B3 Flashcards
(270 cards)
1
Q
What is your nervous system?
A
It detects changes in your external environment, processes it and responds to it accordingly
2
Q
What are the 3 main stages to a nervous response?
A
- Change in environment
- Detecting the stimulus
- A response occurs from the effectors
3
Q
What is a stimulus?
A
A change in the environment
4
Q
What are the sensory receptors?
A
A group of cells that detects the stimulus
5
Q
What are the effectors?
A
Muscles or glands
6
Q
How do muscles respond to a impulse?
A
They contract which causes movement
7
Q
How do glands respond to an impulse?
A
They release hormones
8
Q
Where are receptors cells found?
A
In your sense organs
9
Q
What do receptor cells do?
A
They change the stimulus into electrical impulses that travel along neurones to your central nervous system
10
Q
What is your central nervous system (CNS) made up of?
A
Your brain and spinal cords - delicate nervous tissue so are protected by bones
11
Q
What protects the brain?
A
The skull
12
Q
What protects the spinal cord?
A
The vertebral column (backbone)
13
Q
What are the receptor cells for you eyes?
A
Light
14
Q
What is the stimulus for your eyes?
A
Light
15
Q
What are the receptor cells for you tongue?
A
Taste
16
Q
What is the stimulus for your tongue?
A
Chemical
17
Q
What are the receptor cells for your skin?
A
Pressure and temperature
18
Q
What are the stimuli for your skin?
A
Pressure and heat
19
Q
What are the receptor cells for your nose?
A
Small and taste
20
Q
What are the stimuli for your nose?
A
Chemical and chemical
21
Q
What are the 3 types of neurones?
A
Sensory neurones
Relay neurones
Motor neurones
22
Q
What do sensory neurones do?
A
Carry electrical impulses from receptor cells to the CNS
23
Q
What do relay neurones do?
A
Carry electrical impulses from sensory neurones to motor neurones
24
Q
What do motor neurones do?
A
Carry electrical impulses from the CNS to effectors
25
What are nerves made of?
Hundred or thousands of neurones
26
What are the steps involved in a nervous reaction?
1. Stimulus
2. Receptor cells
3. Sensory neurone
4. Spinal cord
5. Brain
6. Spinal cord
7. Motor neurone
8. Effector
9. Response
27
How long does a nervous reaction usually take?
0.7 seconds
28
What is a coordinated response?
When you brain takes in a lot of information at the same time (all the time) and makes responses based on the information
29
What does a coordinated response usually end with?
A series of impulses being sent to different parts of the body to produce the required action
30
What a reflex action?
Faster, automatic, involuntary actions
31
What is different about a reflex action?
They miss out the brain so your body can react even faster
32
How long do reflex actions usually take?
0.2 seconds
33
What is an example of a reflex action?
Cutting your hand on broken glass - biceps contract to pull the arm away
34
What are the basic reflex actions?
Basic bodily functions:
Breathing
Heart rate
Digestion
35
What are the steps in a reflex action?
1. Stimulus
2. Receptor cells
3. Sensory neurone
4. Spinal cord
5. Motor neurone
6. Effector
7. Response
36
What is a reflex arc?
The nerve pathway that an impulse follows
37
Describe a reflex arc with steps (draw the flow diagram then add the sentences to make is specific).
1. Stimulus - very hot saucepan
2. Receptor cells - temperature receptors in skin
3. Sensory neurone
4. Spinal cord
5. Motor neurone
6. Effector - biceps muscle contracts
7. Response - hand pulled away
38
What is the cornea?
Transparent coating on the front of the eye
39
What does the cornea do?
Protects the eye, refracts light entering the eye
40
What is the pupil?
Central hole in the iris
41
What does the pupil do?
Allows light to enter the eye
42
What is the iris?
A colouring ring is muscle tissue
43
What does the iris do?
Alters pupil size by contracting or relaxing
44
What is the lens?
Transparent biconvex lens
45
What does the lens do?
Focuses light clearly onto the retina
46
What are the ciliary muscles?
Ring of muscle tissue
47
What do the ciliary muscles do?
Alters the shape of the lens
48
What are the suspensory ligaments?
Ligament tissue
49
What do the suspensory ligaments do?
Connects the ciliary body to the lens
50
What is the optic nerve?
Nervous tissue
51
What does the optic nerve do?
Carries nerve impulses to the brain
52
What does refracts mean?
Changes direction of
53
How are images formed (step by step)?
1. Cornea refracts incoming light rays - provides focus on the light
2. Light passes pupil
3. Light refracted again by lens - creates sharp image on retina
5. Photoreceptors in retina produce nervous impulse (when expose to light)
6. Impulse travels down the optic nerve to brain
7. Brain interprets the impulses as a visual image
54
What are photoreceptors?
Light sensitive cells
55
What happens when your ciliary muscle contracts?
Your lens becomes more convex (fatter) - to focus on nearby objects
56
What happens when your ciliary muscle relaxes?
You lens becomes less convex (thinner) - to focus on distant objects
57
How is short-sightedness caused?
A person’s lens being too strong or the eyeball is too long
58
How is long sightedness caused?
A person’s lens being too weak or by the eyeball being too short.
59
Why are images blurry when you are short sighted?
The light rays meet in front of the retina (not on it) making the image blurry
60
How do you correct short-sightedness?
A CONCAVE lens bends the lights rays outwards before entering the eye.
61
Why is the image blurry in long sightedness?
The lights rays don’t meet on the retina (wider) so the image is blurred.
62
How do you correct long-sightedness?
A CONVEX lens lens bends light rays inwards before they enter the eye.
63
What are the 2 types of photo preceptor cells in the retina?
Rods
Cones
64
What do rods do?
Respond to light
Allow you to see in low light level
They aren’t responsive to different colours
65
What do cones do?
Respond to different colours
Different cone cells respond to red, blue and green
66
How does colour blindness happen?
When people don’t have certain cones in their retina
67
What is the most common form of colour blindness?
Red-green - people can’t distinguish between red and green light
68
Who does red-green colour blindness mainly affect?
Males - it is genetically inherited
69
What are the 5 main areas of the brain?
Cerebrum
Cerebellum
Medulla
Hypothalamus
Pituitary gland
70
What does the cerebrum do?
Controls complex behaviour - learning, personality, memory and thought
71
What does the cerebellum do?
Controls involuntary movements - posture and balance
72
What does the medulla do?
Controls automatic actions - heart rate and breathing rate
73
What does the hypothalamus do?
Regulates water balance and temperature
74
What does the pituitary gland do?
Stores and releases hormones that may regulate body functions
75
What are the difficulties when investigating brain functions?
Patients must give consent for medical information to be shared
Many case studies need to be analysed to draw reliable conclusions
Several areas of the brain may be involved with a specific function
Some people believe animal testing is unethical
76
How can you investigate brain function?
Placing electrodes inside the brain
CT scans (x-rays)
MRI scans - powerful magnets
77
What does placing electrodes in a brain do?
They transmit electrical impulses which result movement in different parts of the body - can link area of brain to body region it controls
78
What are the systems in the mammalian nervous system?
Central nervous system (CNS)
Peripheral nervous system (PNS)
79
What does the central nervous system consist of?
Brain
Spinal cord
80
What does the peripheral nervous system consist of?
All the neurones that connect the CNS to the rest of the body
81
What is nervous system damage?
Damage to any part of your PNS or CNS
82
What are examples of how you can get nervous system damage?
Injury - falling off a ladder
Disease - diabetes or cancer
A genetic condition - Huntington’s disease
Ingesting a toxic substance such as lead
83
Why is nervous system damage bad?
It prevents impulses from being passed effectively though the nervous system.
E.g - sport injury damage neurone - explain neurone function
84
What are some effects of nervous system damage?
Inability to detect pain
Numbness
Loss of coordination
85
What happens if you injure your peripheral nervous system?
It has a limited ability to regenerate but surgery is needed for major injuries
86
What can damage to the central nervous system lead to?
Loss of control of body conditions
Paralysis
Memory loss or processing difficulties
87
Why is it difficult to repair the spinal cord?
It consists of 31 pairs of nerves each containing nerve fibres, repairing 1 nerve without damaging others is extremely hard
88
How could you treat a brain tumour?
Radiotherapy and chemotherapy
89
How could you treat damaged brain tissue?
Surgery to remove it
90
How could you help brain function?
Deep brain stimulation - insertion of an electron
91
What is different about repairing the CNS to the PNS?
The PNS has limited regeneration but the CNS cannot regenerate
92
What are hormones?
Chemical messengers
93
Where are hormones made?
The endocrine glans and secreted into the blood
94
How are hormones transported around the body?
Blood transports the hormones in the plasma around the body
95
How fast are hormonal responses?
Fairly slow and long lasting (e.g puberty)
96
What is homeostasis?
Keeping the conditions in your body constant
97
What does the hypothalamus and pituitary gland do?
Produce hormones that regulate production of other hormones
98
What does the thyroid gland do?
Produce thyroxine
99
Where is adrenaline produced?
Adrenal glands
100
Where is insulin produced?
The pancreas
101
Where is oestrogen and progesterone produced?
Ovaries (females)
102
What produces testosterone?
The testes
103
How do hormones do their job?
The diffuse out the blood and bind to specific receptors for that hormone found on the membrane or cytoplasm of cells in the target organs
104
What are target cells?
The cells that bind to their specific hormone
105
What do hormones do once bound?
They stimulate the target cells to produce a response
106
What is the endocrine system?
The name given to all the endocrine glands and the hormones produced
107
What does the endocrine system do?
Controls and coordinates body processes with the nervous system
108
What do the endocrine system and nervous system both do?
Send messages around the body to provide information about any changes in the internal and external environment and how to respond to that.
109
What are the attributes of nerves as a messaging system?
Very fast
Transport by electrical impulses through the axon of a nerve
Short acting duration
Target a precise area
110
What are the attributes of hormones as a messaging system?
Slow
Transport in the blood
Duration is longer acting
Target a larger area
111
What is the main function of thyroxine?
Regulates the body’s metabolic rate
112
What is BMR?
The speed at which the body transfers energy from its chemical sores to perform functions
113
How does thyroxine influence the metabolic rate?
By stimulating almost every tissue in the body to produce protein
By increasing the amount of oxygen that cells use
114
What else does thyroxine do?
Is affects:
Heart rate
The rate at which calories are burned
Skin maintenance
Growth
Heat production
Fertility
Digestion
115
Where are the adrenal glands?
Near the kidneys
116
What is hypothyroidism?
An under-active thyroid where the thyroid gland doesn’t produce enough thyroxine
117
How are most cases of hypothyroidism caused?
By the immune system attacking the thyroid gland and damaging it
By a result of treatment for an overactive thyroid
118
What are some symptoms of hypothyroidism?
Tiredness
Weight gain
Depression
Dry skin/hair
Muscle aches
Being sensitive to the cold
119
What is hyperthyroidism?
An overactive thyroid
120
How can hypothyroidism be treated?
Taking tablets daily to increase thyroxine
121
What are some symptoms of hyperthyroidism?
Weight loss
Increases heart rate
Anxiety
Excessive sweating
Tremors
Fatigue
122
How can hyperthyroidism be treated?
Radioiodine treatment
Surgery to remove some of the thyroid
123
What is the function of the thyroid gland?
To take iodine and convert in into thyroxine by combining idioine with the amino acid tyrosine
124
What do the adrenal glands do?
Helps regulate:
Your metabolism
Immune system
Blood pressure
Response to stress
125
What do the adrenal glands do at times if stress?
They secrete adrenaline which prepares the body for the fight or flight response
126
What does adrenaline do?
Causes the body to respire faster
Increase the rate of ATP production
Increases rate of breathing
Increases heart rate
Diverts blood away to muscles
127
What is negative feedback?
An important type of control used for homeostasis
128
What is the negative feedback cycle?
Conditions in the body change
Change detected by a receptor
Corrective mechanisms activated by an effector
Conditions returned to set point
Corrective mechanisms switched off
Back to the beginning
129
How are thyroxine levels controlled?
When more energy in needed, the hypothalamus causes the pituitary gland to release more TSH (thyroid stimulating hormone) which stimulates the thyroid gland to release thyroxine and vice Vera’s
130
How are adrenaline levels controlled?
The brain signals the adrenal glands to secrete adrenaline and the signal stops when adrenaline is no longer needed
131
What is the menstrual cycle?
A monthly cycle during which a woman’s body gets ready for pregnancy that lasts roughly 28 days
132
What happens during the menstrual cycle?
The uterus lining starts to thicken, ready to receive a fertilised egg during which an egg starts to mature in one of the ovaries. 14 days ovulation happens and the lining of the uterus remains thick
133
What happen if an egg is fertilised?
It may implant in the uterus lining to be protected and receive nutrients - The woman is now pregnant
134
What happens in the egg isn’t fertilised?
The uterus lining and egg are removed form the body - known as a period or menstruation
135
What is ovulation?
When the egg is released from the ovary
136
What 4 hormones control the menstrual cycle?
FSH - follicle stimulating hormone
Oestrogen
LH - Luteinising hormone
Progesterone
137
Where is FSH secreted from?
The pituitary gland
138
What does FSH do?
It travels to the ovaries where it causes an egg to mature
Also stimulates ovaries to produce oestrogen
139
What does oestrogen do?
Made and secreted by the ovaries that causes the uterus lining to build up.
140
What happens as oestrogen levels rise?
They inhibit the production of FSH which prevents more than 1 egg from maturing
Stimulates the pituitary gland do release LH
141
What does LH do?
When LH levels peak in the middle of a cycle, ovulation is triggered
142
What does progesterone do?
Maintains the uterus lining and levels of this hormone stay high throughout pregnancy
143
What does the blood oestrogen graph look like?
Two long lasting peaks
144
What does the blood LH level graph look like?
Relatively low until ovulation - a large peak in the middle
145
What does the blood FSH graph look like?
Increases as the end and beginning with a small peak in the middle
146
What does the blood progesterone graph look like?
A large, long peak 3/4 of the way through the graph
147
What is a contraception?
Any technique used to prevent pregnancy
148
What are the different types of NON-HORMONAL contraceptives?
Condom
Diaphragm/cervical cap
IUD, coil
149
How does a condom work?
Placed over penis or inside the vagina to prevent sperm from entering and it also prevents the spread of STIs
150
How does a diaphragm/cervical cap work?
Inserted into vagina to cover cervix and prevents sperm from entering uterus x removed after 6 or more hours after intercourse but isn’t effective unless in combination with a spermicide
151
How does an IUD work?
Inserted into uterus - releases copper which stops sperm from surviving in the uterus and fallopian tubes - can also prevent implantation of a fertilised ovum and works for 5-10 years
152
What are examples of hormonal types of contraceptives?
Combined pill (oestrogen and progesterone)
Progesterone
Intrauterine system - IUS
153
How does the combined pill work?
Prevents ovulation. Thickens mucus from the cervix, stopping sperm from reaching an ovum. Prevents implantiation of a fertilised egg into uterus wall
154
How often do you have to take the combined pill?
Daily for 21 of the menstrual cycle
155
How does a progesterone pill work?
Thicken mucus from the cervix, stopping sperms from reaching an ovum - also thins uterus lining preventing implantation and can prevent ovulation
156
How often must the progesterone pill be taken?
Around the same time daily
157
How does the IUS work?
Inserted into the uterus. Thicken mucus from the cervix, stopping sperms from reaching an ovum - also thins uterus lining preventing implantation and can prevent ovulation (same as progesterone pill)
158
How long does the IUS last?
3-5 years
159
How effective is the male condom?
98%
160
How effective in the female condom?
95%
161
How effective are the diaphragm and cap?
92 - 96%
162
How effective are the hormonal methods of contraception?
Over 99%
163
How effective is the IUD?
Over 99%
164
What are some causes of infertility?
Blocked sperm ducts
Not enough sperm produced
Lack of mature eggs produced in the ovaries
Failure of the ovaries to release an egg
Blocked fallopian tubes
165
Which hormone can be used to treat infertility and what is it known as?
FSH as an artificial fertility drug
166
Why is FSH known as an artificial fertility drug?
It stimulates eggs to mature in the ovaries and triggers oestrogen production
167
What does IVF stand for?
In vitro fertilisation
168
How does IVF work?
It involves collecting sperm and giving the mother FSH and LH to ensure as many eggs mature as possible for them to be extracted - they are then fertilised outside the body
169
What are the disadvantages of IVF?
No pregnancy
Multiple pregnancies
170
What are the considerations around IVF?
It isn’t natural
Allows parents to conceive who otherwise wouldn’t be able to
Older parents can have children
Can result in multiple births
Very expensive
Allows young women to focus on careers and have children later in life
171
What is tropism?
When plants detect stimuli in their environment and respond by growth in a particular position
172
What is phototropism?
Growing towards the light so the plant can photosynthesise more, for more food, to grow faster and increase chance of survival
173
What is gravitropism?
Growing in the same direction as gravity - mainly the roots so as to provide anchorage and be nearer to water
174
What is auxin?
A plant hormone that enables a plant to row towards or away from a stimulus
175
Where is auxin made?
Tips, shoot or roots of a pant
176
What does auxin do?
Stimulates shoot cells to grow more but inhibits the growth of root cells
177
How do plans respond to light?
Auxin moves to the side unaffected by light, increasing the length of that side so the shoot can bend towards light.
Auxin also gets evenly distributed if light falls evenly on a plant so the plant grows straight
178
How do plants respond to gravity?
They produce auxin on the lower side originally but afterwards, it goes to the top left of the plant root to inhibit that growth so the plant grows towards gravity
179
How are roots and auxin related?
The root grows more on the side with the least auxin
180
What does ethene do for plants?
Causes plant fruits to ripen by stimulating the conversion of starch into sugar (ripe fruit taste sweeter than unripe)
181
What are the different plant hormones?
Auxins
Ethene - only one that is a gas
Gibberellins
182
What does gibberellins do?
Promotes growth, especially stem elongation
Also end the dormancy period of seeds and buds which allows shoots and flowers opening
183
Why do many weed killers contain auxins?
Makes the weed grow to fast and this rapid, uncontrolled growth kills the plant
184
How is auxin used to make identical plants/clones?
Cut off part of the plant and dip it into rooting powder (contains auxins) and plant it - few days later new roots anchor into soil and get nutrients
185
How can one delay ripening?
Spraying auxin on it to delay ripening and allows harvest to be collected at the same time - can prevent fruit from dropping off trees early
186
How can hormones be used to ripen fruit?
Ethan is prayed on fruit trees so their fruit ripen quicker which allows fruit to be ready earlier in the growing season
187
How can seedless fruit be produced?
Auxins are applied to unpollinated flowers which then produces seedless fruit
188
How are seeds produced in a fruit?
They are produced after a plant is pollinated by insects or the wind
189
How are hormones used to control dormancy?
Gibberellins is prayed on seeds so the germinate during the winter because seeds usually remain dormant near the end of summer so they don’t die in the winter
190
What is normal body temperature?
37 degrees Celsius as it is the optimum temperature for enzymes
191
Why is being cold bad?
A low core temperature causes enzyme reaction to occur too slowly - respiration doesn’t release enough energy causing cells to die
192
What temperature makes you at Rio’s of hypothermia?
Below 35 degrees Celsius
193
What is it bad if your core temperature is too high?
Your enzymes may denature so body reactions cannot occur and you might die
194
What is responsible for regulating body temperature?
The thermoregulatory centre in the brain
195
What does the thermoregulatory centre depend on?
Signal from receptor cell in the skin (for external temp) and internal receptor cells (for blood temp)
196
What happens when a change in temperature is detected?
The brain causes different parts of the body to respond by sending impulses to effector - homeostasis
197
What happens when get too hot?
Body hairs lower so the hairs on the skin lie flat
Sweat glands produce sweat
Vasodilation
198
How does body hairs lowering reduce body temperature?
It prevents an insulating layer of air being trapped around the body
199
How does sweating reduce body temperature?
As water in sweat evaporates, energy is transferred by heating from your body to the environment, causing a reduction in temperature
200
What is vasodilation?
When blood vessels supplying capillaries near the surface of the skin widen
201
How does “vasodilation” reduce body temperature?
It increases blood flow through capillaries which increases heat loss by radiation
202
What happens when you get too cold?
Body hairs rise
Sweat glands don’t produce sweat
Shivering
Vasoconstriction
203
What is vasoconstriction?
Blood vessels supplying capillaries near the surface of your skin narrow
204
How does “body hairs rising” cause you to get warmer?
It traps a layer of air close to the skin which insulates the body
205
How does “vasoconstriction” cause you to get warmer?
It reduces blood flow through capillaries which reduces heat loss
206
How does “shivering” cause you to get warmer?
Your muscles contract and relax quickly causing cells to respire more quickly which transfers extra energy by heating
207
Why is high glucose (blood sugar level) bad?
If it is maintained over a long period of time, body systems can be damaged - especially nerves and blood vessels
208
Why is low glucose (blood sugar levels) bad?
It can prevent cells from respiring effectively
209
What does the pancreas do if blood sugar level is too high?
It releases insulin
210
What does insulin do?
It travels in the blood to the liver which stimulates the liver to turn glucose into glycogen which is then stored in the liver - less glucose reduces blood sugar levels
211
What does the pancreas do if blood sugar levels are too low?
It releases glucagon
212
What does glucagon do?
Makes the liver change glycogen back into glucose which is then released into the blood to increase blood sugar levels
213
What happens if you have type 1 diabetes?
Your body cannot produce insulin as the person’s own immune system has destroyed the pancreatic cells that make insulin
214
When does type 1 diabetes usually start?
It normally begins in childhood
215
How is type 1 diabetes controlled?
Regular injections of insulin
216
What should a type 1 diabetic do?
Eat a balanced diet and exercise regularly
217
What happens when you have type 2 diabetes?
You cannot effectively use insulin - the person’s cells do not produce enough insulin or the body doesn’t respond to it
218
When does type 2 diabetes usually occur?
Usually occurs later in life and is linked to obesity
219
How it type 2 diabetes controlled?
Regulating a person’s carbohydrate intake through their diet and matching this to their exercise levels- overweight people are encouraged to lose weight
220
What are extreme ways of helping type 2 diabetes?
Drugs are used to stimulate insulin production or insulin injections are given
221
What is excretion?
Removal of waste products
222
What is lysis?
When there is too much water present, it moves into blood cells causing them to swell and burst
223
What is too little water or too much solute bad?
Water will diffuse out of your blood cells, causing them to shrink
224
What is urine?
A toxic solution containing excess water, urea, excess salts and other waste substances
225
What do your kidneys do?
Filter urea out of your blood and produce urine constantly
226
What does the bladder do?
Stores urine until you urinate
227
What is the ureter?
A tube in which urine passes from the kidneys to the bladder
228
What does the renal artery do (in terms of kidneys)?
It brings blood containing urea and other substances in solution to the kidney
229
What does the renal vein do (in terms of the kidney)?
Carries blood away from the kidney after urea and other substances have been removed
230
What is the urethra?
A tube in which urine passes to the outside of the body
231
What is the first step of urine production?
1. Small molecules (including water, glucose, urea and salts) pass into tubes inside the kidney - blood cells are too large and so remain in the capillaries.
2. Selective reabsorption happens
232
What is the second stage of urine production?
Kidneys put back any useful substances into the blood
233
What is selective reabsorption?
When the kidneys put back any useful substances into the blood
234
What are the useful substances that the kidneys out back into the blood?
All the glucose
Any salts the body needs
Some water
235
Why does urine vary?
If you are short of water, kidneys produce little urine and water is saved for the body’s use which makes dark yellow urine and vice versa
236
What is the capsule of a kidney?
Outer membrane of the kidney that helps to maintain the kidney’s shape and protect it from damage
237
What is the cortex of a kidney?
The outer part of the kidney?
238
What is the medulla of the kidney?
The inner part of the kidney
239
What, inside the kidney, produced urine?
Microscopic tubules called nephrons
240
Where is top of the nephron?
The cortex
241
Where is the lower section of the nephron found?
The medulla
242
What is the lower section of a nephron called?
The loop of Henlé
243
How many nephrons do each kidney approximately contain?
1 million
244
How does blood enter the kidney and from where?
Blood enters the kidney under high pressure from the renal artery which contains many branches, each of which leading to a glomerulus
245
What does a glomerulus contain?
A knot of capillaries
246
Why do the blood vessels narrow at the exit of the glomerulus?
To increase the blood pressure which forces small molecules out the capillary wall and into the bowman’s capsule.
247
Why do proteins remain in the bloodstream?
It is too large to fit through the capillary walls
248
How do the kidneys work (steps)?
1. Blood enters the kidney under high pressure form renal artery which leads to a glomerulus from the many branches
2. Blood vessels narrow at the exit of the glomerulus to force out small molecules in high pressure
3. They go out the capillary wall into the bowman’s capsule
4. Selective reabsorption happens through the nephron tubule
5. The filtrate passes through the loop of Henlé and the collection ducts - regulate salt and water in the body
6. Excretion occurs and the urine collects in the collecting duct which travels to the bladder before leaving the body
249
How does the body control how much urine is produced?
The hypothalamus detects the water potential of blood as it passes the brain and it responds by secreting the amount of ADH needed.
250
What does ADH stand for?
Anti-diuretic hormone
251
Where does ADH get secreted from?
The pituitary gland
252
What does ADH do?
It travels in the bloodstream to the kidney where it makes the walls of the collecting ducts more permeable to water which means more water is reabsorbed into the body
253
What happens if water potential is too low?
More ADH is produced - more water is reabsorbed from the nephron into the blood stream - less water is lost from the body
254
What does an INCREASED amount of ADH mean for urine produced?
A small volume of concentrated urine is produced
255
What happens in blood water concentration is too high?
Less ADH is produced - less water is reabsorbed from the nephron into the blood stream - more water is lost
256
What are some examples of when you would need more water?
When you take part in strenuous exercise
When you are exposed in high temperatures
257
What is lost from the body when you sweat?
Water
Salts
258
How does the body respond to a lack of water?
Your body triggers the thirst response
An impulse is sent to your brain which informs you to take on more fluids
You become dehydrated
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What is dehydration?
A condition when you have not taken enough water into your body
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What are some symptoms of dehydration?
Passing of dark, concentrated urine
Headaches and dizziness
A lack of energy
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What happens if a person is dehydrated for a longer period of time?
The kidneys and liver may suffer permanent damage and eventually you may die
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How does the body respond to too much water”
Kidneys produce more dilute urine
Water will move by osmosis into your cells
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Why is it bad to consume a large amount of water rapidly?
Water moves into your cells by osmosis, causing them to burst
Concentration of sodium in blood plasma drops
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What are extreme causes of water moving into your cells by osmosis?
Muscle cramping, confusion, seizures
When water moves to brain cells, it can cause death.
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What does a hypertonic drink contain?
High levels of glucose and salts
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What does a hypotonic drink contain?
Low levels of glucose and salrs
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What does an isotonic drink contain?
Ion concentrations equal to those in blood plasma
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What type of athlete would use a hypotonic drink?
Endurance athletes as the drink will give them the electrolytes needed while running
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What type of athlete would drink hypertonic drinks?
Athletes that require rapid glycogen replenishment - body building or sprinters and the drinks have more carbs
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What type of athlete would use an isotonic drink?
It rehydrates you rapidly so football players or tennis players
