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Biology > Communication and Homeostasis - Module 5 > Flashcards

Communication and Homeostasis - Module 5 Flashcards

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1
Q

cell signalling

A

the release of a chemical by one cell that is detected by another using a receptor
The 2nd cell carries out a response
This occours in the endocrine and nervous system

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2
Q

define Homeostasis

A

the maintenance of a constant internal environment

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3
Q

What has to be maintained theough homeostasis

A

-Body temp
-Blood glucose conc.
-Blood salt conc.
-Water potential of blood
-Blood pressure
-Carbon dioxide concentration

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4
Q

What in their environment to animals respond to

A

external + internal stimuli

E.g: Temp, glucose

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5
Q

What in their environment to plants respond to

A

external + internal stimuli

E.g: light intensity

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6
Q

stimuli =

A

internal + external changes in an environment

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7
Q

Receptors

A

-Detect stimuli
-specific to one particular stimulus
-Can be cells e.g: photoreceptors connected to nervous system or can be proteins on cells surface membranes

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8
Q

Effectors

A

Cells that bring about a response to a stimulus. Include muscles cells and cells found in glands

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9
Q

Negative feedback=

A

keeps things around normal level
a system reacts to a change in a way that pushes it back to its stable state

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10
Q

Process of negative feedback [mechanism]

A

-Receptors detect when a level (e.g glucose or temperature) is too high / low.
-This information is communicated by the nervous system or the hormonal system to effectors.
-The effecters respond to counteract the change, bringing the level down to normal

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11
Q

Positive feedback mechanism=

A

they react to a change in a way which amplifies it from a stable state

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12
Q

proces of positive feedback mechanism

A

-Receptors detect the change and the effectors respond by further increasing the level away from the normal level

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13
Q

is positive feedback involved in homeostasis

A

no as it doesn’t keep he internal environment at a constant

It is useful to rapidly activate bodily processes

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14
Q

2 examples of positive feedback and their basic description

A

1)Blood clotting- during formation of blood clot, platelets become active and release a chemical that triggers more platelets to be released

2) During childbirth - when head of baby presses against cervix, release of oxycotin is stimulated. Oxycotin stimulates uterus to contract, pushing the head of the baby harder towards the cervix, .: more oxycotin is released

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15
Q

what is an Ectotherm

A

Animals that can’t control their body temperature internally.

This means their body temperature depends on their surroundings.

They control their temperature by changing their behaviour

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16
Q

What is an Endotherm?

A

Animals that can control their body temperature internally by homeostasis

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17
Q

example of an endotherm

A

Mammals and birds

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18
Q

example of ecotherm

A

invertebrate, fish, reptiles, amphibians

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19
Q

Name 3 behavioural ways ecotherms warm up

A

Bask in sun

Conduction

exothermic metabolic activity

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20
Q

How do ecotherms bask in the sun

A

-orientate body so that max SA exposed to sun

Also extend areas of body- to absorb more radiation from the sun

eg: liards bask in sun long enough to be fast enough to catch prey
locusts spread wings

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21
Q

How do ecotherms use Conduction to warm up

A

Press body against warm ground

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22
Q

Example of ecotherm using exothermic metabolic activity to warm up

A

Galapagos Iguanas contract muscles to vibrate, increasing cellular metabolism

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23
Q

name 2 physiological ways ectotherms regulate temperature

A

-alter skin colour
-alter heart rate

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24
Q

advantages of being an ectotherm

A

Don’t need to use as much energy on regulating body temperature, so don’t ae to eat as much and can use energy for growth

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25
Q

Disadvantages of being an ectotherm

A

May be not capable of activity in winter so need to hibernate

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26
Q

How to Ectotherms cool down (behavioural)

A

-Shaellter from sun, sometimes using mud or water
-press body agains cold stones
-minimise SA to sun
-Minimise body movement

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27
Q

name 5 ways in which endotherms Cool down (physiologically)

A

-vasodilation
-Increased sweating
-large SA:V ratio
-Pilorelaxation (hair relax)
-Animals panting

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28
Q

name 5 ways in which endotherms Warm up (physiologically)

A

-vasoconstriction
-piloerection ( traps insulating layer of air)
-Shivering
-Raising feathers
- Release hormones such as adrenaline, require homeostatic system receptors to detect change

29
Q

Bhehavioural responses to a change in temperature for endotherms

A

-Wear clothes

-live in house

30
Q

disadvantage and a advantage of being an endotherm

A

(-) need more food

(+) Can survive without shelter

31
Q

Endocrine Gland

A

gland that secretes hormones directly into the blood

32
Q

Exocrine Gland

A

Gland that secretes substances into a duct which carries the molecule to where it is needed

33
Q

Pathway of hormonal control

A

Stimulus - Receptors - Hormone - Effectors - Response

34
Q

Different types of hormones

A

-Protein + peptide hormones (non-steroid)

-Steroid hormones

35
Q

Steroid hormones

properties, examples,

A

-Lipid soluble
-Can pass through membrane into cells and act directly on the DNA

-Testosterone, oestrogen, Progesterone

36
Q

Protein + peptide hormones (non-steroid)
properties, examples

A

-Derivatives of amino acids
-Not soluble so do not enter cell

-Adrenaline, insulin, glucagon, HGH, FSH, LH

37
Q

Process of thermoregulation after a rise in core body temperature caused by external temperature or exercise

A

-This is detected by the thermoregulatory centre in the hypothalamus and the peripheral temperature receptors in the skin
-Hypothalamus sends impulses to effectors which respond by causing Vasodilation of arterioles , sweating or panting,
-Core body temperature returns to normal

38
Q

what is a hormone

A

Molecule released by endocrine gland into the blood. Act as chemical messengers sending signals to a target/tissue cell

39
Q

when is Adrenaline released and where from

A

-Secreted from Adrenal gland when theres a low concentration of glucose in the blood, when you’re stressed or when you’re exercising

40
Q

how does Adrenaline cause a Response in Target tissue?

A

-Adrenaline = 1st messenger
-binds to specific receptors in cell membrane of many cells
-when adrenaline binds, it activates an enzyme in the membrane called adenylyl cyclase.
-Activated adenylyl cyclase catalyses production of secondary messenger = cyclic AMP (cAMP) from ATP
-cAMP activates a cascade of enzyme reactions

41
Q

what does the cortex of the adrenal gland do

A

uses cholesterol to make steroid hormones =
-mineralocorticoids (ALDOSTERONE) control sodium + potassium in blood
-Glucocorticoids (CORTISOL) help control the metabolism of proteins + carbohydrates in the liver

42
Q

What does the Adrenal medulla do

A

secretes Catecholamine hormones (modified amino acids) E.g: noradrenaline and adrenaline

43
Q

Effects of Adrenaline and Noradrenaline

A

Make energy available in the short term:
-Increase heart rate + stroke volume
-general vasoconstriction to raise blood pressure
-dilation of pupils
-increased mental awareness
-inhibits gut action
-body hair stands on end
-relaxes smooth muscle in bronchioles

-Cause cells to break down glucagon into glucose
-constricts some blood vessels so that blood is diverted to the brain and muscles

44
Q

\effects of cortisol and aldosterone

A

-Stimulates breakdown of fats and proteins into glucose
= increased energy available so brain and muscles can respond to situation

  • Increased blood volume and pressure by increased uptake op sodium ions and water into kidney

-Supress immune system

45
Q

What type of gland is the pancreas

A

acts as both an endocrine and exocrine gland

46
Q

when does the pancreas act as an endocrine gland?

A

in the regulation of blood glucose concentration, makes insulin and glucagon and releases them into the bloodstream

47
Q

when does the pancreas act as an exocrine gland?

A

in digestive system,

produces enzymes and releases them into the small intestines via a duct

48
Q

Islets of Langerhans

A

areas of the pancreas that contains endocrine tissue. Found in clusters around blood capillaries -> secretes hormones directly into blood

49
Q

properties of alpha cells and their role

A

-Secrete GlucAgon

-Larger and more numerous than Beta cells

50
Q

what di Beta cells secrete

A

Insulin

51
Q

what are the normal blood glucose levels

A
  • 90mg 100cm^-3
  • 4-6 mmol dm^-3
52
Q

how do alpha and beta cells react to a rise in blood glucose concentration above the normal value

A

Beta cells detect this
-alpha cells stop secreting glucagon and the beta cells secrete insulin into the blood plasma

53
Q

After insulin is secreted into the blood plasma, what does it bind to?

A

complementary receptors on the plasma membrane of hepatocytes and muscle cells

54
Q

after insulin binds to receptors on cells , what happens

A

This activates adenylyl cyclase enzyme, causing ATP to be converted into cAMP, the second messenger.

This causes a series of enzyme controlled reactions to start taking place inside the cell

55
Q

What enzyme controlled reactions to start taking place inside the cell due to Insulin ?

A

-higher uptake of glucose by the cells,
Due to glucose Channel proteins being inserted into the membrane
-glycogenesis (formation of glycogen)
-More glucose converted to fats
-more glucose used in respiration

56
Q

how do beta and alpha cells react to a fall in blood glucose concentration below the normal value

A

-alpha cells start secreting glucagon
-beta cells stop secreting insulin into the blood plasma

57
Q

After being secreted into the blood, what does Glucagon do?

A

binds to complementary receptors on plasma membrane of hepatocytes

58
Q

after glucagon binds to receptors, what happens

A

Liver cells respond by activating :
-Gluconeogenesis (formation of glucose from fatty acids or amino acids)
-Glycogenolysis (Breakdown of glycogen into glucose)
-less respiration of glucose

59
Q

name for diabetes

A

diabetes Mellitus

60
Q

what does Type 1 diabetes cause

A

-unable to produce insulin
-B cells in the Islets of Langerhans do not produce insulin

61
Q

what does type 2 diabetes cause

A

-Cannot effectively use insulin

either because:
-B cells don’t produce enough Insulin
-person’s body cells don’t respond properly to Insulin

62
Q

when is type 1 diabetes usually developed, why

A

in childhood

possibly due to autoimmune response where white blood cells attack Beta cells

possibly a genetic link

63
Q

Treatment of type one diabetes

A

-regular insulin injections
-test blood glucose levels (hyperglycemia = high blood sugar vs hypo)
-

64
Q

where did and now where do we get insulin to treat diabetes

A

-From pigs and cows

-Now from GM bacteria

65
Q

Cures for type 1 diabetes [Potential]

A

-pancreas transplant
-Injected totipotent stem cells, stimulated to create B cells

66
Q

Explain why person with Diabetes type 2 not responding to Insulin

A

-usually glycoprotein insulin receptor on cell membrane not working properly
=Cells lose responsiveness to Insulin so glucose stays in bloodstream

67
Q

Treatment for Diabetes type 2

A

-monitor diet, regulate carb and glucose levels
-Monitor exercise levels

If these don’t work:
-Metformin = usually first medicine to be perscribed,
-sulfonylureas
-Thiazolidinediones

68
Q

what do the blood insulin and blood glucose levels of a diabetic person look like ?

A

B Insulin = very low
B glucose = very High

69
Q

anticoagulant

A

medicines that help prevent blood clots.

Biology (45 decks)

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