Neurons

Question 1

Dendrites

Answer 1

Receptors

Question 2

Soma

Answer 2

Cell body

Question 3

Axon Hillock

Answer 3

Impulse generating region

Question 4

Axon

Answer 4

Conducts electrical impulses away from the soma

Question 5

Schwann Cells/Myelin Sheath (Neurilemma)

Answer 5

Insulation for axon to prevent signal loss

Question 6

Nodes of Ranvier

Answer 6

Connection between two Schwann cells

Question 7

Axon Terminals

Answer 7

End that provides contact with another neuron (presynaptic)

Question 8

Sodium/Potassium Pump

• Steps (5)
• Ratio (Na+:K+)
• Resting voltage
• Permeability

Answer 8

1) 3 Na+ inside bind to “pump”
2) ATP to ADP + Pi
- Energy to change “pump” shape
3) 3 Na+ released outside
4) 2 K+ bond to “activated pump”
- Changes shape to original
5) 2 K+ released inside

• Ratio: 3Na+:2K+
• Net ratio = 1+ outside of cell
• Resting voltage = -70m/v (voltage inside - voltage outside)
• Resting cell membrane is more highly permiable to K+ and only slightly permeable to Na+ (ion channels)

Question 9

Neuromuscular Junction (Synapse) - Steps (5)

Answer 9

1) Influx of Na+ and Ca2+ ions into axon terminal
2) Ca2+ binds to vesicles with ACh inside - draws vesicles toward presynaptic membrane
3) Vesicles bind to presynaptic membrane and release ACh into synaptic cleft via exocytosis
4) ACh binds to ACh receptors on postsynaptic membrane causing Na+ channels to open, allowing Na+ to enter muscle cell
5) Once membrane has been depolarised enough, Ca2+ will start to enter muscle cell (voltage-gated calcium release).

• ACh = Acetylcholine

Question 10

Types of Summation (4 types)

Answer 10

• Subthreshold: membrane potential doesn’t reach threshold
• Temporal summation: 2 same signals in succession, reaches threshold
• Spatial summation: 2 different signals cause membrane potential to reach threshold
• Spatial summation of EPSP and IPSP: doesn’t reach threshold

Question 11

Muscular Contraction - Steps (7)

Answer 11

1) ACh released across synaptic cleft and attaches to ACh receptors
2) Na+ entry initiates action potential which propagates along sarcolemma and down T tubercles
3) Action potential in T tubercle activates voltage-sensitive receptors which release Ca2+ from sarcoplasmic reticulum
4) Ca2+ bind to troponin causing it to change shape which removes blocking action of tropomyosin from actin active sites
5) Contraction. Myosin heads attach and detach from actin. ATP powers this
6) Removal of Ca2+ by active transport after action potential ends
7) Tropomyosin blockage restored