coordination & response Flashcards
2.80 - 2.95B
1
Q
2.80 animals and plants respond to what
A
changes in their environment
2
Q
2.80 why do animals and plants need to be able to respond to changes
A
to coordinate the activities of their different organs
3
Q
2.80 what are examples of internal / external environment changes
A
changes in temperature or pH
4
Q
2.80 in order to function properly and efficiently organisms have
A
different control and communication systems that ensure their internal conditions are kept relatively constant
5
Q
2.81 physiological control systems maintain what
A
the internal environment with restricted limits through a process known as homeostasis
6
Q
2.81 what is homeostasis
A
the maintenance of a constant internal environment
7
Q
2.81 two examples of homeostasis
A
body water content and body temperature
8
Q
2.81 why is homeostasis critically important
A
it ensures the maintenance of optimal conditions for enzyme action and cell function
9
Q
2.81 examples of physiological factors that are controlled by homeostasis in mammals include
A
core body temperature
metabolic waste (e.g. carbon dioxide and urea)
blood pH
the concentration of glucose in the blood
the water potential of the blood
the concentration of respiratory gases (carbon dioxide and oxygen) in the blood
10
Q
2.81 homeostatic mechanisms in mammals require
A
information to be transferred between different parts of the body
11
Q
2.81 what are the two communication systems in mammals that require information to be transferred to different parts of the body
A
the nervous system
the endocrine system
12
Q
2.81 homeostasis is what
A
the control or regulation of the internal conditions of a cell or organisms
13
Q
2.81 examples of homeostasis of internal conditions
A
water content (of an individual cell or of the body fluids of an organism)
temperature
pH
blood pressure
blood glucose concentration
14
Q
2.81 why is it important for an organism to keep internal conditions within set limits
A
to ensure they stay healthy and maintain optimum conditions to allow the organism to function in response to internal and external changes
15
Q
2.81 if the internal conditions of homeostasis exceed the set limits
A
the organism may die
16
Q
2.81 homeostasis maintains optimal conditions for what
A
enzyme action and all cell functions
17
Q
2.81 homeostasis ensures
A
hat reactions in body cells can function and therefore the organism as a whole can live
18
Q
2.81 the core body temp of humans is kept close to
A
37 degrees celsius
19
Q
2.81 why core body temp of humans kept close to 37
A
a temperature change would stop essential enzymes from functioning optimally
20
Q
2.81 to keep the body temp at 37 the human body must be able to
A
make a coordinated response to any rise or fall in body temperature
21
Q
2.81 body temperature is monitored and controlled by what
A
the thermoregulatory centre in base of the brain as blood passes through it
22
Q
2.81 the thermoregulatory centre contains what
A
receptors that are sensitive to the temperature of the blood
23
Q
2.81 the skin also contains temperature receptors and
A
sends nervous impulses to the thermoregulatory centre
the brain then coordinates a cooling or heating response depending on what is required
24
Q
2.81 water loss via the lungs - during breathing - or skin - during sweating - cannot
A
be controlled
25
2.81 the volume of water lost in the production of urine
can be controlled by the kidneys
26
2.81 water can be reabsorbed from the filtrate as it passes along the collecting ducts
if the water content of the blood is too high then less water is reabsorbed, if it is too low then more water is reabsorbed
this causes either a large amount of dilute urine to be produced, or a small amount of concentrated urine
a hormone called ADH controls this process
27
2.82 a co-ordinated response requires
a stimulus, a receptor and an effector
28
2.82 homeostasis is under what type of control
involuntary / automatic
29
2.82 what does involuntary / automatic control mean
the brain stem (or non-conscious part of the brain) and the spinal cord are involved in maintaining homeostasis – you don’t consciously maintain your body temperature or blood glucose level
30
2.82 automatic control systems involve
nervous responses or chemical responses e.g. hormones
31
2.82 all control systems that carry out a coordinated response require what
a stimulus
a receptor
a coordination centre
an effector
32
2.82 what is the stimulus
a change in the environment e.g. a change in glucose levels in the blood, a change in body temperature etc
33
2.82 what is the receptor
receptor cells that detect stimuli
34
2.82 what is the coordination centre
the brain, spinal cord and pancreas, which receives and processes information from receptors
35
2.82 what is an effector
a muscle or gland, which brings about responses to restore optimum levels
36
2.82 a coordinated response such as what
stuff required when there is not enough water in the blood
37
2.83 plants respond to what
stimuli
38
2.83 plants need to be able to grow in response to certain
stimuli
39
2.83 plants need to be able to grow in response to what
light
40
2.83 plants need to be able to grow in response to
light or gravity
41
2.83 why do plants grow in response to light
to ensure their leaves can absorb light for photosynthesis
42
2.83 why do plants grow in response to gravity
to ensure that shoots grow upwards and roots grow downwards
43
2.83 what are the directional growth responses made by plants - in response to light / gravity - known as
tropisms
44
2.83 what are tropisms
the directional growth responses made by plants in response to light and gravity
45
2.83 if growth is towards the stimulus in plants the tropism is
positive
46
2.83 if growth is away from the stimulus in plants the tropism is
negative
47
2.83 what does it mean if the tropism is positive
the growth is towards the stimulus
48
2.83 what does it mean if the tropism is negative
the growth is away from the stimulus
49
2.84 a response to light in a plant is
phototropism
50
2.84 a response to gravity in a plant is
geotropism (or gravitropism)
51
2.84 as the shoot grows upwards, away from gravity & towards light shoots show
a positive phototropic response and a negative geotropic response
52
2.84 give an example of a positive phototropic response and a negative geotropic response
when a shoot grows upwards, away from gravity and towards the light
- so leaves are able to absorb sunlight
53
2.84 as roots grow downwards into the soil away from light and towards gravity shoots show
a negative phototropic response and a positive geotropic response
54
2.84 give an example of a negative phototropic response and a positive geotropic response
when a shoot grows downwards, away from the light and into the soil, towards gravity
- in order to anchor the plant and absorb water and minerals from the soil
55
2.84 stimulus of light
give the name of response
positive response
negative response
phototropism
growth towards the light source - shoots
growth away from the light source - roots
56
2.84 stimulus of gravity
give the name of response
positive response
negative response
geotropism
growth towards source of gravity - roots
growth away from source of gravity - shoots
57
2.84 definition of phototropism
growth towards or away from the direction of the light source
58
2.84 definition of geotropism
growth towards or away from the source of gravity
59
2.85 plants produce what ? for growth responses
plant growth regulators
(similar to hormones in animals)
60
2.85 what are plant growth regulators called
auxins
61
2.85 why do plants produce auxin
to coordinate and control directional growth responses such as phototropisms and geotropisms
62
2.85 why do plants produce plant growth regulators
to coordinate and control directional growth responses such as phototropisms and geotropisms
63
2.85 what is a plant growth regulator
auxin
64
2.85 what is auxin
a plant growth regulator
65
2.85 what coordinates & controls directional growth responses such as phototropisms and geotropisms
auxin
66
2.85 auxin coordinates & controls directional growth response such as
phototropisms and geotropisms
67
2.85 auxin is mostly made where
in the tips of growing shoots and then diffuses down into the region where cell division occurs
68
2.85 why is the region behind the tip of a shoot important
it is the only region that is able to contribute to growth by cell division and cell elongation
69
2.85 auxin stimulates the region behind the tip of the shoot to
elongate
70
2.85 the more auxin there is
the faster the cells will elongate and grow
71
2.85 if light shines around the tip of a shoot, auxin is distributed
evenly throughout
72
2.85 if light shines around the tip of a shoot, auxin means the cells in the shoot grow
at the same rate
73
2.85 if light shines predominantly on one side of a shoot, auxin is distributed
and concentrates on the shaded side
74
2.85 if light shines predominantly on one side of a shoot, auxin means the cells in the shoot grow
and elongate on the shaded side, and grow faster than the cells on the sunny side
75
2.85 unequal growth on either side of the shoot causes
the shoot to bend and grow in the direction of the light
76
2.85 positive phototropism in plants shoots is a result of
auxin accumulating on the shaded side of a shoot
77
2.85 what is better to write in relation to phototropism / geotropism instead of
'grows towards the light'
cell elongation
78
2.86 there are two different control systems in humans that work together to do what
respond to stimuli
79
2.86 what are the two different control systems that respond to stimuli
the nervous system
the hormonal system - also known as the endocrine system
80
2.86 changes in our external environment or in the internal environment of our bodies act as
stimuli
81
2.86 the nervous and hormonal systems do what to stimuli
coordinate a suitable response to stimuli
82
2.86 what allows us to coordinate and regulate body functions
our systems coordinating to make a suitable response to stimuli - external / internal environment
83
2.86 the nervous system & endocrine / hormonal system allow us to do what
to coordinate and regulate body functions by making a suitable response to stimuli - external / internal environment
84
2.86 information is sent through the nervous system as what
electrical impulses
85
2.86 what are electrical impulss
electrical signals that pass along nerve cells known as neurones
86
2.86 what are nerve cells known as in the nervous system
neurones
87
2.86 impulses that travel along neurones travel at
very high speeds
up to 100 metres per second
88
2.86 what allows rapid responses to stimuli in the nervous system
the impulses travelling at very high speeds along neurones
89
2.86 what is an example of a rapid response to stimuli
the withdrawal reflex which causes you to move your hand away fast when it touches a flame
90
2.86 the nervous system coordinates the activities of what receptors
sensory receptors
91
2.86 what are the three thing the nervous system coordinates activity for
sensory receptors, decision-making centres in the central nervous system and effectors such as muscles and glands
92
2.86 the nervous system coordinates the activities of decision-making centres in what
the central nervous system
93
2.86 the nervous system coordinates the activities of muscles and glands which are
effectors
94
2.86 the nervous system is used to
control functions that need instant or very rapid responses
95
2.86 information is sent through the endocrine system as
chemical substances known as hormones
96
2.86 hormones are carried by what
the blood and therefore can circulate around the whole body
97
2.86 hormones transmit information from one part of the organism to another and bring about what
a change - they provide a signal that triggers a response
98
2.86 hormones alter what
they alter the activity of one or more specific target organs
99
2.86 what are hormones used to control functions
that do not need instant responses
100
2.86 hormones are produced by what
endocrine glands
101
2.86 the endocrine glands that produce hormones in animals are collectively known as the
endocrine system
102
2.86 what is a gland
a group of cells that produces and releases one or more substances (a process known as secretion
103
2.86 comparison between nervous & endocrine system
1. made of
2. type of message
3. speed of action
4. duration of effect
1. N: nerves, brain & spinal cord E: glands
2. N: electrical E: chemical hormone
3. N: very fast E: slower
4. N: short - until the nerve impulses stops
4. E: long until the hormone is broken down in the body
104
2.86 comparison between nervous & endocrine system
made up of
N: nerves, brain & spinal cord
E: glands
105
2.86 comparison between nervous & endocrine system
type of message
N: electrical
E: chemical hormone
106
2.86 comparison between nervous & endocrine system
speed of action
N: very fast
E: slower
107
2.86 comparison between nervous & endocrine system
duration of effect
N: short - until the nerve impulses stops
E: long until the hormone is broken down in the body
108
2.86 what are nerves
bundles of neurones
109
2.87 what does the central nervous system consist of
the brain and spinal cord which is linked to the organs by nerves
110
2.87 the human nervous system consists of
CNS - the central nervous system, the brain an spinal cord
PNS - the peripheral nervous system, all of the nerves in the body
111
2.87 information is sent through the nervous system as
electrical impulses - electrical signals that pass along nerve cells known as neurones
112
2.87 a bundle of neurones is known as what
a nerve
113
2.87 the nerves spread out from the central nervous system to
all other regions of the body
and to all the sense organs
114
2.87 the CNS acts as
a central coordinating centre
for the impulses that come in from or are sent out to any part of the body
115
2.88 stimulation of receptors in the sense organs send what
electrical impulses along nerves into and out of the central nervous system resulting in rapid responses
116
2.88 what results in rapid responses
stimulation of receptors in the sense organs send electrical impulses along nerves into and out of the central nervous system
117
2.88 a stimulation of receptors in the sense organs sends what
electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses
118
2.88 what is the pathway through the nervous system
stimulus → sensory neurone → relay neurone → motor neurone → effector → response
119
2.88 what is a stimulus received by
a stimulus is received by a sensory (receptor) neurone
120
2.88 what are most receptors specialised to
most receptors are specialised to detect particular stimuli
121
2.88 what happens when a receptor is stimulated
it produces electrical impulses
122
2.88 where do the impulses travel to along the sensory neurone
to the central nervous system
the coordinator is either the brain or the spinal cord
123
2.88 in the central nervous system the impulses are passed on to what
a relay neurone
124
2.88 the relay neurone links to what
a motor neurone
125
2.88 when the relay neurone links to a motor neurone the impulses travel along it until
they reach the effector
126
2.88 what is the effector
its what carries out the response
127
2.88 what may an effector be
a muscle or gland
128
2.88 describe the nerve pathway from stimulus to response
- stimulus - is detected by receptor
- sensory neurone
- relay neurone - CNS
- motor neurone
- impulses are sent along the sensory neurone, then the relay neurone and then the motor neurone
- the impulses received by effector
- response
129
2.89 neurones do not do what
they do not go into direct contact with eachother
130
2.89 what are dendrites
branched nerve fibres which receive nerve impulses and pass them towards a cell body
131
2.89 the dendrites of two neurones meet to make what
to make a connection between the neurones
132
2.89 when two dendrites meet what is formed
a junction known as a synapse
133
2.89 what is a synapse
where the axon of one neurone connects with the dendrite of another or an effector
they help coordinate activities and are unidirectional
134
2.8 what is an axon
a single nerve fibre that carries nerve impulses away from a cell body
135
2.89 at a synapse there is what
a very small gap between the neurones
136
2.89 what is the gap between neurones called
the synaptic cleft
or synaptic gap
137
2.89 electrical impulses cannot what
travel directly from one neurone to the next due to the synaptic gap
138
2.89 can electrical impulses travel directly from one neurone to the next
no due to the synaptic gap
139
2.89 electricity can/cannot do what with the synaptic gap
electricity cannot jump the gap
140
2.89 for electrical impulses to transfer
the electrical signal is briefly converted to a chemical signal that can cross the synaptic gap
141
2.89 what are the chemical signalling molecules used for
to transfer the signal between neurones at a synapse
142
2.89 what can pass in the synaptic gap
a chemical signal known as neurotransmitters
143
2.89 to pass the synaptic gap the electrical signal is converted to what
a chemical signal
144
2.89 what is the chemical signalling molecules called
neurotransmitters
145
2.89 what are neurotransmitters
chemical signalling molecules that are used to transfer the signal between neurones at a synapse that can cross the synaptic gap
146
2.89 when the neurotransmitters meet the neurone on the opposite side the signal is converted back
back into an electrical impulse which can then pass along the neurone
147
2.89 the electrical impulse travels along the
axon of the first neurone
148
2.89 what is the presynaptic neurone
the axon of the first neurone
149
2.89 when the electrical impulse travels along the axon of the first neurone / presynaptic neurone what does it trigger
it triggers the end of the presynaptic neurone to release chemicals called neurotransmitters from vesicles
150
2.89 what do vesicles fuse with
the presynaptic membrane, releasing their contents into the synaptic gap
151
2.89 the neurotransmitters diffuse across the synaptic gap and bind with what
bind with receptor molecules on the membrane of the second neurone
known as the postsynaptic membrane
152
2.89 what is the postsynaptic membrane
the membrane on the second neurone
153
2.89 after the neurotransmitters diffuse across the synaptic gap and bind with receptor molecules on the postsynaptic membrane what is stimualted
it stimulates the second neurone to generate an electrical impulse which then travels down the second axon
154
2.89 the neurotransmitters are destroyed to prevent what
continued stimulation of the second neurone
- otherwise the neurotransmitters would cause repeated impulses to be sent
155
2.89 to prevent continued stimulation of the impulses,w hat happens to the neurotransmitters
they are destroyed
156
2.89 synapses ensure impulses can what
only travel in one direction
157
2.89 pathway of how an impulse is passed on at a synapse
1. an impulse arrives at the end of the presynaptic neurone
2. vesicles move towards & fuse with the presynaptic membrane
this releases neurotransmitters into the synaptic gap
3. the neurotransmitters diffuse across the synaptic gap - down a concentration gradient
4. neurotransmitters attach the to receptors on the postsynaptic membrane
5. this triggers an impulse which travels along the postsynaptic neurone
6. the neurotransmitters are recycled or destroyed once an impulse is sent
158
2.89 neurotransmitters move by what
diffusion
which requires a concentration gradient & is a passive process
159
2.89 receptors that are complementary in shape to neurotransmitters are located where
on the postsynaptic neurone
160
2.89 drugs such as heroin, ecstasy & cocaine can bind to neurotransmitter receptors that what
triggers impulses in different regions of the brain
161
2.90 what is a reflex response also known as
an involuntary response
162
2.90 a reflex response does not involve what
the conscious part of the brain as the coordinator of the reaction
163
2.90 awareness of a response happens when
after the response has been carried out
164
2.90 responses are what
automatic and rapid
165
2.90 what helps minimise damage to the body and aids survival
responses are automatic and rapid
166
2.90 why are automatic and rapid responses helpful
they minimise danger to the body and aid survival
167
2.90 name examples of reflex responses that help us avoid serious injury
pain-withdrawal, blinking, and coughing
168
2.90 the reflex arc is what
the pathway of reflex response
169
2.90 reflex arc pathway
stimulus -> receptor -> sensory neurone -> intermediate relay neurone -> motor neurone -> effector -> response
170
2.90 what is the pathway taken by electrical impulses as they travel along neurones
stimulus -> receptor -> sensory neurone -> intermediate relay neurone -> motor neurone -> effector -> response
171
2.90 give the example of the reflex response when someone stands on a pin
- the pin (the stimulus) is detected by a
- (pain/pressure/touch) receptor in the skin on the person's foot
- a sensory neurone sends electrical impulses to the spinal cord (the coordinator)
- an electrical impulse is passed to a relay neurone in the spinal cord (part of the CNS)
- a relay neurone synapses with a motor neurone
- a motor neurone carries an impulse to a muscle in the leg (the effector)
- when stimulated by the motor neurone, the muscle will contract and pull the foot up and away from the sharp object (the response)
172
2.91 the eye is what
a highly specialised sense organ containing receptor cells that allow us to detect the stimulus of light
173
2.91 the retina of the eye contains what
two types of receptor cells
174
2.91 what are two types of receptor cells in the retina
rods and cones
175
2.91 which receptor cells in the eye are sensitive to light
the rods
176
2.91 which receptor cells can detect colour
the cones
177
2.91 the eye is a sense organ that contains what
light receptor cells
178
2.91 what type of organ is the eye
a sense organ
179
2.91 what are the structures in the eye
cornea
iris
lens
retina
optic nerve
pupil
conjunctiva
ciliary muscle
suspensory ligaments
sclera
fovea
blind spot
180
2.91 describe the structure of the cornea
a transparent lens that refracts light as it enters the eye
181
2.91 describe the structure of the iris
controls how much light enters the pupil
182
2.91 describe the structure of the lens
transparent disc that can change shape to focus light onto the retina
183
2.91 describe the structure of the retina
contains light receptor cells – rods (detect light intensity) and cones (detect colour)
184
2.91 describe the structure of the optic nerve
sensory neuron that carries impulses between the eye and the brain
185
2.91 describe the structure of the pupil
hole that allows light to enter the eye
186
2.91 describe the structure of the conjunctiva
a clear membrane that covers the white of the eye and the inside of the eyelids; it lubricates the eye and provides protection from external irritants
187
2.91 describe the structure of the ciliary muscle
a ring of muscle that contracts and relaxes to change the shape of the lens
188
2.91 describe the structure of the suspensory ligaments
ligaments that connect the ciliary muscle to the lens
189
2.91 describe the structure of the sclera
the strong outer wall of the eyeball that helps to keep the eye in shape and provides a place of attachment for the muscles that move the eye
190
2.91 describe the structure of the fovea
a region of the retina with the highest density of cones (colour detecting cells) where the eye sees particularly good detail
191
2.91 describe the structure of the blind spot
the point at which the optic nerve leaves the eye, where there are no receptor cells
192
2.92 what is the function of the eye
focusing on near and distant objects
193
2.92 the way the lens brings about fine focusing is called what
accommodation
194
2.92 what is accommodation
the way the lens brings about fine focusing
195
2.92 what shape and texture is the lens
it is elastic and its shape can be changed
196
2.92 how can the lens shape be changed
the suspensory ligaments attached to it become tight or loose
197
2.92 how does the lens change shape
the changes are brought about by the contraction or relaxation of the ciliary muscles
198
2.92 what happens when the ciliary muscles contract or relax
the lens changes shape
199
2.92 what happens in the eye when an object is close up
the ciliary muscles contract (the ring of muscle decreases in diameter)
this causes the suspensory ligaments to loosen
this stops the suspensory ligaments from pulling on the lens, which allows the lens to become fatter
light is refracted more
200
2.92 what is the result when an object is close to the eye
light is refracted more by lens to focus on near objects
201
2.92 what happens in the eye when an object is far away
the ciliary muscles relax (the ring of muscle increases in diameter)
this causes the suspensory ligaments to tighten
the suspensory ligaments pull on the lens, causing it to become thinner
light is refracted less
202
2.92 what is the result when an object is far away from the eye
light is refracted less allowing the eye to focus on a distant object
203
2.92 what happens to the ciliary muscles, suspensory ligaments, lens and light refraction when the eye focuses on near objects
ciliary muscles: contracted
suspensory ligaments: loose
lens: fatter
light refraction: more
204
2.92 what happens to the ciliary muscles, suspensory ligaments, lens and light refraction when the eye focuses on distant objects
ciliary muscles: relaxed
suspensory ligaments: tight
lens: thinner
light refraction: less
205
2.92 the suspensory ligaments are not muscles so you cannot say they contract or relax, instead what do you say
tighten or loosen
206
2.92 the pupil reflex is what
a reflex action
207
2.92 why does the pupil reflex
to protect the retina from damage
208
2.92 to protect the retina from damage the pupil does what
the pupil has a reflex action called the pupil reflex
209
2.92 what happens to the pupil in dim light
the pupil dilates (widens) in order to allow as much light into the eye as possible to improve vision
210
2.92 what happens to the pupil in bright light
the pupil constricts (narrows) in order to prevent too much light from entering the eye and damaging the retina
211
2.92 in what type of light does the pupil dilate
dim light
212
2.92 in what type of light does the pupil constrict
bright light
213
2.92 what happens to the radial muscles of the iris, the circular muscles of the iris and the pupil in dim light
radial muscles of the iris: contracted
circular muscles of the iris: relaxed
pupil is: dilated - light enters eye
214
2.92 what happens to the radial muscles of the iris, the circular muscles of the iris and the pupil in bright light
radial muscles of the iris: relaxed
circular muscles of the iris: contracted
pupil is: constricted - less light enters eye
215
2.92 explain the eye in a dark environment
photoreceptors detect the change in environment to being dark
radial muscles contract
circular muscles relax
pupil dilates
more light enters the eye
216
2.92 explain the eye in a bright environment
photoreceptors detect the change in environment to being bright
radial muscles relax
circular muscles contract
pupil constricts
less light enters the eye
217
explain the pupil reflex in regard to bright light
radial muscles: relaxed
circular muscles: contracted
pupil size: narrow
light entering eye: less
218
explain the pupil reflex in regard to dim light
radial muscles: contracted
circular muscles: relaxed
pupil size: wide
light entering eye: more
219
2.93 the skin is what
our largest sense organ
220
2.93 what does the skin contain that lets us detect external stimuli
many different receptors
221
2.93 why does the skin contain many different receptors
it allows us to detect various external stimuli including touch, pressure, pain, heat and cold
222
2.93 give examples of external stimuli our skin can detect
touch, pressure, pain, heat and cold
223
2.93 structures in the skin also do what
they play an important role in regulating body temperature - an example of homeostasis
224
2.93 mention the structures in the skin that can increase or reduce heat loss to the surroundings
muscles
fatty tissue
arteriole
sensory neurone
sweat gland
dermis
capillaries
muscle
epidermis
free nerve ending
sweat pore
hair
check save my exams diagram - skin and temperature
225
2.93 what are the cooling mechanisms in humans - non detailed
vasodilation of skin capillaries
sweating
flattening of hairs
226
2.93 what are the cooling mechanisms in humans - detailed
vasodilation of skin capillaries
heat exchange (both during warming and cooling) occurs at the body's surface as this is where the blood comes into closest proximity to the environment
one way to increase heat loss is to supply the capillaries in the skin with a greater volume of blood, which then loses heat to the environment via radiation
arterioles (small vessels that connect arteries to capillaries) have muscles in their walls that can relax or contract to allow more or less blood to flow through them
during vasodilation, these muscles relax, causing the arterioles near the skin to dilate (get wider) and allowing more blood to flow through capillaries
sweating
sweat is secreted by sweat glands
this cools the skin by evaporation which uses heat energy from the body to convert liquid water into water vapour
flattening of hairs
the hair erector muscles in the skin relax, causing hairs to lie flat
this stops them from forming an insulating layer by trapping air and allows air to circulate over the skin and allows heat to leave by radiation
227
2.93 describe the vasodilation of skin capillaries for the cooling mechanism in humans
heat exchange occurs at the body's surface as this is where the blood is closest proximity to the environment
one way to increase heat loss is to supply the capillaries in the skin with a greater volume of blood which then loses heat to the environment via radiation
arterioles have muscles in their walls that can relax causing the arterioles near the skin to dilate and allows more blood to flow through capillaries
228
2.93 describe sweating for the cooling mechanism in humans
sweat is secreted by sweat glands
this cools the skin by evaporation which uses heat energy from the body to convert liquid water into water vapour
229
2.93 describe the flattening of hairs for the cooling mechanism in humans
the hair erector muscles in the skin relax, causing hairs to lie flat
this stops them from forming an insulating layer by trapping air and allows air to circulate over the skin and allows heat to leave by radiation
230
2.93 describe the responses in the skin when the body temperature is too high and needs to decrease
sweat glands excrete sweat which cools the skin as it evaporates
hair erector muscles will relax
vessels dilate to increase blood flow to the skin
231
2.93 what are the warming mechanisms in humans - non detailed
vasoconstriction of skin capillaries
shivering
erection of hairs
232
2.93 what are the heating mechanisms in humans - detailed
vasoconstriction of skin capillaries
one way to decrease heat loss is to supply the capillaries in the skin with a smaller volume of blood, minimising the loss of heat to the environment via radiation
during vasoconstriction, the muscles in the arteriole walls contract, causing the arterioles near the skin to constrict (get smaller) and allowing less blood to flow through capillaries
vasoconstriction is not, strictly speaking, a 'warming' mechanism as it does not raise the temperature of the blood but instead reduces heat loss from the blood as it flows through the skin
shivering
this is a reflex action in response to a decrease in core body temperature
muscles contract in a rapid and regular manner
the exothermic metabolic reactions required to power this shivering generate sufficient heat to warm the blood and raise the core body temperature
erection of hairs
the hair erector muscles in the skin contract, causing hairs to stand on end
this forms an insulating layer over the skin's surface by trapping air between the hairs and stops heat from being lost by radiation
233
2.93 describe the vasoconstriction of skin capillaries for the heating mechanism in humans
one way to decrease heat loss is to supply the capillaries in the skin with a smaller volume of blood - this minimises the heat loss to the environment via radiation
234
2.93 describe shivering for the heating mechanism in humans
this is a reflex action in response to a decrease in core body temperature
muscles contract in a rapid & regular manner
the exothermic metabolic reactions required to power this shivering generate sufficient heat to warm the blood and raise the core body temperature
235
2.93 describe the erection of hairs for the heating mechanism in humans
the hair erector muscles in the skin contract
this causes the hairs to stand on end
this forms an insulating layer over the skins surface by trapping air between the hairs and stops heat from being lose by radiation
236
2.93 describe the responses in the skin when the body temperature is too low and needs to increase
the hair stands upright trapping the air around the skin
trapped air is an excellent insulator
hair erector muscles will contract
vessels constrict reducing blood flow to the skin
remember - heat energy transfer always occurs from hotter regions to cooler regions
radiation is heat energy transfer by electromagnetic radiation
conduction and convection are the other two types
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2.93 what is the core body temperature of humans kept close to
37 degrees celsius
238
2.93 why is the core body temperature of humans kept close to 37 degrees celcius
it is tightly controlled as a change in core body temperature of more than 2 degrees celsius can be fatal
239
2.93 to keep the body at a core body temperature the human body must be able to do what
make a coordinated response to any rise or fall in body temperature
240
2.93 temperature recepters are also known as what
thermoreceptors
241
2.93 what are thermoreceptors also known as
temperature receptors
242
2.93 where are the temperature receptors / thermoreceptors found
in the skin and hypothalamus
243
2.93 what can detect minute changes in body temperature
temperature receptors or thermoreceptors
244
2.93 what do the temperature receptors / thermoreceptors do
they detect minute changes in body temperature
245
2.93 the brain does what when there is a change in body temperature
the brain coordinates a cooling or heating response depending on what is required
246
2.93 temperature regulation is an example of what
homeostasis
247
2.93 what happens when there is an increase in body temperature
thermoreceptors in the hypothalamus and skin can detect change
this leads to increased sweating, vasodilation & hairs lie flat against the skin
this leads to a decrease in body temperature
248
2.93 what happens when there is an decrease in body temperature
thermoreceptors in the hypothalamus and skin detect change
this leads to shivering, vasoconstriction & skin hairs erect
this leads to an increase in body temperature
249
2.94 what is a hormone
it is a chemical substance produced by a gland and carried by the blood
which alters the activity of one or more specific target organs
250
2.94 what do hormones do
they are chemicals that transmit information from one part of the organism to another and bring about a change
251
2.94 what are the important hormones
adrenaline
insulin
testosterone
progesterone
oestrogen
252
2.94 what is adrenaline known as
the fight or flight hormone as it is produced in situations where the body may be in danger
253
2.94 what does adrenaline cause
a range of different things to happen in the body, all designed to prepare it for movement
254
2.94 what does adrenaline do to the body - non-detailed
an increase in heart & breathing rate
diverts blood flow towards muscles
dilation of the blood vessels inside muscles
breaks down stored glycogen into glucose
255
2.94 what does adrenaline do to the body - detailed
increase in heart rate and breathing rate - ensures glucose and oxygen can be delivered to muscle cells (and carbon dioxide can be taken away from muscles cells) at a faster rate
diverting blood flow towards muscles and away from non-essential parts of the body such as the alimentary canal - ensures an increased supply of the reactants of respiration (glucose and oxygen)
dilation of the blood vessels inside muscles - ensures more blood can circulate through them (again, supplying more glucose and oxygen)
breaking down of stored glycogen to glucose in the liver and muscle cells, with glucose released by the liver being transported to active muscle cells - ensures a higher blood glucose concentration for increased respiration in muscle cells (providing greater energy for movement)
256
2.94 blood glucose concentration is an example of what
homeostasis
257
2.94 too high a level of glucose in the blood can lead to what
the cells of the body losing water by osmosis which can be dangerous
258
2.94 too low of glucose in the blood can lead to what
the brain receiving insufficient glucose for respiration potentially leading to a coma or even death
259
2.94 what works together to control blood glucose levels
the pancreas and liver
260
2.94 the pancreas and liver work together to do what
control blood glucose level
261
2.94 what happens if the blood glucose concentration gets too high
cells in the pancreas detect the increased blood glucose levels
the pancreas produces the hormone insulin, secreting it into the blood
insulin stimulates muscles and the liver to take up glucose from the bloodstream and store it as glycogen (a polymer of glucose)
this reduces the concentration of glucose in the blood back to normal levels, at which point the pancreas stops secreting insulin
261
2.94 to maintain blood glucose levels the pancreas acts as what and does what
the pancreas acts as an endocrine gland (making and secreting hormones into the bloodstream)
262
2.94 explain the regulation of blood glucose levels
- blood glucose levels rise
- pancreas releases insulin
- insulin stimulates uptake of glucose into the liver
- liver stores excess glucose as glycogen
- blood glucose levels reduce
263
2.94 where is testosterone produced
in the male testes
264
2.94 what is testosterone responsible for
the development of secondary sexual characteristics in males
265
2.94 what is responsible for the development of secondary sexual characteristics in males
testosterone
266
2.94 where is progesterone produced
in the female ovaries
267
2.94 what is progesterone responsible for
maintaining the uterine lining during pregnancy
268
2.94 what is responsible for for maintaining the uterine lining during pregnancy
progesterone
269
2.94 where is oestrogen produced
in the female ovaries
270
2.94 what is oestrogen responsible for
for the development of secondary sexual characteristics in females and regulating the menstrual cycle
271
2.94 what is responsible for the development of secondary sexual characteristics in females and regulating the menstrual cycle
oestrogen
272
2.94 adrenaline source, role and effect
adrenal gland
readies the body for a 'fight or flight' response
increases heart and breathing rate
273
2.94 where is adrenaline produced
adrenal gland
274
2.94 insulin source, role and effect
pancreas
lowers blood glucose levels
causes excess glucose in the blood to be taken up by the muscles and liver and converted into glycogen for storage
275
2.94 testosterone source, role and effect
testes
main sex hormone in males
development of male reproductive organs and secondary characteristics
276
2.94 progesterone source, role and effect
ovaries
maintains pregnancy
maintains the uterus lining to cushion the fertilised egg and allow it to develop
277
2.94 oestrogen source, role and effect
ovaries
main sex hormone in females
development of female secondary sexual characteristics and regulation of the menstrual cycle
278
2.95B what are the three advanced hormones you need to know
ADH antidiuretic hormone
FSH follicle-stimulating hormone
LH luteinising hormone
279
2.95B what does ADH stand for
antidiuretic hormone
280
2.95B what does FSH stand for
follicle-stimulating hormone
281
2.95B what does LH stand for
luteinising hormone
282
2.95B ADH if the water content of the blood falls below a certain level
the blood is too concentrated
receptors detect this and stimulate the pituitary gland to release more ADH
this causes the collecting ducts of the nephrons to become more permeable to water
this leads to more water being reabsorbed from the collecting ducts
the kidneys produce a smaller volume of urine that is more concentrated (contains less water)
283
2.95B ADH if the water content of the blood rises above a certain level
the blood is too dilute
receptors detect this and stimulate the pituitary gland to release less ADH
this causes the collecting ducts of the nephrons to become less permeable to water
this leads to less water being reabsorbed from the collecting ducts
the kidneys produce a larger volume of urine that is less concentrated (contains more water)
284
2.95B ADH source, role and effect
pituitary gland
controlling the water content of the blood
increases the permeability of the collecting ducts in the kidneys to water, increasing the reabsorption of water back into the blood
285
2.95B FSH source, role and effect
pituitary gland
causes ovary to develop a mature egg cell
stimulates the development of egg cells in the ovary and the release of oestrogen
286
2.95B LH source, role and effect
pituitary gland
causes ovary to release a mature egg cell
stimulates the release of an egg cell from the ovary (ovulation) and the release of progesterone
