Theme 1: The Nerous System

Question 1

What is the organisation of the Central Nervous System?

Answer 1

Central nervous system
/ \
Peripheral nervous system Peripheral nervous system
- sensory afferent neurones - motor efferent neurones
- transmit somatic and viseral - transmit impulses from
Impulse to the CNS The CNS
/ \
Autonomic NS. Somatic NS
/ \
Sympathetic NS. Parasympathetic NS

Question 2

What does the central nervous system comprise of?

Answer 2

The brain
The spinal chord

Question 3

What does the peripheral nervous system comprise of?

Answer 3

Cranial Nerves
Sensory (afferent) nerves
Motor (efferent) nerves
Spinal nerves
The Somatic Nervous System
The Autonomic Nervous System

Question 4

What is the specialist cells in the nervous system?

Answer 4

Neurones

Question 5

What is the primary function of the of a neurone?

Answer 5

To transmit electrical impulses to the major structures throughout the body

Question 6

Label this diagram of a neurone

Answer 6

A - cell membrane
B - dendrites
C - cell body (soma)
D - axon
E - oligodendroycte
F - node of rangier
G - myelin sheath
H - synapse

Question 7

What are the functions of the cell body, the dendrites, the axon and the axon terminals in the neurone?

Answer 7

The cell body - contains the cells organelles to maintain function of the neurone

the dendrites - these structures protrude out of the cell body and collect electrical implied from other neurones

the axon - the axon carries electrical impulses down the axon terminal where synapse junctions are located, around the axon there is supporting structures called the myelin sheath > they help speed up electrical impulses, node of ranvier are the gaps in the myelin sheath

*the axon terminal** - contain the synapse junction whivh are the end point for electrical impulses to travel, the trigger neurotransmitters to cross the synapse junctions to another neurone / body tissue structure

Question 8

What are the three types of neurones?

Answer 8

Sensory - these have long dendrites and short axons.

Motor - these have short dendrites and long axons.

Relay - these have short dendrites and can have either short or long axons.

Question 9

What are the the different structures of neurones?

Answer 9

Unipolar - don’t worry only found in flies

bipolar - involved in sensory perception, found near sensory pathways committed to sight, smell taste and touch hearing and balance

pseudounipolar sensory neurons that have no dendrites, with one branch connecting from the cell body to peripheral regions e.g. skin, muscles joins and the other end connecting to spinal chord.

multipolar majority of all neurones in the body, include motor and relay neuournes within the brain and spinal cord.

Question 10

What are sensory neurones?

Answer 10

Also called afferent neurones, they help transmit sensory information from sensory receptors to the central nervous system, the brain translate these impulses to sensations such and hearing, tast

Most sensory neurones are pseudounipolar

Question 11

What are motor neurones?

Answer 11

Efferent neurones

Dedicated to carrying impulses from CNS to muscles to generate movement, they do this by real easing neurotransmitters to tigger muscle movement

Most are located in brain stem or spinal cord (part of CNS) and connects to muscles, glands and organs throughout the body > transmit signals to either directly or indirectly control muscle movement

Two types }
lower motor neurone (spinal cord > muscle of body)
Upper motor neurone (brain > spinal cord)

Multipolar

Question 12

What are relay neurones?

Answer 12

These neurons are also called interneurons, and these allow sensory and motor neurons to communicate with each other. Relay neurons connect various neurons within the brain and spinal cord, and are easy to recognize, due to their short axons.

Alike to motor neurons, interneurons are multipolar.

Question 13

What are the steps for an action potential

Answer 13

1. When the axon is not transmitting it sits at -70mV inside has a negative charge whilst outside has a positive charge due to more sodium ions in the Extracellular fluid (** polarised**)
2. depolarisation because of a neurotransmitters a sodium ions enter the cell, it slowly raises from -70mV to -55mV where the sodium-volted gated channels open and na+ rushes in the cell raising to +30mV hyper polarisation, like a domino effect the Na+ gates open down the cell.
3. ** repolarisation ** when it reaches 30+ mV the sodium-volted gated channels close allowing the potassium-gated channels to open allowing k+ to leave and voltage reduces
4. Resting potential by a sodium-potassium pump which pump 3 n+ back out the cell and 2 K+ into the cell NS back to -70mV

Question 14

What happens once to electrical impulse have travelled down the axon?

Answer 14

It reaches the axon terminal and the synapse junction between either two nerve cells or body tissue

Question 15

What happens during a synapse junction transmission?

Answer 15

1. When the electrical impulse arrives at the axon terminal, calcium volted-gated channels will open
2. Axon terminals contain vesicles that contain vesicles, that in turn contain specific neurotransmitter } either excitory which will carry on further APs or inhibitory neurotransmitter which slow down/stop APs

>excitatory pathway
3. When ca+ enters the axon terminal it triggers vesicles containing acetylcholine to move to the synapse junction, fuse with plasma membrane and realise NT into synapse junction

4. Will travel across the synapse junction to myocyte which will contain receptors specific to NT. Receptors open sodium gate for next AP

** >inhibitory pathway**
3. Inhibitory NT cross synapse in same way, instead of trigger NA+ it triggers CL- channels to open which lower resting potential and stops an AP from happening

Question 16

What is the central nervous system?

Answer 16

Brain + spinal chord

Primary function
1. Help maintain homeostasis
2. Control network for vital functions

Question 17

Brain sits in a layer of cerebrospinal fluid, what are the four subdivisions of the brain?

Answer 17

The cerebrum
The diencephalon
The cerebellum
The brain stem

Question 18

What is the cerebellum?

Answer 18

Largest portion of the brain contains the hemisphere lobes within the cortex and basal ganglia

1. Outer layer is the cerebral cortex, wiggly externa and folds
2. Where grey matter of neurones
3. Inner matter where myelinated white matter of neurons
4. Longitudinal fissure is largest fissure and separates brain into two hemispheres

Question 19

What is the left brain responsible for?

Answer 19

Sensory stimulus
Motor control of RIGHT side of body
Speech language and comprehension
Analysis and calculations
Time and sequencing
Recognition of words, letters and numbers

Question 20

What is the right hemisphere resposible for?

Answer 20

Sensory stimulus of Left side of body
Motor control of left side of body
Creativity
Spatial ability
Context / perception
Recognition of faces places and objects

Question 21

Label the four lobes of the brain

Answer 21

A - frontal lobe
B - Parietal lobe
C - the temporal lobe
D - Occipital lobe

Question 22

What is the 4 structures of the frontal lobe?

Answer 22

1. Prefrontal lobe - voluntary behaviours, social behaviour, intellegence thinking
2. Promotor area - planing and eduction of motor movements
3. Primary motor area - primary area for voluntary motor movement dedicated areas for specific body parts
4. Broca’s area - primarily focused on speech ability and motor movement of the facial muscles for verbal and non verbal comunications

Question 23

2hat the partial lobe responsible for?

Answer 23

Majority of sensory perception and spiritual awareness

Using ventral and coral visual visual pathways, helps us finger out where things are

Contains the somatosensory association area which interprets sensory information from the body like pain, touch, temp and pressure, each part of body has its own area (homunculus maps)

Question 24

What is the occipital lobe responsible for?

Answer 24

The occipital lobe is responsible for visual interpretation that comes from our eyes. It is able to interpret motions, shapes, colour and where we are (orientation). It does this through a structure called the primary visual area.

Question 25

What is the temporal lobe responsible for?

Answer 25

Memory

Hearing/ auditory capability - primary auditory area, homunculus mapping is done to distiningish different sounds

Helps which speech, language, smell, recounting personal information

Language comprehensive in the wernickes area

Question 26

What is the diencephalon three main structures? And its functions

Answer 26

1. Pineal gland - responsible for secreting melatonin and key role in sleep cycle, alertness and awareness.
2. The thalamus - sensory and motor relay station. Relays info from brain stem and distributes to correct lobes in brain. Movement, timing and attention
3. The hypothalamus
   - connects to autonomic nervous system and limbic system
   - managing thirst, hunger, emotions, body temp and circadian rhythms
   - connects to pituitary gland (ADH + oxytocin + adrenaline)

Question 27

What is the limbic system involved with?

Answer 27

Sense of smell, emotional regulation and memory formation

Question 28

What are the main structures of the limbic system?

Answer 28

• The olfactory bulb - smell! And relays to cerebrum
• the Amygdala - almond shaped responsible for emotional responses - interacts with hippocampus to have strong emotions with them
• the hippocampus - has 2 in each hemisphere, neurogenesis occurs here - the process of where new nerve cells are made from stem cells
• memory and learning and spatial navigation

Question 29

What health conditions in the limbic system often associated with?

Answer 29

Mental health conditions
Depression/anxiety

Question 30

What is the cerebellum?

Answer 30

The cerebellum acts as a motor calibration unit, ensuring that motor neural impulses are more precise and coordinated to where they need to go.

-responsible for helping us to stand and walk, because it ensures the motor electrical impulses travel directly to all muscle groups in the feet, legs, back and abdominal core.

Question 31

What is the importance of the brain stem?

Answer 31

The brainstem is the most important structure in the brain, lying deep within the base of the brain.

The brainstem further coordinates motor signals which help with reactions such as reflexes, and finer movements of the limbs and face. It also helps with many homeostasis autonomic functions, such as respiratory and cardiovascular control

Question 32

What are the three main parts of the brain stem?

Answer 32

1. The midbrain - helps with controlling eye movement, connects with spinal chord and cerebrum, descending neural pathways that connect the central brain to the spinal chord.
2. The pons - 11/12 cranial nerves that control facial movement, sensory information + fine tuning motor control, balance and posture + auditory information primarily enters through the pons + regulate breathing
3. The medulla - HOMEOSTATSIS, respiratory centre, autonomic/ reflux control of our breathing + vomiting centre + cardiovascular control
   directly links to spinal chord via axons

Question 33

What are the meninges?

Answer 33

Located outer layer of brain and its main role is to provide further protection for the brain

** the dura, arachnoid and the pia mater**

Question 34

What are the three layers of the meninges?

Answer 34

The dura - sits below the skull and is two fused layers made up of elastic tissue

<subdural>

The arachnoid space - sits under the dura, spider web like structure made up of fibrous tissue

<subarachnoid>

Pia mater this membrane that is expensed to the surface of the brain, capillaries penetrate the pia mater in order to allow o2 and nutrients.

</subarachnoid></subdural>

Question 35

What is the spinal chord designed to do?

Answer 35

To connect the medulla all the way down to the second lumbar vertebrae.
- connects CNS to the PNS,
- relays sensory info to brain for interpretation (pain touch, temp)
- transmission of efferent motor information from brain to muscles to help coordinate movement
- can coordinate reflex arcs

• White matter, which are myelinated axons of nerve cells, as found on the outer part of the spinal cord due to rapid transmission required to the brain. The grey matter, containing the cell body of nerve cells, allow for transmissions to cross the spinal cord depending on which spinal tract is needed to stimulate (information about the spinal tracts is below).*

Question 36

What are the protective layers of the spinal column?

Answer 36

Dura mater - found on the outside of the spinal column which lies underneath the vertebrae of the spinal plates. Unlike the brain, this dura mater contains adipose tissue and blood vessels.

Arachnoid mater - this is the middle protective layer and this layer is similar to the brain’s arachnoid space. It contains the subarachnoid space which is where you find cerebral spinal fluid passing through.

Pia mater - forms the final protective layer and faces the spinal.

Question 37

What is the Peripheral nervous system??

Answer 37

SENSORY AND MOTOR RESPONSES

**Efferent and affrerent neurones

Afferent - transmit sensory imput to the CNS

Efferent - transmit impulses from CNS to glands, muscles and organs**

12 pairs of cranial nerves.
31 spinal nerves.
Sensory (afferent) neurons.
Motor (efferent) neurons.
The Somatic Nervous System.
The Autonomic Nervous System - further split into:
Sympathetic Nervous System
Parasympathetic Nervous System

Question 38

What is the somatic nervous system

Answer 38

The somatic nervous system helps coordinate voluntary control of muscle groups

• triggered by the primary motor cortex which sends signals peripheral motor neurone to trigger voluntary movement

Question 39

What is the autonomic nervous system?

Answer 39

Coordinates autonomic functions such as homeostatsic mechanisms to maintain body

Split into two parts > sympathetic and parasympathetic nervous systems

Question 40

What are the two parts of the autonomic nervous system?

Answer 40

The sympathetic nervous system
flight or fight response

= is responsible for triggering motor responses that react to emotional or physical activity

• the release of hormones such as nor-adrenaline and adrenaline
• the release of glucose from energy stores
  > this results in blood flow to skeletal muscle and increased cardiac output due to higher heart contraction

This is why we feel increased heart rate when nervous

• the amygdala activates to more increase emotional responses and alertness

Question 41

What is the parasympathetic nervous system

Answer 41

Is triggered when body is at rest or sleeping, triggered by the realise of acetylcholine

• this means that the body is at rest can reduce metabolism to save energy stores or restore body function in preparation for further activity

Question 42

Difference between the sympathetic and parasymapthic nervous system on organs/systems

Answer 42

Question 43

What different influences of pain is there?

Answer 43

Environmental factors - how exposed an individual is to danger can shape our attitude to pain.

Upbringing and previous experiences - exposure to pain can influence the dynamics of how the body detects and/or modulates pain.

Genetic traits - genetic factors can influence the pain pathway in individuals.

Emotions - emotional responses can either amplify or reduce our pain perception.

Culture/Spirituality - different views about pain can shape how we feel about pain.

Age - pain perception like many things is a developing system, so age plays a crucial part.

Question 44

What is the pain perception pathway?

Answer 44

Transduction > transmission > perception > modulation

Question 45

What are nociceptors?

Answer 45

Are free nerve endings that are found throughout the skin, superficial tissues and the lining of every major organ except the brain

• sense noxious stimuli whether it is mechanical, thermal or chemical by sending action potentials through a dedicated network condition of afferent neurons

Question 46

What are the different types of nociceptors?

Answer 46

A-beta fibres - non-noxious mechanical stimuli such as touch

B- beta fibres - noxious mechanical stimulate that require rapid localisation to pain area (highly myelinated fibres)

C- fibres - thermal and chemical no is stridulate, unmyelinated so response is slower and allows voluntary control