human nervous system brain its parts and functions

 

Human nervous system is centralized and most complicated type of nervous system.

Human nervous system divides into two major categories i.e central and peripheral nervous system

CENTRAL NERVOUS SYSTEM

The central nervous system consists of the brain and spinal cord. It is referred to as “central” because it combines information from the entire body and coordinates activity across the whole organism.

BRAIN

 

 

Human brain is enclosed within the cranium. It is major control and command centre of the body. It receives signals from the body's sensory organs and outputs information to the muscles.  Brain is wrapped in three protective membranes called meninges and empty ventricles are filled with a Cerebro Spinal Fluid (CSF). It gives protection to the brain.

Parts of Human Brain.

Fore Brain

Fore brain is the largest part of brain where all the conscious activities takes place.  Fore brain further divided into three main parts.

1)    CEREBERUM

The cerebrum is the largest upper part of the brain. It is a scaring portion of the brain which we can see easily when the brain is dissected. It is divided into two Hemispheres

a)    Left hemisphere

The left hemisphere is present at the left side of the brain but it regulates the right side of the body.

b)    Right hemisphere

the right hemisphere is present at the right side of the brain but it regulates the left side of the body.

Cerebral cortex

The cerebral cortex is the outermost layer of the cerebrum, or its grey matter. In humans, this grey matter has an uneven surface with many folds.

The cerebral cortex also contains four major lobes and each lobe contains its own set of functions.

• the frontal lobe
• the parietal lobe
• the occipital lobe
• the temporal lobe

In general, the cerebrum controls all voluntary actions. It is also the control centre for:

• sensory processing
• emotional control
• personality   
• learning
• problem solving
• language and speech
• visual information
• imagination
• creativity
• music interpretation.

Frontal lobe

Frontal lobe is present at the front of brain and it controls following functions of human body.

• speech
• behavior and personality
• emotions
• body movement
• intelligence and self-awareness

Parietal lobe

parietal lobe is present at the right side of brain and it controls following functions of human body

• language and symbol use
• visual perception
• sense of touch, pressure, and pain
• giving meaning to signals from other sensory information

Temporal lobe

Temporal lobe is present at the dorsal side of brain and it controls following functions of human body

• memory
• hearing
• understanding language
• organization and patterns

Occipital lobe

occipital lobe is present at the centre of brain and it controls following functions of human body

• light
• colour
• movement

2)    Thalamus

Thalamus lies just above the hypothalamus it guides stimuli towards the appropriate part of the cortex.

3)    Limbic system

limbic system is the emotional control centre of the body. It covers both sides of the thalamus under the cerebrum. Limbic system further divides into

a)    Hypothalamus

b)    Hippocampus

c)     Amygdala

 

Hypothalamus

The hypothalamus is a small region of the brain. It's located at the base of the brain, near the pituitary gland. While it's very small, the hypothalamus plays a crucial role in many important functions such as

·       Blood pressure

·       Body temperature

·       Homeostasis

·       Hunger

 

Hippocampus

The hippocampus is a small, curved formation in the brain that plays an important role in the limbic system. The hippocampus is involved in the formation of new memories and is also associated with learning and emotions.

Amygdala

The part of brain which is mainly associated with the emotional process. It produces sensation of pleasure, punishment and sexual arousal upon stimulation.

MID BRAIN

Mid brain is relatively very small and integrates sensory information like vision, odour as well as sensory information from spinal cord and pass them to froe brain

HIND BRAIN

The hindbrain is located at the back of the head and looks like an extension of the spinal cord. It consists of the following parts.

Cerebellum

It is very crucial part of brain present just below the cerebrum. It is responsible for muscle coordination. Cerebellum also assist the vision. Cerebellum plays role in learning new movements as well such as riding a bicycle, dancing, writing drawing etc.

Medulla oblongata

it lies just above the spinal cord and controls unconscious activities like breathing, heart beat blood pressure, coughing, sneezing, vomiting, hiccupping etc. these activities are also termed as reflexes.

Pons

pons lies on the ventral side of medulla oblongata. It helps in regulating facial muscle coordination, sleeping and awakening.

SPINAL CORD

 It is a thick, whitish butterfly shaped nerve cord that lies below the skull, extends down through the neural canal of vertebrae up to the hips.

In cross section, the spinal cord is differentiated into two areas, outer part called white matter an inner grey part called grey matter. The outer region consists of neurons while the inner consists of nerve fibres of grey matter.

Functions

 Spinal cord serves as an express way for signals between autonomic nervous systems and brain. It is also the control centre for many reflexes.

PERIPHERAL NERVOUS SYSTEM

The PNS is all the nerves that branch out from the CNS components and extend to other parts of the body to the sense organs, muscles, and glands.

The primary function of the peripheral nervous system is to connect the brain and spinal cord to the rest of the body and the external environment. The peripheral nervous system transmits information to and from the CNS.

There are two types of nerves arises from the peripheral nervous system.

1)    Cranial nerves

Cranial nerves are those which arise from brain and connects brain from different parts of the body. There are 12 pairs of cranial nerves

2)    Spinal nerves

Spinal nerves are major nerves of body arises from the spinal cord.

The PNS consists of somatic and autonomic nervous system

Somatic nervous system: it is associated with the voluntary control of the body movement and works with the skeletal system and glands of the body.

Autonomic nervous system: it is associated with the involuntary control of the body such as blood pressure, digestion respiration etc.