Chapter 5 + 6 Flashcards

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1
Q

Stimulus response model

A
Stimulus 
Receptor
Transmission of message/Control centre
Effector
Response
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2
Q

Cell signalling steps

A

Signal reception
Transduction
Response

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3
Q

Signal transduction

A

The cascade of events originating outside of the cell leading to a specific cellular response

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4
Q

Signal transduction basis

A

Amplification

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5
Q

Types of signalling

A

Autocrine, paracrine, synaptic, endocrine

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6
Q

Autocrine signalling

A

Secreting cell acts on itself by secreting hormone into extracellular fluid

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7
Q

Paracrine signalling

A

Secreting cell acts on nearby target cells by secreting hormones into extracellular fluid

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8
Q

Synaptic signalling

A

Nerve cell releases neurotransmitter into synaptic cleft, stimulating target cell

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9
Q

Endocrine system

A

System of ductless glands that produce hormones and release them directly into the bloodstream

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10
Q

Signalling molecules

A

Carry signals or messages from one cell to another

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11
Q

Hormones

A

Signalling molecule that is produced in an endocrine gland that is release into and transported via the bloodstream to target cells/tissues where it elicits a specific response

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12
Q

Internal environment

A

The fluid surrounding living cells within a multicellular organism

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13
Q

Examples of internal environment

A

Lymph, plasma, extracellular fluid, cerebrospinal fluid,

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14
Q

Plasma

A

The fluid portion of blood in which blood cells are suspended

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15
Q

How is extracellular fluid and plasma separated

A

Capillaries

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16
Q

Does internal/external environment vary much

A

Internal not much, external can

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17
Q

Cerebrospinal fluid

A

Fluid that bathes the brain and spinal cord

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18
Q

What exchanges occur between extracellular fluid and plasma

A

Passing nutrients, gasses, waste, glucose

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19
Q

What exchanges occur between extracellular fluid and cells

A

Nutrients, waste, glucose, amino acids

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20
Q

Intracellular fluid is

A

Cytosol

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21
Q

Homeostasis definition

A

The maintenance of a relatively stable internal environment within narrow limits

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22
Q

What’s involved in homeostasis

A

Detecting change, counteracting change

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23
Q

Variables controlled in body

A

Nutrients, blood volume, temperature, blood pressure, water, oxygen gas, ions, carbon dioxide gas, pH

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24
Q

Nutrients are required for

A

Energy, repair and growth

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25
Q

Two systems used to communicate and coordinate functions in body

A

Endocrine and nervous

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26
Q

Difference between hormone and neuron pathways

A

Speed, blood vs neurons, hormones longer lasting, hormones take longer time to respond to

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27
Q

Similarities with endocrine and nervous

A

Rely on chemical messengers

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28
Q

Negative feedback system

A

System of control in which change in a variable is detected and action occurs to produce a change in the opposite direction

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29
Q

Positive feedback

A

Physiological mechanism that enhances further change in a particular variable that provoked the initial change

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30
Q

Two ways signalling molecules cause cell to elicit a response

A

Pass through membrane, enter nucleus and bind to receptor

Bind to receptor in membrane, undergoes change in shape, second messengers, they travel along cell and activate other proteins which activates other proteins, until response occurs

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31
Q

cAMP

A

Cyclic adenosine mono phosphate

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32
Q

Three types of signalling molecules

A

Peptide, steroid hormones, amino acid derivatives signalling molecules

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33
Q

Hydrophilic

A

Peptide, amino acid derivative

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34
Q

Lipophilic

A

Steroid

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35
Q

Lifespan of steroid

A

Synthesised on demand, leaves by diffusion, long lifespans

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36
Q

Lifespan of protein and amino

A

Made in advance, stored, short lifespan, exocytosis

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37
Q

Exception

A

Thyroxine is hydrophobic

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38
Q

cAMP

A

Second messenger

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39
Q

Core temperature

A

Temperature of internal cells

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40
Q

pH of enzymes and nerve cells

A

Generally 7.4

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41
Q

Receptors

A

Chemical structures, often on the surface of cells that receive signals from hormones, neurons or cytokines

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42
Q

Target cells

A

Cells with appropriate receptors able to receive particular hormonal or nervous message

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43
Q

Second messenger molecule

A

Often protein, that acts as an intermediary in the transfer of message e.g. G protein

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44
Q

What happens after hormones have delivered message to target cells

A

Digested by enzymes

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45
Q

Detecting and responding

A
Production of signal
Detecting of signal 
Transfer of signal
Response 
Switching off signal
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46
Q

Endocrine signalling

A

Hormones act on cells

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47
Q

Pheromones

A

chemicals that, when released by one animal, elicit a response in another animal of the same species; in particular, act as a sex attractant for mating in many insect species

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48
Q

Pheromones are…

A

specific

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49
Q

Central nervous system (CNS)

A

in vertebrates, the brain and spinal cord.

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50
Q

Peripheral Nervous System (PNS)

A

in vertebrates, all nerve cells that in whole or part lie outside the brain and spinal cord.

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51
Q

Two divisions of the PNS

A

the sensory and motor divisions.

52
Q

Sensory (afferent) division

A

informs the central nervous system about the internal environment, via visceral sensory neurons, and about the external environment, via somatic sensory neuron.

53
Q

Motor (efferent) division

A

also called efferent division; part of nervous system that transmits nervous impulses from the central nervous system to muscles and glands.

54
Q

The sensory division is made up of the

A

somatic sensory neurons and visceral neurons.
Somatic sensory neurons - neurons that carry information to the central nervous system from the external environment via the sense. visceral sensory neurons: transmit information to the central nervous system from the internal environment of the body.

55
Q

Somatic sensory neurons

A

neurons that carry information to the central nervous system from the external environment via the sense. visceral sensory neurons: transmit information to the central nervous system from the internal environment of the body.

56
Q

Visceral sensory neurons

A

transmit information to the central nervous system from the internal environment of the body.

57
Q

What does the motor division do

A

transmits impulses away from the CNS to effector organs.

Effector organs - organs that respond to stimuli from the nervous system.

58
Q

Effector organs

A

organs that respond to stimuli from the nervous system.

59
Q

Somatic nervous system

A

also called voluntary nervous system; in vertebrates, group of nerves transmitting signals away from the brain and spinal cord to skeletal muscles.

60
Q

Autonomic nervous system

A

also called involuntary nervous system; in vertebrates, nerves that transmit messages away from the brain and spinal cord to smooth (involuntary) muscle, heart and various glands. Also called involuntary nervous system.

61
Q

The autonomic system has two parts

A

sympathetic and parasympathetic nervous system.

62
Q

Sympathetic nervous system

A

part of the autonomic nervous system that supports physical activity of the body.

63
Q

Parasympathetic nervous system

A

calms body down, maintains homeostasis, reverses effects

64
Q

Cell body

A

that part of a neuron that contains the nucleus.

65
Q

Axon

A

extension of a nerve cell along which impulses are transmitted away from that cell.

66
Q

Axons vary in length from…

A

a few millimetres to over a metre.

67
Q

Dendrites

A

branched extensions of nerve cell that transmit impulses to that cell.

68
Q

Myelin Sheath

A

fatty substance forming an outer covering around some axon. For speed and protection.

69
Q

Nerve

A

bundle of parallel axon and dendrite fibres surrounded by connective tissue.

70
Q

Three types of neurons

A

affector, effector and connecting neurons.

71
Q

Affector neurons

A

also called sensory neurons; type of nerve cell that transmits information about changes in external or internal conditions to the central nervous system.

72
Q

Effector neurons

A

also called motor neurons; type of nerve cell that transmits information from the central nervous system to muscle cells or glands.

73
Q

Connecting neurons

A

also called interneurons; type of nerve cell, located in the central nervous system, that links sensory and effector neurons.

74
Q

Reflex arc

A

stimulus, receptor/affector, CNS (interneurons), effector, response

75
Q

A nerve that is not responding to a stimulus is said to be

A

‘resting’ or ‘at rest’

76
Q

Nerve impulse

A

change that occurs in the electrical charge along a neuron membrane in response to a particular stimulus.

77
Q

Transmitter substance

A

compounds produced and released at the ends of axons e.g. acetylcholin

78
Q

Synapse

A

the junction between two neurons

79
Q

Neurotransmitter

A

chemical released by a neuron axon into the synaptic cleft between it and the target cell; stimulates or inhibits the target cell.

80
Q

Neurohormones

A

hormones released by the axon end of a neuron into the bloodstream.

81
Q

Pituitary

A

endocrine gland attached to the hypothalamus that influences the production of thyroxine by the thyroid.

82
Q

Antitoxins

A

protein produced by animals in response to toxin

83
Q

Anti-venom

A

chemical that acts to neutralise the effect of a venom.

84
Q

Meninges

A

membranous tissue surrounding the brain and spinal cord and separated from them by a thin layer of fluid.

85
Q

Thalamus

A

sensory information

86
Q

Hypothalamus

A

regulating body, hormones

87
Q

Venom vs toxin

A

venom is fluid injected by other animals, toxins are chemicals that are poisonous to organism

88
Q

Osmoregulation

A

maintenance of constant internal salt and water concentrations in internal fluids (homeostasis) in spite of different concentrations in the external environment.

89
Q

What would happen if cells couldn’t communicate

A

couldn’t have a stable environment

90
Q

Nerves

A

long pieces of tissue that transmit electrical messages extremely rapidly between tissues

91
Q

Action potential

A

when the axon hillock generates its own electrical transmission when the sum of the signals is sufficiently excitatory

92
Q

Process of action potential

A
  • The action potential is propagated rapidly through the axon until the synaptic terminal, where it transmits its signal to the next neuron or to another tissue. The myelin sheath makes the action potential travel faster along the axon.
  • excited, causes sodium pump send in sodium which increases voltage, sodium closes, then potassium pump sends ion which decreases voltage, potassium pump closes causing action potential to return to normal,
93
Q

Na/K pump

A

pump that transports Na+ ions out go the axon and K+ ions into the axon

94
Q

Na/K pump is made of a

A

protein

95
Q

What does Na/K pump do

A

ensures there is no build up of Na+ ions inside the axon and K+ ions outside the cell by pumping them back where they came from

96
Q

When extra Na+ ions are inside axon

A

they travel along the axon to the next segment of the axon, increasing the voltage there. Here there are NAVs that have not yet been activated. The increase in voltage causes these NaVs to open, leading to an action potential at that segment of axon. This causes an action potential in the next segment, and the next and so on. This is how the action potential is propagated along the axon.

97
Q

All action potentials are…

A

the same (either on or off)

98
Q

What is it called when all action potentials are the same

A

all or nothing effect

99
Q

Only thing that differs in action potential

A

frequency

100
Q

What happens to Na when K is opened

A

inactivated, can’t open

101
Q

Hyper-polarised

A

when it is just lower than normal

102
Q

Hyper-polarised definition

A

takes more stimulation than usual to propagate another action potential

103
Q

Absolute refractory period

A

just after Na channels close

104
Q

Relative refractory period

A

when voltage is lower than normal

105
Q

Where do neurotransmitters bind to next neuron

A

protein receptors in dendrite

106
Q

When reaches axon terminal

A

calcium channels activated, so Ca2+ ions enter act as vesicles of neurotransmitters (signalling molecules)

107
Q

Ca2+ is involved in release of

A

neurotransmitters

108
Q

When neurotransmitter binds

A

causes the voltage to increase, (excitatory signal), or decrease (inhibitory signal)

109
Q

What happens to neurotransmitter

A

immediately re-uptaken by synaptic terminal or digested by enzyme

110
Q

What happens if neurotransmitter not re-uptaken or digested

A

re-stimulates neuron,

111
Q

Auxin

A

growth and elongation, apical dominance (lateral buds don’t develop while shoot is growing)

112
Q

Tropism

A

growth

113
Q

Positive/negative tropism

A

positive grows towards, negative grows away

114
Q

Geotropism

A

gravity

115
Q

Phototropism

A

light

116
Q

Auxin goes away from

A

light

117
Q

Who did the coleoptile experiment for auxin

A

Darwin

118
Q

Cytokinins

A

growth and division of plant cells

119
Q

Gibberellins

A

growth and development of plant cells, seed germination

120
Q

Abscisic acid

A

inhibits plant growth and development, closure of stomata to prevent excessive loss of water

121
Q

Ethylene

A

ripening of fruit, abscission of leaves

122
Q

Florigen

A

controls flowering

123
Q

Important to remember about florigen

A

not considered a hormone

124
Q

Cell junctions

A

junctions that allow molecules to readily pass between adjacent cells without crossing membranes

125
Q

Cell-cell recognition

A

communication by interaction between molecules protruding from their surfaces