2 - Biological Bases of Behaviour

Question 1

What is the nervous system and how is it structured?

Answer 1

Communication system which receives messages about our environment, monitors our body and sends messages to control and direct all that we do.

Two sections: CNS -> brain and spina cord, and PNS -> autonomic and somatic.

Question 2

Hindbrain

Answer 2

Location: Base of the brain near the back of the skull.

Function: Controls vital activities over which we have no conscious control, such as breathing.

Structures: cerebellum, medulla and pons.

Question 3

Cerebellum

Answer 3

Function: Receives messages from the sensory organs, spinal cord and other parts of the bain and uses this information to regulate posture and balance and coordinate fine muscle movements.

Damage: stumbling gait when intoxicated by alcohol.

Question 4

Medulla

Answer 4

Location: base of the hindbrain in front of the cerebellum.

Function: controls vital functions such as heart rate, breathing, digestion and swallowing.

Damage: life support

Question 5

Midbrain

Answer 5

Location: sits on top of the hindbrain under the cerebral hemispheres.

Function: acts like the brain’s sensory switchboard passing information from the spinal cord to the forebrain and vice versa. Receives messages from all the senses except smell and sends them on to higher brain regions that deal with hearing, seeing etc.

Also receives replies that it sends that it directs to the cerebellum.

Question 6

Reticular formation

Answer 6

Location: centre of the midbrain running from the forebrain to the hindbrain.

Function: Network of nerves one finger thick which screen oncoming information so that higher brain centres can attend to important information and not be overloaded with less important info.

RAS (reticular activating system) plays a role in controlling sleeping and levels of alertness by increasing or decreasing arousal level and muscle tone in response to feedback from the brain.

Question 7

Forebrain

Answer 7

Most highly developed and largest part of the brain, and is important for how we think, feel and behave.

Structures: hypothalamus, thalamus and cerebral cortex.

Question 8

Thalamus

Answer 8

Location: In line with our ears in the middle of our head.

Structure: 3cm and made up of two oval parts which sit side by side in the two hemispheres.

Function: filters info from all the senses except smell and passes it onto the appropriate part of the brain for processing. Also plays a role in regulating our level of arousal, by being connected to the RAS.

Damage: reduced sense of touch, or visual or hearing impairment. Arousal reduced.

Question 9

Hypothalamus

Answer 9

Location: below the thalamus.

Structure: small, about the size of a grape.

Function: Regulate the release of hormones controlling body temp, sex drive, biological clock etc.

Question 10

Cerebrum

Answer 10

Location: Comprises most of the forebrain, lying above and in front of the cerebellum.

Structure: Outer layer, the cerebral cortex and masses of neural tissue where nerves form connections. Split into the hemispheres separated by a deep groove.

Question 11

Cerebral cortex

Answer 11

Location: over and around most of the other brain structures.

Structure: wrinkled and is a soft pinkish-grey colour.

L and R hemispheres are almost symmetrical, with sensory and motor functions found in the same place in each hemisphere.

Question 12

Corpus callosum

Answer 12

Structure: thick band of fibres

Function: connects the two hemispheres of the cerebral cortex, which allows messages to be sent from one to the other.

Question 13

Left and Right Hemispheres specialisations

Answer 13

Left:

• Reception and processing of sensations from R-side
• Control of voluntary movements of the R-side
• Language-based tasks (speaking, reading)
• Analytical thinking and sequential processing

Right:

• Reception and processing of sensations from L-side
• Control of voluntary movements of the L-side
• Visual-spatial tasks
• Appreciation of art and music

Question 14

Frontal lobe

Answer 14

Location: at the front of each hemisphere.

Functions:
- Control of voluntary movement
- Abstract thinking
- Regulation of emotional behaviour
- Personality

Damage: personality change, capacity for problem solving and reasoning reduced.

Question 15

Temporal lobe

Answer 15

Location: Under the cerebral hemispheres.

Function: receive and process auditory information, both verbal and non-verbal.

Damage: language ability

Question 16

Occipital lobe

Answer 16

Location: at the back of the brain above the cerebellum

Function: Receive and process visual information such as shape, colour and motion.

Damage: vision

Question 17

Parietal lobe

Answer 17

Location: on top of the cortex

Function: receive info about touch, temp, position in space and muscle movement.

Damage: reduce in bodily feelings.

Question 18

Neuron

Answer 18

Type of cell which is specialised to receive, transmit and process information.

Question 19

What is the structure of a neuron?

Answer 19

• Cell body (soma): nucleus
• Dendrites
• Axon
• Myelin sheath
• Nodes of ranvier
• Axon terminals

Question 20

Neuron: cell body

Answer 20

Contains the nucleus that controls the maintenance and function of the cell.

Function: integrates info received from dendrites and passes it to the axon.

Energy needed for processes such as growth and repair is provided for by mitochondria in the cell body and the dendrites.

Question 21

Dendrites

Answer 21

Fine finger-like protrusions which receive oncoming info from other neurons and transmit it to the cell body. More = more info taken in.

Question 22

Axon

Answer 22

Function: passes info from cell body to other neurons or cells in glands or muscles.

Question 23

Myelin sheath

Answer 23

In motor and sensory neurons, interrupted periodically leaving gaps called Nodes of ranvier.

Function: speed up the transition of the electrical signal, and allow nutrients to enter the axon and waste to leave. Also protects the axon.

Question 24

Synaptic gap

Answer 24

Transmission of impulses occurs at synapses in the gap between the axon terminal and dendrite.

Here the electrical impulses are converted into a chemical signal that crosses the gap.

Question 25

Case study: Phineas Gage

Answer 25

- Help us to understand the relationship between brain structure and function - 1848 was a 25yr old railway worker. - Rod through his left cheek out the top of his skull, causing damage to his frontal lobes. - Change: polite, pleasant, hard-working —> loud, impulsive, moody and dishonest, less organised. - Now we know the frontal lobes are important for planning, self-control and personality.

Question 26

Stroke

Answer 26

Occurs when the blood supply to a part of the brain is cut off through a blockage or break in a cerebral artery. Some brain tissue dies. Diff. body functions are affected depending on where the stroke has occured.