homeostasis

• Define homeostasis

  Homeostasis is the regulation of the internal conditions in a cell or organism to maintain optimum conditions for function in response to internal and external changes
• what does the human body control in terms of homeostasis

  blood glucose concentration

  body temperature

  water levels
• what kind of responses do automatic control systems have?

  nervous response and chemical response
• what do control systems include?

  cells called receptors ( detect stimuli)

  coordination centres ( they process the information received from the receptors, brain, spinal cord and pancreas)

  effectors bring about responses to bring the conditions in the body back to optimum level e.g muscles , glands
• what is the the role of the nervous system

  the nervous system enables humans to react to their surroundings and to coordinate their behaviour
• how are nerve cells adapted?

  Nerve cells are called neurones. They are adapted to carry electrical impulses from one place to another
• nerve cells

  A) neurone

  B) nerve

  
• what is meant by a stimulus

  a change in environment ( internal or external body conditions)
• what do negative feedback respond to?

  Negative feedback responds to changes in conditions without us having to think about it
• Describe the role of the endocrine system

  The endocrine system passes information by hormones
• Describe the role of Nervous systems

  The nervous systems sends information in the form of electrical impulses.
• Function of the nervous system

  • Receptors ( change in an environment)
  • information is passed along neurons as electrical impulses ( goes to the co-ordination)
  • it reaches to the CNS ( central nervous system)( brain and spinal cord)
  • The CNS coordinates the response of effectors ( making sure that all the effector organs are involved in a particular response and are responding at the same time)
• what are synapses

  a synapse is a gap or junction
• What type of chemical do synapses release?


  Neurotransmitters
• How do the electrical impulses trigger?

  The neurons released by neurotransmitters diffuse into the two neurons, which triggers the electrical impulse
• what are reflex reactions 


  reflex reactions are rapid and automatic, they do not involve the conscious part of the brain
• which two words describe reflex reactions

  rapid

  automatic
• what is the difference between a receptor and the function of an effector? give examples

  Receptors are cells that can detect a change in environment, which is also called a stimulus, an example of receptors are the retina in eyes reacting to light. An effectors effects a response from the receptor and it causes the effector muscle to contract. An effector can also be a gland ( hormone)
• Describe the reflex arc

  receptors

  sensory neurons

  relay neuron

  motor neuron

  effector

  A) relay neuron runs through the motor and sensory neuron

  B) sensory neuron an impulse transmitted down to the CNS

  C) Receptor- detects the stimulus

  D) motor neurons - impulse moves down from the CNS to MN

  E) Effector- contracts muscle

  
• Describe the reflex arc caused by bright light

  the stimulus caused by the bright light is detected by the receptor in the eye. the receptor generates a nervous impulse that passes along the sensory neuron to the relay neuron. impulses then passes along the motor neuron to the effector ( the muscle in the iris). the muscle contracts and reduces the light entering the eye.
• What is the endocrine system purpose?

  the endocrine system helps regulates metabolism, growth, reproduction, sleep and mood
• what does the endocrine system release into the blood?

  it secretes hormones into the blood
• what are hormones 


  hormones are chemical messengers made from protein- that means they contain lots of ribosomes
• how is the endocrine system different from the nervous system

  the endocrine system is much slower than the nervous system but the effects lasts much longer.
• why is the pituitary gland known as the master gland

  it secretes other hormones that act on other glands such as

  • Follicle stimulating hormone and Luteinising hormones ( sex hormones which have an impact on the ovaries)
  • It also produces thyroid stimulating hormone which stimulates the thyroid glands that make the thyroxine
• what is the role of a thyroid gland?

  thyroid glands release thyroxine

  • this stimulates the basal metabolic rate which is necessary for growth and development
• what is the impact of high level of thyroxine?

  high levels of thyroxine increases the formation of glycogen, lipids and protein that which increases that rate of respiration
• what is controlled by the amount of thyroxine secreted

  it is controlled by negative feedbacks loops

  • the receptor cells detect more thyroxine is required, so the control centre tells the effector gland to synthesise the thyroid to boost metabolism
  • this continues until level rise too high and then the receptor cells detect this and the control centre tells the thyroid to stop making the hormone
• What does the Endocrine system help with?

  The Endocrine system helps regulate metabolism, growth, reproduction, sleep and mood
• why should we maintain a blood sugar level

  • it is important for regular energy level as the cells need glucose in order to perform respiration to release energy- this needs to be done consistently to maintain a blood sugar
  • To prevent damage to cells- if the blood rises too high or falls too low then cells can shrivel up due to water being sucked out of them, or burst open as they absorb too much water
• label the structure of the Endocrine system

  A) The pituitary gland

  B) adrenal gland

  C) ovaries

  D) Testes

  E) pancreas

  F) Thyroid Gland

  
• Label the roles of each gland

  A) Master gland, makes FSH and LH hormone

  B) Produces Adrenaline

  C) produces Oestrogen

  D) Produces Testosterone

  E) Produces insulin

  F) Produces Thyroxine

  
• Label the Pituitary gland

  A) liver

  B) pancreas

  C) Receptor

  D) Pancreatic gland

  E) Hormone

  F) blood capillary

  G) Non target cells

  H) target cells

  
• label the how negative feedbacks control blood glucose

  A) blood glucose level rises

  B) pancreas is stimulated

  C) insulin is secreted

  D) insulin stimulates glucose uptake from blood

  E) blood glucose level falls

  F) pancreas are stimulated

  G) glucagon is released

  H) glucagon stimulates liver to release glucose

  
• how is blood sugar maintained?

  • Simple sugar glucose is converted into much longer larger storage molecule call Glycogen
  • when cells need simple sugars it is converted back into glucose
• which two hormones control the blood sugar level?

  • insulin
  • glycagon
• what does insulin and Glucagon do? 


  1. insulin causes glucose to convert into glycogen
  2. Glucagon converts glycogen into glucose
• what happens when blood glucose level is high?


  when blood glucose level rise too high and more sugar:

  • excess sugar needs to be stored so insulin is made
  • pancreas secrete insulin
• Where is Glycogen stored

  in the liver
• what is diabetes?

  A chronic non-communicable disease affecting the body's ability to maintain consistent blood sugar