Homeostasis and Bioenergetics Flashcards
(158 cards)
1
Q
Define metabolism
A
The sum of all reactions in a cell or body
2
Q
Define metabolic rate
A
The speed at which chemical reactions take place in the body
3
Q
What 5 reactions does metabolism include?
A
Respiration, protein synthesis, formation of lipids from 3 fatty acids and glycerol, conversion of glucose to carbohydrate glycogen and starch, break down of excess protein to form urea which is excreted in urine
4
Q
Define respiration
A
An exothermic chemical reaction that transfers energy from glucose and occurs in every cell
5
Q
What is the energy produced in respiration used for? 5 things
A
Allows muscles to contract so movement can occur, growth and repair, keeping mammals and birds body temperature’s steady in colder surroundings, enzyme controlled reactions, breakdown and synthesis of new molecules
6
Q
What is aerobic respiration?
A
Most reactions take place in the mitochondria and it requires oxygen and glucose, produces carbon dioxide water and energy
7
Q
What is anaerobic respiration?
A
Most reactions take place in the cytoplasm and it uses glucose but produces less energy and also lactic acid, does not require oxygen
8
Q
When would anaerobic respiration be useful?
A
In a cell where there is high energy demand but not enough oxygen to produce all energy needed by aerobic respiration alone, e.g when you do vigorous exercise like sprinting
9
Q
Is aerobic respiration endo or exothermic and why?
A
Exothermic because it produces energy and the reaction gets hot
10
Q
Why does heart rate increase when u do exercise?
A
Muscles need energy from respiration to contract and when you exercise some muscles contract more frequently so more energy is required which comes from increased respiration, the increase in respiration in your cells means they need oxygen so breathing rate increase to get more oxygen into the blood, heart rate increases to get oxygenated blood around body faster which removes CO2 more quickly aswell. Oxygen intake increases therefore diffusion decreases
11
Q
How do the muscles contract in aerobic respiration?
A
Long periods
12
Q
How do the muscles contract in anaerobic respiration?
A
For short periods and they fatigue
13
Q
What 2 things does respiration provide energy for?
A
Enzyme controlled reactions, breakdown and synthesis of new molecules
14
Q
Define homeostasis
A
Maintaining a constant internal environment
15
Q
What 2 things does homeostasis involve?
A
Regulation of the internal conditions of a cell, organism maintaining optimum conditions in response to internal and external changes
16
Q
What 3 things maintain the same in homeostasis?
A
Blood sugar levels, water levels, temperature
17
Q
Why is homeostasis important?
A
Chemical reactions cannot occur if our temperature is not constant because enzymes have an optimum temperature to work in
18
Q
Which two words classify homeostatic responses?
A
Nervous or chemical
19
Q
Which three key components are involved in homeostatic responses?
A
Coordination centre, receptor, effector
20
Q
Which two organs is the Central Nervous System made up of?
A
Brain, spinal cord
21
Q
Name the 7 components (in order) of the Stimulus-Response pathway
A
Stimulus, receptor, sensory neurone, coordinator, motor neurone, effector, response
22
Q
Define stimulus
A
A detectable change in the internal or external environment
23
Q
Define receptor
A
A specialised cell or group of nerve endings that respond to sensory stimuli, they can form part of larger more complex organs (the retina of the eye is covered with light receptor cells)
24
Q
Example of a stimulus
A
Temperature increase
25
3 examples of a receptor
Temperature receptors on skin, taste receptors on tongue, sound receptors in ears
26
Define sensory neurone
Nerve cells within the nerve system responsible for converting external stimuli from the organisms environment into internal electrical impulses
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Two examples of a coordinator
Brain (conscious), spinal cord (automatic reflex)
28
Define motor neurone
Passes electrical messages to effectors
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How are the sensory and motor neurones connected?
Relay neurone
30
Define effector
An organ, gland or muscle which responds and becomes active in response to a stimulus
31
What are two examples of responses to temp increase!
Sweating (automatic reflex) ,removing clothing (conscious)
32
Name 8 features of a nerve cell?
Nucleus, axon, synapse, dendrites, myelin sheath, cytoplasm, cell membrane
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What do dendrites do?
Make connections to other nerve cells
34
What is a synapse?
A gap between nerve cells because they cannot make contact
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What does the long axon do?
Carry impulses to other parts of body
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What is the myelin sheath?
Fatty tissue insulating the axon to allow it to pass messages quicker
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What are neurotransmitters?
Chemical released into synapse and diffuses across
38
What is insulin?
A chemical which is a hormone, it lowers our blood sugar levels
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What is insulin produced by?
Pancreas
40
What four things affect our blood sugar levels?
Diet, exercise, stress, medication
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Why is our blood sugar level important?
Glucose is required for respiration which is the production of energy
42
What are 6 symptoms of diabetes?
Increased thirst, increased hunger, increased urination, lack of energy, blurry vision, cuts and sores which don’t heal properly
43
How do insulin and glucagon work?
Antagonistically (doing opposite jobs). Insulin lowers blood sugar levels and glucagon raises them
44
What are the 5 steps to lowering the body’s blood sugar levels
Eating foods containing carbohydrate puts glucose into the blood from the gut, our body’s response is to secrete insulin from the pancreas, excess sugar is taken by insulin and absorbed by the liver and muscle cells, it is stored there as glycogen which can be broken down into glucose when the body needs energy, blood sugar levels return to normal
45
What are the 4 steps to raising blood sugar levels?
If do not eat for a long period our blood sugar levels decrease, our body responds by secreting glucagon from the pancreas into the blood, glucagon tells glycogen to break down into glucose and spread into the blood, blood sugar levels return to normal
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What three things does negative feedback involve?
Returns the body to normal, corrective mechanism, reverses a change
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What is the age of onset for type 1 diabetes?
Juvenile
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What is the age of onset for type 2 diabetes?
Adult
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What is the cause of type 1 diabetes?
The immune system mistakes the body’s own healthy cells for foreign invaders and attacks and destroys insulin-producing beta cells in the pancreas, preventing insulin production
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What is the cause of type 2 diabetes?
Inability of beta cells to produce appropriate quantities of insulin (insulin resistance caused by obesity)
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What is the progression of type 1 diabetes?
Abrupt
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What is the progression of type 2 diabetes?
Gradual
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What are the 3 treatments of type 1 diabetes?
Insulin therapy which involves several insulin injections throughout the day most likely at mealtimes which makes sure glucose is removed from the blood quickly after the food has been digested, stopping the level getting too high, the amount of insulin which is injected depends on the person's diet and how active they are. People with Type 1 diabetes need to limit the intake of food rich in simple carbohydrates which cause the blood sugar levels to rise rapidly, take regular exercise to remove excess glucose from the blood
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What is the treatment for type 2 diabetes?
Weight loss by eating a carbohydrate-controlled diet and getting regular exercise
55
What are the four risk factors of type 1 diabetes?
Family history, age, geography, genetics
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What are 8 risk factors of type 2 diabetes?
Prediabetes, obesity, immediate family member with type 2 diabetes, over age 45, physically inactive, excess belly fat, previously had gestational diabetes, polystic ovarian syndrome
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What are three symptoms specific to type 1 diabetes?
Irritability, mood swings, unintentional weight loss
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What are two symptoms specific to type 2 diabetes?
Numbness, tingling in hands and feet
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What is diabetes?
Chronic disease which affects the way your body regulates blood sugar. Cells do not absorb glucose , leading to chronically high blood sugar levels
60
Name the 4 main hormones involved in the menstrual cycle
Oestrogen, progesterone, follicle stimulating hormone, luteinising hormone
61
Where is FSH secreted from and what does it do?
Pituitary gland, causes eggs in ovary to mature, surrounded by cells called the follicle
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What does LH do?
Stimulate the release of the egg at ovulation
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What do oestrogen and progesterone do?
Stimulate build up and maintenance of uterus lining
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How long does the menstrual cycle take?
28 days
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How are hormones involved in the menstrual cycle? 12 points
FSH is secreted from pituitary gland, egg begins to mature, FSH stimulates secretion of oestrogen from ovary, uterus lining builds up again into a thick spongy layer full of blood vessels ready to receive a fertilised egg, increased levels of oestrogen inhibit FSH and stimulate release of LH, ovulation occurs, LH levels drop and progesterone increases secreted from empty follicle, progesterone inhibits FSH and LH, uterus lining maintained by progesterone, when progesterone levels fall the lining starts to break down
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What happens at the start of the menstrual cycle and how long does this last?
Shedding the lining of ur uterus, 1-7 days usually 4-5
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What happens between days 7-10 of the menstrual cycle?
uterus lining builds up again into a thick spongy layer full of blood vessels ready to receive a fertilised egg
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What happens between days 11-18 of menstrual cycle?
Mature egg released from ovaries
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What happens between days 19-28 of menstrual cycle?
Uterus lining is maintained until day 28 and if no fertilised egg has landed on uterus wall by then the spongy lining it starts to break down and the cycle starts again
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What happens after the 14th day if the egg is not fertilised?
Lining is shed
71
How do you maximise chance of getting pregnant?
Try for baby every other day between 7 days before and after ovulation because the sperm can last 3 days after entering the female whereas the egg after being released by ovulation lasts only one day
72
Give 3 examples of hormonal methods of contraception
Oral contraceptives which contain oestrogen can be taken every day to keep its level permanently high to inhibit FSH production and after a while egg production and development stops and stays stopped, injection or implant (under skin of arm) or skin patch of slow release progesterone which stops ovaries releasing eggs, plastic intrauterine devices release a hormone (progesterone)because progesterone can stimulate the production of a thick mucus which prevents any sperm getting through and reaching the egg
73
Give 5 examples of non hormonal contraceptives
Copper intrauterine devices (small structures inserted into uterus) which prevent survival of sperm, spermicidal agents kill or disable speed, abstaining from intercourse when an egg may be in the oviduct, surgical methods of male and female sterilisation (vasectomy- cutting/tying fallopian tubes which connect ovaries to uterus or sperm tube which connects testes and penis), barrier methods (condoms), diaphragm (shallow plastic cup) placed over cervix before sex which forms a barrier but has to be used with spermicides
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Where does the foetus develop?
Uterus
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Where does the egg travel?
Fallopian tube/ oviduct
76
Give 4 positives of hormonal methods of contraception
Contraceptive pill of oestrogen&progesterone is easy to use, it is over 99% effective, intrauterine devices are very effective and last up to five years, implant can last up to 3 years, progesterone injection lasts 2 to 3 months
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Give 3 positives of non hormonal contraceptives
Condoms have no side effects, spermicides are readily available, barriers can prevent STDs
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Give 4 negatives of hormonal contraceptives
Intrauterine devices can cause period problems or infections, potential side effects of oestrogen&contraceptive pill e.g raised blood pressure and nausea (progesterone only pill has fewer side effects though and is just as effective), contraceptive pill doesn't protect against STDs, contraceptive patches only last one week
79
Give 5 negatives of non hormonal methods of contraception
Intrauterine devices can cause period problems or infections , surgery is permanent, condoms can become damaged easily, surgical methods have a risk of infraction, spermicides only 70-80% effective
80
Why are FSH and LH often termed 'fertility drugs'?
Some women have levels of FSH that are too low to cause their eggs to mature so no eggs are released so FSH and LH can be given to women to stimulate ovulation however this doesn't always work so they may have to try multiple times which can be expensive and too many eggs could be stimulated which results in multiple unexpected pregancies
81
What happens in in vitro fertilisation? 7 steps
Mother given FSH and LH to stimulate the maturation of several eggs, undergoes several weeks of injections, eggs collected from mother, fertilised by sperm of father, if the man has a low sperm count Intra-Cytoplasmic Sperm Injection is used where soerm is injected directly into an egg, fertilised eggs develop into embryos, when the eggs are tiny balls of cells one or two embryos are inserted into the uterus
82
What are 3 religious arguments against IVF?
Goes against gods will, involves destruction of discarded embryos which goes against sanctity of life, some people think it could lead to the selection of preferred characteristics like eye colour due to genetic testing of embryos before implantation
83
What is an economic argument against IVF?
Costs £4300-5500 but the average success rate in the UK is about 26%
84
What are 5 moral/social arguments against IVF?
Destruction of discarded embryos, unnatural, inflated population could cause demand, cause mother stress as they can have a severe reaction to the hormones e.g vomiting/abdominal pain/dehydration, multiple eggs inserted could cause multiple births
85
What syndrome can IVF lead to?
Ovarian hyper stimulation syndrome which results in a build up of fluid in the mothers lungs which can cause death
86
What are two limitations of ivf?
Could miscarry at any stage, sperm may not be mobile enough
87
What is a religious argument for IVF?
The purpose of marriage for catholics and Jews is to have children
88
What is an economic argument for IVF?
Funded by NHS in some areas
89
What are 2 moral/social arguments for IVF?
Bringing new life into the world, everyone has the right to have a family
90
What is a hormone?
A chemical messenger produced in the body to control and regulate activity of certain cells or organs
91
What part of the brain secretes hormones?
Pituitary gland
92
What hormone stimulates contractions of the womb before a baby is born?
Oxytocin
93
How does keeping the level of progesterone high for most of the menstrual cycle act as contraception?
Keeping the level of LH and FSH los prevents ovulation
94
What are two arguments for using hormones as contraceptives?
Very effective, prescribed by doctor
95
What are two arguments against using hormones as contraceptives?
Religious beliefs, no protection against aids
96
Define negative feedback
Initiating corrective mechanisms whenever the internal environment deviates from its normal or acceptable level. Therefore an example would be when high levels of one hormone inhibit the production of another hormone.
97
What are the products of aerobic respiration?
Carbon dioxide and water
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What are the products of anaerobic respiration?
Lactic acid
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What are 4 similarities between aerobic and anaerobic respiration?
Need glucose (reactant), energy is a product, mitochondria is the organelle involved, exothermic
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Why is the use of IVM better economically than IVF?
One cycle costs only £1700
97
How is IVM better socially than IVF?
Hormone treatment only lasts 7 das as oppose to several weeks for IVF which causes less stress for the mother
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What is a risk of IVM?
Baby could be born with birth defects
98
What 2 things does negative feedback do?
Maintains a steady state, reverses changes
99
Which produces a lot of energy: aerobic or anaerobic respiration and why?
Aerobic because there is incomplete oxidation of glucose in anaerobic
100
Give 4 examples of negative feedback
Insulin and glucagon, sex hormones, osmoregulation, thermoregulation
101
What are the 6 stages to negative feedback
Optimum conditions, change away from optimum conditions, receptor detects change, communication system informs effector, effector reacts to reverse change, return to optimum conditions
102
How does the body respond to cold temperatures? 4 steps to thermoregulation
Vasoconstriction of arterioles, shivering, piloerection (hairs stand up), increased metabolism
103
How does the body respond to hot temperatures? 4 steps to thermoregulation
Vasodilation of arterioles, sweating, pilorelaxation (hairs lie flat), decreased metabolism
104
What happens without thermoregulation?
If you are too cold you get hypothermia (below 35.5), if you are too hot you get hyperthermia (above 37.5)
105
What 6 things does adrenaline allow the body to do?
Increase heart rate and breathing rate, cause pupils to dilate to let more light in, increase mental awareness, divert blood away from digestive system and to larger muscles, boost delivery of oxygen and glucose to your brain and muscles
107
What does homeostasis in mammals involve?
Physiological control systems which maintain the internal environment within restricted limits
107
Why is the use of glucose and nitrate ions to form amino acids important?
Protein synthesis occurs for growth and repair
108
Why is the conversion of glucose to carbohydrates important?
Starch: storage of glucose for when photosynthesis cannot occur. Glycogen: Storage of glucose un the muscles for respiration. Cellulose: strengthens the cell wall
109
Why doesn’t adrenaline involve a negative feedback loop?
Secreted from adrenal glands and carried rapidly round your body to multiple organs when in fear, stressed, angry, or excited because your brain sends nervous impulses to the adrenal glands. It triggers mechanisms that increase the supply of oxygen and glucose to the brain. Once danger is over adrenal glands stop secreting adrenaline
110
Why is the formation of lipid molecules important?
Energy storage, hormones, cell membrane
111
Why should excess proteins be broken down to form excess urea for excretion?
They can be toxic
112
How does the level of thyroxine in the blood usually remain stable?
Negative feedback: pituitary gland secretes thyroid stimulating hormone, thyroid gland uses iodine and amino acids from your diet to produce thyroxine, sensors are in the brain If the levels rise too high the secretion of TSH is stopped which reduces the amount of thyroxine so level in blood falls back to normal
113
Why is keeping temperature in our bodies constant important?
Enzymes have an optimum temperature which they work best at and enzyme-substrate complexes form quickly. If the temperature reaches too high the active site becomes denatured and rate of reaction stops. Enzymes are important in our body as they are involved in vital processes like respiration which is important because energy produced is used to build larger molecules (growth and repair) and keep warm
115
Why is yeast used to make bread and alcoholic drinks?
Yeast respires anaerobically to produce ethanol (used in alcoholic drinks) and carbon dioxide (used to make bread rise)
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Equation for anaerobic respiration in muscle cells
glucose -> lactic acid
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Equation for anaerobic respiration in plant and yeast cells
glucose -> ethanol + carbon dioxide
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Why are reflexes faster than information transmitted by neurones?
Neurones transmit information very quickly to and from the brain and your brain quickly decides what to do but reflexes are rapid automatic responses that don't involve the conscious part of the brain
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What is anaerobic respiration in yeast cells called?
Fermentation
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Why is the pituitary gland in the brain called the master gland?
The many hormones it produces to regulate body conditions act on other glands, directing them to release hormones that bring about change
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Why are reflexes important? 2 reasons
Important sign of nervous system development and function, can reduce the chances of being injured
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How does the body react to increased demand for energy during exercise? 3 ways
Heart rate, breathing rate and breath volume increase to supply the muscles with more oxygenated blood but if insufficient oxygen is supplied anaerobic respiration takes place in the muscles
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What causes a build up of lactic acid in the muscles in anaerobic respiration?
Incomplete oxidation of glucose which creates an oxygen debt
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How is lactic acid turned back to glucose?
Blood flowing through the muscles transports lactic acid to the liver where it is converted back to glucose
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Why is liquid paraffin in the test tube when investigating anaerobic respiration in yeast cells?
Prevent air getting in
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How could you give a reproducible way to measure rate of anaerobic respiration in yeast cells?
Collect CO2 in a gas syringe in a certain amount of time using a stopwatch
126
What effect does caffeine concentration have on reaction time?
The higher the caffeine concentration, the SHORTER (don't say faster) the reaction time
127
Why are reflex reactions important?
They are fast reactions to protect the body from harm
128
Define oxygen debt
The extra amount of oxygen the body needs after exercise to react with accumulated lactic acid and remove it from the cells. This means you have to keep breathing hard after stopping exercising (when anaerobic respiration has taken place) to get more oxygen into your blood which Is transported to cells
129
Where is oestrogen produced?
Ovaries
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Where are FSH and LH produced?
pituitary gland
131
Give 3 advantages of using progesterone patches rather than an oral contraceptive
Fewer side effects, don't need to remember to take the pill everyday, hormone from patch goes straight into bloodstream but pill can be vomited up
132
Compare how information is transferred from a neurone with how information is transferred across a synapse
In the synapse, a chemical called neurotransmitters is released and the message diffuses across. Reflexes are much faster than an electrical impulse because they have a shorter distance to travel
133
Describe a method to investigate the effect of caffeine concentration on reaction time. 7 points
Student A measures concentration of caffeine in a coffee so they can increase or decrease this each time - use decaffeinated as a control measure, student B holds a ruler and student As thumb and finger are level with the zero on the ruler, student As sits and their arm should be resting on the table to stop them moving it up and down, student B drops a ruler for student A to catch after drinking a cup of coffee, the higher up the ruler it has been caught the slower the reaction time, do 3 tests for each coffee concentration then work out a mean, control other factors in the room like light intensity/dropping ruler from the same height/making sure person has not had caffeine or medication prior to the experiment
134
What does oxygen form when it reacts with lactic acid?
CO2 and water
135
How does your body cope with a high level of lactic acid?
Blood that enters your muscles transports lactic acid to the liver where it is converted back to glucose
136
How can you measure effect of exercise on the body? 7 points
Measure breathing rate by counting breaths and take your pulse by putting two fingers o your wrist or neck and counting for 1 min after: sitting down for 5 mins, then after 5 mins gentle walking, then after 5 mins slow jogging, then after 5 mins running. To reduce effecr of any random errors do this as a group then plot on a bar chart the average pulse/breathing rate for each exercise
137
What is the difference between responses in single celled organisms and multi cellular organisms?
A single celled organism can just respond to its environment but the cells of multi cellular organisms need to communicate first so as multi cellular organisms evolved they developed nervous and hormonal communication systems
138
How is the Central Nervous System connected to the body?
By the sensory neurones and motor neurones
139
How do neurones transfer nerve signals?
Transferred by chemicals (neurotransmitters) which diffuse across the gap, these chemicals set off a new electrical signal in the next neurone
140
Give 2 examples of reflexes
If someone shines a bright light in your eyes your pupils automatically get smaller to let less light into the eye which stops the eye getting damaged, if you get a shock your body releases the hormone adrenaline automatically and doesn't wait for you to decide that you're shocked
141
What is a reflex arc?
Information passed in a reflex (from a receptor to an effector)
142
How do reflexes go through the spinal cord or an unconscious part of the brain? 4 points
When a stimulus is detected by receptors impulses are sent along a sensory neurone to the CNS, when impulses reach a synapse between sensory and relay neurone they trigger chemicals to be released which cause impulses to be sent along the relay neurone, when impulses reach a synapse between relay and motor neurone it triggers chemicals to be released and impulses are sent along the motor neurone to the effector, then a response occurs like a muscle contracting
143
How can computers measure reaction time?
A person being tested clicks the mouse when they see a stimulus on the screen e.g a box changing colour, the computer gives a more precise reaction time as the possibility of human error has been removed, the measurement is more accurate as they record reaction time in milliseconds
144
Function of ovaries
Produce oestrogen which is involved in the menstrual cycle
145
Function of testes
Produce testosterone which controls puberty and sperm production
146
Function and location of thyroid
Located in the throat. Produces thyroxine which is involved in the regulation of metabolic rate, heart rate and temperature
147
Function and location of adrenal gland
Located on top of kidneys. Produce adrenaline
148
Function of pancreas
Produce insulin to regulate blood glucose levels
149
Identify 6 endocrine glands
Pituitary gland, testes, ovaries, pancreas, adrenal glands, thyroid
150
Identify 3 differences in the ways hormones and nerves carry messages
Nerves have very fast action whereas hormones have a slower action, nerves act for a very short time but hormones act for a long time, nerves act on a very precise area whereas hormones act in a more general way
151
What does your body do in puberty?
Starts releasing sex hormones which trigger sexual characteristics like facial hair in men and breasts in women, but also hormonal changes like mood swings, causes the eggs to mature in womens ovaries. In men the hormone is testosterone and in women it is oestrogen
152
How have advances in technology improved IVF? 3 points
Advances in microscope techniques have improved techniques and success rate, specialised micro tools have been developed to use on eggs and sperm under the microscope and to remove single cells from the embryo for genetic testing to check it is healthy, time-lapse imaging using a microscope and camera built into the incubator means the growth of embryos can be continuously monitored to help identify those more likely to develop into a successful pregnancy
153
What does thyroxine do?
Regulates basic metabolic rate and is also important for loads of processes in the body like protein synthesis for growth and development
