biology paper one

• homeostasis is maintainin the internal conditions of the body to maintain optimum conditions for enzyme activity
• the nervous system consists of the brain, spinal cord, and nerves
• receptors detect stimuli
• the coordination center receives and processes information then produces a response
• effectors bring about responses
• sensory neuron sends impulses (from a sensory receptor) to a relay neurone in the spinal cord/CNS
• a motor neurone is a neurone that carries impulses from the CNS to the effector organs
• relay neurones connect sensory and motor neurone
• neurones connect via synapse which is a gap between two neurons.neurone transmitters pass through which attach to the other receptors on other side.the transmitters diffuse across then bind to special receptors which will trigger impulse in next neurone
• reflex arcs bypass the brain and go directly to the effector
• the cerebal cortex is the outer layer of the brain and is responsible for conscious thought and memory
• cerebellum is the part of the brain that controls muscle coordination and balance
• the medulla oblongata is responsible for for unconscious activtiy such as breathing
• the hypothalamus is responsible for linking the nervous system to the endocrine system
• the cornea refracts light as it enters
• the iris is the colored part of the eye that controls the size of the pupil
• the lens focuses light onto the retina
• the retina contains light receptor
• cilary muscles are responsible for changing the shape of the lens
• optic nerve sends an image to the brain
• hormones are chemicals produced by your glands to regulate internal conditions
• the endocrine system consist of pituitary gland, thyroid gland, adrenal gland, pancreas, ovaries, testes, and thymus
• • control of blood gluclose:TOO HIGH.....pancreas produces hormone insulin which allows glucose to move from the blood into the cells so levels fall backTOO LOWpancreas produced glucagon which causes glycogen to be turned into glucose and released into the blood so levels rise
• you can treat type one diabetes through insulin injections or by eating a diet low in carbohydrates
• you can treat type 2 diabetes by: eating a healthy diet exercising
• long sighted is when the light focuses past the retina and is fixed with a convex lens
• short sighted is where light focuses before the retina and can be fixed with a concave lens
• hormones involved in the menstrual cycle include FSH/LH/oestrogen/proestorgen
• first in the cycle FSH is released by pituitary to mature the egg and stimulate growth this triggers the release of oestrogen which thickens the lining of uterus LH is released which results in ovulation - the release of the egg
• roles of hormonal contraception include -blocking ovulation (release of an egg from the ovaries)-altering mucus in the cervix making it harder for sperm to travel-changing the endometrium so it cannot support a fertilized egg
• IVF :The mother is given FSH to mature eggs in her ovaries. The mature eggs are then removed and fertilised in a petri dish. Once the embryo(s) are large enough they can be implanted back into the mother.
• advantages of IVF include: no risk of pregnancy loss, no risk of miscarriage, no risk of infection
• disadvantages of IVF include: high cost, risk of multiple births, and the chance of the embryo not implanting
• plant stimuli include phototropism,gravitropism,thermotropism
• • Auxin goes in an opposite direction to light.When the sun light hits the plant from on top, it will grow straightIf sun comes an angle the shaded side grows more quickly so the plant tilts (as auxin goes to the shaded side)
• when you are too hot, the body vasodilation of blood vessels - red skinsweat glands produce sweat - when evapourated cools body down through the transfer of heathair on skin lies flat to trap less air
• when you are too cold the body vasonconstriction of blood vessels - palehairs erect trapping a layer of air to act as a insulatorno sweat glands work to maintain heat
• when we are cold we shiver because our skeletal muscles contract and relax rapidly which occurs through respiration which releases heat(exothermic) to heat body up
• CO2 is bad in the body because it dissolves into the plasma causng carbonic acid which will decrease the PH of our blood - more acidicthis means enzymes will denature causing organ failure
• the urea cycle:proteins are obtained through foods such as egg,chickenamino acids are absorbed (when proteins are broken down) into the liverliver then removes a proportion of these amino acidsammonia acid forms (NH3)this forms urea which goes into kidney and is excreted out