CNS is the part of nervous system 1 hat com role whole body and itself. The central nervous system is consist of brain and spinal cord.
`text{(i) Brain}`
It: is the anterior portion of the CNS, which is in
the cranial cavity, cranium of the skull It weight from
1220 to 1400 grams Structurally, it consists of three
membranes (meninges)
• Piamater membrane Innermost thin, very delicate, vascular and inverts the brain closely. ·
• Arachnoid membra.ne outer to piamater thin, webby structure.
• Duramater membrme cutcrmost, tough membrane, adhering cosely tn the inside Brain have following parts.
`text{(a) Forebtrain}`
• It is the largest part of brain.
• It occupies 2/3 portion of brain.
• It is the main thinking part of brain.
• It consists of two parts, i.e. cerebrum and diencephalon.
• Cerebrum is the most developed part in human. It is divided into right and left cerebral hemispheres connected by corpus callosum.
• Cerebrum consists of many fold having small grooves (sulci), large grooves (fissures) and bulges between two (gyri).
• Diencephalon is consists of three parts, i.e. thalamus, hypothalamus and epithalamus.
• Thalamus controls emotions and memory.
• Hypotha.lamus control visceral activities. It helps to maintain homeostasis, control thirst, hunger, temperature, respiration, heartbeat.
`text{(b) Midbrain}`
• It is made of two parts, i.e. cerebral peduncle and corpora quadrigema. It lies between the hindbrain and forebrain.
• If consists of group of fibres that arouses the forebrain when something unusual happens.
• Midbrain is responsible for vision and heary.
`text{(c) Hindbrain}`
• It consists of the medulla, cerebellum and pons.
The medulla is the swelling at the tip of the brain that serves as the passage way for nerves extending to and from the brain.
• The pons is the swelling between the medulla and
midbrain. The pons acts as a bridge between various portions of the brain.
• Hind brain is responsible for muscular activities breathing, coughing, etc.
`text{(ii) Spinall Cord}`
• It extends from the base of the brain and is continuous to second lumbar vertebra. In adult, the spinal cord ranges from 42 to 45 em in length.
• It mainly lies in the neural canal of the vertebral column.
• It is basically the posterior part of CNS, which runs mid-dorsally within the vertebral column. The three meninges, i.e. du.ramater, arachnoid and piamater, which covers the brain, also continue over the spinal cord.
• The two indentations, i.e. posterior median calculus and the anterior median tissues separates the spinal cord into left and right haves.
• The inner area is the grey matter, while outside to it are white columns called the white matter.
Functions of Spinal Cord
(i) The stimuli passes from and to the brain through the spinal cord.
(ii) It also act as the centre of spinal reflex action.
2. Peripheral Nervous System (PNS)
• The nerves that originate from central nervous system connect either with receptor or effector organs from peripheral neural system.
• Nerves, which arises from brain are called cranial nerves while the nerves originating from the spinal cord are termed as spinal nerves.
• It relays impulse from the CNS to skeletal muscles. In human body there are 12 pairs of cranial nerves and 31 pairs of spinal nerves.
3. Autonomic: Nervous System (ANS)
It transmit impulse from the CNS to the involuntary organs and smooth mussed of the body. This system was discovered by Langley in 1921. It is further divided into two types
(i) Sympathetic Nervous System Accelerates heartbeat, enlarge pupils, supply blood to muscles, contract nerves of urinary bladder, lowers the intestinal digestion activities, helps in blood clotting, increased secretion of sweat glands, make breathing easier and promote liver to release sugar and decrease bile production are some activities controlled by this nervous system.
(ii) Parasympathetic Nervous System Works just analogs to the sympathetic nervous system, i.e. slows down heartbeat, dilates arteries and lower blood pressure, speeds up peristalsis, stimulate salivary gland secretion, contracts gall bladder, promotes pancreas for secretion, decreases the secretion of sweat glands, etc.
CNS is the part of nervous system 1 hat com role whole body and itself. The central nervous system is consist of brain and spinal cord.
`text{(i) Brain}`
It: is the anterior portion of the CNS, which is in
the cranial cavity, cranium of the skull It weight from
1220 to 1400 grams Structurally, it consists of three
membranes (meninges)
• Piamater membrane Innermost thin, very delicate, vascular and inverts the brain closely. ·
• Arachnoid membra.ne outer to piamater thin, webby structure.
• Duramater membrme cutcrmost, tough membrane, adhering cosely tn the inside Brain have following parts.
`text{(a) Forebtrain}`
• It is the largest part of brain.
• It occupies 2/3 portion of brain.
• It is the main thinking part of brain.
• It consists of two parts, i.e. cerebrum and diencephalon.
• Cerebrum is the most developed part in human. It is divided into right and left cerebral hemispheres connected by corpus callosum.
• Cerebrum consists of many fold having small grooves (sulci), large grooves (fissures) and bulges between two (gyri).
• Diencephalon is consists of three parts, i.e. thalamus, hypothalamus and epithalamus.
• Thalamus controls emotions and memory.
• Hypotha.lamus control visceral activities. It helps to maintain homeostasis, control thirst, hunger, temperature, respiration, heartbeat.
`text{(b) Midbrain}`
• It is made of two parts, i.e. cerebral peduncle and corpora quadrigema. It lies between the hindbrain and forebrain.
• If consists of group of fibres that arouses the forebrain when something unusual happens.
• Midbrain is responsible for vision and heary.
`text{(c) Hindbrain}`
• It consists of the medulla, cerebellum and pons.
The medulla is the swelling at the tip of the brain that serves as the passage way for nerves extending to and from the brain.
• The pons is the swelling between the medulla and
midbrain. The pons acts as a bridge between various portions of the brain.
• Hind brain is responsible for muscular activities breathing, coughing, etc.
`text{(ii) Spinall Cord}`
• It extends from the base of the brain and is continuous to second lumbar vertebra. In adult, the spinal cord ranges from 42 to 45 em in length.
• It mainly lies in the neural canal of the vertebral column.
• It is basically the posterior part of CNS, which runs mid-dorsally within the vertebral column. The three meninges, i.e. du.ramater, arachnoid and piamater, which covers the brain, also continue over the spinal cord.
• The two indentations, i.e. posterior median calculus and the anterior median tissues separates the spinal cord into left and right haves.
• The inner area is the grey matter, while outside to it are white columns called the white matter.
Functions of Spinal Cord
(i) The stimuli passes from and to the brain through the spinal cord.
(ii) It also act as the centre of spinal reflex action.
2. Peripheral Nervous System (PNS)
• The nerves that originate from central nervous system connect either with receptor or effector organs from peripheral neural system.
• Nerves, which arises from brain are called cranial nerves while the nerves originating from the spinal cord are termed as spinal nerves.
• It relays impulse from the CNS to skeletal muscles. In human body there are 12 pairs of cranial nerves and 31 pairs of spinal nerves.
3. Autonomic: Nervous System (ANS)
It transmit impulse from the CNS to the involuntary organs and smooth mussed of the body. This system was discovered by Langley in 1921. It is further divided into two types
(i) Sympathetic Nervous System Accelerates heartbeat, enlarge pupils, supply blood to muscles, contract nerves of urinary bladder, lowers the intestinal digestion activities, helps in blood clotting, increased secretion of sweat glands, make breathing easier and promote liver to release sugar and decrease bile production are some activities controlled by this nervous system.
(ii) Parasympathetic Nervous System Works just analogs to the sympathetic nervous system, i.e. slows down heartbeat, dilates arteries and lower blood pressure, speeds up peristalsis, stimulate salivary gland secretion, contracts gall bladder, promotes pancreas for secretion, decreases the secretion of sweat glands, etc.