The human nervous system and hormonal conditions

• Homeostasis

  Maintaining a stable internal environment
• You have loads of automatic control systems that regulate y internal environment such as hormonal and nervous
• There are control system that maintain your body temperature, blood glucose and water content
• Negative feedback

  When the level of something gets too high or too low your body uses negative feedback to bring it back to normal
• Level increases

  Receptor detects a stimulus - level is too high. The coordination centre receives and processes the information then organises a response. effectors produce a response which counteracts The change and restores the optimum level - the level decreases. the effectors will cary on Producing a response for as long as they’re stimulated by coordination centre. this might cause the opposite problem making the level change to much. Luckily the receptors detect if the level becomes too different and negative feedback starts again.
• Level decreases

  Receptor detects a stimulus - level is too low. The coordination centre receives and processes the information then organises a response. effectors produce a response which counteracts The change and restores the optimum level - the level increases. the effectors will carry on Producing a response for as long as they’re stimulated by coordination centre. this might cause the opposite problem making the level change to much. Luckily the receptors detect if the level becomes too different and negative feedback starts again.
• Stimuli

  Changes in the environment
• Central nervous system

  in vertebrates this consists of the brain and spinal cord. in mammals, the CNS is connected to the body by sensory neurones and motor neurones
• Sensory neurones

  The neurones that carry electrical impulses from The receptors to The CNS
• Motor neurones

  The neurones that carry electrical impulses from CNS to effectors
• Effectors

  All your muscles and glands which respond to nervous impulses
• Receptors

  Cells that detect stimuli
• muscles and glands are known as effectors. muscles contract in response to nervous impulses whereas glands secrete hormones
• The CNS is a coordination centre - it receives information from the receptors and then coordinates a response. the response is carried out by effectors
• The connection between two neurones is called a synapse. the nerve signal is transferred by chemicals which diffuse across a gap. these chemicals then Set off a new electrical signal in the next neurone.
• Reflexes are automatic response to a stimuli that don’t involve the conscious part of your brain
• The passage of information in a reflex is called a reflex (from receptor to effector) is called a reflex arc
• Reflex arc goes through the central nervous system
• 1. Neurones in the reflex go through the spinal cord or the unconscious part of the brain
• 2.When stimuli is detected by receptors, impulses are sent along sensory neurone to relay neurone in the CNS
• 3. At the synapse between sensory neurone and relay neurone, chemicals are released triggering impulses to be sent along the relay neurone
• 4. At the synapse between relay neurone and motor neurone, chemicals are released causing impulses to be sent along the motor neurone
• 5. Impulses travel along the motor neurone to the effector
• Reaction time is the time it takes to respond to a stimulus
• measure effect of caffeine on reaction time

  The person being tested should sit with their arm resting on the edge of the Table. hold ruler vertically between thumb and forefinger and make sure zero end of the ruler is level with their thumb and finger then let go without any warning. the person being tested should try to catch the ruler. the further down the ruler its caught the slower the reaction time. repeat experiment several times and cal mean distance. the person being tested should then have a caffeinated drink and after 10 minutes repeat steps 1 to 5
• Hormones are chemiCal molecules released directly into the blood and only affect cells of particular organs
• The pituitary gland produces many hormones that regulate body conditions. its sometimes called ‘master gland’ because these hormones act on other glands, directing them to release hormones that bring about change

  
• Ovaries produce oestrogen which is involved in the menstrual cycle

  
• Testes produce testosterone which controls puberty and sperm production in males

  
• Thyroid gland produces thyroxine which is involved in regulating the rate of metabolism, heart rate and temperature
• Adrenal gland produces adrenaline which is used to prepare the body for a flight or fight response
• The pancreas produces insulin which is used to regulate the blood glucose level
• Nerves are fast action. act for a short time and over a precise area
• Hormones are slower action. act for a longer time and act in a more general way
• Carbohydrate contain glucose. metabolism removes glucose from cells and vigorous exercise. excess glucose can be stored as glycogen in the liver and in muscles
• Level of glucose must be kept steady. insulin and glucagon control these changes in negative feedback
• Blood glucose level is too high - insulin is added 


  Blood with too much glucose < insulin secreted by pancreas < too much glucose and insulin < glucose moved from blood into liver and muscles cells and insulin as well < insulin makes liver turn glucose into glycogen < blood glucose removed
• Blood glucose level is too low - glucagon is added 


  Blood with too little glucose < glucagon secreted by pancreas < too little glucose and glucagon < glucose released into blood by liver and glucagon < glucagon makes liver turn glycogen into glucose < blood glucose increased
• Type 1 diabetes

  Pancreas produces too little or no insulin so their blood glucose level can rise to a level that can kill them. people need insulin therapy - several injections of insulin throughout the day usually at mealtimes. this makes sure they glucose is removed from the blood quickly once the food has been digested stopping level getting too high. amount of insulin injected depends on persons diet and how active they are. people need to be limiting food rich in simple carbohydrates and regular exercise which helps remove excess glucose from blood.
• Type 2 diabetes

  Person becomes resistant to their own insulin. this can also cause a person blood sugar level to rise to a dangerous level. obesity is a major risk factors in developing the disease . It can be controlled by eating a carbohydrate controlled diet and regular exercise