Homeostasis and Hormones Flashcards
what does our body do to keep warm?
Shivering – uses energy
Releasing energy from food
Vasoconstriction
Hairs stand on end
what does our body do to keep cool?
Sweating which evaporates transferring heat to the environment
Vasodilation
Hairs lie flat
what is homestasis?
The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.
what happens when RECEPTOR detects a stimulus is too high
EFFECTOR produces a response which counteracts the change and restores the optimum level = level increases
what happens when RECEPTOR detects a stimulus is too low
EFFECTOR produces a response which counteracts the change and restores the optimum level = level decreases
Homeostasis is controlled by…..
Automatic control systems including;
nervous responses
chemical responses.
Homeostasis maintains optimal conditions for ……
Enzyme action and all cell functions
What 4 important things does your body need to keep the same?
Body temperature
30-40 = death
Blood glucose
Water content
Ion levels (salts)
what are some examples of things in your body that need to be kept constant?
One example of the things that needs to be kept constant is the body clock which is normally 37oF. If this goes too high you start to shiver and your hair lies flat. If it goes too low you start to sweat and your hair stands up trapping a layer of conducting air.
Another thing that has to be kept constant is the uear. The kidney produces it and liver removes it from the blood.
Homeostasis
Maintenance of a constant internal environment
Ions
Salts in your body that need to be kept constant
Hypothalamus
The homeostasis control centre of the brain
Thermoregulation
Controlling body temperature
Body temperature
37°C
Diabetes
Disease where the pancreas does not produce enough insulin
Sweating
Method by which heat is taken away from the body via evaporation
Hormone
Chemical messenger used by the organs of the body
How do we get rid of waste? And what would happen if it were to built up?
urine and faeces. chemical reactions and damage cells
What can happen if there is too much or too little water?
damage to cells
What is the sensor in the body that detects heat?
thermoregulatory center in the brain and skin
What is the sensor in the body that detects heat?
Why do we need to keep body temperature the same?
heatstroke, dehydration can occur hypothermia and deatg
What controls the blood glucose levels?
pancreas
Most animals need to find food, avoid danger and find a mate
How is the nervous system vital to all of these?
The nervous system is how animals (including humans) detect changes in the environment around them. Receptor cells detect these changes
Where are most of our receptor cells are located?
They are usually found clustered together in our sense organs, such as the eyes, ears and skin
How the nervous system works
The nervous system carries electrical signals through the body very fast
Stimulus
Receptor
Central nervous system
Effector
hearing a loud noise…..
What is the STIMULUS ?
What are the RECEPTOR/S ?
What is the RESPONSE ?
What is the STIMULUS ? Loud noise
What are the RECEPTOR/S ? Sound Receptors – in the ears
What is the RESPONSE ? Jump / Block ears
where are our receptors found?
Receptors are found in our sense organs
They detect a stimulus
what is the central nervous system made up from?
The central nervous system is made up of the brain and the spinal cord. The Brain is protected by the bone from the skull and the Blood Brain Barrier and the spinal cord is protected by the spinal vertebrae.
what is the function of the peripheral nervous system?
The main function of the PNS is to connect the central nervous system to the limbs and organs.
Unlike the CNS, the PNS is not protected by the bone of spine and skull, or by the blood-brain barrier, leaving it exposed to toxins and mechanical injuries.
nerve
Bundles of neurones.
Neurones
Cells that carry electrical signals from our sense organs to the CNS.
Stimulus
Something that is detected by the receptors in our sense organs.
Central nervous system
Made up of the brain & spinal cord.
Impulses
Electrical signals carried by your nervous system.
Motor neurones
These cells carry information from the CNS to the muscle cells
Sensory neurons
Specialised cells that can carry an electrical signal.
What are the two types of effector?
Effectors =
1.Muscles
2. glands
how do effectors respond?
Muscles respond to the arrival of impulses by contracting
Glands respond by releasing hormones
what is the nervous system pathway?
1) Stimulus
eg: bee on hand
2) Receptor (detects stimulus)
touch/pressure receptor
3) Sensory neurone (travels as an electrical impulse)
4) CNS (brain & spinal cord - coordinator. Decides what action to take)
5) Motor neurone ( travels as an electrical impulse)
6) Effector
eg muscle or gland
7) Response (what the effector does)
eg: arm move
What are we investigating? Reaction time
The aim of the investigation is to measure how a certain factor affects the reaction time.
What could we change during the experiment?
Variables that we can change:
- listening to music vs not listening to music
- listening to pop music vs listening to classical music
- girl vs boy
- older student vs younger student
- exercise vs no exercise
- left hand vs right hand
- caffeine vs no caffeine
Explain why the experiment was carried out 5 times instead of just once?
Ensures the experiment is repeatable, and gives a wide range of data
What is the advantage of calculating an average distance?
It improves the accuracy, and allows you to discount outliers. Gives a value closer to the true value.
How could the experiment be improved to improve the accuracy?
Repeat the experiment more times. Use a computer based test to give a more precise idea of reaction time. (computer can time in milliseconds so results are more accurate. Computer tests are more random so remove the possibility of predicting).
The investigation is looking at the subjects reaction time. State one ethical consideration that must be taken into account in your investigation.
Ensure that the person doing the test has given their permission.
What is different about a reflex reaction?
It is automatic, doesn’t involve conscious thought and is for our own protection
What does a sensory neuron connect?
Receptors and the CNS
What kind of message is sent in a neuron?
Electrical impulse
What is a synapse?
The connection between neurones
What factors which may affect our reaction time?
Caffeine
Medication
Drugs
Alcohol
Age
Level of training/practice
Level of tiredness
Where is the impulse transmitted to? Reflex arc
The spinal cord
What is not involved in the reaction to begin with?
reflec arc
The brain
What is the reaction of the reflex arc?
To retract the part of the body (hand) without input from the brain
why does the reflex arc not include the brain?
To make the reaction faster and so we cannot override the response.
Each reflex action takes the follows the pathway:
stimulus → receptor → sensory neurone → relay neurone (in the spinal cord) → motor neurone → synapses → effector → response
what is a synapes
Where one neurone meets another there is a tiny gap this is called a synapse.
what happens at the synapse
The electric impulse reaches the axon terminal
The axon terminal releases a chemical neurotransmitter substance into the gap.
This is detected by the next neurone which generates a new electrical signal
what distrupt synapses?
PAINKILLERS and SMOKING disrupt synapses.
what are the organs of the endocrine system
Thyroid gland
Thymus
Pancreas
Ovaries
Testes
Adrenal gland
Pituitary gland
what is the endo system?
The endocrine system is composed of glands which secrete chemicals called hormones directly into the bloodstream.
The blood carries the hormone to a target organ where it produces an effect.
Compared to the nervous system the effects of the endocrine system are;
slower but act for longer.
What are hormones?
These are chemicals (large molecules) messengers
what do hormones do?
Chemicals secreted by glands
Directly into the bloodstream
Blood carries it to the target organ
Only on the target organ does the hormone produces an effect
The effect is much slower and lasts longer than nervous response
pituitary gland:
master gland
controlled by the hypothalamus in the brain.
Controls the internal environment of your body in homeostasis.
It is responsible for controlling the amount of urine we produce with a hormones called ADH.
It also stimulates egg development in women, with a hormone called Follicle stimulating hormone (FSH)
adrenal gland:
prepares the body for a ‘fight or flight’ which is triggered by adrenaline.
This gland also produces cortisol (controls our stress levels).
pancrease:
produces the hormone insulin
responsible for controlling the level of glucose in your body.
thyroid gland:
releases a hormone called thyroxine that control the body’s metabolism (the way the body uses energy).
It also stimulates and controls growth.
thymus;
It develops a special type of white blood cells called lymphocytes.
ovaries:
produce oestrogen and progesterone which are hormones involved with the menstrual cycle and sexual maturity in females.
testies:
produce testosterone which is involved in the development of sexual maturity and puberty in males. Also produces sperm cells.
why is the pituitary gland the mater gland?
Known as the ‘master gland’ because it secretes several hormones into the blood
what is the endochine systme composed of?
glands
what controls blood glucose level?
insulin and glucagon
what happens when you eat carbohydrates?
glucose goes into the blood from the gut
what does the normal metabolism of cells remove from the blood?
glucose
what moves a lot of glucose from the blood?
vigorous Exercycle
excess glucose can be stored as……………. in the ………. and the ……….
excess glucose can be stored as…..glycogen……….. in the ..liver…….. and the ……muscles….
what are changes on the blood controlled by?
the pancreas, using the hormones, insulin and glucagon, in a negative feed back cycle
what happens if blood glucose level is too high
1) insulin is released by the pancreas
2) insulin tells the cells to take glucose out of the blood and turn it into glycogen and store it
3) blood glucose back to normal
what happens if blood glucose level is too low
1) glucagon is released by the pancreas
2) glucagon tells the liver to break glycogen in to glucose and release this into the blood
3) Blood glucose back to normal
symptoms of diabetes?
Thirst
Frequent urination
weight loss
Tiredness
Fatigue
Blurred vision
What is the difference between type 1 and type 2 diabetes?
Type 1 diabetes is when no insulin is produced by your pancreas and Type 2 diabetes is either there is not enough insulin produced by your pancreas or it is being produced but not working properly.
What are the risk factors of Type 2 diabetes?
The risk factors for Type 2 diabetes are being overweight, a family history of the disease, high blood pressure, poor diet and lack of exercise, age and ethnicity – South-Asians have a greater risk.
How could you reduce the risk of developing type 2 diabetes?
You can reduce your risk of Type 2 diabetes by maintaining a healthy body weight, exercising
What causes diabetes?
The amount of sugar in the blood is usually controlled by a hormone called insulin
When food is digested and enters your bloodstream, insulin moves glucose out of the blood and into cells, where it is broken down to produce energy
However, if you have diabetes, your body is unable to break down glucose into energy
This is because there is either not enough insulin to move the glucose, or the insulin produced does not work properly.
Possible impacts of diabetes:
Injecting oneself with insulin
Monitoring blood sugar level
Risk of experiencing hypo/hyperglycaemia
Change in diet
Weight loss
Kidney damage
Heart attack
Stroke
Amputation
Blindness
Coma
Death
Type I diabetes - Treating it
If you are diagnosed with type 1 diabetes, you will need insulin injections for the rest of your life.
The injected insulin allows glucose to be taken into your body cells, and converted to glycogen in the liver → keeps the blood glucose level steady
Have to be careful about the amount of carbohydrates you eat, and have regular meals
Exercise is important, but needs careful planning
Type 2 diabetes - Treating it?
Many people can control their blood glucose by taking three steps:
Eating a balanced diet with carefully controlled levels of carbohydrates
Losing weight
Doing regular exercise
If this doesn’t work, there are drugs that help insulin work better on the body cells
If none of these treatments work, you will probably need insulin injections
Reasons for increase in type 2 diabetes:
High sugar diets
High fat diets
Increase in obesity
Lack of exercise
Benefits of human
insulin
Cheaper to make it.
Can be produced in large quantities.
Human and pig insulin is not quite the same as human insulin so there is a chance of humans being allergic.
Cows and pigs pancreases have to be mashed up which means they have to be slaughtered.
Meal Planning for a Diabetic:
Eat three regular meals a day to stabilise blood sugar levels
Eliminate refined sugar products from the diet and maintain a low GI diet
Eat food with low sugar content and use artificial sweeteners and diabetic food alternatives
Increase intake of high fibre foods, e.g. wholemeal/wholegrain products.
Reduce intake of saturate fats to decrease risk of CHD and stroke
Each starch based carbohydrates for slow release energy
puberty changes in women
Ovaries start producing eggs
Oestrogen produced
Breasts develop
Hips grow
Menstruation
puberty changes in men
Testosterone produced
Usually puberty starts later
Larynx grows
Chest broadens
Oestrogen and progesterone
Builds up the lining of the womb
Luteinising hormone
Causes the release of the egg
FSH
Controls the maturation of the egg
Testosterone
Stimulates the production of sperm
How long is one menstrual cycle?
28 days
On which day of the menstrual cycle does the period start?
Day 1
On which day of the menstrual cycle is an egg released from the ovary?
Day 14
What happens to the lining of the uterus if an egg is not fertilised?
It breaks down and leaves through the vagina as a period.
Does a woman have periods while she is pregnant? Explain your answer.
No, because the lining remains inside the uterus – it is where the embryo is attached.
How long does a period usually last in the 28 day cycle?
5 days
Day 1 – 7
menstral cycle
first day of a woman’s period.
uterus comes away and exits through the vagina as blood.
Day 7 - 13
menstral cycle
lining of the uterus begins to build up again.
caused by oestrogen and progesterone.
egg starts to mature in one of the ovaries.
This is caused by Follicle stimulating hormone (FSH)
Day 14 (The Middle)
an egg is released by an ovary into the oviduct.
This is caused by a hormone called luteinising hormone (LH)
Day 14 - 17
During this time the egg travels down the oviduct and into the uterus hoping to be fertilised.
Day 18 - 28
If the egg is not fertilised then the lining of the uterus begins to break down.
FSH secreted by?
Pituitary gland
fsh role
Stimulate eggs to mature
Stimulates ovary to produce oestrogen
lh secreted by
Pituitary gland
lh role
Stimulates the release of egg at ovulation
Oestrogen secreted by
Ovary
Oestrogen role
Stimulates development of uterus lining
Inhibits FSH
Stimulates LH
Progesterone secreted by
Ovary
Progesterone role
Maintains the lining of the uterus
Inhibits FSH and LH
Hormonal contraceptives:
use hormones to prevent fertilisation by influencing the menstrual cycle.
Progesterone and oestrogen are used to prevent eggs from maturing.
Non-hormonal methods:
tend to be barrier methods
Barrier methods stop sperm from reaching the egg.
eg:
Condoms
Female condoms
Cap
Spermicide:
Spermicides kill sperm which prevents them from being able to swim through the cervix into the uterus.
Hormones contol of fertility:
Hormones can be used to stop eggs being released in the menstrual cycle.
Progesterone and Oestrogen are used to prevent FSH being released so an egg will not mature.
Surgical method:
The man’s sperm ducts may be tied or cut to stop sperm from exiting the penis.
The woman’s oviducts may be tied or cut to prevent a mature egg from entering the oviduct and uterus.
IVF :
In vitro fertilisation (IVF): fertilisation in the laboratory outside the mother’s body.
how does ivf work?
A female chooses to have the treatment and uses either her partners sperm or a sperm donor.
She is given FSH to stimulate the maturation of many eggs.
After an ultrasound, a doctor uses a needle to collect the eggs from the female’s ovary.
The eggs are combined with sperm outside the body in a process called fertilisation.
Any successfully fertilised eggs become an embryo and are implanted back into the uterus lining.
This develops into a foetus and grows in the uterus for the next 9 months.
Criteria you need to meet before you can have IVF on the NHS, such as:
not having any children already, from both your current and any previous relationships
being a healthy weight
not smoking
falling into a certain age range (for example, some CCGs only fund treatment for women under 35)
Problems with multiple births
Lead to low birth weight
Possible harm to the moth/fetus/embryo/baby/miscarriage
Premature complications
Oral contraceptives contain ……………………, which stop the production of ……………………. This means no …………………… mature
Oral contraceptives contain hormones/oestrogen, which stop the production of FSH. This means no eggs mature.
…………………… can be used as a fertility drug, to stimulate …………………… to mature in the ……………………. These eggs can be used in …………………… treatments.
FSH can be used as a fertility drug, to stimulate eggs to mature in the ovaries. These eggs can be used in IVF treatments.
advantages of IVF?
chance for infertile couples to have children
genetic screening of embryos could decrease suffering from genetic diseases
spare embryos can be stored for future pregnancies or stem cell research
disadvantages of IVF?
expensive
not equally available to all
low success rate
could lead to eugenics
often leads to multiple pregnancy
issues concerning disposal of embryos
inherited infertility may be passes onto children
what is adrenaline released by
adrenal glands (they are just above the kidneys)
what is adrenaline released by
adrenal glands (they are just above the kidneys)
when is adrenaline secreted
stressful or scary situations, your brain detects fear or stress and sends nerve impulses to the adrenal glands, which respond by secreting adrenaline
how does adrenaline get the body ready for flight or fight
it triggers mechanisms that increase the supply of oxygen and glucose to cells in the brain and muscles.
what system controls the levels of hormones and other substances in the blood
negative feedback cycle
what does thyroxine do?
regulates metabolic rate - the speed at which chemical reactions in the body occur while the body is at rest.
stimulates photosynthesis for growth and development
what is thyroxine released in response to?
thyroid stimulating hormone TSH which is released from the pituitary gland.
how doe the negative feedback cycle keep the amount of thyroxine in the blood at the right level
when the level of thyroxine in the blood is higher than normal, the secretion of thyroid stimulating hormone from the pituitary gland is inhibited. this reduces the amount of thyroxine released from the thyroid gland, so the level in the blood falls back towards normal.
what happens when you eat a meal
1) blood glucose increases due to eating the meal
2) insulin is released from the pancreas
3) insulin causes glucose to enter the cells
4) glucose is stored as glycogen in the liver
5) blood glucose now = normal
6) blood glucose drops
7) glucagon hormone released from pancreas
8) glucagon takes the stored glycogen and converts it back to glucose
