The Nervous System

Question 1

What is the structural organisation of the nervous system?

Answer 1

There are two subdivisions
1. The central nervous system (CNS)
- brain
- spinal cord
- lined by meninges
- surrounded by cerebrospinal fluid (csf)

2. the peripheral nervous system (PNS)
   The network of nerves outside the brain and spinal cord, connecting the CNS to the rest of the body
   - nervous tissue
   - cranial/spinal nerves
   - ganglia (groups of nerve cell bodies)
   - Nerve endings (innervaing tissue and organs)

Question 2

What are the functions of the nervous system

Answer 2

the nervous system performs a range of activties that can be grouped into 3 basic functions
- sensory function: collects and recieves information (input)
- integrative function: interprests and processes information
- motor function: elicits an appropriate response to information

Question 3

What are the cells of the nervous system

Answer 3

Glial Cells: support nourish and protect they include
- astrocytes
- macroglia
- satellite cells
- ependymal cells
- oligodendrocytes
- schwann cells
able to divide/ regenerate

Neurons:
- main dunctional cell of the nervous system
- unable to regenerate

Question 4

describe astrocytes:

Answer 4

• only found in the CNS
  key functions…
• creation of the blood brain barrier
• provide structural support
• responsible for scar formation following CNS injury

Question 5

Describe Microglia:

Answer 5

• found in CNS
  key functions…
• remove cellular debris and damaged nervous tissue, destroy microbes

Question 6

Describe Epindymal cells

Answer 6

• only found in CNS
  key function…
• production and circulation of cerebrospinal fluid

Question 7

Describe oligodendrocytes

Answer 7

• only found in the CNS
  key functions…
• wrap their processes around axons of neurons
• assist in conduction of action potentials down a neuron

Question 8

Describe satellite cells

Answer 8

• only found in the PNS
  key functions:
• support and protect neurons
• control extracellular environment

Question 9

Describe schwann cells

Answer 9

• only found in the PNS
  key function…
• assist in conduction of action potentials down a neuron

Question 10

Describe the structure of a neuron

Answer 10

Dendrites:
- sensors
- recieve information
Cell body (soma)
- houses nucleus and organelles
Axon
- pathway for electrical signalling
Axon terminal
- communication point
- site of synapse
Myelin sheath:
- insulating coat
- assists with speed of conduction
- nodes of ranvier are the gaps/ breaks between the myelin

Question 11

What is the neuron function

Answer 11

dendrites collect electrical signals

cell body integrates incoming signals and generates outgoing signal to axon

axon passes electrical signals to dendrites of another cell or to an effector cell

Question 12

What are the properties of a neuron

Answer 12

Excitable
- resoond to environmental changes
Conductive
- send electical signals
Secretory
- secrete neurotransmitters

Question 13

What are the structural classification of neurons

Answer 13

Unipolar
- a single process extending from the cell body
Bipolar
- two processes extending frim the cell body
Pseudonunipolar
- one process extending from the cell body that then splits into two
Multipolar
- multiple processes extending from cell body

Question 14

What are the 3 functional classifications of neurons

Answer 14

Motor Neurons:
- transmit signals from the CNS to PNS to effector organs
Sensory Neruons:
- recieve input/ detect changes in the environment
- transmut signal from PNS to CNS
Interneurons
- store and process information and reside within the CNS only

Question 15

describe the structural organisation of neuron to nerve

Answer 15

nerve = bundle of axons + associated connected tissue

from inside to outside…
Myelinated axon + schwann cell (wrapped in endoneurium)
inside
fasicle (wrapped in perineurium)
inside
nerve (wrapped in epineurium)

Question 16

How do neurons talk to each other

Answer 16

through action potential

Question 17

what are action potentials

Answer 17

electrical signals sent across the membrane

Question 18

How are action potentials sent

Answer 18

Action potentials move from one neuron to the next, across the synapse

Question 19

what is a membrane potential and how is it able to be altered

Answer 19

the difference in charge between the extracellular and intracellular environment of a cell

A neuron has…
ion gated channels
ion leakage channels
active ion pumps
in the plasma membrane that alter the charge of the membrane, altering the membrane potential

Question 20

How are there changes in the membrane potential

Answer 20

Voltage-gates channel: respon to changes in electrical charge active transport of sodium or potassium

Leakage channels: Always open or ‘leaking’ flows with concentration gradient (passive transport)

Sodium-potassium pump: uses ATP to continuously pump ions against the concentration gradient (active transport)

Question 21

How do action potentials happen and why?

Answer 21

Occur as a result of rapid change in the membrane potential

electrical impulse in response to specific change in the activity of the ion gated channels

Question 22

what are the stages of an action potential

Answer 22

1. resting
2. threshold
3. depolarisation
4. peak
5. repolarisation
6. hyperpolarisation

Question 23

What is a saltatory vs continuous conduction

Answer 23

Staltatory conuction only occurs myelinated neurons
- action potential jump and resart at each gaps in the myelin (nodes of ranvier)
- fast transmission

Continuous conduction only occurs in unmyelinated axons
- one single axon potential travels the entire way down the axon
- slower transmission

Question 24

what are the anatomical divisions of the brain

Answer 24

cerebrum
- left and right hemispheres
diencephalon
- thalamus
- hypothalamus
brainstem
- midbrain
- pons
- medulla oblongata
cerebellum

Question 25

What are the functional areas of the cerebrum

Answer 25

motor areas: initiate and control movements sensory areas: recieve and process information association areas: perform functions related to either sensory or motor areas

Question 26

what are the primary functional areas of the brain lobes

Answer 26

Frontal lobe: - primary motor cortex, relays signals to control bodily movements Paretal lobe: - primary somatoensory cortex, reciees and interprets sensory information Temporal lobe: - primary auditory cortex, processing all sounds and tones Occipital lobe: - primary visual cortex, recieves and interprets visual information

Question 27

What is the structure of the spinal cord

Answer 27

coloumn of nervous tissues that connects the brain and the PNS forms two way communication between the brain and the rest of the body contains different regions that correspond to areas of the body - cervical - thoratic - lumbar - sacral and coccygeal

Question 28

explain spinal nerves:

Answer 28

anterior/ ventral roots contain motor neurons posterior/ dorsal roots contain sensory neurons spinal nerves form where the anterior and posterior roots come together as they exit the spinal cord

Question 29

What are sensory receptors

Answer 29

sensory nerves carry information from the body (PNS) to the CNS

Question 30

what are the 5 sensory receptors?

Answer 30

1. thermoreceptors: detect temperature 2. mechanoreceptors: detect touch press, pressure, vibration 3. chemoreceptors: detect chemical stimuli 4. photoreceptors detect light 5. nocireceptors: detect pain