14. Coordination and Response Flashcards
1
Q
Definition of Iris
A
A coloured ring of circular and radial muscle that controls the size of the pupil and so controls the amount of light entering the eye
2
Q
Definition of Cornea
A
A transparent, curved layer at the front of the eye that refracts the light entering and helps to focus it
3
Q
Definition of Lens
A
A transparent, convex, flexible, jelly-like structure that refracts light to focus it onto the retina and to produce an image. This final adjustment is called accommodation.
4
Q
Definition of Retina
A
A light-sensitive layer at the back of the eye made up of rods, which detect light of low-intensity, and cones, which detect different colours.
5
Q
Definition of Optic Nerve
A
Transmits electrical impulses from the retina to the brain
6
Q
Definition of Conjunctiva
A
Thin layer covering the front of the eye which protects the cornea
7
Q
Definition of Eye Muscles
A
Allow the eyeball to move from side to side and up down
8
Q
Definition of Sclera
A
Tough non-elastic coat, that is white in colour and protects the eyeball
9
Q
Definition of Ciliary Muscles and Suspensory Ligaments
A
Cause the lense to change shape and so allow fine focusing onto the retina
10
Q
Definition of Choroid
A
Layer of blood vessels inside the sclera which supplies food and oxygen to the eye
11
Q
How does they eye respond to bright light?
A
Circular muscles of iris contract to reduce diameter of pupil.
Less light can enter and the retina is protected from bleaching.
12
Q
How does they eye respond to dim light?
A
Radial muscles of iris contract to make the diameter of the pupil larger, allowing a larger amount of light to reach and stimulate the light-sensitive cells in the retina.
13
Q
What is the job of the aqueos / vitreous humour?
A
They create outward pressure on the sclera, which keeps the spherical shape of the eyeball.
14
Q
What does the ciliary body produce?
A
Aqueos humour
15
Q
What is the blind spot?
A
Part of the retina on top of the optic nerve which doesn’t contain any light-sensitive cells.
16
Q
How do our eyes detect light
A
STAGE 1
Light from a source travels towards the eye
STAGE 2
Light passes through the cornea and enters the eye. The cornea refracts the light rays.
STAGE 3
Light passes through the lens, which changes shape to refract the light even more. This is how the eye focuses light.
STAGE 4
Light rays hit the back of the retina. The light receptors detect the light and a nerve impulse is sent along the optic nerve to the brain.
17
Q
What type of organ is the eye?
A
A sense organ
18
Q
What type of receptors does it contain?
A
Light receptors
19
Q
What are rod cells sensitive to?
A
They’re sensitive to light at LOW INTENSITIES.
Rod cells are more sensitive to light than cone cells.
They do NOT detect colour.
20
Q
What are cone cells sensitive to?
A
They’re sensitive to COLOUR and light at HIGH INTENSITIES.
Humans have 3 different types of cone cells, each sensitive to a different range of colours (ones which respond to red, green or blue)
21
Q
Definition of suspensory ligaments
A
Attachment between the lens and the ciliary muscles which keeps the lens in place and allows its shape to be changed by the ciliary muscles.
22
Q
Definition of cillary muscles
A
Small muscles attached to suspensory ligaments which alter the shape of the lens
23
Q
How does the eye focus on distant objects?
A
Ciliary muscles relax, eyeball becomes more spherical
Suspensory ligaments tighten, pulling lens thin
To focus distant objects, the lens must be thin so light rays are only slightly refracted
24
Q
How does the eye focus on close objects?
A
Ciliary muscles contract, pull eyeball inwards (bulges forward)
Suspensory ligaments loosen, causing the lens to thicken
To focus on close objects, the lens needs to be thick to refract the light rays greatly
25
In the Iris Reflex, in what way do the circular and radial muscles in the iris work together?
They work antagonistically
they oppose each other in their actions
when circular muscles contract, pupil constricts
when radial muscles contract, pupil dilates
26
In what type of vision do the rod cells help?
Night vision
27
Where are the cone cells concentrated?
In the fovea
28
What is the fovea’s purpose?
allows objects to be examined in fine detail
- the centre only contains cones, this is where colour discrimination occurs
29
When does the fovea work in full efficiency?
In bright light
30
What happens if the image falls on the blind spot?
It cannot be seen
31
Definition of long-sightedness
When a person can see distant objects clearly, but close objects appear blurred
32
Definition of short-sightedness
When a person can see near objects clearly, but distant objects appear blurred
33
Definition of colour blindness
When a person cannot tell the difference between certain colours, often red or green
34
Why can long-sighted people not focus clearly on objects close-by?
The image is focused BEHIND their retina, not ON their retina
Due to weak eye muscles which are unable to contract enough to make lens thick enough to focus near objects.
35
What is the scientific name for long-sightedness?
Hyperopia
36
Why can near-sighted people not focus clearly on objects in the distance?
the image is formed IN FRONT of their retina
due to overstrong eye muscles which cannot relax enough to make the lens thing enough leading to light rays being bent too much so image is blurred
37
What is the scientific name for short-sightedness?
Myopia
38
In what 2 ways can eye-sight be corrected?
Glasses / contact lenses
39
How do lenses help?
Help focus light onto the retina
40
In what 2 more modern ways can sight problems be corrected?
Laser eye surgery
involves using a highly precise laser to change shape of cornea
alters refraction of light as it enters eye, enabling it to be focused onto the retina correctly
Artificial lens
- faulty eye lens can be removed and replaced by an artificial lens that focuses light onto the retina properly
41
What type of lens is used to correct long-sightedness?
A CONVEX lens
42
What type of lens is used to correct near-sightedness?
A CONCAVE lens
43
What causes colour-blindness?
Caused by a lack of a certain type of light receptor (cone) in the retina
44
What colours are hard to distinguish for a colour blind person?
red and green
45
Why do cataracts occur?
Occur as a result of changes in the lens
46
What happens to the lens if there’s a cataract?
The lens becomes less transparent, which leads to a decrease in vision. Eyes will appear cloudy.
47
What age group is most likely to develop cataracts?
Old people
48
How is cataracts treated?
Affected lens is removed and replaced with a new, artifical lens
49
When are objects most clearly seen by the rod cells?
At night by not looking directly a them
50
When are objects most clearly seen by the cone cells?
During daylight by looking directly at them
51
Why is there a layer of pigment behind the rods and cones?
Prevents internal reflection which might lead to multiple or blurred images.
52
How does the image differ when formed on the retina?
it’s inverted and diminished (smaller)
- brain corrects the inversion and change in size
INTERGRATION
53
How can we see colours which aren’t just, red, green or blue?
Seen by light waves hitting more than one type of cone
54
What is presbyopia?
A condition of old age (over 40) where people lose the ability to focus on near objects as the lens becomes less elastic
55
What does the nervous system enable humans to do?
Enables humans to react to their surroundings and coordinate their behavior
56
What is it made out of?
A network of nerves
57
What do nerves do?
Transmit electrical impulses between the brain, spinal cord, and the rest of the body.
58
What is the role of nerves?
to transmit electrical impulses
59
What is the CNS (central nervous system) made up of?
The brain and the spinal cord
60
What helps the CNS carry out its responses?
Coordinates responses via:
receptors
sensory neurones
motor neurones
effectors
61
What does the PERIPHERAL nervous system consist of?
Consists of neurones that travel to and from the CNS.
62
What is the peripheral nervous system’s role?
Connects the CNS to the body
63
What is a nerve?
A bundle of many neurones
64
What is a neurone?
An individual nerve cell
65
What do neurones do?
Neurones carry electrical impulses between receptors, the CNS and effectors
66
What do nerves do?
Nerves carry electrical impulses from the CNS to the rest of the body
67
What do receptors do?
detect change/ stimuli
68
What does the CNS do?
Coordinate a response
69
What do effectors do?
Carry out a response
70
What are effectors and why are they called that?
Often glands or muscles
Called that because they go into action when they recieve nerve impulses of hormones.
71
What are nerve impulses from sense organs to the CNS called?
sensory impulses
72
What are nerve impulses from the CNS to the effectors called?
motor impulses
73
How does the nervous system act as a COORDINATOR?
Acts as a coordinator by directing responses to stimuli such as changes in body conditions
74
How do sensory receptors help to coordinate a response?
Sensory receptors, located in sense organs, stimulate sensory neurones.
75
What do relay neurones do?
Relay neurones in CNS stimulate motor neurones
76
What are examples of responses that effectors can carry out?
muscle contraction
- hormone secretion
77
What is the junction between 2 neurones called?
A synapse / synaptic cleft
78
How do electrical impulses pass between neurones?
When an electrical impulse reaches the end of the first neurone, it triggers the release of a chemical. This chemical is called NEUROTRANSMITTER
79
How does the neurotransmitter travel?
Diffuses across the gap
80
Does the process of the electrical impulse travelling over the synapse slow down the speed of nerve impulses?
Yes
81
Do synapses control the direction of impulses? If so, how?
Yes
- neurotransmitter substances are synthesised on only one side of the nerve impulse, while receptor molecules are only present on one side
82
How does heroin interact with receptor molecules at synapses?
Stimulates receptor molecules in synapses in the brain, triggering the release of dopamine
83
How do spider toxin and the toxin released by tetanus affect the nervous system?
Breaks down vesicles, releasing mass amounts of transmitter substance and disrupting normal synaptic function.
84
What is a reflex?
A very fast, automatic response to a stimulus that does not involve direct coordination by the concious part of the brain. They are INVOLUNTARY.
85
What are reflexes coordinated by?
Reflex arcs
86
What does a reflex arc consist of?
Consists of an electrical impulse being directly transmitted from a sensory neuron, via a relay neuron, to a motor neuron, to stimulate a rapid response.
87
Why are reflexes so fast in bringing about a response?
This is because when the electrical impulse reaches the CNS, it often only passes through the spinal cord, and not the brain.
88
How is the brain informed that a reflex reaction has occured?
If the reflex signal does not initiialy pass through the brain, a seperate impulse can be sent from the spinal cord to the concious part of the brain.
89
Why are reflexes important?
Help protect the body from danger
90
What is reaction time?
Time taken for a response to occur in reaction to a stimulus
91
What are the 3 types of neurones?
Motor, Sensory, Relay
92
Where do motor neurones carry signals from and to?
From the CNS to effectors
93
Where do sensory neurones carry signals from and to?
From the receptors / sense organs to the CNS
94
Where do relay neurones carry signals from and to?
Connect motor and sensory neurones
95
Where are the cell bodies of the neurones mainly located?
brain or spinal cord
96
What types of neurones can a nerve contain?
A combination of sensory and motor nerve fibres (axons) in order to carry many different impulses
97
What is an impulse?
A series of electrical pulses which travel down the axon
98
At what speed does a nerve impulse travel?
100m/s -1
99
Are all nerve impulses similar?
Yes
100
What is a spinal reflex?
Examples
A reflex that uses relay neurones in the spine cord
- withdrawing the hand from a hot object
101
Examples of reflexes that take place in the head?
location: not coordinated by brain
Iris reflex
Blinking
Coughing
102
Synapse definition
A junction between 2 neurones
103
What is a voluntary action?
One which requires a concious decision by the brain
Unlike a reflex action, it does not happen automatically
choice in selection of the response
104
What is the main function of the brain during voluntary actions?
To coordinate the actions so that they happen in the right sequence and at the right time and place.
105
Definition of a sense organ?
Example
Sense organs are groups of sensory cells, responding to specific stimuli, such as light, sound, touch, temperature and chemicals.
e.g eye / ear
106
Definition of stimulus
A change in the enivronment (light, tempertaure, pressure) which produces a reaction in a living organism.
107
list 5 sense organs and the stimuli they respond to
ear - sound, body movement (balance)
eye - light
nose - chemicals (smells)
tongue - chemicals (taste)
skin - temperature, pressure, touch, pain
108
What is the special property of sensory cells and organs?
They are able to convert one form of energy into another
e.g eyes can convert light energy into electrical energy (of nerve impulse)
109
Describe the reflex arc of coughing
STIMULUS - Particles making contact with the lining of the respiratory tree
RESPONSE - Violent contraction of the diaphragm and internal intercostal muscles
110
What is the survival value of coughing?
Prevents lungs being damaged or infected, so that gas exchange remains efficient
111
What is the survival value of the knee-jerk reflex?
The leg can support the body’s wait during walking
112
Describe the reflex arc of swallowing
STIMULUS - Food particles making contact with the back of the throat
RESPONSE - Contraction of the muscle of the epiglottis, which closes off the entrance to the trachea
113
What is the survival value of swallowing?
Prevents food entering the respiratory pathway so that lungs are not damaged
114
What does the white matter in the spine contain?
Contains the nerve fibres
115
What does the grey matter in the spine contain?
Contains cell bodies of the motor neurones
116
Can impulses travel both ways?
No
- synapses act as valves, forcing impulses to travel 1 way
117
What is intergration?
When the CNS processes information from receptors and passes instructions to effectors to tell the organism how to respond
118
What is a cranial reflex?
Reflexes that use the brain as a relay centre without conscious involvement.
119
Where do learned reflexes take place?
In the lower regions of the brain
120
How are learned reflexes activated?
need a stimulus from a higher region, but once started always lead to the same response
121
What is the system called that controls the reflexes which help keep a constant internal environment in the body ?
Examples of such reflexes
Autonomic nervous system
e.g breathing, heart beat, peristalsis
122
How can the brain communicate with the other parts of the body?
Via the spinal cord
123
definition of involuntary action
Does not involve any consious decision by the brain
organism has no choice
response automatically follows the stimulus
124
How are learned reflexes formed?
Each time a particular stimulus leads to a certain response, that impulse passes along the same route
e.g talking, cycling
125
What is a transducer?
Something which can convert one type of energy into another
- sense organs convert energy
126
What are the 4 types of receptors?
Photoreceptor - light
Chemoreceptor - chemicals
Thermoreceptor - changes in temp.
Mechanoreceptor - mechanical changes such as changes in length
127
Where can you find them?
p - rod cells in retina of eyes
c - taste buds
t - t in skin
m - hair cells in ear (hearing and balance)
128
Where can you find them?
p - rod cells in retina of eyes
c - taste buds
t - t in skin
m - hair cells in ear (hearing and balance)
129
What is a conditioned reflex?
Learned reflexes in which the final response has no natural relationship to the stimulus
130
Can conditioned reflexes be unlearnt? How?
Yes
- if the unnatural stimulus is not repeated with the natural one`
131
What is the endocrine system?
A collection of endocrine glands found throughout the body that secrete hormones directly into the bloodstream
132
Definition of hormone
A hormone is a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs
133
How does a hormone bring about a response?
Receptors on the cell membranes of cells in the target organ recognise the hormone.
The cells then respond by changing their cellular activity to bring about a particular effect.
134
5 differences between the endocrine and the nervous system?
transmission of chemicals / electrical impulses
transmission via blood / in nerves
slow transmission / rapid transmission
hormones dispersed throughout body / impulse sent directly to target organ
long-term effects / short-term effects
135
What is similar about the nervous and the endocrine system?
Can carry messages long distances in the body
136
What does the endocrine system coordinate?
Coordinates the activity of many different organs and bodily functions.
137
In what process does the E system play a key role in?
How?
HOMEOSTASIS
- enables cells to alter their activity in response to changes in body conditions
138
What can happen if the E system isn’t working properly?
Can prevent internal conditions from being regulated effectively.
139
What does the pituitary gland do?
Secretes several types of hormone in response to changes in body condition
140
What is special about some pituitary hormones?
Used to regulate the activity of other endocrine glands, which secrete the own hormones in response
141
What gland secretes adrenaline?
Adrenal gland
142
What parts of the body does adrenaline target?
Heart, blood vessels, liver
143
When is adrenaline released?
In times of fear or stress
144
Effects of adrenaline
increasing heart rate
increasing blood pressure
increasing blood flow to muscles
relaxing the airways and increased breathing rate
stimulating the liver to convert glycogen to glucose, which is released into the blood to increase blood glucose levels
pupils dilate
145
What do the effects of adrenaline increase?
the body’s metabolism
146
Advantages of increased heart rate and blood pressure
Increases the flow of blood to the muscles
147
Advantages of relaxing the airways and increasing breathing rate
Allows more oxygen to enter the lungs where it is taken up into the blood
148
Advantages of the release of glucose from the liver
Increases blood glucose levels, allowing more glucose to be delivered to the muscles
149
The overall advantage of adrenaline
Adrenaline increases the supply of oxygen and nutrients to the muscles - priming them for action
150
Why is the increase of oxygen and glucose to the brain good?
Primes the brain for activity
- coordinating a response to the stress that has stimulated the secretion of adrenaline
151
What happens after the hormones have taken action and are no longer needed?
Do not remain permanently in the blood
- changed by the liver into inactive compounds and are excreted by the kidneys
152
Do endocrine glands deliver their secretion through ducts?
NO
- hormones picked up directly from glands by the blood circulation
153
What can cause hormonal changes to be slower?
depend on the speed of circulatory system (time taken for hormone to travel)
time it takes for cells to change their chemical activities
154
What changes can hormones cause/ take part in?
growth rate, puberty, pregnancy
155
What is the adrenal medulla and what is its role?
Part of the adrenal gland
Receives nerve impulses from the brain and releases adrenaline
156
What is the process that leads to adrenaline being released?
In response to a stressful situation, nerve impulses are sent from the brain to the adrenal medulla, which releases adrenaline into the blood
157
Is the pancreas an endocrine (ductless) gland?
YES
158
What are islets?
Hormone-producing cells are arranged in small isolated groups called islets
159
what are exocrine glands?
glands which secrete substances through a duct or tube
160
What do the ovaries produce?
oestrogen and progesterone
control puberty in females (make female secondary sexual characteristics develop) including development of breasts and hips.
control the menstrual cycle and ovulation
161
What do the testes produce?
Testosterone
controls puberty in males, including deepening hair, stronger muscles and growth of body hair
controls development and release of sperm
162
How is hormone production controlled by feedback control?
hormones regulate their own production
as the level of hormone in the blood rises, it switches off (INHIBITS) its own production so that the level never gets too high
as the level of hormone in the blood falls, it switches on (STIMULATES) its own production so that the level never gets too low.
163
What 2 hormones secreted by the pituitary gland control the secretion of further hormones by the reproductive organs?
LH and FSH
164
In females, what do LH and FSH stimulate the secretion of?
oestrogen progesterone by the ovaries
165
In males, what do LH and FSH stimulate the secretion of?
Stimulate testes to produce testosterone
166
What are the female secondary sexual characteristics?
breasts develop
hips widen
pubic hair grows
eggs are released
167
What are the male secondary sexual characteristics?
voice deepens
pubic hair grows
facial hair grows
sperm are produced
168
Basic summary of how reproductive hormones take part in the menstrual cycle
Hormones stimulate the maturation and release of an egg from the ovaries approximately every 28 days.
169
Why is it important that the uterus lining thickens prior to ovulation during the menstrual cycle?
If an egg is fertilised, it implants itself in the uterus lining.
Uterus lining provides the fertilised egg with a supply of oxygen and nutrients, enabling it to develop into an embryo.
170
What happens if an egg is not fertilised?
Uterus lining breaks down and the menstrual cycle begins again.
171
What are sense organs?
Sense organs are a group of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals.
172
What is the function of the cornea of the eye?
Cornea is transparent and refracts light.
173
What is the function of the iris of the eye?
Iris controls how much light enters the pupil.
174
What is the function of the lens of the eye?
Lens is transparent and can change shape to focus light onto the retina.
175
What is the function of the retina of the eye?
Retina contains light recepetor cells, some sensitive to light of different colours (rods - detect light intensity; cones - detect colour).
176
What is the function of the optic nerve of the eye?
Optic nerve sensory neurone that carries impulses from the eye to the brain.
177
What is the function of the pupil of the eye?
The pupil is a hole that allows light to enter the eye.
178
What is the pupil reflex?
This is an involuntary reflex action carried out to protect the retina from damage in bright light and allows more light to enter your eye in dim light.
179
Explain the pupil reflex limited to changes in dim light intensity and pupil diameter.
In dim light, the pupil dilates to allow more light to enter the eye to improve vision.
180
Explain the pupil reflex limited to changes in bright light intensity and pupil diameter.
In bright light, the pupil constricts to allow less light to enter the eye to protect the retina from damage (bleaching).
181
Explain the pupil reflex in terms of the antagonistic action of circular and radical muscles in the iris in regards to dim light.
In dim light, radical muscles contract, circular muscles relax and the pupil dilates and more light to enter the eye.
182
Explain the pupil reflex in terms of the antagonistic action of circular and radical muscles in the iris in regards to bright light.
In bright light, radical muscles relax, circular muscles contract and the pupil constricts and less light enters the eye to protect the retina from damage by bleaching.
183
What muscles work antagonistically in the eye?
The muscles that work antagonistically are the radical muscles and the circular muscles of the eye.
184
Define the accommodation of the eye?
Accommodation is the function of the eye in focusing on near and distant objects.
185
How can the shape of the lens be changed?
The lens is elastic and its shape can be changed when the suspensory ligaments attached to it become tight of loose.
186
Explain accommodation to view near objects in terms of the contraction and relaxation of the ciliary muscles, tension in the suspensory ligaments, shape of the lens and refraction of light.
The ciliary muscles contract which causes the suspensory ligaments to loosen making the lens fatter and curved and light is refracted more by the lens to focus on the nearby object.
187
Explain accommodation to view distant objects in terms of the contraction and relaxation of the ciliary muscles, tension in the suspensory ligaments, shape of the lens and refraction of light.
The ciliary muscles relax which causes the suspensory ligaments to tighten and pull on the lens marking it thinner and less curved and light is refracted less, allowing the eye to focus on the distant object.
188
There are two types of receptor cells in the retina: NAME THEM.
There are two types of receptor cells in the retina:
- Rods which are sensitive to dim light.
- Cones which distinguish between different colours in bright light.
189
Describe the distribution of rods in the retina of a human.
Rods are evenly distributed and less tightly packed at the periphery of the retina; absent at the fovea.
190
Describe the distribution of cones in the retina of a human.
Cones are found tightly packed in the fovea.
191
Outline the function of rods.
Greater sensitivity of rods for night vision.
192
Outline the function of cones.
Three different kinds of cones, absorbing light of three different colours (red, blue, green) for colour vision.
193
What is a nerve impulse?
An electrical signal that passes along nerve cells called neurons
194
What does a receptor do?
Detects a change in stimulus
195
What does the central nervous system consist of?
Brain and spinal cord
196
What does the peripheral nervous system contain?
Every other part- nerves
197
Define voluntary action
An action completed with conscious thought and under our own will
198
Define involuntary action
An action completed without conscious thought
199
Define involuntary action
An action completed without conscious thought
200
What is a relay neurone?
Short and are located in the CNS , connecting sensory and motor neurones
201
What is a sensory neurone?
Long and have a cell body branching off the middle of an axon. Carry impulses from sense organ to CNS
202
What is a motor neurone?
Long and have a cell body at one end with long dendrites branching off. Carry impulses from the CNS to muscles and glands.
203
Describe the simples reflex arc
Stimulus is detected by receptor in the skin
Sensory neurone sends electrical impulses to spinal cord
Electrical impulse is passed on to a relay neurone in spinal cord
Relay neurone carries impulse to motor neurone which carries it to a muscle in the arm
Muscle contracts and pulls hand up and away from hot object
204
Define reflex action
Automatically and rapidly integrating and coordinating stimuli with the responses of effectors
205
Define synapse
Junction between two neurones
206
Describe a synapse
The impulse reaches the end of one neurone
Vesicles release neurotransmitters into synaptic gap
Neurotransmitter diffuses across gap and binds with receptors
New impulse is triggered in the next neurone
207
Describe a synapse
The impulse reaches the end of one neurone
Vesicles release neurotransmitters into synaptic gap
Neurotransmitter diffuses across gap and binds with receptors
New impulse is triggered in the next neurone
208
What do synapses ensure?
That impulses travel in one direction only
209
What substances affect synapses?
Heroin
alcohol
nicotine
210
Define sense organs
Groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals
211
What does the cornea do?
Refracts light and helps to focus it
212
What does the cornea do?
Refracts light and helps to focus it
213
What does the iris do?
Controls how much light enters the pupil
214
What does the lens do?
Refracts light to focus it into the retina
215
What does the retina do?
Contains light receptors some sensitive to light of different colours
216
What is the optic nerve?
Transmits electrical impulses from retina to brain
217
What happens when the eye gets exposed to bright light?
The radial muscle contracts and the circular muscle relaxes and the pupil decreases in size letting less light in
218
What happens when the eye gets exposed to a lack of light?
The radial muscle relaxes and circular muscles contract and the pupil increases in size to let more light in
219
What happens when we are looking at a distant object?
Ciliary muscles relax
Suspensory ligaments stretch thin
lens become thinner
light is refracted less
220
What happens when we are looking at a near object?
Ciliary muscles contract
Suspensory ligaments slack
Lens becomes fatter
light is refracted more
221
Which cells do we have in our eye?
Rods and cones but there are more rods than cones
222
What does the fovea contain?
Only cone cells
223
What is the fovea?
An area on the retina with lots of photosensitive cells so it has the highest visual activity
224
When do rods function?
In low light intensities= night vision- greater sensitivity
225
What do cones do?
They detect red blue and green.
226
What is homeostasis?
Maintenance of a constant internal environment and is the control of internal conditions within set limits achieved by negative feedback
227
Give examples of internal conditions
Temperature
blood pressure
water concentration
glucose concentration
228
When does negative feedback happen?
When conditions change from the ideal point and returns conditions to this set point
229
What are negative feedback mechanisms usually?
A continuous cycle of bringing levels down and then bringing them back up so that overall they stay withing a narrow range of what is considered normal
230
What is the ideal body temperature for enzymes?
37 C
231
What is hyperthermia?
When heat gain exceeds heat loss and the temperature rises
232
What is hypothermia?
When heat loss exceeds heat gain and the temperature falls.
233
Where is regulation controlled?
In the hypothalamus which contains receptors sensitive to the temperature of the blood.
234
Where are there temperature receptors?
The skin and sends impulses via sensory neurones
235
What is the top layer of the skin called?
Epidermis
236
What is the lower layer of the skin called?
Dermis
237
What is the dermis made of?
Connective tissue
238
What does the connective tissue contain?
Elastic fibres and collagen fibres
239
What happens as a person gets older?
Fibers lose their elasticity so the skin becomes loose and wrinkled
240
What does the dermis contain?
Sweat glands
241
What do the sweat glands do?
They secrete a liquid called sweat which is mostly water with small amounts of salts and urea dissolved in it
242
How does sweat travel?
It travels up the sweat ducts and onto the surface of the skin through the sweat pores
243
What happens when it is too warm?
Hair erector muscle relaxes lowering the hair
a thin insulating layer of air is trapped above the skin
more heat is lost to the environment by evaporation convection and radiation
244
What happens when it is too cold?
The hair erector muscle contracts raising the hair
the hairs trap a thicker layer of air above the skin
The air insulates the skin
245
What is underneath the dermis?
A layer of fat called adipose tissue
246
What does the adipose tissue do?
Helps insulate the body against heat loss and acts as an energy reserve
247
What is shivering?
When muscles in some parts of the body contract and relax very quickly
248
How does shivering help?
Heat is generated in the muscles and warms the blood as it flows through them
249
What does the dermis contain?
Blood vessels and nerve endings
250
What do the nerve endings do?
They are sensitive to touch, pain, pressure and temperature
251
What happens to our arterioles when we are cold?
They become narrower
252
What is it called when our arterioles contract?
Vasoconstriction
253
How does Vasoconstriction help?
Reduces the amount of heat loss from blood by radiation as less blood flows through the surface of the skin
254
What happens when our arterioles when we are hot?
They dilate
255
What is it called when our arterioles dilate?
Vasodilation
256
How does Vasodilation help?
there is more blood and bc there is a lot of blood near the surface of the skin heat is readily lost from the blood into the air by radiation.
257
What is an effector?
An effector is a part of the body that creates a response such as muscles
258
What happens when the body temperature raises?
Temperature receptors in the skin detect an increase
Nervous impulse sent to the hypothalamus and it coordinates a response
sweat is released and blood vessels dilate
259
What is produced when blood glucose rises?
Insulin
260
What happens when blood glucose rises?
Insulin produced
stimulates the liver
muscle cells to convert excess glucose into glycogen
261
How are blood glucose levels controlled?
Negative feedback mechanism involving glucagon and insulin
262
Where are insulin and glucagon produced?
Pancreas
263
Why do cells need glucose?
To respire to release energy
264
Why is too much glucose not good for cells?
water moves out of the cells and into the blood by osmosis
265
What is type 1 diabetes?
A condition where the blood glucose levels are not able to be regulated as the insulin secreting cells in the pancreas are not able to produce insulin
266
What happens if you have Type 1 diabetes?
the blood glucose levels are too high
267
How can you treat type 1 diabetes?
Injecting insulin
268
What can having high or low blood glucose concentrations cause?
Damage to numerous body organs
269
What is hyperglycaemia?
When the blood glucose concentration goes up and stays up
270
What is hypoglycaemia?
When the blood glucose drops very low
271
What can hypoglycaemia cause a person to feel?
very tires
confusion
irrational behaviour
272
How can people monitor type 1 diabetes?
Levels of physical activity
their diet affects the amount of insulin needed
273
Give two examples of homeostasis
Osmoregulation (body water content)
Thermoregulation (body temperature)
274
What is thermoregulation
Temperature regulation
275
Why is thermoregulation important?
Enzymes denature if temp too high
Cell membranes become fragile as temp rises
Diffusion rates rise with night temps and fall with lower temps
Liquids such as blood become more viscous (thicker) as temp falls
276
What controls thermoregulation
The hypothalamus
277
Protective functions of the skin
Tough water proof barriers between body and external environment
Regulates body temp
Contains sensory receptors to detect external environment changes
Protection from infection
278
What are the two main layers in the skin
The upper epidermis and lower dermis
279
What is the function of melanin
Absorbs ultraviolet light and protects the cells DNA from damage
280
Mammals and birds are what?
Endotherms
281
What can endotherms do
Maintain an internal environment that doesn’t change when external environmental temperatures change
282
Amphibians reptiles insects and fish are what
Ectotherms
283
Why can endotherms survive extreme temperatures better?
Temperature affects Ectotherms a lot more
284
Which animal will lose heat more quickly. A mouse or an elephant?
A mouse because it has a big surface area to volume ratio
285
What happens to sweat glands in the cold?
Sweat is not produced so sweat doesn’t move onto skin surface
286
What happens to sweat glands in hot temps
Sweat produced, water in sweat evaporates from the skin. This uses heat energy from the blood which will reduce heat energy and so cool you down
287
Why is it important for organism to control their internal environment?
So enzymes can control cell function and enzymes need specific conditions to work efficiently
288
Name two ways in which organisms achieve this coordination
Through hormonal control (endocrine control)
Through nervous control (nervous system)
289
What is the stimulus
Change in environment that triggers a reaction (eg a stimulus effects an endocrine gland to release a hormone)
290
What is the receptor
This receives the stimulus (e.g a receptor molecule on a cell membrane for a hormone)
291
What is the effector
The part of the organism that carries out the reaction to the stimulus (e.g a muscle or a gland)
292
What are glands?
Small structures responsible for making and secreting specific chemicals
293
What hormone is secreted by the pituitary gland in the brain?
A.D.H anti-diuretic hormone
Hormone for water regulation
294
What do the adrenal glands produce?
Adrenaline
295
Where are the adrenal glands?
Above the pancreas
296
What does pancreas secrete
Insulin
Controls blood sugar levels
297
What do the ovaries produce
Oestrogen and progesterone
298
What do the testis (singular) testes(plural) produce
Testosterone
299
How can you tell endocrine glands and exocrine glands apart?
Exocrine glands have tubes which secretes the hormones where as endocrine glands are just there.
ONE HAS A TUBE OR DUCT THAT LEADS/CONNECTS IT TO ANOTHER PART OF THE BODY
300
How do hormones work when they reach their target organs?
They lock onto receptor on their target cells. This triggers a reaction. Afterwards the hormones travel to the liver and are broken down
301
Explain how the adrenal gland can help an athlete running (e.g Ella because she’s a bloody pro)
Adrenaline is produced and passed into the blood, the breathing rate becomes quicker causing more oxygen to be taken in and more carbon dioxide removed. The heart beats faster so more oxygen is passed into the blood. This means that more respiration occurs and more energy ATP and glucose is released which increases blood sugar levels. This gives the athlete more energy and they can run faster and for longer.
302
What is homeostasis
Maintaining a constant internal environment
303
What is the conjunctiva?
A thin membrane protecting the eye
304
What is the pupil?
A “black hole” that lets light in
305
What is the iris?
A coloured thing that controls the amount of light let into the eye
306
What are the ciliary muscles?
Muscles controlling the thickness and curvature of the eye
307
What is the cornea?
Bends light to form an image and is also there for protection.
308
What is the lens?
The big thing behind the pupil that fine tunes the image. (Tallula I thinks it’s the thing that we spent ages trying to cut.😂)
309
What is the vitreous humour?
A stiff jelly that supports the back of the eye. Makes up the inside of the eye ball
310
What is the suspension ligament?
The ligament that supports and suspends the lens
311
What is the retina?
The back of the eye that contains rods and cones
312
What’s the choroid?
The bit behind the retina that contains a good blood supply and melanin which absorbs light to avoid internal reflection and glare
313
What is the blind spot?
A part with no receptors present
314
What is the optic nerve?
It contains the sensory neurones linking the retina to the midbrain
315
What is the sclera?
The bit behind the choroid. It is tough and fibrous to prefect the eye
316
What is a fovea? (Yellow spot)
Contains only come cells. Most sensitive part of the retina for colour vision
317
What does the eye do to focus on near objects?
Ciliary muscles contract which slackens the suspension ligament
Muscle tension on the lens is lower
Lens becomes fatter and more curved allowing light to refract more.
318
What is the near point
The closet an object can be from the eye without appearing blurred.
319
What is the aqueous humour?
A watery liquid filling the front of the eye.
320
Structure of a neurone
Cell membrane, cytoplasm, nucleus
Dentrites (the spiky bits on the end of the main part of the cell)
Axon(the but the electric impulse travels down)
Fatty sheath (protects the axon)
Nerve ending
321
What is the gap between neurones called?
Synapse
322
What is a synapse?
The gap where chemical messages pass from nerve ending to other neurone.
323
What is the CNS made up of
The central nervous system is made of the brain, spinal chord and is protected by bones, it is linked to organs via nerves.
324
What are the three types of neurones called??
Sensory neurones, relay neurones, motor neurones
325
What is geotropism or gravitropism a response to
Gravity
326
What is a coleoptile?
The first shoot emerging from soil
327
What is auxin
A plant growth hormone responsible for geotropism
328
If you shine light on a plant where does the auxin go?
To the dark side.
329
In a shoot a high concentration of auxin….
Causes cell elongation
330
In a root a high concentration of auxin…
Stops cell elongation
331
Directional growth response:
Positive (growth towards stimulus)
Negative (growth away form stimulus)
332
What is phototropism a response to
Light
333
Synapse
junction between two neurons
334
Sense organ
group of receptor cells responding to specific stimuli : light, sound, touch, temperature and chemicals
335
Hormones
a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs
336
homeostasis
maintenance of a constant internal environment
337
Autonomous nervous system
brain ( no control)
338
Peripheral nervous system
nerves and spinal cord
339
central nervous system
brain and spinal cord
340
brain is protected by the
skull
341
ANS is
independent, cant control
342
Receptors:
parts of the body that detect stimuli
343
types of receptors
1) thermo- receptors ( heat)
2) thigmo-receptors ( pain/pressure)
3)chemoreceptors (taste/ chemicals)
4)photoreceptors (sight)
5) audio receptors ( sound)
344
Coordinators:
parts of the body that pass on info about stimuli to the effector
345
Effectors
parts of the body that make a response to the stimuli
- For example: muscles and glands
346
3 types of neurones
1) motor neurone
2) sensory neurone
3) relay neurone
347
relay neuron is AKA
inter neurone
348
motor neurons are located at the
terminals
349
what do motor neurones do
takes the impulse from the brain or spinal cord to the effector
350
what do sensory neurones do
takes the impulse from the receptor of the stimuli to the spinal cord or brain
351
order when a stimuli is received
stimuli ➟ receptors ➟ sensory neuron ➟central nervous system
352
nerve impulse
an electrical signal that passes along nerve cells called neurons
353
impulse inside nerve cell
electrical
354
impulse outside nerve cell
chemical but ➟ electrical
355
1 neuron to another
travel through neurotransmitters
356
dendrite
recieves impulses
357
axon
gives impulse
358
Voluntary actions
those we choose to make and the decisions to make them occur in our brains.
These are also known as cranial reflexes as impulses are sent to the brain before a decision is made.
359
Involuntary actions
occur unconsciously. They are also known as spinal reflexes , as impulses don’t
reach the brain.
360
Reflex arc
sensory neurone ➟ relay neuron ( spinal cord )
➟ motor neurone ➟ effector
361
what triggers an impulse in the synapse
presynaptic membrane releases neurotransmitters. neurotransmitters move from their region of higher concentration to their region of lower concentration down the concentration gradient. which then binds with the complimentary neuro receptors on the surface of the post synaptic membrane triggering an impulse .
362
Amphetamines and other excitatory drugs stimulate the release of neurotransmitters in the brain, which makes the person more
alert, suppresses appetite
363
Heroin and beta-blockers are inhibitory drugs. These drugs reduce the release of neurotransmitters by
acting on neuron membranes
364
Heroin acts on the postsynaptic neuron to reduce the transmission of neurotransmitters, and this reduces the
sensation of pain and creates a feeling of euphoria .
365
how does the intake of heroin cause someone to go depressed?
heroin breaks down to form morphine, which is known to cause depression. presynaptic membrane releases morphine molecules. morphine molecules move from their region of higher concentration to their region of lower concentration down the concentration gradient. and these morphine molecules are the exact same shape as the neurotransmitters so they bind with neuro receptors on the postsynaptic membrane and block neuro transmitters from reaching the receptor, stimulating depression.
366
Beta-blockers are taken to reduce
BP and heart rate.
367
Beta-blockers lodge themselves in the receptors of
postsynaptic neurons, preventing impulses from flowing
368
cornea description
The front part of the sclera. Is convex
and transparent
369
cornea function
Protects the front of the eye and
refracts light
370
iris description
A coloured ring of circular and radial muscle that controls the size of the pupil and so controls the amount of light entering the eye
371
iris function
Pigmented so light cannot pass
through. Muscles contract and relax to
control the size of the pupil.
372
lens decription
Transparent, biconvex, flexible disc
behind the iris attached by the
suspensory ligaments to the ciliary
muscles
373
lens function
Brings light entering through the pupil
to a focus on the retina
374
retina description
Lining of the back of the eye
containing rods and cones
375
retina function
Screen on which images are formed as
a result of light being focused onto it
by the cornea and lens
376
optic nerve description
Bundle of sensory neurons at the back
of the eye
377
optic nerve function
Carries signals from the photoreceptors to the brain
378
Pupil reflex
Radial and circular muscles are antagonistic pair. This means they work together, but their effects are produced by contrasting actions
379
pupil reflex in bright light
In bright light, Radial muscles relax, and circular
muscles contract causing the pupil to constrict .
This reduces the amount of light entering the eye,protecting the retina.
380
pupil reflex in dim light
In the dim light, radial muscles contract and
circular muscles relax causing the pupil to dilate . This increases the amount of light entering the eye
381
Accommodation
the term used to describe the changes that occur in the eye when focusing on far and
near objects
382
As light enters the eye
it must be bent so that the image can be seen clearly. Most of the refraction is done by the cornea and some by the lens.
383
The shape of the lens is controlled by the
antagonistic muscle pair consisting of the ciliary muscle and the suspensory ligaments.
384
For a distant object:
❖ Ciliary muscles relax
❖ The pressure inside the eye pulls the suspensory ligaments tight, pulling the lens into an elliptical shape.
385
For a near object:
❖ Ciliary muscles contract to counteract the pressure in the eye
❖ Suspensory ligaments become slackened and the lens has a more circular shape
386
There are two types of photoreceptors in the eye
❖ Rods
➢ Sensitive to levels of low light and send impulses when it is dark.
➢ Black and white
❖ Cones
➢ Sensitive to the light of high intensity
➢ Three types (Red, Blue, and Green) (Mixtures of these are also found)
387
The fovea is the center of the retina and contains
cones and no rods.
388
Each cone has its
neuron to the brain so
this area in the middle of our visual field gives us a very detailed image. The rest of the retina contains rods and few cones. This area gives us our peripheral vision which is not as detailed.
389
endocrine glands
releases hormones directly into the blood
390
Exocrine glands
glands which secrete substances through a duct or tube
391
endocrine glands organ
1) pituitary gland
2) adrenal glands
3) pancreas
4) tests (male)
5) ovaries ( female)
392
pituitary gland releases which hormones and effects
hormone:FSH, LH
effects:Controls growth, sperm and egg production
393
adrenal gland releases which hormones and effects
hormone: adrenaline
effect:Released in fight or flight situations
394
The pancreas releases which hormones and effects
hormone: inulin, glucagon
effect: Insulin lowers blood glucose, and glucagon increases it
395
testes (male) releases which hormones and effects
hormone: testosterone
effect: Stimulates development during puberty
396
Ovaries (Females) release which hormones and effects
hormone: estrogen
effects:Control menstrual cycle and stimulate development
397
esponses necessary to survive in ‘fight or flight’ situations are coordinated by
adrenaline
398
adrenaline can
increasing breathing rate, increased heart rate, widening the pupils so more light
enters the eye, converting glycogen in the liver to glucose, coordinates increased uptake of O 2 and changing blood distribution so O 2 and glucose get to muscles.
399
how does adrenaline increase these things
➢ Air passages widen to allow more air into the body
➢ Arterioles in the brain and muscles dilate
➢ Arterioles in other parts of the body constrict
400
Adrenaline secretion can increase as a result of
fear or stress
401
nervous system structures
nerves
402
endocrine system structures
secretory glands in cell
403
nervous system form of info
electrical impulses
404
endocrine system form of info
hormones
405
nervous system pathways
along neurones
406
endocrine system pathways
in the blood
407
nervous system speed of info transfer
fast
408
endocrine system speed of info transfer
slow
409
nervous system longevity of responses
short lived
410
endocrine system longevity of processes
slow or longlasting
411
nervous system target area
specific effector
412
endocrine system target area
Whole tissue or organ
413
nervous system response examples
Muscle contraction or secretion
by glands
414
endocrine system response examples
Conversion of glycogen to
glucose, protein synthesis, rate
of respiration
415
negative feedback
In negative feedback, a change sets off a response that cancels out the change to restore conditions to their normal levels.
416
When carbs are eaten,
the amount of glucose in the blood increases. The pancreas secretes insulin into
the blood which stimulates liver cells to convert glucose into glycogen. This reduces the concentration of glucose in the blood.
417
When glucose levels in the blood are low
for example after exercise, the pancreas secretes glucagon which stimulates liver cells to break down glycogen into glucose and increase glucose concentration levels in the blood.
418
Type 1 diabetes
The pancreas cannot produce sufficient insulin
Symptoms: tiredness, thirst, unexplained weight loss, blurred vision, frequent urination
Treatment: Insulin doses are to be taken before meals
419
largest organ in the body
skin
420
skin functions
❖ Protects the body from damage
❖ Stops pathogens from entering
❖ Prevents too much water loss
❖ Detects temp. changes
❖ Detects pressure changes (pain)
421
controlling body temperature in the heat
the brain detects an increase in blood temp. The brain sends impulses to increase the rate of sweating so that more heat is lost by evaporation. Hair erector muscles contract to allow hairs to lie flat.
No shivering.
422
controlling body temperature in the cold
the brain detects a decrease in blood temp. Sweat glands stop producing sweat, hair erector muscles relax to raise the hairs which trap air, providing insulation. Body shivers to generate heat from
respiration.
423
vasodilation
In hotter weather, muscles of arteriole walls relax causing them to dilate/widen. There is now an increased flow of blood to capillaries which means more heat is lost to the surroundings by convection and radiation
424
vasoconstriction.
In cooler weather, the muscles of the arteriole walls contract and make the artery narrower. Blood may also be redirected to veins via shunt vessels, under the fat layer of the skin. There is now a decreased flow of blood to capillaries which reduces the amount of heat lost by convection and radiation.
425
Gravitropism
esponse in which parts of a plant grow towards or away from gravity
❖ Roots are positively gravitropic as they grow in the direction of gravity
❖ Shoots are negatively gravitropic as they grow upwards, away from gravity
426
Phototropism
response in which parts of a plant grow towards or away from light
❖ Shoots are positively phototropic as they grow towards light
❖ Roots are negatively phototropic as they grow away from light. Either ways, they are not
sensitive to light
427
The role of auxins
❖ Auxin is made solely on the shoot and root tips
❖ It then spreads throughout the plant from the tips
❖ Distributed unequally in response to light and gravity
❖ Stimulate cell elongation - eventually growth
❖ A high concentration of auxins promotes growth in the shoot but inhibits growth in the root
❖ In shoots, auxins move to the side away from light, in roots auxins move to the lower side
428
positive phototropism
where? stem tip
direction growth? growth towards light
adv? maximum light for photosynthesis
429
negative phototropism
where? the root tip
direction of growth? growth away from light
adv? less chance of drying out
430
positive geotropism
where? root tip
direction of growth? towards gravity
adv? more chance of finding moisture
431
negative geotropism
where? shoot tip
direction of growth? away from gravity
adv? more chance of finding light
432
Synthetic auxins are very effective as
Selective Weedkillers
433
why are herbicides like 2.4-D sprayed on broad level weeds?
tends to run off thinner leaves.
434
how do auxins increase the growth rate of weeds
by increasing the rate of cell division
435
why do all weeds eventually die
cannot produce enough food to sustain the growth
436
Electrical impulses travel along
neurones
437
Mammalian nervous system consist of
The central nervous system (CNS) consisting of the brain and the spinal cord
The peripheral nervous system (PNS) consisting of the nerves outside of the
brain and spinal cord.
438
Role of the nervous system is
coordination and regulation of body functions.
439
Reflex arc:
receptors detect stimulus and generate impulse, it travels to sensory
neurone, then relay neurone, then to motor neutron, then to the effector.
440
A reflex action
a means of automatically and rapidly integrating and coordinating
stimuli with the responses of effectors (muscles and glands).
441
synapse
A junction between two neurones
442
Structure of synapse include:
presence of vesicles containing neurotransmitter molecules
Synaptic gap/cleft
receptor protein
443
Events at a synapse:
An impulse stimulates the release of neurotransmitter molecules from vesicles
into the synaptic gap.
The neurotransmitter molecules move from their region of higher concentration to their region of lower concentration down their concentration gradient across the gap
Neurotransmitter molecules bind with receptor proteins on the next neuron
An impulse is then stimulated in the next neuron.
444
Synapses ensure that
impulses travel in one direction only.
445
Sense organs
groups of receptor cells responding to specific stimuli: light,
sound, touch, temperature and chemicals.
446
cornea function
refracts light
447
iris function
controls how much light enters the pupil
448
lens function
focuses light on to the retina
449
retina function
contains light receptors, some sensitive to light of different colours
450
retina function
contains light receptors, some sensitive to light of different colours
451
optic nerve function
carries impulses to the brain
452
As light intensity increase,
diameter of pupil decrease so that less light enters the
eye and prevent damage. The antagonistic muscles, circular muscles contract and
radial muscles relax.
453
As light intensity decrease,
diameter of the pupil increase so that more light enters the
eye and prevents damage. The antagonistic muscles, circular muscles relax and
radial muscles contract.
454
Distant object
Ciliary muscles relax, suspensory ligament pulled tight (tension on
suspensory ligament increase). the lens becomes thin/ less convex.
455
Near object
Ciliary muscles contract, suspensory ligament slackened (tension on
suspensory ligament decrease). the lens becomes thick/ more convex.
456
There are three different kinds of cone cells
red, green and blue
457
Fovea is almost entirely cones,
packed tightly together
458
Rods
are found further out
on the retina and are less tightly packed.
Rod cells are more sensitive at night
459
Hormone
a chemical substance, produced by a gland and carried by the blood,
which alters the activity of one or more specific target organs.
460
Adrenal gland secrete
adrenaline.
461
Pancreas secrete
insulin and glucagon
462
Testes
secrete
testosterone
463
Ovaries secrete
estrogen
464
Effect of adrenaline:
increased breathing rate
increased heart rate
increased pupil diameter
increase in blood glucose concentration
465
Speed of action of nervous system is faster than
hormonal control system. Duration
of effect of hormonal control system is longer than the nervous system
466
Homeostasis
maintenance of a constant internal environment
467
Insulin decreases
blood glucose concentration.
468
In negative feedback:
There is a set point – a normal level that the system tries to maintain.
There is a ‘measuring device’ that keeps track of whether the level is within the
range of the set point.
If the level goes outside the set point, this triggers events to happen that bring
the level back into line again.
469
If blood glucose concentration is too high
it is detected by the pancreas, pancreas
release insulin, insulin stimulate liver cells to absorb glucose from blood across the
partially permeable membrane. Liver cells convert glucose to glycogen and store
glycogen in liver cells, this results in reduction of blood glucose concentration until it
reaches the set, normal point.
470
If blood glucose concentration is too low
it is detected by the pancreas, pancreas
release glucagon, glucagon stimulate liver cells to convert store glycogen into
glucose, and release this glucose into the blood. This results in increase of blood
glucose concentration until it reaches the set, normal point.
471
Treatment of type 1 diabetes:
-insulin ;
-by injection / insulin pump ;
- regular blood glucose tests
regular meals and controlled diet
472
If the internal temperature is above normal
it is detected by the brain. Vasodilation of
arterioles occur, more blood flows to the skin, so more heat is lost form the blood,
decreasing the internal temperature. Sweating occurs which gives a cooling effect
and decreases the internal body temperature
473
If the internal temperature is below normal
it is detected by the brain.
Vasoconstriction of arterioles occur, less blood flows to the skin, so less heat is lost
form the blood, increasing the internal temperature. Adipose tissue in skin act as
insulation and reduce heat loss. Shivering produce heat and help to keep the body
warm.
474
Gravitropism
a response in which parts of a plant grow towards or away from
gravity.
475
Phototropism
response in which parts of a plant grow towards or away from the
direction of the light source
476
examples of the chemical control of
plant growth
Phototropism and gravitropism
477
How auxin work:
auxin is made in the shoot tip
auxin diffuses through the plant from the shoot tip
auxin is unequally distributed in response to light and gravity
auxin stimulates cell elongation
