Category: Biology Second Paper

(i) It controls muscle tension of voluntary muscles.
(ii) Maintains body balance and posture.
(iii) It determines the direction of movement.

Two equal hemispheres coiled under the cerebral hemispheres are called cerebellum. The hemispheres are connected by two vermis. It is the largest part of the hindbrain. Its outer part is made up of gray matter and the inner part is made up of white matter. Its average weight is about 150 grams.

The posterior part of the brain is called the hindbrain. It consists of 3 parts. namely-
1. Cerebellum: Two equal hemispheres coiled under the cerebral hemispheres are called cerebellum. The hemispheres are connected by two vermis. It is the largest part of the hindbrain. Its outer part is made up of gray matter and the inner part is made up of white matter. Its average weight is about 150 grams.
Functions of the cerebellum
(i) It controls muscle tension of voluntary muscles.
(ii) Maintains body balance and posture.
(iii) It determines the direction of movement.
2. Pons: The thick band on the opposite side of the cerebellum is called the pons. It lies above the medulla oblongata.
Pons’ work
(i) It acts as a relay station between the nervous system and the brain.
(ii) It regulates the rate of respiration.
(iii) It coordinates muscle activity.
(iv) 5th-8th carotid nerves arising from the pons perform various functions of the body.
3. Medulla oblongata: The pyramidal shaped part located below the pons is called the medulla oblongata. Its length is about 3 cm, width 2 cm and thickness 1.2 cm.
Functions of the medulla oblongata
(i) It acts as a control center for respiration, digestion, constriction of blood vessels, secretion of saliva, heartbeat etc.
(ii) regulates blood pressure, defecation, alimentary canal peristalsis etc. (RRAR) Protects the connection between the brain and the nervous system.
(iii) It gives rise to the 9th, 10th and 11th carotid nerves and controls various functions.

(i) Maintains connections between forebrain and hindbrain.
(ii) It combines visual and auditory information.
(iii) It generates reports.

The fluid-filled narrow tube in the midbrain is called cerebral aqueduct. It connects the 3rd and 4th ventricles.

Two cylindrical parts on the lateral side are called cerebral peduncle.

The two spherical parts on the surface are called corpora quadrigemina. It is divided transversely to form four segments.

The small and compact area between the hypothalamus and the cerebellum is called the midbrain or mesencephalon. The midbrain consists of two spherical parts on the dorsal side and two cylindrical parts on the dorsal side.

The small and compact area between the hypothalamus and the cerebellum is called the midbrain or mesencephalon. The midbrain consists of two spherical parts on the dorsal side and two cylindrical parts on the dorsal side. It consists of three parts. namely-
1. Corpora quadrigemina: The two spherical parts on the surface are called corpora quadrigemina. It is divided transversely to form four segments.
2. Cerebral peduncle: Two cylindrical parts on the lateral side are called cerebral peduncle.
3. Cerebral Aqueduct: The fluid-filled narrow tube in the midbrain is called cerebral aqueduct. It connects the 3rd and 4th ventricles.
Functions of the Mesencephalon
(i) Maintains connections between forebrain and hindbrain.
(ii) It combines visual and auditory information.
(iii) It generates reports.

(i) It acts as a center of the autonomic nervous system.
(ii) acts as the center of hunger, thirst, sweat, sleep, anger, suffering, hatred, love, anxiety etc.
(iii) It regulates body heat.
(iv) It secretes ADH.
(v) It secretes two types of neurohormones namely vasopressin and oxytocin.
(vi) It regulates tropic hormone secretion with the help of neurohormones.