Biology Unit 4.6 - The Brain

Question 1

What is the brain?

Answer 1

Located within the skull covered by meninges, where cerebrospinal fluid supplies the brain neurons with oxygen and nutrients produced in ventricles

Question 2

What are the three main regions of the brain?

Answer 2

• Forebrain - cerebrum, thalamus, hypothalamus
• Midbrain - nerve fibres connecting hind and forebrains
• Hindbrain - medulla oblonata, cerebellum

Question 3

What are ventricles?

Answer 3

Spaces filled with cerebrospinal fluid that supply the neurones with oxygen and glucose

Question 4

What is the cerebrum?

Answer 4

Structure divided into two hemispheres connected by a bundle of nerves called the corpus callosum, where the cotex is the outer layer composed of grey matter, and the inner area is composed of white matter

Each hemisphere has four lobes:
* Frontal - reasoning, planning, part of speech and movement, emotions and problem solving
* Parietal - somatosensory functions and taste
* Temporal - language, learning and memory
* Occipital - vision

Question 5

What is the function of the cerebrum?

Answer 5

Integrates sensory functions and initiates voluntary motor functions, which is also responsible for learning, reasoning, personality, and memory

Question 6

What is the hypothalamus?

Answer 6

Main control region of the autonomic nervous system, linking the brain to the endocrine system, via the pituitary gland, which regulates body temperature, blood solute concentration, thirst, hunger and sleep

Question 7

What is the thalamus?

Answer 7

Relay centre sending information to and from the cerebral cortex

Connects with other areas of the brain, forming the limbic system

Question 8

What is the hippocampus?

Answer 8

Interacts with other areas of the cortex, involved with learning, reasoning, personality, and consolidating memories into a permanent store

Connects with other areas of the brain, forming the limbic system

Question 9

What is the cerebellum?

Answer 9

Coordinates precision and timing in voluntary muscular activity, posture and learning motor skills

Question 10

What is the medulla oblongata?

Answer 10

Controls heart rate, ventilation and blood pressure, and contains important centres of the autonomic nervous system, while connecting the brain to the spinal cord

Question 11

What is the autonomic nervous system?

Answer 11

Controls automatic functions of the body by the antagonist activity of the sympathetic and parasympathetic nervous systems

Question 12

What is the sympathetic nervous system?

Answer 12

Uses noradrenaline to produce stimlatory effects, preparing the body for activity (fight-or-flight)

Originates in the thoracic and lumbar regions of the spinal cord, which connects to many organs in the body

Question 13

What is the parasympathetic nervous system?

Answer 13

Uses acetylcholine to produce inhibitory effects, promoting restorative body functions, which is more discrete in its actions (rest and digest)

Originates from the brainstem as cranial nerves III, IX, and X, and the sacral region of the spinal cord, which connects to many organs

Question 14

What is the cerebral cortex?

Answer 14

Outer layer of the cerebrum (2-3mm deep) which is highly folded to increase surface area for information processing, composed of millions of neurons and is grey matter with many cell bodies

Question 15

What is the function of the cerebral cortex?

Answer 15

Responsible for most conscious thoughts and actions

Question 16

What are the three functional areas of the cerebral cortex?

Answer 16

• Somatosensory cortex
• Somatomotor cortex
• Association areas

Question 17

What is the somatosensory cortex?

Answer 17

Receive nerve impulses from receptors

Located in the parietal lobe and integrates sensory functions from the opposite side of the body

Question 18

What is the somatomotor cortex?

Answer 18

Sends nerve impulses to appropriate effectors via motor neurons

Consists of three regions:
* Primary - located in the frontal lobe in front of the somatosensory cortex
* Premotor - located in the front of the primary motor cortex
* Secondary - located in front of the premotor cortex

Neurons cross over in the medulla oblongata and innervate the effectors on the opposite side of the body

Question 19

What are association areas?

Answer 19

Form most of the cerebral cortex, and receive impulses from sensory areas and associate it with previously stores information from memory so it can be interpreted and given meaning to initiate appropriate responses, which are passed to motor areas

Question 20

What are sensory and motor homunucli?

Answer 20

Show relative proportions of the sensory and motor areas of the body

Sensitive areas with many sensory neurons are large e.g., the tongue, lips, etc, while areas with many motor neurons can perform intricate movements e.g., the hands and face

Question 21

What is Broca’s area?

Answer 21

Located in the frontal lobe, just above the temporal lobe, only in the left hemisphere

Motor neurons from here innervate the muscles involved with producing speech

Damage to the area, means speech can be understood but speaking is in short sentences, lacking fluency

Question 22

What is Wernicke’s area?

Answer 22

Area that spans the upper part of the temporal lobe and the lower part of the parietal in the left hemisphere

Responsible for interpreting written and spoken language

Damage to this area means that speech cannot be understood but fluency is unaffected

Question 23

What is the arcuate fasciculus?

Answer 23

White matter tract that runs parallel to the superior longitudinal fasciculus

Connects Wernicke’s and Broca’s area