Chapter 5 + 6 Flashcards
(125 cards)
1
Q
Stimulus response model
A
Stimulus Receptor Transmission of message/Control centre Effector Response
2
Q
Cell signalling steps
A
Signal reception
Transduction
Response
3
Q
Signal transduction
A
The cascade of events originating outside of the cell leading to a specific cellular response
4
Q
Signal transduction basis
A
Amplification
5
Q
Types of signalling
A
Autocrine, paracrine, synaptic, endocrine
6
Q
Autocrine signalling
A
Secreting cell acts on itself by secreting hormone into extracellular fluid
7
Q
Paracrine signalling
A
Secreting cell acts on nearby target cells by secreting hormones into extracellular fluid
8
Q
Synaptic signalling
A
Nerve cell releases neurotransmitter into synaptic cleft, stimulating target cell
9
Q
Endocrine system
A
System of ductless glands that produce hormones and release them directly into the bloodstream
10
Q
Signalling molecules
A
Carry signals or messages from one cell to another
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
12
Q
Internal environment
A
The fluid surrounding living cells within a multicellular organism
13
Q
Examples of internal environment
A
Lymph, plasma, extracellular fluid, cerebrospinal fluid,
14
Q
Plasma
A
The fluid portion of blood in which blood cells are suspended
15
Q
How is extracellular fluid and plasma separated
A
Capillaries
16
Q
Does internal/external environment vary much
A
Internal not much, external can
17
Q
Cerebrospinal fluid
A
Fluid that bathes the brain and spinal cord
18
Q
What exchanges occur between extracellular fluid and plasma
A
Passing nutrients, gasses, waste, glucose
19
Q
What exchanges occur between extracellular fluid and cells
A
Nutrients, waste, glucose, amino acids
20
Q
Intracellular fluid is
A
Cytosol
21
Q
Homeostasis definition
A
The maintenance of a relatively stable internal environment within narrow limits
22
Q
What’s involved in homeostasis
A
Detecting change, counteracting change
23
Q
Variables controlled in body
A
Nutrients, blood volume, temperature, blood pressure, water, oxygen gas, ions, carbon dioxide gas, pH
24
Q
Nutrients are required for
A
Energy, repair and growth
25
Two systems used to communicate and coordinate functions in body
Endocrine and nervous
26
Difference between hormone and neuron pathways
Speed, blood vs neurons, hormones longer lasting, hormones take longer time to respond to
27
Similarities with endocrine and nervous
Rely on chemical messengers
28
Negative feedback system
System of control in which change in a variable is detected and action occurs to produce a change in the opposite direction
29
Positive feedback
Physiological mechanism that enhances further change in a particular variable that provoked the initial change
30
Two ways signalling molecules cause cell to elicit a response
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
31
cAMP
Cyclic adenosine mono phosphate
32
Three types of signalling molecules
Peptide, steroid hormones, amino acid derivatives signalling molecules
33
Hydrophilic
Peptide, amino acid derivative
34
Lipophilic
Steroid
35
Lifespan of steroid
Synthesised on demand, leaves by diffusion, long lifespans
36
Lifespan of protein and amino
Made in advance, stored, short lifespan, exocytosis
37
Exception
Thyroxine is hydrophobic
38
cAMP
Second messenger
39
Core temperature
Temperature of internal cells
40
pH of enzymes and nerve cells
Generally 7.4
41
Receptors
Chemical structures, often on the surface of cells that receive signals from hormones, neurons or cytokines
42
Target cells
Cells with appropriate receptors able to receive particular hormonal or nervous message
43
Second messenger molecule
Often protein, that acts as an intermediary in the transfer of message e.g. G protein
44
What happens after hormones have delivered message to target cells
Digested by enzymes
45
Detecting and responding
```
Production of signal
Detecting of signal
Transfer of signal
Response
Switching off signal
```
46
Endocrine signalling
Hormones act on cells
47
Pheromones
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
48
Pheromones are...
specific
49
Central nervous system (CNS)
in vertebrates, the brain and spinal cord.
50
Peripheral Nervous System (PNS)
in vertebrates, all nerve cells that in whole or part lie outside the brain and spinal cord.
51
Two divisions of the PNS
the sensory and motor divisions.
52
Sensory (afferent) division
informs the central nervous system about the internal environment, via visceral sensory neurons, and about the external environment, via somatic sensory neuron.
53
Motor (efferent) division
also called efferent division; part of nervous system that transmits nervous impulses from the central nervous system to muscles and glands.
54
The sensory division is made up of the
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
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.
56
Visceral sensory neurons
transmit information to the central nervous system from the internal environment of the body.
57
What does the motor division do
transmits impulses away from the CNS to effector organs.
| Effector organs - organs that respond to stimuli from the nervous system.
58
Effector organs
organs that respond to stimuli from the nervous system.
59
Somatic nervous system
also called voluntary nervous system; in vertebrates, group of nerves transmitting signals away from the brain and spinal cord to skeletal muscles.
60
Autonomic nervous system
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
The autonomic system has two parts
sympathetic and parasympathetic nervous system.
62
Sympathetic nervous system
part of the autonomic nervous system that supports physical activity of the body.
63
Parasympathetic nervous system
calms body down, maintains homeostasis, reverses effects
64
Cell body
that part of a neuron that contains the nucleus.
65
Axon
extension of a nerve cell along which impulses are transmitted away from that cell.
66
Axons vary in length from...
a few millimetres to over a metre.
67
Dendrites
branched extensions of nerve cell that transmit impulses to that cell.
68
Myelin Sheath
fatty substance forming an outer covering around some axon. For speed and protection.
69
Nerve
bundle of parallel axon and dendrite fibres surrounded by connective tissue.
70
Three types of neurons
affector, effector and connecting neurons.
71
Affector neurons
also called sensory neurons; type of nerve cell that transmits information about changes in external or internal conditions to the central nervous system.
72
Effector neurons
also called motor neurons; type of nerve cell that transmits information from the central nervous system to muscle cells or glands.
73
Connecting neurons
also called interneurons; type of nerve cell, located in the central nervous system, that links sensory and effector neurons.
74
Reflex arc
stimulus, receptor/affector, CNS (interneurons), effector, response
75
A nerve that is not responding to a stimulus is said to be
'resting' or 'at rest'
76
Nerve impulse
change that occurs in the electrical charge along a neuron membrane in response to a particular stimulus.
77
Transmitter substance
compounds produced and released at the ends of axons e.g. acetylcholin
78
Synapse
the junction between two neurons
79
Neurotransmitter
chemical released by a neuron axon into the synaptic cleft between it and the target cell; stimulates or inhibits the target cell.
80
Neurohormones
hormones released by the axon end of a neuron into the bloodstream.
81
Pituitary
endocrine gland attached to the hypothalamus that influences the production of thyroxine by the thyroid.
82
Antitoxins
protein produced by animals in response to toxin
83
Anti-venom
chemical that acts to neutralise the effect of a venom.
84
Meninges
membranous tissue surrounding the brain and spinal cord and separated from them by a thin layer of fluid.
85
Thalamus
sensory information
86
Hypothalamus
regulating body, hormones
87
Venom vs toxin
venom is fluid injected by other animals, toxins are chemicals that are poisonous to organism
88
Osmoregulation
maintenance of constant internal salt and water concentrations in internal fluids (homeostasis) in spite of different concentrations in the external environment.
89
What would happen if cells couldn't communicate
couldn’t have a stable environment
90
Nerves
long pieces of tissue that transmit electrical messages extremely rapidly between tissues
91
Action potential
when the axon hillock generates its own electrical transmission when the sum of the signals is sufficiently excitatory
92
Process of action potential
- 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
Na/K pump
pump that transports Na+ ions out go the axon and K+ ions into the axon
94
Na/K pump is made of a
protein
95
What does Na/K pump do
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
When extra Na+ ions are inside axon
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
All action potentials are…
the same (either on or off)
98
What is it called when all action potentials are the same
all or nothing effect
99
Only thing that differs in action potential
frequency
100
What happens to Na when K is opened
inactivated, can’t open
101
Hyper-polarised
when it is just lower than normal
102
Hyper-polarised definition
takes more stimulation than usual to propagate another action potential
103
Absolute refractory period
just after Na channels close
104
Relative refractory period
when voltage is lower than normal
105
Where do neurotransmitters bind to next neuron
protein receptors in dendrite
106
When reaches axon terminal
calcium channels activated, so Ca2+ ions enter act as vesicles of neurotransmitters (signalling molecules)
107
Ca2+ is involved in release of
neurotransmitters
108
When neurotransmitter binds
causes the voltage to increase, (excitatory signal), or decrease (inhibitory signal)
109
What happens to neurotransmitter
immediately re-uptaken by synaptic terminal or digested by enzyme
110
What happens if neurotransmitter not re-uptaken or digested
re-stimulates neuron,
111
Auxin
growth and elongation, apical dominance (lateral buds don’t develop while shoot is growing)
112
Tropism
growth
113
Positive/negative tropism
positive grows towards, negative grows away
114
Geotropism
gravity
115
Phototropism
light
116
Auxin goes away from
light
117
Who did the coleoptile experiment for auxin
Darwin
118
Cytokinins
growth and division of plant cells
119
Gibberellins
growth and development of plant cells, seed germination
120
Abscisic acid
inhibits plant growth and development, closure of stomata to prevent excessive loss of water
121
Ethylene
ripening of fruit, abscission of leaves
122
Florigen
controls flowering
123
Important to remember about florigen
not considered a hormone
124
Cell junctions
junctions that allow molecules to readily pass between adjacent cells without crossing membranes
125
Cell-cell recognition
communication by interaction between molecules protruding from their surfaces
