Nervous system

Question 1

Human nervous system

Answer 1

Network of nerve cells and fibres which transmits nerve impulses between parts of the body.
It receives and processes sensory information from the environment, and transmits motor information around the body, that, in turn determines our reaction to environmental stimuli.

Question 2

Divisions of the nervous system.

Answer 2

1) Central Nervous System

2) Peripheral Nervous System

Question 3

Central Nervous System

Role of the brain and spinal cord

Answer 3

Composed of the brain and spinal cord.

The brain receives and processes information and co-ordinates a response.

The spinal cord connects the brain to the rest of the body. It sends information from the sensory neurons in various parts of the body to the brain and it relays motor commands back to muscles and organs via motor neurons.

Question 4

Peripheral Nervous System

Answer 4

Peripheral NS is connected to the spinal cord and consists of all the nerves outside the Central NS

It carries sensory information from the body to the Central NS and motor information from the Central NS to the body.

Consists of the Somatic NS and Autonomic NS.

Question 5

Somatic Nervous system

Answer 5

Transmits sensory information to the Central NS and carries out its motor commands
Involved with voluntary muscle movements

Question 6

Autonomic Nervous system

Answer 6

Carries information between the central NS and internal bodily structures (heart, lungs, glands) that carry out basic life processes

Divided into sympathetic and parasympathetic

Question 7

Sympathetic Nervous System

Answer 7

Readies the body for the fight, flight or freeze response when its exposed to threats.

E.G Stops digestion, increases heart rate, dilates pupils, diverts bloody away from the stomach to the muscles

Question 8

Parasympathetic Nervous System

Answer 8

Supports more mundane, or routine activities, that maintain the body’s store of energy (e.g regulating blood sugar levels, secreting saliva)

When the threat has passed the parasympathetic NS resumes control from the sympathetic NS

E.G heart rate lowers, blood pressure lowers, pupils constrict, stop sweating, digestion increases, bladder control

Question 9

Types of neurons

Answer 9

Sensory / afferent neurons: Transmits information from the sensory cells in the body to the brain. (Peripheral NS)

Interneurons: Provide links between the sensory neurons and motor neurons (organises and integrates) (Central NS)

Motor / efferent neurons: Transmits commands from the interneurons to the glands, organs and muscles of the body

Question 10

Anatomy of a neuron:

Dendrites role:

Answer 10

Receive input from other neurons.

Question 11

Anatomy of a neuron:

Cell body / soma role:

Answer 11

Includes a nucleus which controls the neuron.

Question 12

Anatomy of a neuron:

Axon role:

Answer 12

Transmits information to the other neurons.

Question 13

Anatomy of a neuron:

Myelin Sheath:

Answer 13

“Fatty covering” that insulates the axon from chemical and physical stimuli that might interfere with the transmissions of nerve impulses. Speeds up neural transmissions.

Question 14

Anatomy of a neuron:

Axon terminals role:

Answer 14

Allow for the branching out of the axon which contain synaptic knobs at the end of terminal.

Question 15

Anatomy of a neuron:

Synaptic knobs role:

Answer 15

Contains vesicles which hold neurotransmitters involved in moving signals to the adjacent cells.

Question 16

Anatomy of a neuron:

Synapse role:

Answer 16

The space between neurons where transmission occurs.

Question 17

What are the function of glial cells?

Answer 17

Provide the structural framework that enable a network of neurons to remain connected.

Supply nutrients and oxygen to neurons so they can function
Destroy and remove dead neurons
Soak up excess neurotransmitters at the synapse that can clog the communication between neurons.
Block the entrance of toxic barriers to the brain.

Question 18

Types of Glial cells:

Hint: AMOS -SS

Answer 18

Central NS:
Astrocytes, microglia, oligodendroglia

Peripheral NS:
Satellite cells, schwann cells

Question 19

Stages of neural communication

Answer 19

Resting potential, threshold, depolarisation (action potential), repolarisation

Question 20

What is resting potential

Answer 20

The neuron is not sending an electrical signal
The inside of the neuron is negative (relative to the outside) otherwise known as polarised
There a re more “positive” sodium ions outside the cell and more “negative” potassium ions inside the cell
The voltage inside the cell is -70mV

Sodium outside, potassium inside. Positive outside, negative inside

Question 21

What is threshold

Answer 21

An event (stimulus) causes the resting potential to move toward 0mV.
Neurotransmitters bind with receptors at dendrites, this increases the charge of the cell. When the charge reaches -55mV this causes sodium channels to open.
When the threshold is reached an action potential will always fire

(If neuron does not reach this critical threshold level, then no action potential will fire) ( All or nothing event)

Question 22

What is depolarisation (Action potential)

Answer 22

After the threshold has been reached depolarisation occurs. This is when positively charged sodium ions rush into the cell via sodium channels causing the cell to become positive.
Inside the cell rushes to +40mV (action potential)
This process is called depolarisation because cell which was polarised now reverses that polarisation
Process only occurs in one section of a cell at a time before triggering the adjacent section, this movement of a positive charge along the axon is called an impulse.

Question 23

What is repolarisation

Answer 23

After the action potential has occurred, the cell returns to its resting state.
Potassium channels open, potassium rushes out of the cell, reversing the depolarisation (repolarisation)
This starts to make the cell more negative so that it returns to resting potential.
Then sodium pumps remove the sodium and the cell eventually returns to resting potential.

The neural impulse (action potential) continues to travel along the axon until it reaches the terminal button.

Question 24

What is the lock and key process

Answer 24

Receptor sites are specifically designed to only bind with certain neurotransmitters. Their characteristic pattern allows them to match the pattern of the neurotransmitter like a lock matches a key. The receptor site has a complementary structure to the neurotransmitter.

Question 25

What effects do neurotransmitters have

Answer 25

Excitatory: they excite the post synaptic neuron to fire
Inhibitory: They inhibit the post synaptic neuron from firing

Question 26

What are the regions of the brain

Answer 26

Hindbrain, midbrain, forebrain

Question 27

What is the cerebal cortex

Answer 27

The largest region of brain and plays a key role in memory, attention, perception, cognition, awareness, thought, language and consciousness.

Question 28

The cerebral cortex is…

Answer 28

Convoluted (folded) - allows for greater surface area (0.25m squared) compared to volume
Divided into 2 halves called hemisphere

Question 29

What is the function of the cerebral cortex

Answer 29

Receiving and processing sensory information

Initiating motor responses

Question 30

Contralateral organisation:

Answer 30

Right hemisphere receives sensory info from the left hand side of the body and controls movements on left hand side of body

Question 31

What is gyri

Answer 31

The elevation points of the brain

Question 32

What is sulci

Answer 32

The folds or groove that seperate gyri

Question 33

Longitudinal fissure

Answer 33

Separates the 2 hemispheres in the cerebral cortex

Question 34

Specialised functions of the left hemisphere

Answer 34

Verbal functions: speaking, reading, writing

Analytical functions: Logical reasoning, critical evaluation

Non verbal: sensory and motor functions from the right hand side of the body

Question 35

Specialised functions of the right hemisphere

Answer 35

Spatial and visual thinking: jigsaws, recognising faces, creativity

Recognition of emotions relating to facial expressions

Sensory and motor functions from the left hand side of the body

Question 36

Corpus Callosum

Answer 36

Bridge of nerve tissue that connects the two cerebral hemispheres

Allows for communication between the two hemispheres