Brain

Question 1

What are the characteristics of the nervous system?

Answer 1

IRRITABILITY – responds to stimuli
CONDUCTION – transmits action potentials over long distances
INTEGRATION – can analyse and interpret information

Question 2

What are the basic components of a nerve cell?

Answer 2

Nerve cells consist of a cell body, dendrites that receive signals, and an axon for signal transmission.

Question 3

Differentiate between the central and peripheral nervous systems.

Answer 3

The central nervous system includes the brain and spinal cord, while the peripheral nervous system comprises nerves extending throughout the body.

Question 4

Define sensory and motor nerves.

Answer 4

Sensory nerves transmit signals from sensory organs to the central nervous system, while motor nerves carry signals from the CNS to muscles and glands.

Question 5

Explain the concept of specialised sensory nerve endings (receptors).

Answer 5

Receptors are structures at the ends of sensory neurons that detect specific stimuli, converting them into electrical signals for transmission.

Question 6

What factors influence the ability to localise a particular sensation?

Answer 6

The ability to localise a particular sensation depends on:-

1.Number of Receptors
2.Sensitivity of Receptors
3.Size and Arrangement of Receptive Fields

Question 7

Describe the adaptation of sensory nerve endings.

Answer 7

Sensory nerve endings adapt by decreasing their responsiveness to a constant stimulus, allowing the nervous system to focus on changes in the environment rather than constant stimuli.

Question 8

What is a receptive field?

Answer 8

The area of skin supplied by a single Sensory Neuron

Question 9

What is the function of the receptive field?

Answer 9

Each Receptive Field may contain many receptors

Each Sensory Neuron will give information about a specific area of the body surface

Question 10

What is two-point discrimination in the context of sensory perception?

Answer 10

Two-point discrimination refers to the ability to distinguish between two separate points of tactile stimulation on the skin.

Question 11

How does two-point discrimination vary across different regions of the body?

Answer 11

Two-point discrimination varies across different regions of the body due to differences in the density of sensory receptors.

Areas with a high receptor density, like the fingertips, lips, and tongue, exhibit better discrimination because each receptor has a smaller receptive field.

Areas with lower receptor density, such as the back, have poorer two-point discrimination.

This phenomenon is linked to the precision of spatial localisation in sensory perception.

Question 12

What factors contribute to the differences in two-point discrimination across body regions?

Answer 12

Receptor density - the size of receptive fields

Neural processing in the somatosensory cortex

Question 13

What are the basic structural features of the spinal cord, including white matter, grey matter, dorsal and ventral roots, and spinal nerves?

Answer 13

The spinal cord comprises of:

1. white matter (nerve fibers)
2. grey matter (neuronal cell bodies)
3. dorsal and ventral roots (containing sensory and motor fibers, respectively)
4. spinal nerves formed by the combination of these roots.

Question 14

Define white matter, grey matter, dorsal, and ventral roots, and spinal nerves.

Answer 14

White matter contains nerve fibres
Grey matter houses neuronal cell bodies
Dorsal roots carry sensory information into the spinal cord
Ventral roots transmit motor signals out
Spinal nerves are bundles formed by the combination of dorsal and ventral roots.

Question 15

What are the components of a reflex?

Answer 15

Reflexes consist of a sensory receptor - afferent neuron -integrating center (often in the spinal cord) - efferent neuron - effector organ.

Question 16

Provide an example of a simple spinal reflex, such as the stretch reflex.

Answer 16

The stretch reflex occurs when a muscle is stretched, activating sensory receptors (muscle spindles), leading to a rapid contraction of the muscle to prevent overstretching.

Question 17

What types of sensory information are conveyed by the two major ascending pathways?

Answer 17

The spinothalamic pathway transmits pain and temperature sensations

The dorsal column pathway conveys touch, pressure, and proprioceptive information (body position).

Question 18

Explain the functions of the major descending pathways, specifically the corticospinal and extrapyramidal pathways.

Answer 18

The corticospinal pathway controls voluntary movements

The extrapyramidal pathway regulates subconscious and reflexive movements.

Question 19

Describe the concept of the crossing of sensory and motor nerve pathways in the CNS.

Answer 19

Sensory pathways typically cross to the opposite side of the brain, ensuring that sensory information from one side of the body is processed in the contralateral hemisphere. Motor pathways, like the corticospinal tract, cross at the level of the medulla or spinal cord, leading to contralateral motor control.

Question 20

Give a general account of the main parts of the brain and their basic functions (cerebrum, diencephalon, thalamus, hypothalamus, midbrain, pons, medulla, cerebellum).

Answer 20

The cerebrum is responsible for movement and temperature
The diencephalon includes the thalamus (sensory relay) and hypothalamus (homeostasis)
The midbrain controls reflexes
The pons and medulla regulate vital functions
The cerebellum coordinates motor activities.

Question 21

Describe the locations of the functionally important regions of the cortex: - e.g. primary sensory, visual, auditory areas

Answer 21

Somatosensory in parietal lobe
Visual in occipital lobe
Auditory in temporal lobe.

Question 22

Describe how the different body parts are represented on the sensory and motor areas of the cortex

Answer 22

Motor areas control voluntary movements

Sensory areas process sensations from specific body regions.

Question 23

Give a simple account of the location and general function of the cranial nerves

Answer 23

Cranial nerves, located in the brainstem, serve various functions like sensory input (vision, hearing) and motor control (facial expressions, swallowing), connecting the brain to the head and neck.

Question 24

Describe the two fluids circulating in the brain - the cerebrospinal fluid (CSF) and the blood, and be familiar with the concept of the blood-brain barrier

Answer 24

Cerebrospinal fluid (CSF) circulates within the brain and spinal cord, providing cushioning and nutrient exchange. Blood, carrying oxygen and nutrients, is supplied to the brain. The blood-brain barrier regulates substance passage between blood and brain, maintaining a stable environment.

Question 25

Where do the cerebral arteries arise from?

Answer 25

The cerebral arteries arise from the Circle of Willis at the base of the brain