Quizlet Y10 Flashcards
What is the nervous system?
The network of nerve cells that transmits nerve impulses between parts of the body
What are neurones?
Basic cells of the nervous system that carry electrical impulses around the body
What is in the central nervous system?
The brain and the spinal cord
What is the peripheral nervous system?
The parts of the nervous system outside the brain and spinal cords (like neurones)
What is a stimulus?
A change in an organism’s surroundings
What is a receptor?
A structure that allows a living organism to sense the conditions of their internal or external environment
What is a sensory neurone?
A neurons that carries impulses from the sensory organs to the CNS
What is a coordinator?
The CNS, which formulates a response to a stimulus before sending impulses to an effector
What is a motor neurone?
A neurone that sends impulses from the CNS to an effector
What is an effector?
A structure that acts in response to a stimulus, like muscles contracting or glands secreting hormones
What is a response?
A reaction to a stimulus
What is a reflex arc?
A nerve pathway involved in a reflex action, made of a sensory neurone, relay neurone and motor neurone
What is a relay neurone?
A type of neuron found in the spinal cord involved in reflex actions
What is a reflex response?
A quick and involuntary reaction to a stimulus
What is a synapse?
A gap between neurones where information is transmitted from one neurone to the next in chemical form
What is a neurotransmitter?
A chemical that is released from the ends of an active neurone and diffuses across the synapse to other neurons
What is the brain?
A mass of nerve tissue consisting of billions of interconnected neurones.
What is the cerebral cortex?
The outer region of the cerebrum which controls memory, consciousness, language, thought, perception and memory
What is the cerebellum?
Part of the brain which controls fine motor skills, like coordination, precision and accurate timing
What is the medulla?
The base of the brainstem which controls heartbeat and breathing (unconscious activities)
What is the eye?
A sense organ which detects light and is responsible for vision
What is the sclera?
The white outer part of the eye which provides protections
What is the cornea?
The transparent tissue that covers the front of the eye and controls and focuses the entry of light into the eye. It is fixed and can’t adjust its focus
What is the iris?
The coloured part of the eye behind the cornea that regulates the size of the pupil to regulate the amount of light that reaches the retina
What is the pupil?
The dark opening in the centre of the iris
What is the lens?
A transparent structure located behind the iris which focuses light onto the retina. It can change shape to adjust focus
What are the ciliary muscles?
Muscles which work with the suspensory ligaments to adjust the shape of the lens in order to focus on near/far objects
What are suspensory ligaments?
Ligaments which work with the ciliary muscles to adjust the shape of the lens in order to focus on near/far objects
What is the retina?
The light-sensitive surface at the back of the eye, containing light and colour receptor cells
What is the optic nerve?
The nerve that carries neural impulses from the receptor cells of the eye to the brain
What are rod cells?
light receptor cells- highly sensitive and responsible for vision in dimly lit conditions
What are cone cells?
colour receptor cells, responsible for the perception of colour
What is the reflex response to dim light?
circular muscles relax, radial muscles contract so the pupil widens
What is the reflex response to bright light?
circular muscles contract, radial muscles relax so the pupil constricts
What happens to the eye so it can focus on a near object?
ciliary muscles contract and suspensory ligaments loosen, making the lens thicker so it refracts the light rays more strongly
What happens to the eye so it can focus on a distant object
ciliary muscles relax and suspensory ligaments pull tight, making the lens thinner so it only slightly refracts light rays
What is hyperopia?
long-sightedness- the person has difficulty focusing on nearby objects because the light rays focus behind the retina
What is myopia?
short sightedness- the person has difficulty focusing on distant objects because the light rays focus in front of the retina
What are the causes of hyperopia?
the lens is too weak or the eyeball is too short
What are the causes of myopia?
the lens is too strong or the eyeball is too long
What lens is used to correct myopia?
concave lens
How do concave lenses work?
They spread out the light rays so that the image focuses on the retina
What lens is used to correct hyperopia?
convex lenses
How do convex lenses work?
they refract light inwards so the image focuses on the retina
Name some modern sight treatments?
Hard and soft contact lenses, laser surgery to correct the shape of the cornea, lens replacement
What happens if the body is too cold?
enzymes won’t have enough energy for successful reactions
What happens if the body is too hot?
the enzymes will denature and be unable to function
What is the thermoregulatory system?
Part of the brain sensitive to the blood temperature
What is vasodilation?
The widening of the blood vessels. This increases the amount of blood near the surface of the skin, allowing more heat to be transferred to the surroundings
What is the purpose of swear?
To reduce heat energy from the skin as it evaporates
What is vasoconstriction?
The narrowing of the blood vessels, which reduces the amount of blood near the skin’s surface and allows less heat to be transferred to the surroundings
What is the purpose of shivering?
To cause increased respiration rates and release energy as heat
What happens if the body temperature is too low?
vasoconstriction and shivering
What happens if the body temperature is too high?
vasodilation and sweating
How is information from receptors carried to the brain to coordinate a response?
receptor -> sensory neurone -> relay neurone > motor neurone -> effector
What are the endocrine glands?
pituitary glands
thyroid glands
pancreas
adrenal glands
ovaries/testes
What hormones are produced in the pituitary gland?
FSH (follicle stimulating hormone)
HGH (human growth hormone)
ADH (antidiuretic hormone)
LH (leutinising hormone)
What is the function of FSH?
causes eggs to mature
stimulates oestrogen production
What is the function of LH?
causes ovulation
stimulates the empty follicle to release progesterone
What is the function of HGH?
controls growth
What is the function of ADH?
controls the water content of the body via the kidney
What hormone is made in the thyroid gland?
thyroxine
What is the function of thyroxine?
increases metabolism
What hormone is produced in the adrenal gland?
adrenaline
What is the function of adrenaline?
responsible for the fight or flight response( increases heart rate, breathing rate and blood pressure to provide more energy and oxygen for the muscles)
What hormones are produced in the pancreas?
insulin and glucagon
What is the function of insulin?
lowers blood glucose levels
What is the function of glucagon?
raises blood glucose levels
What hormones are produced in the ovaries?
progesterone and oestrogen
What is the function of progesterone?
maintains the thickness of the uterus lining. It inhibits FSH and LH
What is the function of oestrogen?
controls the secondary sexual characteristics in females and maintains/thickens the lining of the uterus. It inhibits FSH and stimulates the release of LH
What hormone is produced in the testes?
testosterone
What is the function of testosterone?
controls the secondary sexual characteristics in males and stimulates sperm production
What happens if the blood glucose level is too low?
It is detected by the pancreas, which then secretes glucagon. Glucagon travels in the blood to the liver where it breaks down glycogen to glucose. The glucose is released into the blood and the blood sugar level returns to normal. This is a catabolic reaction
What happens if the blood glucose level is too high?
It is detected by the pancreas which then secretes insulin. Insulin travels in the blood to the liver where it converts the glucose to glycogen. The glycogen is stored and the blood sugar level returns to normal. This is an anabolic reaction
Describe Type 1 diabetes
The pancreas is unable to produce (enough) insulin. Without insulin, the body’s cells are unable to take up glucose. The blood glucose level becomes uncontrollably high, and glucose is excreted in the urine
Describe Type 2 diabetes
The body’s cells no longer respond (effectively or at all) to the insulin being produced. The insulin levels end up being constantly high
Why does diabetes result in tiredness?
If there is more glucose in the bloodstream, there is less glucose in the body cells, so they then don’t have enough energy
Why does diabetes result in frequent urination?
The body is trying to remove the sugar and lower the high glucose levels
Why does diabetes result in blurred vision?
The water leaves the lens as the glucose levels are too high
Why does glucose result in weight loss?
Fats and proteins are used as an alternate energy source
Why does glucose result in thirst?
The body needs more water to dilute the blood glucose concentration
How can diabetes be treated?
insulin pumps, diet and exercise
Where does deamination take place?
in the liver
What is deamination?
In the liver, excess amino acids have their amino groups removed to become ammonia
Why is ammonia then converted to urea?
Ammonia is highly toxic, so is immediately converted to to a urea, a less toxic compound which can be excreted from the body via the kidneys
How can kidney disease/failure be treated?
Dialysis or a transplant
Describe machine dialysis/haemodialysis
Blood passes into an external machine, containing a fluid containing glucose and ions. There is a thin membrane separating the blood from the dialysis fluid, so the urea ,salts and waste products pass from the blood into the dialysis fluid. The clean blood is returned to the body
Describe peritoneal dialysis
It uses the inside lining of your abdomen as a filter for your blood, as it contains thousands of blood vessels like your kidneys
What are the positives of a kidney transplant?
-patients can lead a more normal life
-cheaper for the NHS
What are the disadvantages of a kidney transplant?
-immunosuppressants have to be taken, which also lead to increased risk of infection
-there is a shortage of organ donors
-operation carries risks
- kidneys only last 8-9 years
What are the positives of a dialysis?
-there is no shortage
-there is no need for immunosuppressant drugs
-reduces symptoms of kidney disease
-home dialysis can also be done
What are the disadvantages of a dialysis?
-patient must limit their salt and protein intake
-expensive for the NHS
-regular dialysis sessions are needed, impacts their lifestyle
-only works for a limited amount of time before a transplant is needed
What is ADH responsible for?
regulating the reabsorption of water back into the blood
Where is ADH produced?
It is produced in the hypothalamus and stored in the pituitary gland
What happens if the blood is too diluted?
The hypothalamus senses the blood is too diluted, so secretes less ADH into the bloodstream. This is detected by the kidney, which makes the kidney less permeable, so less water is reabsorbed
What hormones are in the menstrual cycle?
FSH
LH
Oestrogen
Progesterone
How does IVF occur?
- The woman is given FSH and LH to stimulate egg production
- The woman is sedated but conscious and eggs are collected
- a sperm sample is collected from the father
- Eggs and sperm are mixed and monitored microscopically
- Any embryos are allowed to develop for 5 days. They are then selected and planted into the uterus
State some problems with fertility treatment
There can be spare fertilised embryos (unethical to kill/research on them ) or there could be multiple births (dangerous). It is very emotionally and physically stressful and the success rates are not high
How does a condom work?
Provides a barrier to sperm so they are unable to enter the vagina and fertilise the egg
How does spermicidal cream work?
kills sperm, can be used with a diaphragm
How does a diaphragm work?
Used with a spermicidal cream and acts as a barrier in the vagina to prevent sperm from entering the uterus
Name 3 hormonal methods of contraception
combined pill, progesterone-only pill, intrauterine device (IUD)
Explain negative feedback
the action taken by the body to return something to an optimum level following a deviation from that level.
State 2 hormones that are controlled by negative feedback
insulin and glucagon
What happens in filtration?
urea, glucose, water, amino acids, ions and minerals are absorbed into the nephron from the bloodstream
What can’t be filtered into the nephron?
red blood cells and large proteins, as they are too big to fit through the capillary walls
What happens in selective reabsorption?
glucose for respiration, water, amino acids and some minerals/ions are reabsorbed into the bloodstream
What isn’t reabsorbed into the bloodstream?
urea (nitrogen), excess water and some ions
How does the body maintain water and nitrogen balance in the body?
the kidneys
What are hormones?
chemical messengers released by glands into the blood and carried to a target organ or organs
