GS notes on "Human Brain"

HUMAN BRAIN

The brain is the most complex part of the human body. This three-pound organ is the seat of intelligence, interpreter of the senses, initiator of body movement, and controller of behavior.

The brain can be divided into three basic units: 

1. The forebrain, 
2. The midbrain, and 
3. The hindbrain

The forebrain is the largest and main thinking part of the brain. It has regions which receive sensory impulses from various receptors. Separate areas of the fore-brain are specialised for hearing, smell, sight and so on.

• Cerebrum

The Midbrain connects the forebrain to the hindbrain. 

• Hypothalamous

The hindbrain controls the body’s vital functions such as respiration and heart rate.

• Pons
• Medulla
• Cerebellum

➽CEREBRUM [Largest part of the human brain]

• It sits at the topmost part of the brain. 
• It is the source of intellectual activities. 
• It holds your memories, allows you to plan, enables you to imagine and think. 
• It allows you to recognize friends, read books, and play games.
• It controls the voluntary motor actions.
• It is the seat of learning and memory.
• It is the site of sensory perceptions; like tactile and auditory perceptions.
• It is divided into two hemispheres; called cerebral hemispheres.

➽HYPOTHALAMUS 

• It lies at the base of the cerebrum. 
• It controls sleep and wake cycle (circadian rhythm) of the body. 
• It also controls the urges for eating and drinking.
• It gets the adrenaline flowing during a test or job interview. 

➽CEREBELLUM 

• It lies below the cerebrum and at the back of the whole structure.
• It coordinates the motor functions. 
• It is responsible for precision of voluntary actions and maintaining the posture and balance of the body.
• Example: When you are riding your bicycle; the perfect coordination between your pedaling and steering control is achieved by the cerebellum.

➽MEDULLA 

• It forms the brain stem; along with the pons. 
• It lies at the base of the brain and continues into the spinal cord. 
• It controls various involuntary functions 
• Example : heart beat, respiration, size of the pupil, blood pressure, salivation and vomiting etc.

➽THALAMUS

• a major clearinghouse for information going to and from the spinal cord and the cerebrum.

Cerebrospinal fluid (CSF) is a watery fluid that circulates through the brain's ventricles (cavities or hollow spaces) and around the surface of the brain and spinal cord. 

NEURON

Neurons are the core components of the brain and spinal cord of the central nervous system (CNS).

Functions of the three parts of a neuron:

➨Axon: It conducts messages away from the cell body.

➨Dendrite: It receives information from axon of another cell and conducts the messages towards the cell body.
➨Cell body: It contains nucleus, mitochondria, and other organelles. It is mainly concerned with the maintenance and growth.

SYNAPSE : It is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron.