Chapter 5.1.3: Neuronal communication

Question 1

What’s one difference between relay neurones and motor neurones?

Answer 1

Relay neurones don’t have a myelinated sheath as faster transmission is not needed (Schwann cells minimise electrical loss)

Question 2

What do the specialised cells on receptor organs do?

Answer 2

Detect energy changes in the surroundings - known as energy transducers

Question 3

What are the axon and the axon hillock?

Answer 3

Axon = carries nervous impulses away from the cell body
Axon hillock = specialised region of tissue which triggers the production of nervous impulses

Question 4

How are neurons specialised to their function?

Answer 4

They’re long so they can transmit messages over long distances, they’re surrounded by a fatty sheath to insulate neurones and they have numerous dendrites to connect to other neurones

Question 5

What is the name of the receptor cell for touch and what form of energy is it received in?

Answer 5

Meissners corpuscles - kinetic

Question 6

What is the name of the receptor cell for smell and what form of energy is it received in?

Answer 6

Olfactory cells - chemical

Question 7

What is the name of the receptor cell for temperature and what form of energy is it received in?

Answer 7

Ruffins ending - thermal

Question 8

What is the name of the receptor cell for pressure and what form of energy is it received in?

Answer 8

Pacinian corpuscles - kinetic

Question 9

What is the name of the receptor cell for placement of limbs and what form of energy is it received in?

Answer 9

Proprioceptors - mechanical displacement

Question 10

What is the name of the receptor cell for balance and what form of energy is it received in?

Answer 10

Semicircular canals hair cells - kinetic

Question 11

What’s the resting potential of the neurone’s membrane?

Answer 11

-65mv

Question 12

Define spatial summation

Answer 12

two or more presynaptic neurones converge and release their NT at the same time onto the same post synaptic membrane

Question 13

Define temporal summation

Answer 13

two or more action potentials arrive in quick succession from the same presynaptic neurone

Question 14

In six steps, outline the process of synaptic transmission

Answer 14

1. action potential arrives = voltage gated calcium ion channels open
2. Influx of calcium ions = presynaptic vesicles to move toward the membrane and fuse - releasing NT into synaptic cleft.
3. NT diffuses across cleft and binds to subunits that bind to the receptor - opens sodium ion channels on post synaptic membrane.
4. Sodium ions flood into post synaptic membrane - excitatory post synaptic membrane.
5. NT broken down so that continual simulation of the PSM does not happen by enzyme
6. Broken down NT re enter presynaptic membrane by diffusion - using ATP they are recombined in secretory vesicles

Question 15

Define inhibitory

Answer 15

Hyperpolarise post-synaptic membrane - prevents AP being generated

Question 16

Define excitatory

Answer 16

Depolarise post- synaptic membrane - trigger AP

Question 17

Describe the 3 ways that drugs and poisons affect the synapse

Answer 17

1. Blocking NT receptors so AP’s aren’t generated
2. Preventing the removal of NT from the synaptic cleft
3. Destroying enzymes which breakdown the NT

Question 18

Name the poison obtained from plants, acting as a muscle relaxant and blocking Acetylcholine receptors

Answer 18

Curane

Question 19

How does cocaine affect the Nervous system?

Answer 19

Causes Noradrenaline to persist in synaptic cleft - blocks reuptake channels

Question 20

How does Sanin affect the Nervous system?

Answer 20

Destroys enzymes, inhibits Acetylcholinesterase - Acetylcholine builds up in cleft
Death occurs by asphyxiation

Question 21

What is the name of the toxic chemical that is used in rat poison, destroys Acetylcholinerase - leading to continual AP’s generated = convulsions = death?

Answer 21

Strychnine

Question 22

Name the 6 components of the nervous system

Answer 22

CNS, peripheral, autonomic, somatic, parasympathetic, sympathetic

Question 23

What are the 2 components of the CNS?

Answer 23

Brain and spinal cord

Question 24

What does the peripheral nervous system do?

Answer 24

Consists of sensory and motor neurones to carry impulses from receptors to CNS and impulses from CNS to effectors

Question 25

What's one difference between the somatic and autonomic nervous system?

Answer 25

Somatic = voluntary and autonomic = usually involuntary

Question 26

What state should the body be in when resting/digesting?

Answer 26

Parasympathetic

Question 27

What state does the sympathetic nervous system cause the body to be in?

Answer 27

Fight/flight

Question 28

What's the name of the membrane that surrounds the brain and what's its purpose?

Answer 28

Meninges membrane - secretes cerebral spinal fluid to act as a shock absorber

Question 29

What's the purpose of neurones?

Answer 29

To transmit action potentials

Question 30

Give an example of a glial cell

Answer 30

Schwann cells

Question 31

What NT is used in the parasympathetic nervous system?

Answer 31

Acetylcholine

Question 32

What two NTs are used in the sympathetic nervous system?

Answer 32

Noradrenaline and acetylcholine

Question 33

Where in the spinal cord do nerves leave from when the sympathetic nervous system is activated

Answer 33

all the way down

Question 34

Where is the medulla oblongata and what does it do?

Answer 34

Top of the spinal cord - Part of the brain that regulates breathing and HR

Question 35

How does the medulla oblongata carry out its function?

Answer 35

Sends out messages via the autonomic nervous system which cause the diaphragm and intercostal muscles to contract and relax regularly

Question 36

What is the cerebellum involved in?

Answer 36

control and coordination of movement and posture

Question 37

Where does the cerebellum receive information from?

Answer 37

CNS and sensory neurones

Question 38

What does the diencephalon consist of?

Answer 38

Hypothalamus and thalamus

Question 39

What does the hypothalamus do and how?

Answer 39

connected to pituitary gland - controls temperature - sends messages to the autonomic nervous system to control shivering and sweating

Question 40

Stating the stimulus, receptor, CNS response, effector and response, describe what happens to prevent damage to the eye

Answer 40

Stimulus - something touches the eye, receptor - sensory nerve endings in cornea, CNS - sensory neurone synapses with a relay neurone and then a motor neurone, effector - Orbicularis oculi muscles contract to shut the eyelid, response - eyelids close to protect eye

Question 41

Stating the stimulus, receptor, CNS response, effector and response, describe what happens when testing the knee reflex

Answer 41

Stimulus - quad muscles stretched, receptor, stretch receptors, CNS - sensory neurone synapses directly with a motor neurone , effector - quads contract, response - lower leg straightens

Question 42

What part of the brain do simple reflex arcs involve?

Answer 42

The unconscious part

Question 43

Give three ways that reflexes benefit our survival

Answer 43

They're innate, fast, involuntary

Question 44

What are three physical responses of fight/flight?

Answer 44

Increase in HR/stroke volume, constricting of blood vessels near skin/digestive tract and relaxation of smooth muscle