Homeostasis and response: The regulation of conditions inside your body to maintain a stable internal environment in response to changes in both internal and external conditions

Homeostasis and response: The regulation of conditions inside your body to maintain a stable internal environment in response to changes in both internal and external conditions

1. Comparison

   • Hormones
     • Act in general way
     • Act for long time
     • Slower
   • Nerves:
     • Fast
     • Act for short time
     • Act on precise area

2. Comparison

   • Nerves:
     • Act on precise area
     • Act for short time
     • Fast
   • Hormones
     • Slower
     • Act for long time
     • Act in general way

3. The endocrine system

   • Pancreas
     • Insulin
       • Regulates blood glucose level
   • Ovaries
     • Oestrogen
       • Menstrual cycle
   • Testes
     • Testosterone
       • Controls puberty
         • Sperm production
   • Adrenal gland
     • Adrenaline
       • Fight or flight response
   • Thyroid gland
     • thyroxine
       • Regulates rate of metabolism
         • Heart rate
           • Temperature
   • Pituitary gland
     • Produces many hormones
       • Hormones produce act on other glands
         • Direct them to release hormones to bring about change
   • Uses hormones
     • Chemical molecules released directly into blood
       • Produced by glands
         • Long lasting effects
       • Only affect particular cells

4. Nervous system

   • Reflexes
     • Reflex arc
       • Measuring reaction time
         • Speed up:
           • Caffeine
             • Control variables
               • Same person
                 • Same hand
               • Same height
               • No caffeine
       • Passes through CNS
     • Help prevent injury
       • Rapid, automatic responses
   • CNS
     • Brain + spinal cord
       • Connected by sensory and motor neurones
         • Motor neurones: carries impulses from CNS to effectors
         • Sensory neurones: carry impulses from receptors to CNS
           • Synapses: connection between 2 neurones
             • Transferred by chemicals
               • Diffuse across gap
                 • Set of new electrical signals in the next neurone

5. Cells need right conditions

   • Enzyme action
     • 3 main components-
       • Effectors
         • Carry out the response which counteracts the change
           • Muscles and glands
             • Glands secrete hormones
             • Muscles contract
       • Coordination cdntres
         • Receives and processes the information and organises a response
           • Brain, spinal cord and pamcreas
       • Receptors
         • Detects stimulus
           • E.g light receptors in eyes