B1.2 Flashcards
What is the nervous systems job?
To detect stimuli because this allows us to coordinate behaviour
What is the definition of stimuli?
Changes in the environment, such as sound, temperature, light and smell
What receptors do eyes have?
Light receptors for sight (rods and cones that both have a cell membrane, cytoplasm and nucleus)
What receptors does the nose have?
Chemical receptors for smell
What receptors does the tongue have?
Chemical receptors for taste
What receptors does skin have?
Ones that are sensitive to touch, pressure, temperature and pain
What receptors do ears have?
Sound receptors and receptors that detect position to help balance
What is the central nervous system?
The brain and spinal chord
When receptors detect a change in the environment where do they send a message to?
The CNS as an impulse
If you touch something hot, what happens to make you move your hand?
(Check this with Dr E book)
Stimulus - receptor in sense organ - sensory neurone - relay neurone - spinal chord - motor neurone - effector (eg muscle) - response (eg move hand)
What are effectors?
A muscle or a gland
What are glands?
Parts of the body which release hormones or sometimes enzymes
What is a synapse?
A small gap between 2 neurones
What are reflexes?
Responses designed to protect you. Does NOT involve the brain.
Stimulus - sensory neurone - spinal chord - relay neurone - motor neurone - effector (e.g. Muscle) - response (e.g. Move hand)
If you aren’t eating or drinking how does your body raise your blood sugar?
A hormone will release glucose from stores in the body from the liver and the muscles
How can body temperature increase?
Exercise
Warm weather
Blood flowing as far as it can from the skin
How can body temperature decrease?
Sweating
Blood flowing closer to the skin to radiate heat
Why does the body require a temperature of 37 degrees Celsius?
Because the enzymes can’t work much above or below 37 degrees Celsius
What does homeostasis mean?
Controlling conditions and substances in the body
Why is water important in the body?
All chemical reactions happen in a watery environment, so reducing the amount of water limits the ability of those chemical reactions
How can water get into the body?
Drinking
Eating
How can water leave the body?
Breathing
Sweating
Urinating
How do ions get into the body?
Eating
How are ions lost from the body?
Sweating
Urinating
What are calcium ions used for?
Strengthening teeth and bones
What are sodium and potassium ions used for?
Helping nerve cells to send messages
How does blood sugar increase?
Eating
Drinking
How does blood sugar decrease?
Exercise
Insulin (a hormone which helps to reduce blood sugar)
What do hormones control in the body?
Blood sugar
Water levels
Release of eggs
Growth
What does the pituitary gland do?
Produces FSH
Produces LH
What does FSH do?
Matures the egg
Produces oestrogen
What does oestrogen do?
Thickens uterus lining
Switches off FSH
Produces LH
What does LH do?
Releases the egg
Switches off oestrogen
What happens on day 1-5 in the menstrual cycle?
Old egg is removed, uterus lining is thinned
What happens on day 1-12 in the menstrual cycle?
New egg matures in ovaries
What happens on day 12-16 in the menstrual cycle?
Egg is released from ovaries
What happens on day 20-28 in the menstrual cycle?
Egg is in womb
What is used to stop pregnancy?
Oral contraceptive
What is used to encourage pregnancy?
IVF
What was the problem with the first contraceptive pills made?
They caused lots of side effects including headaches and high blood pressure
What do contraceptive pills today contain?
A lower dose of oestrogen with progesterone, or just progesterone
What happens in IVF treatment?
~ Fertility drug given to woman containing FSH and LH, which releases eggs
~ Mature eggs removed and put in a glass petri-dish
~ Eggs fertilised with mans sperm, then the eggs grow into embryos (small balls of cells)
~ Embryos put back into the woman’s womb
What do enzymes do?
Ensure reactions in the body happen quick enough to keep us alive
How do plants act towards light?
They grow in a direction so that they are in the sun (this is called phototropism)
What is it called when shoots of plants grow up against gravity?
Negative geotropism / gravitotropism
How do plants ensure they get enough moisture?
Their roots grow towards the force of gravity so they can get all the moisture deep underground
What does the hormone auxin do in plants?
~ Encourages growth of shoots
~ Slows growth of roots
What is the process of phototropism in shoots? (Growing towards light)
~ Auxin flows down shoots
~ When there is a source of light from a direction, the auxin moves away from that direction (which causes the shoot to bend towards the light)
What does auxin do in the roots of a plant?
If a root is growing horizontally, the auxin will move to the bottom, which will slow the growth on that side and the root will bend downwards
What can plant hormones by used for?
~ Encouraging cuttings to grow roots
~ Killing weeds
What are neurones?
Specially adapted cells that can carry an electrical signal
What are plants sensitive to?
~ Light
~ Moisture
~ Gravity
What does auxin control?
~ Phototropism
~ Gravitropism (geotropism)
Where is more stomata found?
More stomata is found on the lower surface of leaf than upper surface
Where do plants mostly lose water vapour from?
Their leaves
When conditions cause more evaporation in a plant?
Hot, dry and windy conditions
What can the stomata do if plants lose water faster than it is replaced by?
The stomata can close to prevent wilting
What is the size of stomata controlled by?
Guard cells
What does the relay neurone do?
Sends a message from one nerve cell to another nerve cell
Why is the hormone oestrogen used in contraceptive pills?
Because it inhibits FSH which stops the process of eggs maturing
