Endocrine system

• What is thermoregulation?


  the process of maintaining a constant body temperature
• Explain how thermoregulation works


  -When your body temp drops below 37* , receptors in the hypothalamus detect the change

  -The receptors send impulses to pituitary gland to secrete hormones into the blood

  -these hormones will bring about wanted response to temperature
• Example of how to control body temperature when cold

  -Vasoconstriction

  -Hair erector muscles contract

  -Shivering
• Explain how vasoconstriction works


  -The blood vessels in your skin will constrict to reduce amount of blood flow to skin

  -Reduces heat loss via radiation

  
• Explain how shivering warms the body.


  Shivering involves muscles contracting and relaxing automatically. This requires a lot of energy from respiration, which in the process releases a lot of heat energy as waste.

  
• Explain how having hair erector muscles contract warms the body


  -When the muscles contract the hair will stand on end (goosebumps)

  -Heat lost by wind/convection is reduced

  -Also heat is trapped around the skin as the wind forms an insulating layer

  
• Ways to cool the body during thermoregulation


  -Vasodilation

  -Sweating

  -Hair erector muscles relax
• Explain vasodilation


  -The blood vessels dilate and increase blood flow to skin

  -This allows more heat to be lost by radiation

  
• Explain how sweating cools the body

  The sweat gland secretes sweat, which travels to the skin's surface

  -When sweat is on the skin it traps heat

  -Sweat has a high specific heat capacity

  -This means it takes a lot if heat to evaporate, so once sweat has trapped enough heat it will evaporate and carry the heat away

  
• Explain how hair erector muscles relaxing cools the body


  -The muscles relaxing causes the hair on your skin to lie flat.

  -This allows more heat to be lost by convection/the wind

  
• Factors that affect heat loss

  Surface area:volume ratio -> if large than there is more surface for heat to be lost via radiation
• Parts of the endocrine system

  1. Pituitary gland

  2. Thyroid gland

  3. Adrenal gland

  4. Thymus

  5. Pineal gland

  6. Hypothalamus

  7. Pancreas

  8. Ovaries*

  9. Testes*
• Function of pituitary gland


  -"master gland"/control other glands

  -Controls growth
• Function of pineal gland


  secretes melatonin, controls sleep wake cycle and the circadian rythm
• Function of hypothalamus


  detects changes in temperature, control of the pituitary gland
• Function of Thyroid gland


  regulates metabolism

  -Secretes Thyroxin T3/T4 + Calcitonin
• Function of Adrenal glands


  -Release adrenaline

  -Control fight or flight response

  -Responds to stressful situations
• Function of Pancreas


  -Secretes: insulin and glucagon

  Produces enzymes that digest fats, proteins, carbohydrates, nucleic acid
• Function of the Ovaries

  -Controls female puberty and reproduction

  Produce eggs, estrogen, and progesterone
• Function of the testes


  -Controls male puberty and reproduction

  Produce sperm and male hormones (testosterone)
• How does the endocrine system work


  -Cells secrete hormones into the blood stream

  -The hormones travel to target cells

  -They bind to complementary receptors

  -Triggers response which will change bodily functions

  
• Difference between nervous response and endocrine response


  -Endocrine involves chemical signals (hormones) vs Nervous: involves electrical signals (impulses)

  -Endocrine: transmits via blood vessels vs Nervous: transmits via neurons

  -Endocrine: slow, long lives response vs nervous: fast, short lived response

  -Endcorine: Always involuntary vs Nervous: Can be voluntary

  -Endocrine: Usually generalised, may continue after stimulus ends vs Nervous: normally localised, stops with stimulus
• How does the brain control adrenaline

  -The receptors in the eyes/skin detect stress stimuli

  -The pituitary will secrete ACTH

  -This ACTH will stimulate the adrenal gland

  -Then cortisol and adrenaline are released

  -When the cortisol is too high the ACTH is no longer produced
• Effects of adrenaline


  -Liver converts glucogen to glucose

  -Increased blood pressure

  -Increased sweating

  -Increased breathing rate

  -Pupils dilate

  -Digestion slows
• Why is glucogen converting to glucose important for fight or flight?

  -The glucose produced will be used for respiration

  -The respiration will provide energy for movements
• Why is increased blood pressure important for fight or flight?


  The increased blood pressure will force the muscles to contract
• Why is increased sweating important for fight or flight?


  Sweat cools body and prevents overheating

  (Respiration produces heat)
• Why is increased breathing rate important for fight or flight


  The increased breathing provides more efficient gas exchange and transport of CO2 and O2 for respiration
• Why are your pupils dilating important for fight or flight?

  the dilation allows more light into the eye and provides more detailed images/vision
• Why is digestion slowing important for fight or flight

  To increase efficiency of O2 use in body (mainly muscles0
• What is glucose?


  blood sugar
• What is glycogen


  Long chains of glucose stored together, which are heavy, large and insoluble
• What is insulin?


  Insulin is a hormone which converts glucose into glycogen (when blood sugar levels are too high)
• What is glucagon


  A hormone secreted by the pancreas when blood glucose is low.
• Response to low glucose


  Pancreas releases glucagon. This triggers the enzymes in the liver to start the break down of glycogen into glucose so it can be used in cells and sent into blood
• Response to high glucose levels


  Pancreas releases Insulin.

  1. Insulin bonds to cell receptors causing the membrane to allow glucose to pass through and be used up in respration

  2. Muscles take in glucose

  3. Liver stores glucose as glycogen and/or fat
• Identify the parts of the endocrine system

  1. pineal gland

  2. pituitary gland

  3. thyroid gland

  4. thymus

  5. adrenal gland

  6. pancreas

  7. ovary

  8. testes

  
• What are the two types of diabetes

  Type 1 and Type 2
• What is type one diabetes


  An autoimmune disease that attacks the beta cells (insulin producers) in the pancreas causing the body to never have insulin
• What is type two diabetes?


  When the body and its cells become resistant to insulin