Animal Physiology 1 Flashcards Preview

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Flashcards in Animal Physiology 1 Deck (66):
1

Who said 'constancy of internal environment is the condition of free life'

Claude Bernard

2

Who coined the term 'homeostasis'?

Walter Cannon

3

Why is it not good to link body temp. to homeostasis?

Ectotherms/endoderms regulate temperature differently

4

What is a cell's maintained resting potential?

-60mV - -80mV

5

How is resting potential measured?

using an intracellular microelectrode

6

What 2 factors are involved with maintaining homeostasis?

Unequal distribution of K+
Selective permeability of cell membranes to K+

7

How is cell resting potential maintained and established?

Sodium-potassium pump
K+ ion channel

8

How does the Na+/K+ pump work?

Uses energy (ATP) to move ions against their conc. gradient

9

In what ratio is Na+ exported and K+ imported?

3:2

10

How does K+ leave cell when channel is open?

Diffusion

11

How can K+ equilibrium be calculated?

Nernst equation

12

Which part of a neuron spikes?

axon

13

What kind of channels are in the axon?

voltage-gated

14

What kinds of channels are in the dendrites?

chemically-gated

15

What is a spike?

brief, pulse-like electrical event

16

How does a spike travel?

propagation

17

How long does a spike last?

1/1000th of a second

18

What is the function of a spike?

Amplifies electrical signal and carries electrical excitation along axon

19

What's occurring at resting potential?

K+ channels open
Membrane potential at constant value

20

Whats happening when threshold is reached?

Na+ channels open
Na+ enter neuron via diffusion
(this is the electrochemical gradient for sodium)

21

What happens in the rising phase?

More and more Na+ enter axon
Axon becomes less negative (~50mV)
Electrochemical gradient and conc. gradient are equal

22

Give an example of a model synapse?

Frog neuromuscular synapse

23

How is neurotransmitter released?

Excitation opens voltage gated Ca++ channels in presynaptic terminals
Ca++ enters cell causing strong electrochemical gradient
Increased Ca++ causes synaptic vesicles to fuse with pre-synaptic membrane

24

What organism is it very clear to see two axons involved in synaptic transmission?

Giant squid axon

25

What is evidence for neurotransmitter release and who did the study?

Llinas and Nicholson injected aequorin into pre-synaptic terminal while recording pre/post potentials

26

Who developed patch clamping?

Neher and Sakmann

27

What kind of channels does a PSP have?

chemically-gated

28

What are toxins used for?

Immobilise prey
Defence

29

Who looked into effect of curare on muscle?

Claude Bernard

30

What toxins target sodium-potassium pump? Where is it from?

Ouabain/Digoxin
Alkaloid found in foxgloves

31

What targets voltage-gated Na+ channels? Where is it from?

TTX - found in pufferfish

32

Who researched TTX? How does it work?

Hodgkin and Huxley
It blocks Na+ channel like a cork

33

What toxin inactivates Na+ channels?

Atracotoxin - made my Sydney funnel web spider

34

What targets voltage-gated K+ channels?

TEA
Apamine (bees)
Dendrotoxin (mambas)

35

What targets voltage-gated Ca++ channels?

Conotoxins

36

Who discovered cone shells and conotoxins?

Olivera

37

How does a cone shell release its toxin?

Harpoon-like radula

38

What toxins target neurotransmitter release?

Botulinum toxin - used in botox, blocks exocytosis
Black widow spider venom - uncontrolled exocytosis

39

What targets the neurotransmitter receptors?

Alkaloid curare - blocks nAch
Alpha bungarotoxin from Bungarus - sticks to nAch receptors

40

What are the neurotransmitters used in vertebrates and arthropods?

Vertebrates - acetylcholine
Arthropods - glutamate

41

What does a sensory cell do?

transduce physical or chemical information into electric signals

42

Name a model receptor cell

Crayfish abdominal stretch receptor

43

What is a proprioceptor

Sense organ that monitors the position or change in position of an animal's body parts

44

In crayfish, which type or stretch receptor adapts more strongly? Which is less strong?

Phasic - adapts more strongly, initial stretch causes many spikes then adaptation occurs

Tonic - sustains spikes throughout duration of stretch

45

What range of tone can humans hear?

10Hz - 20kHz

46

What range of tone can dogs hear?

40Hz - 60kHz

47

What range of tone can a bat hear?

20Hz - 150kHz

48

Where is the basilar membrane least stiff and widest?

the apex

49

What is a good model organism to see photoreceptor cells?

Necturus, a salamander

50

What are rod cells sensitive to?

broad colour
low light levels

51

What are cone cells sensitive to?

particular colours
good for detail in bright light

52

What is the dark resting potential?

-35mV

53

What absorbs light photons?

photopigment molecule Rhodopsin

54

What are rhodopsins made up of?

Opsin
11-cis-retinal

55

What is activated when a light photon is absorbed?

11-cis-retinal ---> all-trans-retinal
Transducing in disc membrane activated
Phosphodiesterase in disc membrane activated
cGMP hydrolysed

56

What is high in conc. in in the cytoplasm in the dark?

cyclic GMP - opens a sodium channel

57

Why is amplification necessary?

high sensitivity in low light conditions

58

Why is adaptation important?

Allows photoreceptors to work in a range of light intensities

59

What organism is a model for image processing?

Limulus - horseshoe crab

60

What do mirror neurons respond to?

The site of objects moving in particular ways

61

Which part of the brain is associated with facial recognition?

Temporal lobe

62

Who established centre-surround receptive field?

Kuffler

63

Who theorised that neurons in the visual cortex respond to light/dark sports poorly but lines or edges vigorously

Hubel and Wiesel

64

What is integration?

Neuron combines different PSPs it receives, enables nervous systems to make decisions

65

What are the two types of integration?

Spatial
Temporal

66

What organism is an invertebrate model for control of behaviour and why?

Aplysia californica

Large neurons, gill withdrawal through siphon structure as a response form touching to protect gill, uses temporal and spatial summation