B5 Homeostasis Flashcards
What is homeostasis?
Regulation of conditions inside the body to maintain a stable internal environment, in response to both internal and external conditions
What 4 internal features are maintained by homeostasis?
Temperature
Water
Glucose
pH
Why is a constant intenal environment important?
So that cells are able to function normally and effectively in any conditions
Why is it important to have a constant glucose level?
Too much glucose can cause diabetes
Too little glucose can cause sweating or trembeling
Why is it important to have a constant water level?
Too much water can cause cells to burst
Too little water may mean they can not function correctly
Why is it important to have a constant body temperature?
High temperature increases kinetic energy of enzymes so they react faster
Low temperature may denature enzymes
What two automatic control systems are involved in homeostasis?
Nervous System
Endocrine System
What are receptors?
They sense external change
What do coordination centres do?
They decide what to do, depending on signals they recieve
Name 3 coordination centres
Brain
Spinal Cord
Pancreas
What are the two types of effectors?
Muscles
Glands
What is the order of compounds in a control centre?
Stimulus Receptor Coordinator Effector Response
What does homeostasis maintain optimum conditions for?
Enzyme Action
Cell Structure
Chemical Reactions
What is a negative feedback loop?
A continuous cycle of events that respond when conditions change away from a set point and causes it to return to a set point
What is the use of the nervous system?
It allows humans to react to their surroundings
What is the CNS?
Central Nervous System - It works as a coordination centre
What does the CNS consist on in vertebrates?
The Brain and Spinal Cord
What are sensory neurones?
Neurnones that carry information as electrical impulses from the receptors to the CNS
Where are receptors located?
In and on organs
What are motor neurones?
Neurones that carry electrical impulses from the CNS to effectors
What are effectors?
Muscles or glands that carry out a response to a nervous impulse
What is a receptor?
Cells that detect a stimuli
What is a synapse?
The connection between two neurones
How does a signal travel across a synapse?
It is transfered into chemicals and diffuses across the gap before setting of a new electrical signal in the next cell
What is a reflex?
A rapid and automatic response that does not involve the concious part of the brain
What is a reay neurone?
A neurone in the spinal cord that allow the CNS to be bypassed and send stimuli from the sensory nerone straight to the motor neurone
What is reaction time?
The time taken to respond to the stimulus
What an reaction time be effected by?
Age, gender or drugs
How can we test reaction time and how caffeine effects it?
Ruler drop test
How do we carry out the ruler drop test?
One person must hold a ruler between anothers thumb and finger at 0cm
They must then drop it without warning and the other person must catch it as quickly as possible
They should then try it after drinking a caffinated drink
Most effective ways of testing reaction time?
Computer tests
What is the brain made up of?
Billiones of nterconnected neurones
Where is the Celebral Cortex?
It is the outer wrinkly section of the brain
What is the function of the Celebral Cortex?
It is responsible for the conciousness, intelligence, memory and language
Where is the Cerebellum?
In the back and lower section of the brain
What is the function of the Cerebellum?
Responsible for muscle coordination
Where is the Medulla?
In front of the spinal cord, below the main section of the brain
What is the function of the Medulla?
Controls unconcious activities (breathing anf heartbeat)
How do we study a brain?
Studying patients with brain damage
Electrically Stimulating the brain
MRI Scans
What does MRI stand for?
Magnetic Resonance Imaging
What does an MRI scan show?
Which area of the brain is active
How do we elctricall stimulate a brain?
Pushing tiny electrodes into the tissue and zapping it with electricty to observe how the body reacts.
Where is the sclera located?
Around the eye
What is the function of the sclera?
It is a tough supporting wall
Where is the cornea located?
It is a transparent, outer layer at the front of the eye
What is the function of the cornea?
It refracts light into the eye
Where is the iris located?
Muscles just below the surface of the eye at the fron that can change size
What is the function of the iris?
Controls the diameter of the pupil and thus the light that goes into the eye
Where is the lens located?
Behind the iris but in front of the main bulk of the eye
What is the function of the lens?
Focuses the light on the retina
Where are the ciliary muscles located?
Behind the iris, on either side of the suspensory ligaments
What is the function of the ciliary muscles?
Help control the shape of the lens and thus helps focus
Where is the suspensory ligament located?
Between the cilliary muscles and the lens, behind the iris
What is the function of the suspensory ligament?
Help control the shape of the lens and thus helps focus
Where is the optic nerve located?
Behind the eye
What is the function of the optic nerve?
Carries impulses to the brain
Where is the retina located?
At the back of the eye
What is the function of the retina?
It has receptor cells that understand the colour and light and understand the image
What damages the retina?
Bright lights
Which reflex protects oour retina?
When there are bight lights a reflex is triggeres that make the pupil smaller so less light enters.
What is the pupil size controlled by?
The Iris contracting/ relaxing
What happens in the eye when you look at a near by object?
The cillary muscle tightens
The suspensory ligament slakens
The lens becomes fatter (more curved)
Therefore light is refacted more
What happens in the eye when you look at a far away object?
The cillary muscle relax
The suspensory ligament pull tight
The lens becomes thinnes (less curved)
Therefore light is refacted less
Why does eye sight get worse with age?
The lens become less flexible and cannot easily spring back into shape and ths cannot focus
What does it mean to be long sighted?
You cannot focus on nearby objects
What causes long-sightedness?
The lens is the wrong shape and doesn’t refact light enough or the eyeball is too short
What does it mean to be short sighted?
You cannot focus on far away objects
What causes short-sightedness?
The lens is the wrong shape and refacts light too much or the eyeball is too long
How can we treat long-sightedness?
A convex lens which curves outwards
Medical name for being long-sighted?
Hyperopia
How can we treat short-sightedness?
A concave lens which curves inwards
Medical name for being short-sighted?
Myopia
Advantages of contact lenses
Lightweight
Good for sport
Comfortable
Invisible
Didvantages of contact lenses
High risk of eye infection
What happens during laser eye surgery?
A laser is used to vaporise tissue, changing the shape of the cornea
Advantages of laser eye surgery
Long term solution
Work for multiple eye problems
Disadvantages of laser eye surgery
Risk of surgical complications
What can be treated by doing surgery to replace the lens?
Long sighted
What are replacement eye lenses made from?
Clear plastic
Advantages of surgically replacing the eye lens
More effective
Disadvantages of surgically replacing the eye lens
Higher risk of complications including damage to the retin
What is our optimum body temperature?
37°C
What part of the brain controls temperature?
The thermoregularity centre
How does the thermoregularity centre calculate our internal body temperature?
It has receptors that are sensitive to the temperature of blood
Responses to high body temperature
Sweat
Vasodilation
Responses to low body temperature
Hairs stand up to trap air
No Sweat
Vasoconstriction
Shiver
Define hormones
Chemical molecules released into the bood that effect certain organs/ tissues and make them change
What is the endocrine system?
The system which links hormones, glands and their targets
What type of effect do hormones give?
Long lasting
Where is the pituitary gland located?
Below the brain
What does the pituitary gland do?
Regulates body conditions
Regulates other glands
Which is the ‘master gland’?
Pituitary Gland
What do the ovary glands do?
Produce oestrogen (needed for the menstrual cycle)
What do the testes glands do?
Produce testosterone (needed for puberty ad sperm production)
Where is the thyroid located?
Near the voice box
What does the thyroid gland do?
Produces thyroxine which regulates temperature, metabolism and heart rate
Where is the adrenal located?
Above the kidney
What does the adrenal gland produce?
Adreneline
Function of Adreneline
Flight or fight instincts
Where is the pancreas located?
Near the kidney
What does the pancreas produce?
Insulin
Function of insulin
Regulates blood glucose levels
Which type of response acts faster?
Nerves
Which type of response lasts longer?
Hormone
Which type of response is more precise?
Nerves
How is excess glucose delt with?
Stored as glycogen in the livers and muscles
Which hormone lowers blood sugar levels?
Insulin
Which hormone increases blood sugar levels?
Glucagon
How does insulin work?
It is secreted by the pancreas and turns glucose into glycogen
How does glucagon work?
It is secreted by the pancreas and turns glycogen into glucose
What is type 1 diabetes?
When the body produces little or no insulin
What is type 2 diabetes?
When a body becomes resistent to their own insulin and this becomes uneffective
How are type 1 diabetes treated?
Insulin injections
How are type 1 dibetes controlled?
Diet
Excersise
Risk factors for type 1 diabetes?
Genetics
Risk factors for type 2 diabetes?
Age
Weight
Genetics
How are type 2 diabetes controlled?
Diet
Excersise
What does the kidney do?
Filter the blood
What three substances are removed from the blood in urine?
Urea
Ions
Water
What substance is converted into urea in the liver?
Ammonia
How are excess amino acids delt with?
Converted to fats and carbohydrates
What is a by product of deamination?
Ammonia
What is deamination?
The conversion of proteins to fats and carbohydrates
Why is an excess or deficit of mineral ions?
It throws of the water - ions balance for osmosis
Why must ions by regulated in the kidney constantly?
The amount of ions lost during sweat are not regulated
When do we loose water in the body?
Sweat and breathing out
Which hormone controls urine concentration?
ADH
What does ADH stand for?
Anti-diuretic hormone
What gland releases ADH?
Pituitary Gland
How does ADH change the concentration of urine?
When water content is low, more is released so that the kidneys absorb more water
When water content is high, less is released so that the kidneys absorb less water
What are the treatments for kidney faliure?
Regular Dialysis
Kidney Transplant
What does dyalisis consist of?
A machiene doing the job of the kidney - keep levels of dissolved substances at normal levels
Why is kidney faliure so serious?
You lose the ability to control levels of ions and water in your blood and therefore intoxicate yourself
What happens in a dyalisis machine?
The persons blood flows between partially permeable membrane surrounded by dyalisis fluid
Waste fuids diffuse back across the barrier
What are dyalisis machines permeable to?
Ions and water substances
What are dyalisis machines not permeable to?
Proteins and such larger molecules
What does dyalisis fluid contain?
Healthy blood concentrations of dissolved ions and glucose
How often are regular dyalisis?
Up to 3 times a week
How long does dyalisis last?
3-4 hours per session
Disadvantages of using dyalisis?
Not pleasent
Expensice
Cause blood clots
Infections
Advantages of using dyalisis?
Gives valuable time until the organ donor is found
Why are most kidneys donated by people who are decesed?
There is a small risk to living donors
How come living donors can donate a kidney with minor risk to temselves?
Adults only require one
What is the greatest risk to someone recieving a donor kidney?
The body may reject it
How can a rejected kidney be prevented?
Drugs but it is not fully effective
Advantages of kidney trnsplants
Long term
Cheaper
Less time spent in hospitals
What is the monthly release of an egg reffered to as?
Menstrual Cycle
What is an example of a secondary characteristic?
Facial Hair
Breasts
etc…
What happens during puberty?
Release of sex hormones
Triggers secondary sexual characteristics
(Eggs mature on women)
What hormone is produced in males during puberty?
Testotorone
Where is testosterone produced?
Testes
What does testosterone do?
Stimulates sperm production
What hormone is produced in females during puberty?
Oestrogen
Where is oestrogen produced?
Ovaries
What does oestrogen do?
Brings about physical changes and the menstrual cycle
What happens roughly between days 1-4 of the menstruel cycle?
Uterus limimg breaks down
What happens roughly between days 4-14 of the menstruel cycle?
The uterus builds up again with a spongy layer full of blood, getting ready to recieve a fertilised egg.
What happens roughly on day 14 of the menstruel cycle?
An egg is released
What is the release of an egg called?
Ovulation
What happens roughly between days 14-28 of the menstruel cycle?
The wall is maintained awaiting fertilisation
What 4 hormones control menstruation
FSH
Oestrogen
LH
Progesterone
What does FSH stand for?
Follicle-Stimulating Hormone
What does LH stand for?
Lutenising Hormone
What does FSH do?
Causes an egg to mature (in a structure called a follicle)
Stimulates ovaries to produce oestrogen
What does Oestrogen do?
Causes the lining of the uterus to grow
Stimulates the release of LH and stops the release of FSH
What does LH do?
Stimulates the release of an egg
What does Progesterone do?
Maintains the liningof the uterus during the second half of the cycle. When this falls so does the lining.
Inhibits (stops) the release of LH and FSH
Where is FSH produced?
Pituitary gland
Where is LH produced?
Pituitary gland
Where is Oestrogen produced?
Ovaries
Where is Progesterone produced?
Ovaries
How does Oestrogen work as a contreceptive?
It prevents the release of an egg when used every day as it inhibits the production of FSH and eventually egg production and delopment stops.
How does Progesterone work as a contreceptive?
It stimulates a think mucus that prevents sperm reaching the egg.
What does the combined oral contraceptive pill consist of?
Progesterone and Oestrogen
What other type of contracetptive pill is there other than the combined oral contraceptive pill?
A prgesterone-only pill which has fewer side effects and is as effective
What is a contreceptive patch?
A 5cmx5cm patch with oestrogen and progesterone that lasts 1 week
What is a contreceptive implant?
A plastic implant that is placed under the skin on the arm that continualy releases progesterone for up to 3 years.
What is a contraeptive injection?
A dose of progesterone that is needed every 2 - 3 months.
What does IUD stand for?
Intrauterine device
What is an IUD?
A T-shaped device inserted in the uterus that kills sperm and prevent implantation of fertilised egg.
What do plastic IUDs do?
Release progesterone.
What do copper IUDs do?
Prevent sperm surviving in the uterus.
What are the two different forms of contraception?
Hormonal and non-hormonal
Why are barrier methods often important even when hormonal contraception used?
They protect against STDs
What is a condom?
A latex worn over the pens or inside the vagina
What is a diaphragm?
A shallow plastic ups that fits over the opening to the cervix
What is spermicide?
A sperm killing cream
Negative side-effects of spermicide
Only 70-80% effect
Can cause rashes and infections
What is steralistaion?
Cutting off or tying the fallopian tubes in women
Cutting off the sperm duct (between the testes and penis) in men
What is the ‘natural method’ of avoiding pregnancy?
Trying not to have sex during fertile days
What does abstinence mean (in terms of avoiding pregnancy)?
Not having sex
How permenant is steralisation?
There is a small chance to reverse it in men but it is very permenant
What is the only method of ‘contreception’ that has 100% effectivness?
Abstinence
What are the positives of using hormones to increase fertility?
It helps people get pregnant when they couldn’t
What are the negatives of using hormones to increase fertility?
It doesn’t always work (doing it several time can be expensice)
Too many eggs can be stimulated resulting in unexpected multiple pregnancies (twins, triplets etc…)
What happens during an IVF?
Eggs are fertilised and grown into embryos in a lab and then introduced into a womans body which improves the chances of pregnancy
What does ICSI stand for?
Intra-Cytoplasmic Sperm Injection
What is ICSI?
A technique used during IVF where sperm are directly injected innto the egg
When is ICSI most effective?
When a man has a low sperm count
Positive of IVF?
Can give an infertile coulpe a child
Negatives of IVF?
Multiple births can happen if more than one embryo growns wich causes complications to mother and babies
Sucess rate is low (26%)
Emotionally and physically stressful
Side effeects to the hormones
Why are some peopke against IVF?
Unused embryos are eventually destroyed
Geetic testing can lead to selecting preffered characteristics
How are levels of hormones controlled by the body?
Negative feedback loops
What is thyroxine released in response to?
TSH which is released in the pituitary gland
What does TSH stand for?
Thyroid Stimulating hormone
What does auxin control?
Growth near tips and shoots of plants
What does auxin control the growth of plants in response to?
Light (phototropism)
Gravity (gravitropism and geotropism)
Where is auxin produced?
Tips
What does auxin do after production?
Move backwars to stimulate the cell elongation process whichoccurs just behind the tips
What happens if the tips of a shoot are removed?
No auxin is produced and the shoot may stop growing
What happens if extra auxin is produced?
Promotes growth at the shoot
Inhibits growth at the root
What results does the extra production if auxin produce?
Shoots grow towards light
Shoots grow away from gravity and roots grow towards it.
How do shoots grow towards light?
More auxin accumulates on the shaded side thna that exposed to the sun causing this side to grow faster and therefore bending it towards the light.
How do shoots grow away from gravity?
More auxin accumulates on the lower side of the shoot causing that to grow faster and thus bend the shoot upwards.
How do roots grow towards gravity?
More auxin accumulates on the lower side of the root causing that to growth to inhibit and thus bend the root downwards.
What practical do we do to investigat plant growth response?
Cress Practical
What do wedo to investigate plant growth response?
Put 10 cress seeds in 3 different petri dishes with moist filter paper
Shine a light onto each dish at a different angle
Leave for a week and observe the response
What are some of the control variables in the investigation into plant growth response?
Number of seeds Type of seed Temperature Water Light intensity
Name 3 commercial uses of auxin
Killing Weeds
Growing from cuttings with root powder
Growing cells in tissue culture
How can auxin be used as a weed killer?
It can be targeted to broad-leaved plants and disrupt their growth (killing them) without disrupting grass and crops
How can auxin be used to grow from cuttings with root powder?
Cuttings alone tend to die but if you add root powder (which contains auxin) it will
Define cutting
A part of a plant that has been cut off (like a branch with a few leaves)
How can auxin be used to grow cells in tissue culture?
They are added to growth mediums to stimulate cells to divide to form both roots and shoots
What are tissue cultures?
Can be used to clone plants from a few cells
What is gibberlin?
A hormone which stimulates
Stems growth
Seed germination
Flowering
Name 3 comercial uses of gibberlin
Controlling dormancy
Inducing flowering
Growing larger fruit
What is dormancy?
The specific conditions needed for seeds to germinate
How does gibberlin control dormancy?
Seeds can be treated with gibberlin to make them fertile all year and also means all seeds become fertile at the same time.
How does gibberlin induce flowering?
It can allow flowers to flower without change in environment
How does gibberlin help grow larger fruit?
Can help grow seedless fruit (which tend to be smaller)
What is ethene?
A gas produced by aging parts of a plant.
What does ethene do?
Influences growth of a plant by controlling cell division. It also stimmulates enzymes that cause fuit to ripen.
How is ethene used commercially?
It helps ripen fruit either on the plant or during transportation
What is the function of the cerebellum?
Controls movement and balance
