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Biology A2 > Bio 4: Communication and homeostasis > Flashcards

Bio 4: Communication and homeostasis Flashcards

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1
Q

Stimulus

A

Any change in the environment that causes a response

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2
Q

Response

A

A change in behaviour or physiology as a result of a change in the environment

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3
Q

Good communication system

A
  • Cover the whole body
  • Enable specific communication
  • Rapid communication
  • Short term and long term
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4
Q

Homeostasis

A

maintenance of the internal environment in a constant state despite external changes

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5
Q

Negative feedback

A

Process that brings about a reversal of any change in conditions. Ensures the optimum steady state can be maintained, as the internal environment is returned to the original set of conditions after any change.

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6
Q

Positive feedback

A

Process that increases any change detected by the receptors. Tends to be harmful.

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7
Q

Ectotherm

A

Organism that relies on external sources of heat to regulate its body temperature

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8
Q

Endotherms

A

Organism that can use internal sources of heat, such as heat generated from metabolism in the liver, to maintain it’s body temperature

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9
Q

Sweat Glands (response to high temp)

A

Secrete more sweat onto skin, water in sweat evaporates, using heat from blood to supply latent heat of vaporisation

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10
Q

Hairs on skin (response to high temp)

A

Hairs lie flat, providing little insulation, thus more heat lost by convection and radiation

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11
Q

Arterioles leading to capillaries in skin (response to high temp)

A

Vasodilation allows more blood into capillaries near the skin surface; more heat can be radiated from the skin surface

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12
Q

Liver cells (response to high temp)

A

Rate of metabolism is reduced; less heat generated from exergonic reactions such as respiration

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13
Q

Skeletal muscles (response to high temp)

A

No spontaneous contractions

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14
Q

Thermoregulatory centre

A

In the hypothalamus, monitors blood temperature and any changes in core body temperature

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15
Q

Cones and rods

A

In the eye retina, detect changes in light intensity and wavelengtyh

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16
Q

Olfactory cells

A

In the nose, detect the presence of volatile chemicals

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17
Q

Taste buds

A

Detect the presence of soluble chemicals

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18
Q

Pacinian corpuscles

A

Detect pressure on skin

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19
Q

Sound receptors

A

Cochlea, detect vibrations in air

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20
Q

Proprioceptors

A

Detect length of muscle fibres

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21
Q

Transducers

A

Convert one energy form to another

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22
Q

Polarised membrane

A

A membrane with a potential difference across it. This is the resting potential

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23
Q

Depolarisation

A

The loss of polarisation across the membrane. The period when sodium ions entering the cell are making the inside less negative with respect to the outside.

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24
Q

Generator potential

A

Small depolarisation caused by sodium ions entering the cell

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25
Q

Action potential

A

Achieved when the membrane is depolarised to a value of about +40mV. The membrane depolarises and reaches a threshold level, sodiums enter and action potential is reached.

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26
Q

Motor neurones

A
  • Action potential from the CNS to an effector
  • Cell body in the CNS
  • Long axon
  • Numerous dendrites
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27
Q

Sensory neurones

A
  • Action potential from sensory receptor to CNS
  • Long dendron
  • Cell body outside of the CNS
  • Short axon
  • Numerous dendrites
28
Q

Resting potential

A

Potential difference across the cell membrane while at rest. This is about -60mV inside the cell compared with the outside.

29
Q

Voltage-gated channels

A

Channels in the cell membrane that allow passage of charged particles or ions. The gate opens and closes, when there is a change in potential difference across the membrane.

30
Q

Threshold potential

A

Potential difference of roughly -50mV, the depolarisation has to reach this value for an action potential to be generated

31
Q

Refractory period

A

The short period of time after firing during which it is more difficult to stimulate a neurone. Ensures that action potentials are only transmitted in one direction.

32
Q

Hyperpolarised

A

When the membrane is more highly polarised than the usual resting state. (More negative than -60mV)

33
Q

Local currents

A

Movement of ions along the neurone. The flow of ions is caused by an increase in concentration at one point, which causes diffusion away from the region of higher concentration.

34
Q

Myelin sheath

A

Insulating layer of fatty matieral, Sodium and potassium cannot diffuse through. Increases the speed of conduction.

35
Q

Saltatory conduction

A

Refers to the ‘jumping conduction’, where the action potential appears to jump from one node of ranvier to the next.

36
Q

Neurotransmitter

A

A chemical that diffuses across the cleft of the synapse to transmit a signal to the postsynaptic neurone

37
Q

Cholinergic synapse

A

Those that use acetylcholine as their transmitter substance

38
Q

Synaptic knob

A

A swelling at the end of the presynaptic neurone. It has many mitochondria for ATP production, large smooth ER, voltage gated calcium channels

39
Q

Synaptic cleft

A

Gap between the two neurones.

- 20 nm wide

40
Q

Post synaptic membrane

A

-Specialised sodium channels

These have five polypeptides. Two for acetylcholine, with specialised receptors.

41
Q

Acetylcholinesterase

A

An enzyme that is in synaptic cleft. It breaks down the transmitter substance acetylcholine. It hydrolyses it to ethanoic acid and choline. This stops the transmission of signals.

42
Q

Hormones

A

Molecules released by endocrine glands directly into the blood. They act as messengers, carrying a signal to a specific target organ or tissue. There are two types, steriod and protein or peptide hormones.

43
Q

Endocrine gland

A

A gland that secretes hormones directly into the blood. They have no ducts.

44
Q

Exocrine gland

A

A gland that secretes molecules into a duct that carries the molecules to where they are used. They do no secrete hormones.

45
Q

Adenyl cyclase

A

An enzyme associated with the receptor for many hormones, including adrenaline. It is found on the inside of the cell surface membrane.

46
Q

Adrenaline.

A

A hormone released by the adrenal glands medulla. It is an amino acid derivative. Effects include: increased heart rate, increased stroke volume, vasoconstriction, increase mental awareness, dilate pupils, stimulate glycogenolysis

47
Q

Steroid hormones

A
  • Mineralocorticoids (e.g. aldosterone) help control sodium and potassium levels in blood
  • Glucocorticoids (e.g. cortisol) help control the metabolism of carbohydrates and proteins in the liver
48
Q

Pancreas

A

Lying below the stomach, it has endocrine and exocrine functions. It has a pancreatic duct which carries fluid to the small intestines. This fluid has amylase, trypsinogen and lipase. It is also alkaline.

49
Q

Islets of Langerhans: alpha

A

Manufacture glucagon (hormone), which raises the blood glucose concetration.
+Glycogenolysis
+more fatty acids in respiration
+Gluconeogenesis

50
Q

Islets of Langerhans: beta

A 
Manufacture insulin (hormone), which lowers the blood glucose concentration
\+More glucose enters cell
\+Glycogenesis
\+Glucose to fats
\+More glucose for respiration
51
Q

Glycogenolysis

A

Glycogen to Glucose

52
Q

Gluconeogenesis

A

Amino acids and fats to Glucose

53
Q

Glycogenesis

A

Glucose to Glycogen

54
Q

Hyperglycaemia

A

State in which blood glucose concentration is too high

55
Q

Hypoglycaemia

A

State in which blood glucose concentration is too low

56
Q

Diabetes: Type I

A

Though to result from immune system attacking beta cells, and destroying them. Therefore insulin can no longer be produced, and excess glucose cannot become glycogen (glycogenesis). Normally treated by insulin injections.

57
Q

Diabetes: Type II

A

Insulin can still be produced, but the responsiveness to insulin has declined. This could be because the receptors on the liver and muscle cells decline, or the insulin level may decrease. Factors causing early onset: obesity, high sugar diet, family history. Normally treated by lifestyle changes.

58
Q

Myogenic tissue

A

Muscle tissue that can initiate its own contractions

59
Q

Pacemaker

A

A region of tissue in the right atrium wall that can generate an impulse and initiates the contraction of the chambers

60
Q

Medulla oblongata

A

Is found at the base of the brain. The region of the brain that coordinates the unconscious functions of the body such as breathing rate and heart rate

61
Q

Cardiovascular centre

A

Specific region of the medulla oblongata that recieves sensory inputs about levels of physical activity, blood carbon dioxide concentrations and blood pressure. It sends nerve impulses to the SAN.

62
Q

Accelerator nerve

A

Increases heart rate

63
Q

Vagus nerve

A

Decreases heart rate

64
Q

Heart rates factors

A
  • Movement of limbs
  • Exercise
  • CO2 concentration
  • Adrenaline
  • Blood pressure
65
Q

SAN

A

Sinoatrial node, region of tissue that can initiate an action potential, which travels as a wave over the atria walls

Biology A2 (8 decks)

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