Brain

Question 1

Brain

Answer 1

The brain is an enlarged, upper part of the spinal cord enclosed in a bony cranium
- it’s like a mushroom, the cap being the cerebrum and the stalk being the brain stem
- at the back, near the top of the brain stem is a bump, the cerebellum
- the lower part of the brain stem is known as the medulla oblongata

Question 2

Cerebrum

Answer 2

• The largest part of the brain, divided into two cerebral hemispheres by a longitudinal fissure.
• the hemispheres are held together by a mass of myelinated nerve fibres, bundled together to form the corpus callosum. Corpus = body, callosum = white. This provides for communication between the central hemispheres and between the cerebral cortex and lower part of the CNS

Question 3

Function of the cerebrum

Answer 3

1. The motor area in the frontal lobe is where all the voluntary movements of the body originate
2. The sensory areas that receive and interrupt impulses from the sense organs:
   - hearing, tasting and smelling in the temporal lobe
   - sight in the occipital lobe
   - skin sensations
3. The association cortex is involved with higher mental activities such as intelligence, memory, perception, language and consciousness

Question 4

Cerebellum

Answer 4

• lies below the cerebrum
• made up of two hemispheres
• named the “tree of life” because white matter looks like branches of a tree

Question 5

Functions of the cerebellum

Answer 5

The cerebellum receives sensory input from the motor region of the cerebrum, the eyes, muscle spindles and the organs of balance in the ears:
1. It processes this info to co-ordinate the actions of the voluntary muscles, so that complicated physical actions can be performed in a smooth, controlled way
2. It is partly responsible for controlling muscle tone
3. Using info from the inner ear, it helps to maintain posture and balance

Question 6

Hypothalamus

Answer 6

Part of the brain lies below the thalamus and above the pituitary gland

Question 7

Functions of hypothalamus

Answer 7

1. Plays an important part in maintaining homeostasis by regulating body temp, water balance and thirst, food intake, sleep-wake cycles
2. Centre for emotional response and behaviour
3. Controllers the functioning of the pituitary (hypophysis) by:
   - secreting hormones like ADH
   - controlling the release of all hormones from both lobes of the pituitary

Question 8

Medulla oblongata

Answer 8

Forms the lowest part of the brain stem

Question 9

Functions of the medulla:

Answer 9

1. Serves as a pathway for impulses to and from the brain
2. Acts as the reflex centre, controlling important reflexes such as heartbeat, breathing, blood pressure (by regulating vasodilation and vasoconstriction, vasodilation is the widening of blood vessels and vasoconstriction is the narrowing of blood vessels), swallowing and peristalsis
3. Controls less important reflexes such as sneezing, coughing, hiccoughing and salivating.

Question 10

What is the cerebrum made up of

Answer 10

• the surface of the cerebrum is made up of a large number of folds (gyri) and grooves (sulci) that enlarge the surface area so that a large amount of brain cells can fit into a small cranial cavity.
• there are four cavities known as ventricles in the centre of the brain. They are filled cerebrospinal fluid.
• the outer 3mm of the cerebrum forms the cerebral cortex. This is made up of a collection of cell bodies of neurons and forms what is called grey matter.
• below the grey matter is an area of white matter made up of a collection of myelinated nerve fibres.

Question 11

Cerebral cortex/ white and grey areas

Answer 11

• the outer 3mm of the cerebrum forms the cerebral cortex. This is made up of a collection of cell bodies of neurons and forms what is called grey matter.
• below the grey matter is an area of white matter made up of a collection of myelinated nerve fibres.