nervous system

Question 1

nervous system

Answer 1

is a communication network+ control centre of body
- maintains homeostasis
- providing systems of internal communication and coordination

Question 2

cell body

Answer 2

contains nucleus + organelles (keeps neuron alive / functioning)

Question 3

dendrites

Answer 3

• short extensions of cytoplasm
  
  • carries nerve impulses into C/b
  • synapse w/ other neurons / receptors

Question 4

axon

Answer 4

long extension of cytoplasm
carries nerve impulses away from C/b
gap between 2 neurons ⇒ junction
connect with skeletal muscles
Connect with glands / other neurons

Question 5

synapse

Answer 5

junction between neuron : axon ↔ dendrite

Question 6

axon terminals

Answer 6

• extensive branches at the end of axon w/ tiny knobs
  
  • terminals at the end release neurotransmitter chemicals
    
    • into synapse of neuromuscular junction

Question 7

myelin sheath

Answer 7

fatty material called myelin sheath,-> refer axon have myelinated and unmyelinated (dont)

Question 8

schwan cells

Answer 8

forms myelin sheath to wrap axon

Question 9

Node of Ranvier

Answer 9

• gap along myelin sheath
• force impulse to flow (leap) from node → node (hence why myelinated neurons have faster neuron transmission than non-myelinated)

Question 10

role of myelin sheath

Answer 10

insulator, protection -> damage, speeds up movement

Question 11

functional types of neurons

Answer 11

sensory, motor, interneurons

Question 12

structural types of neurons

Answer 12

unipolar,bipolar, multipolar, pseudounipolar

Question 13

bipolar

Answer 13

cell body in middle, axon on one end/dendrite on other side, ear, eyes, nose (sensory neuron)

Question 14

unipolar

Answer 14

cell body ti one end, axon, dendrite on the other end, most common neuron

Question 15

multipolar

Answer 15

lots of dendrites , cell body on one end, axons and dendrites on other end

Question 16

pseudounipolar

Answer 16

have prop of unipolar+bipolar neurons , single axon from cell body-> sep in2 2 ext

Question 17

resting membrane potential

Answer 17

The inside of a neurone is more negative than the outside.

This is because potassium (K) ions move out while sodium (Na) ions move in, but at different rates.

The sodium-potassium pump maintains this balance by pushing

3 Na⁺ out and 2 K⁺ in.
This creates a polarised membrane, meaning it has a difference in charge across it.

Question 18

acton potenital

Answer 18

If the stimulus to a neuronee is sufficient enough, the signal will be passed along the neuronee.

Question 19

depolarisation

Answer 19

• sudden ↑ in m/p where the stimulus exceed 15 mV = threshold
• Na+ ligand-gated channels open, caused by stimulation by a neurotransmitter or sensory receptor
• Na+ ions diffuse into neuron ⇒ intracellular fluid becomes less -ve
  -membrane is depolarised

Question 20

repolarisation

Answer 20

• Na+ voltage-gated channels close, stopping influx of Na+ ions
• K+ voltage gated channels are opened = ↑ flow of K+ ions out
  -extracellular fluid +ve again ⇒ returning m/p to its resting state
  - membrane is repolarised
• K+ ions eventually close, but more K+ ions have left the neuron
  
  • making the resting potential more -ve (-90mV)
    -lowering resting m/p ⇒ hyperpolarisation

Question 21

refractory period

Answer 21

during a/P and immediately after, where that part of the neuron is unable to be stimulated again

Question 22

receptors

Answer 22

structure that Is able to detect a change in the body’s internal or external environment

• when stimulated, the body is able to respond to the change

Question 23

stimulus

Answer 23

stimulus- any change, internal or external that causes a response ( pleural= stimuli)

Question 24

thermorecpetors

Answer 24

detect change in temp, in skin+hypo

Question 25

osmoreceptors

Answer 25

changes in osmotic presure, in hypo+ maintain h2o balance

Question 26

chemorecpetors

Answer 26

detect chemcials- O,C02 PH LEVELS , nose,mouth, blood vessels

Question 27

touch recpetors

Answer 27

detect touch pressure, vibrations , in skin+ mucous membranes \ skin, respd to light touch, pressure

Question 28

pain receptors

Answer 28

detect tissue damage, innskin, mucous, and provide protective mechanisms

Question 29

reflexes

Answer 29

is a rapid, automatic response to a change in the external or internal environment 1. stimulus needed 2.involuntary 3rapid stereotyped

Question 30

spinal reflex

Answer 30

reflex carried out by the spinal cord alone

Question 31

spinal reflex arc

Answer 31

Pathway of nerve impulses from receptor to effector.

Question 32

learnt reflexes

Answer 32

- Innate Reflexes: Present from birth, genetically determined (e.g., sucking, blinking). - Acquired Reflexes: Learned through practice and repetition (e.g., balance while cycling).

Question 33

impulse transmission across synaptic cleft

Answer 33

1. When the nerve impulse reaches the axon terminal, it activates voltage-gated calcium ion channels. 2. as there is a higher concentration of ca ions in extracellular fluid , they flow into the cell at the pre-synpatic terminal 3. this causes synaptic vesicles to fuse with the membrane, casuing chemicals called neurotransmitters by exocytosis 4. the neutrotanmitter diffuses across the gap and attaches to receptors on the membrane of the next neuron 5. This stimulates ligand-gated protein channels to open, which allows the influx of sodium ions and initiates an action potential in the post-synaptic membrane.

Question 34

carrier proteins

Answer 34

- by active transport against concentration gradient w/ use of ATP - e.g. sodium - potassium pump for every ATP molecule the pump uses; 3 Na+ ions are moved out 2 K+ ions are moved into the neuron - net export of a single +ve charge per cycle - net reduction of +ve ions inside the cell

Question 35

membrane potential

Answer 35

- extracellular fluid w/ large amounts of Na+ ions and Cl- ions (low K+) - intracellular fluid w/K+ ions + large numbers of ve-charged proteins and other organic substances C/m is impermeable to negatively charged proteins and organic ions and so remains inside the cell - difference between the concentration of the ions in and out of the cell - m/p of a neuron not transmitting a nerve impulse can be measured

Question 36

unmyelinated

Answer 36

- exhibits continuous conduction Depolarisation of one area of the neuron membrane causes a local current flow between neighbouring areas on the membrane - process repeats along the whole length - travels along nerve fibre - refractory period prevents backflow - ions widely distributed on axon

Question 37

myelinated axons

Answer 37

- exhibits saltatory conduction - myelin sheath insulates the neurone, preventing ions from flowing through the mem. - action potential cannot form - depolarisation and the formation of the action potential at a N/R cause A/p to jump from one node→node (myelin is absent at nodes) - ~140 m/s (faster than ~2 m/s → unmyelinated)