Endocrine System

• Define Hormone


  Chemical substances

  Messages that affect the activity of another part of the body
• What is a circulatory hormone?

  Released and transported in the blood whereas local hormones do not circulate within the blood
• What is a localised hormone?

  Act faster than circulatory as they do not required transport to the target organ
• Role of Endocrine System

  Release of hormones to control body function

  E.g initiate the reproductive process, activates fight or flight
• Pituitary Gland 


  Controls/ regulates other hormones function, to control growth/ water retention or ovulation
• Adrenal Glands 


  Produces fight or flight hormones adrenaline to help the body cope with stress
• Functions of the cerebellum

  Regulates motor movements

  Regulated motor balance

  Regulates motor coordination
• How could a prey animal cause the Autonomic Nervous System to react in a prey animal?

  The prey animal senses danger from a predator,

  and the sympathetic division of the autonomic nervous system is activated,

  this causes fight or flight response,

  this directs blood flow to the organs e.g heart, lungs,

  and diverts blood away from less important organs,

  this relaxes the bladder,

  speeding up the heart rate and respiratory rate,

  to enable oxygen to reach muscles to generate swift movement.
• Define Gland 


  An organ that produces substances (usually hormones) into the blood stream
• Effector 


  Tissue or organ that responds to a hormone
• Homeostasis 


  The process of maintaining a constant
• Negative Feedback 


  The process of correcting, then stopping the correction when levels are normal
• The endocrine system is a collection of glands that produce HORMONES that control or regulate the activity of cells or hormones.
• Hormones are the signalling molecules produced by glands and are mostly transported by the circulatory system to regulate physiology and behaviour
• Glands are the organs which synthesise hormones and release them into the blood stream or cavities inside or outside the body
• Glands produce hormones in response to stimuli such as water, temperature, blood sugar, growth, behaviours etc.
• List of Glands:

  • Pituitary Gland
  • Hypothalamus
  • Pineal Gland
  • Parathyroid
  • Thyroid
  • Adrenal Glands
  • Pancreas
  • Ovaries
  • Testes
• Hypothalamus 


  Control centre of the endocrine system.

  It ‘reads‘ and then tells the rest of the system what to do.

  Attached to the pituitary gland.
• Pituitary Gland 


  Attached to base of brain

  It controls/ regulates other hormones functionIt’s function is to control growth, water retention, ovulation etc.
• Thyroid 


  Located in the neck, major role in body metabolism, growth and maturation of body and regulates body functions
• Parathyroid 


  located in the neck and controls the body’s calcium levels
• Adrenal Glands 


  Located on each kidney and helps body cope with producing fight or flight hormones
• Ovaries 


  Female sex organ

  Regulates menstruation and prepares the body for conception and pregnancy
• Testes 


  Male sex organ

  Produces male sex hormone- testosterone which encourages development of sexual characteristics and stimulates sperm production
• Ovaries 


  contain and release eggs necessary for reproduction
• Regulation of blood sugar

  
• Low Blood Sugar 


  Promotes GLUCAGON release in the PANCREAS which stimulates glycogen breakdown in the liver which converts glycogen into glucose as it breaks down and raises blood sugar
• High blood Sugar 


  Promotes insulin release in the pancreas which stimulates glucose uptake from blood and passes through tissue cells and lowers the blood sugar in the liver by breaking down glucose
• All cells around the body have receptors on their surface in order to read these hormones and respond accordingly
• E.g of circulating hormones

  TSH, FSH, insulin
• E.g of locally acting hormone

  Histamine, serotonin,
• What does the hypothalamus release?

  Dopamine

  Growth hormone - releasing hormone

  Somatostatin
• Pineal Gland releases…


  Melatonin
• How does the endocrine system work?

  1. Hypothalamus detects an abnormal level (Ph, water, blood sugar)
  2. Hypothalamus sends signal to repaired gland
  3. The gland produces a hormone that gets secreted into the blood stream
  4. The effector responds to correct abnormal level
  5. Once the level is corrected the hypothalamus detects this and stops sending signals, stopping the entire process.
  6. THIS IS NEGATIVE FEEDBACK LOOP
• Nerves found in Peripheral Nervous System

  Motor/ Efferent nerves

  Sensory/ Afferent Nerves

  Autonomic Nerves
• Afferent nerves are sensory neurons/ nerves

  That carry nerve impulses from sensory stimuli

  Towards the central nervous system/ brain
• Efferent neurons are motor neurons/ nerves that carry neural impulses from central nervous system

  Towards muscles to cause movement
• Hypothalamus 


  Works with pituitary Gland

  Which makes and sends hormones around the body

  Helps maintain body temperature
• Cerebral Cortex 


  Contributes to alertness

  Intelligence

  Memory

  Temperament