Nervous Tissue- Week 10

Question 1

Describe how nerve cell’s structure and cytology are specialised for their role.

Answer 1

Specialised for sending & receiving
signals

Question 2

Identify the roles of glial cells.

Answer 2

Provide support functions
▪ Out number neurons 10 to 1

Question 3

what are the 4 domains (parts) of a nerve cell

Answer 3

• axon
• dendrites
• cell body
• pre-synaptic terminals

Question 4

what is the function of the axon in a nerve cell

Answer 4

Message sending – action potentials

Question 5

what’s the function of dendrites in a nerve cell

Answer 5

Info receiving area
▪ Covered with receptors

Question 6

what are the functions of the cell body of a nerve cell

Answer 6

Integrates inputs & generates signals
▪ Synthesis & processing of proteins

Question 7

what are the functions of the pre-synapse of a nerve cell

Answer 7

▪ Release of neurotransmitter (NT) – synaptic transmission
(Terminal of axon – multiple endings)

Question 8

what are the 4 Specialised cytology of nerves

Answer 8

▪ Large nucleus
▪ Abundant ER, mitochondria & lysosomes
▪ Well developed golgi complex
▪ Cytoskeleton (Neurofilaments, Microtubules)

Question 9

what are the glial cells found in the central nervous system (CNS) and there functions- give 3

Answer 9

• Astrocytes: provide nutrients,
  regulate conc. of ions, structural support, key cell in the blood-brain barrier
  -Microglia; scavenge & degrade dead cells,
  protect brain from microorganisms
  -Oligodendrocytes – form myelin sheaths in CNS

Question 10

what are the glial cells found in the peripheral nervous system (PNS) and there functions

Answer 10

• Satellite cells- provide nutrients & structural support
• Schwann cells – form myelin sheaths
  in PNS

Question 11

Identify the deflections in an action potential

Answer 11

Excitatory and inhibitory graded potentials cancel each other out- EPSP-IPSP cancellation
As the voltage difference between two electrodes (one in the neuron and one outside) changes, If the inside becomes more negative, compared to the outside, it cancels each other out and threshold isn’t reached

Question 12

what is the resting membrane potential inside a cell

Answer 12

-70 mV

Question 13

how is the Na+ and K+ concentrations maintained/ regulated

Answer 13

by ATP Na+/K+ pumps

Question 14

what ion is has the highest concentration in the:
1) intracellular fluid
2) extracellular fluid

Answer 14

1) Potassium ions
2) Sodium ions

Question 15

what is the number to reach threshold potential

Answer 15

-50 mV

Question 16

what happens in depolarisation

Answer 16

mass opening of sodium channels- travels down its conc as its stimulated down its conc into the intracellular fluid/enters the cell

Question 17

what happens in repolarisation

Answer 17

Sodium ion channels close
Potassium ions open
Potassium ions leave the cell- as its positive charge leaving the cell it causes the membrane potential to plummet

Question 18

what is the refractory period

Answer 18

its a period of time when the sodium ion channels can’t be stimulated again, they have to come out of the refractory period to be stimulated again
(stops us from having a continuous line of action potentials)

Question 19

what happens during hyperpolarisation

Answer 19

(when the charge of membrane declines too much- more than -70mV due to K+ leaving)
- some Potassium ion channels remain open
- ATP- Na+/K+ pump restores resting potential (Na+ pumped out & K+ pumped inside the cell)

Question 20

EPSP-IPSP cancellation

Answer 20

Excitatory post synaptic potential - Inhibitory post synaptic potential

Question 21

how are excitatory and inhibitory signals summated

Answer 21

-Spatial summation: excitatory potentials from MANY neurons trigger threshold
-Temporal summation: Many excitatory potentials from ONE neuron triggers threshold

Question 22

Compare and contrast chemical and electrical signals

Answer 22

▪ Chemical synapse – delay of ~1ms
▪ Electrical synapse faster

▪ Chemical synapse – delay of ~1ms
▪ Electrical synapse faster

▪ Chemical synapse – potential for
signal modulation
▪ Electrical synapse – signal relay

*similarity is that they both relay information