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Biology M5 > 14) Communication and Homeostasis > Flashcards

14) Communication and Homeostasis Flashcards

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1
Q

Why do animals need to respond to their environment

A

Increase chance on survival

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2
Q

How does communications occur between adjacent and distant cells

A

-Cell signaling

In nervous system , secrete neurotransmiters
In hormonal system , secrete hormones

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3
Q

Define homeostasis

A

Maintaining internal body coditions within constant limits

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4
Q

Why is it vital maintaining homeostasis

A

To allow cells to function normaly and stop them being damaged

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5
Q

Why is it important to maintain
Temperature
Glucose

A

1) Temperature affects enzyne activity , and they control the rate of metabolic reactions

2)So there is enough available for respiration

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6
Q

What is negative feedback

A

Mechanism where the body restpres level to normaal

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7
Q

what is positive feedback?
Give eg.

A

Amplifies the change , increase the level away from the normal level

eg. Platelets

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8
Q

Why is positive feedback not involved in homeostasis

A

It doesn’t keep internal environment constant

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9
Q

What is the CNA

A

The brain and spinal chord

Process information and decides what to do about it

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10
Q

What is a transducer

A

Converts one form of energy into another

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11
Q

What is a potential difference

A

Where there is a difference in charge between inside and outside of the cell

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12
Q

What causes a change in potential difference>

A

Cell membrane becomes excited, more permeable
allow more ions in and out of cell

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13
Q

What is the change in potential difference called?

A

Generator potential

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14
Q

Describe how pacinian corpuscles work

A

Mechanoreceptors - detect pressure and vibrations

Found in skin , contain end of sensory neurone.

When is stimulated , lamellae is deformed and cause deformation of stretch-mediated sodium channel.
Sodium ions channel open and sodium ions diffuse into the cell , creating a generator potential .
WHen generator potential reach a limit, it triggers an action potential

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15
Q

Whaat is the structure of a sensory neurone

A

Short dendrites
one long dendron
receptor to cell body
short axon carfy impulse from cell body to cns

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16
Q

Describe the structure of the motor neurone

A

Many short dendrites
Impulse from CNA to cell body
1 long axon
Cell body to effector cell

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17
Q

Describe the structure of a relay neurone

A

Many short dendrites
carry nerve from sensory to cell body
1 axon carry impulse from cell body to motorneurone

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18
Q

What is a neurone’s resting state

A

the outside of membrane is postively charges than the inside

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19
Q

What is the value of resting potential

A

-70

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20
Q

what created and mantain restinig potential

A

SOdium-potassium pumps
potassium ion channels

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20
Q

what created and mantain restinig potential

A

SOdium-potassium pumps
potassium ion channels

21
Q

What is the function of sodium potassium pumps

A

Move sodium ions out ,so they cannot diffuse back in.
Creates an electrochemical gradient

Move potassium ions into neurone . permeable to potassium so able to diffuse back out

22
Q

What happens to the cell membrane when there is a stimulus

A

Excites neurone
sodium ions channel open
sodium ions diffuse in down electrochemical grad
Inside is less negative

23
Q

What happens in cell membrane when depolarisation occur

A

when potential difference reach the threshhold (-55mv)
Voltage-gated sodium channels open
more sodium ions diffuse in
eg. of positive feedback

24
Q

What happens in cell membrane when repolarisation occurs

A

Potential difference of +30mv
Sodium ions close
Voltage-gate potassium ions open
Permeable to potassium so ions move out
back to resting potential

25
Q

What happens to cell membrane when hyperpolarisation occurs

A

Potassium ions close too slowly
becomes more negative than resting potential

26
Q

what happens to cell membrane when at resting potential

A

sodium-potassium pump returns membrane to resting potention and maintain until membrane’s excited by another stimulus

27
Q

Why cannot the cell membrane be excited again

A

ion channels are recovering and can’t be mmade to open .
Refractory period

28
Q

Describe why and how action potentials go faster in myelinated neurones

A

Myelin sheath - electrical insulator
High number of sodium ion channels at Nodes of ranvier
Depolarisation occurs at the nodes of ranvier
Hence allows saltatory conduction and is fasr
non-mylenated => slower

29
Q

What happens when an action potential triggers calcium influx

A

AP arrive at synaptic knob of presynaptic neurone
Stimulate calcium ion channels to open
Ca ions diffuse into synaptic knobe

30
Q

What does the release of calcium ions cause

A

Cause synaptic vesicles to move into presynapti membrane
fuse to presynapticc membrane
release neurotransmitter into synaptic cleft by exocytosis

31
Q

How does the neurotransmitter trigger an AP on post-synaptic neurone

A

Bind to specific receptors of post-synaptic membrane
cause sodium ions to open
influc of sodium ions cause depolarisation
neurotransmitter removed from synaptic cleft so response don’t keep happening

32
Q

What is an excitatory synapse

A

neurotransmitter depolarise post-synaptic membrane make an AP

33
Q

What is an inhibitory synapse

A

Neurotransmitter hyperpolarise post-synaptic membrane
preventing AP

34
Q

What is a synaptic divergence

A

one neurone connect to many neurones

35
Q

What is synaptic convergence

A

When many neurones connect to one neurone , info can be amplified

36
Q

What is spatial summation

A

Many neurones release excitatory neurotransmiters to a single neurone.

37
Q

What is temporal summation

A

2 or more impulses arrive right after eachother on the same neurne

38
Q

How does hormones bind to receptors and trigger second messenger

A

Hormone binds to receptor and actives enzyme in cell membrane
Catalyses a signalling molecule ( known and secondary messenger )
activate cascare inside the cell

39
Q

What happens when adrenaline acts as a first messenger

A

binds to cell membrane
activates adenylyl cyclase
cause production of secondary messenger - cAMP from ATP

40
Q

What happens in the Adrenal cortex

A

Secrete steroid hormones
Cortisol + aldosterone
breakdown proteins + fats into glucose
Inc blood volume + pressure
supress immune system

41
Q

what happens in the Adrenal Medulla

A

Protein hormones
**adrenaline + noradrenaline **
SHort term
inc heart/ breathing rate
glycogen-> glucose
Blood diverted to brain and musckes

42
Q

What hormone do alpha cells secrete
(pink cells )

A

glucagon

43
Q

What hormone do Beta cells screte
(purple cells)

A

insulin

44
Q

Describe how Ectotherms control temperature

A

Control by changing their behaviour
Internal temp depends on external temp
Activity level depends on external temp
Variable metabolic rate generate little heat

45
Q

Describe how Endotherms

A

Control by homeostasis
activity level independent when temp is wihtin limits
Constantly high metabolic rate so generate a lot of heat

46
Q

Summarise Type 1 Diabetes

A

No insulin is produced
Auto-immune disease
Destroy Beta Cells
Kidneys are unable to reabsorb glucose

47
Q

How can we treat Type 1 Diabetes

A

Insulin therapy
- REgular injections , insulin pump

-ISlet cell transplantation

-Diet , regular excersise

48
Q

Summarise Type 2 Diabters

A

Beta cells don’t produce enough insulin or body cannot respond to insulin
Often linked to obesity

49
Q

How can we treat type 2 diabetes

A

manage lifestyle changes
Medication
Insulin therapy

50
Q

Why is using GM bacteria to produce insulin better?

A

CHeaper
Larger quantities can be made
Less likely to trigger an allergic response

Biology M5 (6 decks)

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