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biology a level OCR > communication and homeostasis > Flashcards

communication and homeostasis Flashcards

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1
Q

what are the two types of cell signalling

A

neural and chemical

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2
Q

what is cell signalling

A

The way cells adjacent or distant communicate with each other is by cell signalling there are two communication systems (neural and chemical)

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3
Q

what is an example of cell signalling from communicable diseases?

A
  • in the humoral response, t helper cells bind to specific APC’s (clonal selection) before clonal expansion is triggered by cytokine, interleukin 1.
  • T helper cells then bind to specific B lymphocytes, stimulating plasma cell production by cytokine interleukin 2.
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4
Q

what is the nervous system

A

interconnected network of neurones that signal to each other across synapses via neurotransmitters.

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5
Q

what are neurones?

A

neurones are specialised cells, which can conduct electrical impulses very quickly to enable rapid response. e.g. reflexes.

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6
Q

what is the hormonal system

A

cell within the endocrine gland release hormones directly into the blood.

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7
Q

what is a hormone

A

it is a chemical messenger, which has a specific shape which is recognized by specific target cells.

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8
Q

what has longer responses, the hormonal or nervous system

A

the hormonal system

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9
Q

compare the nervous system to the hormonal system

A
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10
Q

outline 3 roles, of glycoproteins in membranes

A
  • antigen for cell recognition
  • binding site for hormones/neurotransmitters
  • receptors for cell signalling
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11
Q

give 5 examples of internal environment

A
  • blood pH
  • internal body temperature
  • blood water potential
  • blood glucose levels
  • blood pressure
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12
Q

give 5 examples of external environment

A
  • external temperature
  • humidity
  • atmospheric oxygen levels
  • pressure on the skin -> pain?
  • sudden loud bang
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13
Q

what is homeostasis

A

the maintenance of a constant internal environment, around a set point, despite environmental changes (interna and external)

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14
Q

what are examples of homeostasis

A
  • thermoregulation -> ensure optimum temp for enzymes
  • blood glucose concentration -> important for respiration + maintaining cells water potential
  • water potential of the blood
  • blood pressure -> to high and it could damage arteries
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15
Q

what is feedback

A

when effectors bring about a response they change the condition of the body and this new condition will be detected by receptors (i.e.. the input has changed) which in turn will affect the response)

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16
Q

what is positive feedback

A
  • the mechanism that increases a change, taking the system further way from the optimum
  • tends to be harmful
  • not involved in homeostasis
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17
Q

why is it necessary to control body temperature?

A

to ensure optimum temperature for enzyme activity ^ in temp, causes an increase in the number of successful collisions, -> to high of a temp means enzymes denature and tertiary structure changes (active site changes shape)

18
Q

what is the key to a good communication

A
  • cover the whole body so the action of all cells and tissues can be coordinated
  • enable localised communication between cells
  • enable long distance communication between cells
  • enable specific communication -> targets specific cell to respond only
  • be rapid -> allowing fast response to rapid changes
  • enable long term responses -> hormones
  • enable short term responses -> neuronal
19
Q

give an example of positive feedback

A
  • blood clotting -> platelets attract more platelets which accelerates clotting.
20
Q

what happens when we increase body temperature

A

hyperthermia - respiratory enzymes denature and organ failure occurs -> (heat + brain have very high energy demands)

21
Q

what happens when we decrease body temperature

A

hypothermia -positive feedback loop, i.e. as temp decreases rate of reaction ^

22
Q

what is core temperature

A
  • operating temperature inside of the body
23
Q

what is peripheral temperature

A
  • the temperature of the skin -> more variable, as influenced by the environment
24
Q

what are the key things to remember about endotherms (warm blooded)

A
  • use heat energy from metabolic reactions, to maintain body temp -> mammals have a high metabolic rate.
  • controls body temperature, within strict limits (set point)
  • uses a variety of methods to control temp, e.g. behavioural + physiological
  • activity level is largely independent of external temperature
25
Q

what are the key things to remember about ectotherms (cold blooded)

A
  • external sources of heat, to maintain temperature
  • unable to control internal temperature, and cannot increases there metabolism accordingly.
  • body temperature fluctuates with external temperature
  • activity level, depends on external temperature
  • more active when it’s warmer
  • likely to exploit a much narrower ecological niche, i.e. have a more specific role in an ecosystem.
26
Q

what will ectotherms do, if they are too cold

A
  • move to a sunny area, to bask in the sun
  • lie on warm surfaces
  • expose more of their body to the sun, to warm up
  • move around, to generate some heat energy -> contraction of muscles.
27
Q

what will ectotherms do if they are too hot

A
  • move out of the sun (seek shade)
  • move under - ground (burrow)
  • decrease the surface area exposed to the sun
  • increase the rate and depth of breathing, to loose water vapour by evaporation
28
Q

suggest why aquatic ectotherms, have relatively few problems in maintaining a stable body temperature

A
  • water has a high specific heat capacity, this means that a large amount of energy is needed in order to raise the temperature of the water by 1 degree, therefore, the temperature remains relatively stable at all times.
29
Q

what is the role of the hypothalamus - thermoregulatory centre

A
  • monitors blood temperature flowing through it via thermoreceptors.
  • receives impulses from the thermoreceptors in the skin
  • send impulses, via motor neurones to the sweat glands, and to the muscle in the arterial walls + to the skeletal muscles and hair erector muscles.
30
Q

what is the role of the sympathetic nerve

A

causes the release of sweat. (autonomic nervous system)

31
Q

shunt vessels, allow blood to bypass capillaries in the surface of the skin ->

A

+ reduce blood flow through the capillaries to reduce heat loss if you to hot, vasodilation of the arterioles increases blood flow in order to increase the amount of heat loss.

32
Q

what is the role of the thermoregulatory centre in the hypothalamus

A

to sense the temperature of blood, flowing through the hypothalamus.

33
Q

what is vasodilation

A

the widening of the blood vessels in order to increase blood flow

34
Q

what is vasoconstriction

A

the narrowing of the blood vessels in order to decrease blood flow

35
Q

describe and explain two physiological mechanism that would be initiated, following a decrease in core body temperature.

A
  • vasoconstriction of arterioles, to reduce heat loss from surface
  • shivering to generate heat from respiration.
36
Q

suggest why the ear provides a more accurate measurement of body temperature than the skins surface.

A

due to sharing its blood supply with the thermoregulatory system, thus meaning that the reading will be much closer to that of the thermoregulatory system, than that of the skin.

37
Q

what are the general features of a negative feedback mechanism

A

to help maintain the internal environment around a set point, furthermore receptors, detect change from that set point and effectors produce change.

38
Q

what are the symptoms of hypothermia

A
  • pale skin + cold
  • shivering violently
  • slow shallow breathing
39
Q

when can hypothermia be useful

A
  • gentle rewarming
  • heart surgery
40
Q

why would it be bad to give someone with hypothermia an alcoholic drink

A

due to alcohol leading to the vasodilation of blood vessels, which in turn will lead to further heat loss thus exacerbating the problem.

41
Q
A

biology a level OCR (32 decks)

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