Co-ordination and Control

• The nervous system - what are its component parts?

  • brain
  • spinal cord
  • nerves (neurones)
• The nervous system - what does it do?

  Enables you to control your body and detects changes in your environment
• Central nervous system (CNS)

  Your brain and spinal cord, the co-ordinate the response to a stimuli
• stimulus

  is a change in your external environment that is detected by a receptor
• receptors

  specialised cells, found in your sense organs, that detect stimuli and change one form of energy into an electrical impulse
• effector

  is a muscle or gland that produces the response to a stimuli
• response

  a change in an organism produced by a stimulus
• Neurone

  A specialised cell that carries electrical impulses around the body
• Nerve Impulse

  A small electrical change that carries information along a neurone
• Synapse

  A gap between neurones
• Neurones

  Receptors (eye) and the effector (muscles) are connected to the CNS by the neurones (nerve cells). The structure of the neurone is adapted to its function of transmitting electrical impulses very quickly across the nervous system.
• What are the three types of neurones?

  Sensory neurone

  Association neurone

  Motor neurone
• The overall response to the environment is described as our behaviour. Sometimes the receptors can be grouped together in a sense organ, for example your eyes, nose and ears.
• What is a voluntary reaction?

  we deliberately choose to do these and they involve conscious thought.
• What are reflex actions?

  these actions do not involve conscious thought
• A reflex action is rapid, automatic response to a stimulus often to avoid harm. They do not involve thinking time as the time taken to consider the response would cause unnecessary damage to the body
• A reflex action involves reflex arc. An electrical impulse travels from the receptor along a sensory neurone, to an association neurone in the spinal cord. The impulse then leaves the spinal cord in a motor neurone and reaches an effector.
• The nerves do not touch, there is a tiny gap between them called the synapse. The electrical impulse slows down at the synapse.
• Reflex actions

  they occur very quickly as there are only three neurones and two synapses . The do not involve conscious thought
• What are hormones?

  Hormones are chemical messages produced by special glands.
• the glands secrete hormones into the blood.

  The hormones travel around the body to the blood.

  The hormones only affect certain organs. These are called target organs
• Hormones act more slowly than nerve impulses.

  Hormones usually act over a longer period of time compared to nerve impulses.
• The nervous system V The hormonal system

  
• What is homeostasis?

  Homeostasis is the maintenance of a constant internal environment. For example the control of blood glucose concentration and the control of the water content of the body.
• Your cells need and exact level of glucose in the blood. Glucose is constantly needed by cells for respiration. However, too much glucose in the blood can cause damage to the body cells due to water loss by osmosis.
• What is Insulin?


  Insulin is the hormone that prevents the concentration of glucose in your blood from becoming too high.
• Where is insulin produced?

  Insulin is produced by special cells in the pancreas, when the blood glucose concentration increases. This happens after a meal rich in carbohydrates. The carbohydrate is digested and then absorbed into the blood.
• Insulin is released by the pancreas into the blood. The insulin travels to the target organ which is the liver.
• Insulin causes the concentration of glucose to decrease by causing the increase absorption of glucose from the blood, so reducing the blood glucose concentration. Insulin causes the conversion of excess glucose into glycogen which is stored in the liver and the muscle cells. Insulin also increases the rate of respiration.
• Negative feedback

  When blood glucose concentration is low, less insulin is produced. This means the above processes do not take place or occurs at a slower rate. This helps raise the concentration of glucose.
• What is diabetes?

  This is a condition where the body does not produce enough insulin to keep blood glucose levels at the normal concentration.
• What are the symptoms of diabetes?

  Glucose in the urine - this is because the blood glucose concentration is so hight that some of the glucose is filtered out by the kidneys and passes into the urine.

  
  

  Individuals are thirsty and because they drink s much they need to go to the toilet a lot

  
  

  Lethargy (tiredness)
• What are the two types of diabetes?

  Type one and type 2 diabetes.
• Type 1 diabetes.

  -normally develops in childhood.

  -Is caused by a lack of insulin-pancreas fails to produce enough insulin.

  -It is usually treated by the injection of insulin and by a carefully controlled diet where the intake of carbohydrates is carefully monitored.

  -If the blood sugar drops too low, a hyperglycaemic attack may occur and unconsciousness will result.

  -If blood sugar concentrations remain too high hyperglycaemia for a long period serious medical conditions can result.
• Type 2 diabetes.

  -Usually only develops in olde people but it is becoming increasingly common in young people.

  -It has a slightly different cause in that insulin is produced but stops working effectively-this is because the person's body cells no longer respond to insulin produced by the pancreas.

  -It is often associated with poor diet, obesity and lack of exercise.

  -treatment of type 2 diabetes includes changes to diet (reducing sugar intake), exercise to achieve weight loss, along with medication in the form of insulin injections.
• What are the long term effects of Diabetes?

  eye damage and even blindness

  heart disease

  strokes

  kidney damage

  These complications are due to high sugar levels damaging the capillaries supplying blood to these areas.
• What are kidneys part of?

  The excretory system.
• What are the kidneys two functions?

  -To remove waste (urea)

  -To carry out osmoregulation.
• What passes through the renal artery?

  bloods passes into each kidney through the renal artery.
• When the blood reaches the cortex of the kidney much of the liquid part of the blood and any substances dissolved in it are filtered out.