 Hypothalamus: The hypothalamus is found just below the thalami. It is the main co ordinating
and control centre for the autonomic nervous system. It's also plays an important role in
Homeostasis.their functions is to controls sleep and alertness, it controls appetite or
feeding,body temperature, amount of water in the blood( osmo regulation) e t c

( b) Mid brain consists of a small and inconspicuous part of the brain. It is a very short region consisting
of optic lobes,pineal body and pituitary gland. Their functions is to connects the forebrain to the
hindbrain and thereby assist in transmission of impulses .
  Optic lobes: it receive sensory impulses from the eye. It is the site of vision.
 Pineal body or Pineal Gland: it is a small endocrine gland in the brain, located near the center of
the brain. its functions are to Produces melatonin which regulates sleep and wake cycles, it also
regulates reproductive hormones and Influences mood and emotional responses.
 Pituitary gland: it is located at the base of the brain situated in the sella turcica (a bony cavity)
their functions is to regulates other endocrine glands and produces hormones controlling
growth, metabolism, and reproductive processes.
(c) Hind brain : the Hind brain is located at the lowermost part of the brain that connects the
spinal cord to the midbrain. It is compose of Medulla Oblongata, Pons and Cerebellum.
 Medulla Oblongata: it controls involuntary functions such as Breathing, Heart rate, Blood
pressure, Swallowing,Vomiting. It also regulates body temperature.
 Pons varolii : it relays messages between cerebrum and cerebellum and controls sleep and
arousal.
 Cerebellum: it coordinates movement and balance. It also regulates posture and muscle tone
and it is responsible for learning and memory (motor skills).

ii. The Spinal Cord

The spinal cord is a long, tubular structure that extends from the base of the brain down the vertebral
column. It serves as a pathway for nerve impulses traveling to and from the brain, facilitating
communication between the brain and the rest of the body.

The spinal cord is also involved in reflex actions, allowing for rapid responses to certain stimuli without
direct involvement of the brain. The spinal cord is enveloped within three membranes:

 The meninges: it support and protect the spinal cord and the brain.
 The spinal canal: The spinal canal is a long, narrow, cylindrical space within the vertebral
column, extending from the base of the skull to the lower back.
 Cerebrospinal fluid: CSF is a clear, colorless fluid surrounding the brain and spinal cord,
providing protection, support, and maintaining homeostasis.

Their functions is to cushions brain and spinal cord against mechanical injury, removing of
waste products and toxins, regulationof intracranial pressure and maintains electrolyte balance

CSF is compose of the following

1. Water (99%)

2. Proteins (0.5-1%)

3. Electrolytes (Na+, K+, Ca2+, Mg2+)

4. Glucose

5. Chloride
Functions of the spinal cord
1.it protects spinal cord and nerve roots
2. It provides space for CSF circulation
3.To facilitates nerve impulse transmission
4. It support spinal column stability.

Spelling drills
Study the words and learn the proper pronunciation
 Thalami/ Thalamus
 Cerebrum
 Cerebrospinal fluid
 Meninges
 Cerebral cortex
 Olfactory lobes
 Hypothalamus
 Pituitary gland
 Optic lobes
 Cerebellum
 Pons varolii
 Medulla Oblongata