Year 11 Flashcards
What is homeostasis
Homeostasis is the regulation of the internal conditions of a cell or organism to mantain optimum conditions for function in response to internal or external changes
How is homeostasis controlled
Homeostasis is controlled by the control systems in the body .These could be endocrine or nervous systems
How are endrocrine and nervous responses controlled
Endocrine responses are controlled by hormones travelling through the bloodstream
Nervous responses are controlled by electrical impulses moving through nerve cells
What is a neuron
A neuron is a nerve cell. There are three types neuron : sensory neurons,relay neurons and motor neurons
How is the structure of the neuron adapted for its function
- Thin projections called dendrites extend from the body cell to connect with other neurones, allowing electrical impulses to pass from one neuron to another neuron
- The axons of most neurons are insulated by a layer called the myelin sheath that ensurses impulses travel rapidly along the axin
What is the nervous systems response to a stimulus
Stimulus –>receptor(stimulus converted to an electrical impulse) —>Sensory neuron —> CNS—> relay neuron—>CNS—>motor neuron—> effector (muscle/gland)—>response
What is the synapse
The synapse is the gap between 2 neurons
How is an electrical impulse transmitted along the synapse
- The electrical impulse reaches the end of the first neuron
- This stimulates the first neuron to release neurotransmitter chemicals
- The neurotransmitter chemicals diffuse across the synapse
- The neurotransmitter chemicals bind to receptors on the second neuron
- This binding or receptor and neurotransmitter chemicals stimulatss the second neuron to transmit an electrical impulse (with the same message as first one ) along its axon
What is a reflex action
A reflex action is an inbuilt , involuntry , protective response
What is the reflex arc
The reflex arc is the nerve path when the response is a reflex action
The electrical impulse goes to the spinal cord rather than going to the brainin the reflex arc
Why are reflex actions important
Reflex actions are important as they are fast,automatic and protective
What is the cerebal cortex responsible for
The cerebal cortex is responisble for memory, consciousness,language and intellegence
What is the cerebellum responsible for
The cerebellum is responsible for co-ordination of muscular activity
What is the medulla responsible for
The medulla is responsbile for unconscious activity such as breathing or heartbeat
Why is analysing brain function and treating brain damage and disease difficult
Analysing the brain and treating brain damage and disease is difficult because :
- The brain is complex and delicate
- The brain is easily damage
- Drugs taken to treat diseases may not reach the brain because of the membranes surrounding it
- It is not fully understood which part of the brain is responsible for what
How can neuroscientists map out areas of the brain and their functions
- Neuroscientist can map out areas of the brain and their functions by studying patients with brain damage
- Observing the changes following damage to a certain part of the brain can provide informatiob on what that part of the brain does
How else can neuroscientists map out different areas of the brain and their functions
Neuroscientist can map out different parts of the brain and their functions by electrically stimulating different parts of the brain.
-This involves pushing an electrode into a part of the brain. There may be physical or mental changes in the individual based on the electrical stimulation,providing evidence of what the role of that area of the brain is
How else can neuroscientists map out the brain and its functions
Neuroscientists can use magnetic resonance imaging to produce a detailed image of the brain. MRI uses strong magnetic fields and radiowaves to produce a detailed images of inside the body e.g the brain. They can be used to show which part of the brain is active during certian activities
What is the function of the cornea
The cornea bends/refracts light onto the lens
What is the function of the lens
The lens has a convex shape to refract light onto the retina
What is the function of the sclera
The sclera is the white outer part of the eye which supports the structures inside the eye. It is strong to prevent damage to the eye
What is the iris and what is its function ?
The iris is the coloured part of the eye. It is a muscle that surrounds the pupil. It contracts or relaxes to alter the size of the pupil
What is the pupil ?
The pupil is a hole in the iris that allows light to enter the eye
What is the retina
The retina is a layer of light sensitive cells at the back of the eye. It contains light receptor cells . Light stimulates these cells and then impulses are sent to the brain
What is the optic nerve
The optic nerve is a nerve that leaves the eye and transmits electrical impulses to the brain
What do ciliary muscles and suspensory ligaments do
Ciliary muscles and suspensory ligaments hold the lens in place and control its shape
What is accomodation of the eye
Accomodation of the eye is the process of changing the shape of the lens to focus on near or distant object
How does the lens change shape for near focussing
The lens becomes thicker and rounder for near focussing (and refracts light more strongly)
How does the lens change shape for distant focussing
-The lens becomes thinner when distant focussing and only slightly refracts light rays
How do suspensory ligaments and ciliary muscles contract for near focussing
-Suspensory ligaments become lax(loosen) for near focussing
Ciliary muscles contract for near focussing
How do the suspensory ligaments and ciliary muscle change for distance focussing
- The suspensory ligaments pull tight / tense during distance focussing
- The ciliary muscles relax during distance focussing
What is the problem with the eyeball in short sightedness
The eyeball is too long in short sightedness(myopia)
What is the problem with the eyeball in long sightedness
The eyeball is too short in long sightedness (hyperopia)
What is the problem with the lens in short sightedness
The lens is too curved( it refracts light too much)in short sightedness
What is the problem with the lens in long sightedness
The lens is too flat in long sightedness-It doesnt refract light enough
How do objects appear with long sightedness and short sightedness
- Distant objects appear blurry with short sightedness
- Close objects appear blurry with long sightedness
Where is the image focussed in long sightedness and short sightedness
- In long sightedness the image is focussed behind the retina.
- In short sightedness the image is focussed in front of the retina
What do convex lenses do ? What can they be used to treat ?
Convex lenses converge light ray (bring light rays together ) so that they converge on the retina
-They are used to treat long sightedness (hyperopia)(going too far )
Wht do concave lenses do? What can they be used to correct ?
Concave lenses diverge light rays (spread them out more) so that they converge on the retina
-This can be used to treat short sightedness(myopia
How does the iris respond to bright light
In bright light the circular muscles of the iris contract and the radial muscles relax in order to make the pupil snakler
How does the iris respond to dim light
In dim light, the radial muscles of the iris contract and the circular muscles relax to make the pupil larger -so more light can enter to create a better image
What are two methods for treating problems with vision
Vision problems can be treated with :
Spectacle lenses:concave (to treat short sightedness)or convex (to treat long sightedness)
-Contact lenses: work in the same way as glasses but can be used during sport and other activities. Hard or soft contact lenses last for different amounts of time
How can laser eye surgery be used to correct problems with vision
Lasers can be used to reduce the thickness or the cornea (so light it refracts light less) to trat short sightedness or to change its curvature(so refracts light more strongly) to treat long sightedness
How can a replacement lens be used to treat hyperopia
Hyperopia can be treated by replacing the lens with one made of clear plastic(or adding to the natural ones with clear plastic). The risks involve damage to the retina and cataracs
How does a response occur in the endocrine system
- The endocrine system is made up of lots of different glands
- These glands secrete hormones directly into the bloodstream
- These hormones travel to target organs and bind to receptors on that organ
- This produces a response
What is a hormone
A hormone is a chemical message produced by a gland. It travels in the blood to a target organ where it produces a response
Where is FSH produced? What is its effect? What is the target organ for it?
FSH is produced by the pituatry gland
The target organ for FSH is the ovaries
FSH stimulates the maturation of an egg in the ovary
Where is LH produced? What is the target organ for LH? What is LH’s affect?
Luteinising is produced by the pituatry gland
The target organ for LH is the ovaries
The effect of LH is that it stimulates the release of an egg from the ovaries
Where is thyroxine produced? What is its effect?What is the target organ for thyroxine ?
- Thyroxine is produced by the thyroid gland
- Its target organ is various organs
- Thyroxine controls metabolic rate of the body
Where is adrenaline produced? What is its affect? What are the target organs for adrenaline?
- Adrenaline is produced by the adrenal gland
- The target organs for it are the vital organs(heart,liver)
- The effect of adrenaline is that it produces a fight or flight response
Where is oestrogen produced? What is its affect? What is the target organ ?
- Oestrogen is produced by the ovaries
- Its target organ is the uterus
- It inhibits the release of the hormone FSH so only one egg is matured per cycle and it stimulates the pituatry gland to release LH
Where is progestrone produced by ? What is its effect ? Ehat is the target organ for progestrone?
- Progestrone is produced by the ovaries
- The target organ for progestrone is the uterus
- The effect of progestrone is that it mantains the lining of the uterus during the pregnancy and the middle of the menstrual cycle
Where is testosterone produced? What is the target organ for testosterone ? What effect does testosterone have?
- Testosterone is produced by the testes
- The target organ for testosterone is the male reproductive organs
- Testoterone controls puberty in males
What does the pancreas do and what two hormones does it release
The pancreas detects ,monitors and controls blood glucose levels
- It releases glucagon if blood glucose levels are too low
- It releases insulin if blood glucose levels are too high
What happens if blood glucose levels are too high
- If blood glucose levels are too high the pancreas gland first detects that blood glucose levels are too high
- The pancreas gland releases the hormone insulin
- Insulin travels in the bloodstream to body cells and the liver
- The body cells take in excess glucose for respiration and the liver converts excess glucose to glycogen
- Blood glucose levels return to normal homeostatic levels
What happens if blood glucose levels are too low
- If blood glucose levels are too low the pancreas gland first detects blood glucose levels are too low
- The pancreas then releases glucagon
- Glucagon travels in the blood to the liver where there is a store of glucose
- Liver converts glycogen back to glucose
- Blood glucose levels rise to normal homestatic levels
What is type one diabetes
Type one diabetes is a disorder in which a persons pacreas cannot produce suffiecent insulin
-Type one diabetes is characterised by uncontrollable high blood glucose levels
What is type 2 diabetes
-Type 2 diabetes is when the body cells stop responding to the insulin produced by the pancreas
What are the risk factors for type one diabetes
The risk factor for type one diabetes is family history
What are the risk factors for type 2 diabetes
The risk factors for type 2 diabetes are family history, lack of exercise and obesity
When is type one diabetes diagnosed and when is type two diabetes diagnosed?
Type one diabetes is diagnosed at childhood or early adulthood whereas type two diabetes is diagnosed at adulthood
What are the symptoms of type one diabetes
The symptoms of type one diabetes are:
- Blurred vision
- frequent urination
- Blood glucose in the urine
- Being really thirsty all the time
What are the symptoms of type two diabetes
The symptoms of type two diabetes are :
- frequent urination
- blurred vision
- Being really thirsty
What are the treatments for type one diabetes
- insulin injections via insulin pump at mealtimes
- limit the intake of carbohydrates containing lots of glucose
What are some treatments for type two diabtetes
Treatments for type 2 diabetes include:
- Increasing exercise
- losing weight
- Decreasing carbohydrate intake
- Taking tablets/insulin to stimulate pancreas
Have there been any scientific breakthroughs in treating type one diabetes
- scientists are working on
- Genetically engineered bacteria to produce human insulin
- Insulin pumps
- Pancreas and pancreatic cell transplants to cure diabetes and genetically engineered pancreatic cells from micd
What are some scientif breakthroughs for type two diabetes
- there are drugs to make insulin more effective in the body
- There are drugs to help the pancreas produce more insulin
- There are drugs to reduce the amount of glucose absorbed from gut
What does a negative feedback mechanism do
A negative feedback mechanism responds to when conditions change from an ideal or set point and returns the conditions back to the set point
What are some examples of conditions controlled by negative feedback
- Thermoregulation -(if body temperatures change mechanisms are induced to return body temperatures back to normal levels
- Blood glucose levels -(insulin lowers blood glucose levels if they are too high and glucagon raises them if they are too low)
What does thyroxine do
Thyroxine regulates metabolic rate in the body (how quickly reactions occur) and is important in growth and development. It is controlled by negative feedback
What happens if there are low thyroxine levels in the bloodstream
If there are low thyroxine levels in the bloodstream :
- The pituatry gland releases thyroid stimulating hormone (TSH)
- This causes the thyroid to release more thyroxine
- Blood thyroxine levels return to normal
What happens to mantain normal levels of thyroxine in the blood
- Once enough thyroxine has been released into the blood
- Release of Thyroid stimulating hormone from the pituatry gland is inhibited
- This leads to less stimulation of the thyroid gland meaning less thyroxine is released
- Normal blood thyroxine levels are maintaned
When is adrenaline produced?where is adrenaline produced?what does adrenaline stimulate?
- Adrenaline is produced in times of fear or stress
- Adrenaline is released by the adrenal gland(on top of the kidneys)
- Adrenaline stimulates a flight or fight reponse
What are the effects of adrenaline
The effects of adrenaline are:
- Increased heart rate and breathing rate to deliver more oxygen and glucose to brain and muscles for more respiration
- Glycogen stored in the liver is converted back to glucose for respiration
- Pupils become dilated to let more light in
- Increased blood flow to muscles
Where is FSH secreted ? What is FSH function ?
- FSH is secreted by the pituatry gland
- FSH causes an egg to mature in the ovary and it stimulates the ovary to release the hormone oestrogen
Where is oestrogen secreted ? What is oestrogens function?
- Oestrogen is secreted by the ovaries
- Oestrogen stimulates the lining of the uterus to grow after menstruation in preparation for pregnancy
- Oestrogen stimulates the pituatry gland to release LH
- Oestrogen inihibts the release of FSH so that only one egg matures per cycle
Where is luteinising hormone secreted? What is luteinising hormonws function?
-Luteinising hormone is secreted by the pituatry gland
- Luteinising hormone stimulates the release of a mature egg from the ovary
- LH inhibits the release of oestrogen
- Luteinising hormone stimulates the ovaries to release progestrone
Where is Progestrone secreted ? What does progestrone do?
-Progestrone is secreted by the ovaries
- Progestrone mantians the lining of the uterus during the second half of the menstrual cycle and during pregnancy
- Progestroen inhibits the release of FSH and LH
What are some hormonal contraceptive methods
- The pill: the pill is an oral contraceptive that contains hormones that inhibit the release of FSH so no eggs mature
- Contraceptive injection : a contraceptive injection is a skin patch or implant of slow releasing progestrone that inhibits the maturation or release of eggs for many months or years
- The coil : the coil is a device that prevents the implantation of an embryo or release of hormones
What are some examples of non hormonal contraceptive methods
- Barrier methods e.g condoms which stop sperm reaching an egg
- Spermicides which kill or disable sperm
- Abstaining from intercourse whilst an egg may be in an oviduct
- Surgical methods of male or female sterilisastion
Which hormones are used in contraceptives
Oestrogen (inhibits FSH ) and progestrone(inhibts LH and FSH)
What are some common causes of infertility
Some common causes of infertility are:
- Low sperm count
- Problems with male or female reproductive system
- Obesity
- Eating disorders e.g anorexia
- Increasing maternal age
Which hormones are used in fertility treatments
- FSH -to stimulate the maturation of a number of eggs at the same
- LH-to stimulate the release of eggs
What are the stages in IVF treatment ?
1) The mother is given fertility drugsvto stimulate the maturation of many eggs
2) The eggs are collected from the mother and fertilised with sperm from the father in the labrotrary
3) The fertilised eggs develop into embryos
4) At the point where the embryos are tiny balls of cells , two or three are implamented into the mothers uterus
What are the disadvantages of IVF treatment
- IVF is both emotionally and physically stressful
- The success rates are not very high with IVF
- IVF can lead to the births of multiple babies which is a danger to the mother and the babies
What is a tropism
A tropism is a directional growth response in which the direction of the response is determined by the direction of an external stimulus
What is phototropism
Phototropism is a plants growth response to light
What is geotropism
Geotropism is a plants growth response to gravity
Where is auxin produced and what does it do ?
- Auxin is a hormone produced in the tips of roots and the tips of shoots
- Auxin controls growth in plants
How do plants shoots and roots respond differently to high concentrations of auxin
- High concentrations of auxin in plants shoots cause them to elongate more
- High concentrations of auxin in plants roots cause them to elongate less
What are the function of some plant hormones
- Gibberellins are important in initiating seed germination
- Ethene controls cell division and ripening of fruits
- Auxin controls cell elongation
How is auxin used in agriculture and horticulture
Auxin is used in argriculture and horticulture
- as a weed killer
- as a rooting powder
- for promoting growth in tissue culture
How is ethene used in the food industry
Ethene is used in the food industry to control the ripening of fruits during storage and transport
What can gibberellins be used for
Gibberellins can be used to :
- end seed dormancy
- promote flowering
- Increase fruit size
How does auxin affect the shoot growth
- Auxin promotes positive phototropism in roots
- auxin is made at the tips of shoots
- If the plant is exposed light in one side auxin accumulates on the side away from the light
- Therefore auxin diffuses to the shaded side
- Auxin stimulates cell elongation in the shaded side
- This causes the shoot to bend towards the light
- Meaning the plant recieves more light ,so photosynthesis happens at a faster rate
What does auxin do in the roots
Auxin promotes positive geotropism in the roots:
- If the root is horizontal auxin moves towards the lower side of the root
- Auxin inhibits cell elongation on the lower side of the root
- The upper side of the roots cells elongate more (as there is less auxin )
- This makes the root bend and grow downwards
- this is likely to be benefitial as there are increased levels on water and nutrients lower down so the plant will have more stabiliyu
What is variation
Variation is the differences in characteristics of individuals in a population/species
What can variation be caused by
Variation can be caused by : the genes a person inherits (genetic causes )
- The environment a person lives in/grew up in (environmental causes)
- A mixture of genetic and environmental causes
What is evolution
Evolution is the change in inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species
Describe Darwins theory of natural selection
- In a species all individuals are different and show a wide range of variation
- This variation is because of differences in their genes (continous mutations)
- Individuals with characterists most suited to the environment (have ab advantage )are more likely to survive and reproduce
- The genes/alleles that allowed these individuals to be succesful are then passed onto their offspring
Why did people not believe Darwin ?
- Darwins theory challenged the idea that God made all living things on earth
- There was insuffient evidence at the time his theory was published to convice scientists at the time
- The mechanism of inheritance/genes was not known until 50 years after Darwins theory had been published
