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nervous system, the eye, Homoestasis of temperature, SKIN, :cucumber: -…

- - - - This means the nervous system is used for very fast responces
  - - - CNS
    - - PNS
      - A nerve is built up from a bundle of neurones
    - - PNS (peripheral nervous system)
        
        Sends impulses from the CNS from around the body, ( receives and acts)
      - The CNS (central nerual system)
        
        Processes impulses received from PNS and gives out responses
  - - - https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2021/10/The-structure-of-a-myelinated-neurone.png
    - - dandrites
        
        They form connections with other neurones
      - Axon
        
        The main long fiber of the neurone which passes information,
        
        they can be extreamely long to be more efficient and carry information faster
      - Cell body
        
        Contains the main parts of a cell like the nucleus evry neurone has it
      - Myelin seath
        
        This is a fatty layer which forms around the axon to insulate it
        
        The gaps between each of them is called a node, the impulses jump from one node to the other.
      - synapses
        
        Neurons don't directly touch each other, this gap is called a synapses
        
        Neurones don't jump from one neuron to another
        
        Instead, they turn into another chemical which can pass through the gap called neurotransmiter
        
        The neurotransmitter is inside a vesicle
        
        A neurotransmitter will turn into an electrical impulse when it reaches the next neurone as it diffuses from one to the other
        
        How impulses pass through a synapse step by step-
        
        the impulse travels through the first axon
        
        When it reaches the end of the neuron, it triggers it and a neurotransmitter is released from the vesicle
        
        These neurotransmi-tters diffuse along the synaptic cleft and it binds to the receptor neuron.
        
        the second neuron then turns the neurotransmitter into an impulse. Then the neurotransmitters are destroyed. ok
        
        image
        
        https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2020/01/A-synapse.png
    - - Relay neurones
        
        Connect sensory and motor neurones ( inside the CNS)
        
        small and small cell body, have many long dandrites
      - Motor neurones
        
        Connect the relay neuron and the effector
        
        Long axon and lots of long dandrites ok
        
        Effectors give out a response, responding to the stimulus
      - Sensory neurons
        
        From sense organs/receptors to CNS
        
        Really long and have a cell body branching from the axon
        
        Receptors sense a stimulus
      - Pictures
        
        https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2020/01/The-three-types-of-neurone.png
  - - - receptor
        
        3.sensory neuron
        
        4.relay neuron
        
        Motor neuron
        
        effector
        
        responce
        
        detects the stimuli
  - - - stimulus detected
        
        receptor detects stimuli
        
        passes through sensory neuron
        
        passes through relay neuron in the spinal chord
        
        passas through motor neuron
        
        the muscle (effector) gives out a responce
- - - - depends
    - - cause development too
    - - depends
  - - - produced in adrenal gland
      - makes changes to the body to prepare for FFF responses.
        
        increase heart rate and breathing
        
        put blood in muscles
        
        turning glycogen into glucose
    - - produced in pancreas
      - regulates blood sugar levels
        
        if it is too high
        
        Insulin stimulates muscles and the liver to take up glucose from the bloodstream and store it as glycogen, this reduces the concentration
        
        if it is too low
        
        Glucagon causes the glycogen stored in the liver to be converted into glucose and released into the blood
        , which increases blood sugar levels
      - diabetes
        
        Types of diabetes
        
        Type 2
        
        CAsued when eating too much sugar, this makes the body acostum to insuline which means insuline's effects are decreased
        
        Type 1
        
        You are born with this type of diabetes
    - - produced in male testies
      - It is responsible for the development of secondary sexual characteristics in males
        
        things like hair growth or production of semen
    - - mantains uterus lining
      - produced in female ovaries
    - - produced in female ovaries
      - It is responsible for the development of secondary sexual characteristics in females and regulating the menstrual cycle
        
        things like breast growth
  - - - hormones that carry out basic bodily functions
    - - Release hormones that control the speed of the metabolism
    - - Insulin and glucagon
        
        insuline moves sugar into cells for respiration
        
        glucagon increases blood sugar levels if they are too low
    - - release adrenaline
    - - Produces oestrogen and progesterone
    - - Release testosterones
  - - - controls water content in blood
      - If blood is too concentrated ( no much water)
        
        more water being reabsorbed (absorbed again)
        
        The kidneys produce a smaller volume of urine that is more concentrated (contains less water)
      - if blood is too dilute (too much water)
        
        Lesss water being reabsorbed
        
        The kidneys produce a larger volume of urine that is less concentrated (contains more water)
    - - FSH causes the maturation of an egg in the ovary
      - stimulates ovares to release estrogen
      - diagram
        
        https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2021/08/Pituitary-hormones_1.png
    - - form a part of the menstrual cycle
      - LH stimulates the release of the egg
      - stimulates ovaries to produceprogesterone
- - - - the nervous system
      - the endocrine system
      - These 2 systems work so the body can respond to a stimulus
  - - - This is the process in which the body maintains a relatively constant level of different factors in the body
      - examples of things controlled by homeostasis would be
        
        metabolic waste
        
        Ph
        
        temperature
        
        the avarage temperature is kept at 36.6
        
        very tightly controlled (no difference of more than 2ª)
        
        the body needs to control the rise and fall of the temperature
        
        the temperature change will be changed by the thermoregulatory centre
        
        The temperature is regulated through negative feedback
        
        https://studymind.co.uk/wp-content/uploads/2022/05/1-42.png
        
        concentration of glucose in blood
        
        concentration of respiratory gasses
      - Definition save my exams:Homeostasis is the control or regulation of the internal conditions of a cell or organism
      - Co-ordinating response
        
        https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2021/07/Coordinating-a-response.png
        
        How does a co-ordinating responce work
        
        A stimulus (change in the enviroment) is given off
        
        A receptor detects the stimuli
        
        A coordination centre, like the brain, where the information is processed, then information is passed
        
        An effector (muscle or gland) which brings out a responce
        
        1 more item...
        
        A stimulus is a change in the internal or external enviroment
- - - - rods
        
        detect light intensity
      - cones
        
        detect colour
- - - - Muscle on the inside
    - - muscle ont he outside
- - - - forms an insulating layer on the skin
      - The hair erector muscles in the skin contract, causing hairs to stand on end
    - - Pincha para editar
      - Muscles contract in a rapid regular manner
    - - less blood to capillaries closer to the skin to stop heat less by radiation
  - - - This stops them from forming an insulating layer by trapping air and allows air to circulate over skin and heat to leave by radiation
      - The hair erector muscles in the skin relax, causing hairs to lie flat
    - - This cools the skin by evaporation which uses heat energy from the body to convert liquid water into water vapour
      - released by sweat glands
    - - Artioles have muscles which contract or relax depending on if they want to make more or less blood pass through
      - heat goes closer to the surface to release heat to the outside