5.1.4

• the endocrine system

  composed of endocrine glands that secrete hormones directly into the blood to travel to target cells
• what types of hormones are there


  peptide based

  lipid based
• peptide based hormones


  first messengers that are not lipid soluble so do not enter cells instead binding to the cell surface or receptors that trigger the releasing of a second messenger inside the cell
• lipid based hormones


  secondary messengers that are lipid soluble so can pass through into the cell and nucleus having a direct effect on DNA. They still need to bind to a receptor inside the cell to work.
• why are hormones an example of negative feedback


  they have the opposite effect on a change and have a short life and are broken down by enzymes and lost in urine so no more are released / they do not trigger more hormones to be released
• types of glands

  endocrine

  exocrine
• endocrine gland


  secrete hormone directly into blood
• exocrine gland


  secrete hormone into duct that delivers it directly to target cells
• where is the adrenal gland located


  above the each kidney
• adrenal gland structure

  A) capsule

  B) cortex

  C) medulla

  D) kidney

  E) blood vessels

  
• what does the adrenal cortex secrete?


  mineralocorticoids

  glucocorticoids / cortisol

  precursors to sex hormones
• mineralocorticoids


  control sodium and potassium ions in blood and the blood pressure. It affects can be seen in the kidneys. Increasing ion absorption in the collecting ducts and distal convoluted tubule increases water retention increasing blood pressure
• glucocorticoids


  control metabolism in the liver
• cortisol


  released in response to stress or low blood sugar stimulating the production of glucose from glycogen
• precursors to sex hormones


  if cortisol is released and the correct enzymes are not present androgens are released and converted to sex hormones within the sex organs
• what type of hormones does the adrenal cortex make


  lipid based as it uses cholesterol to form them
• what does the adrenal medulla secrete


  adrenaline and noradrenaline
• adrenaline


  enables fight or flight response
• symptoms of fight or flight response


  increases: heart rate , blood pressure , pupil dilation , awareness , blood glucose , erection of body hair

  decreases: digestion rate , vasoconstriction , relaxes smooth muscle in lungs ( allowing more oxygen in )
• structure of adrenaline


  polar so cannot enter cell so is detected by specialised receptors on target cells having a widespread effect.
• noradrenaline function


  increases heart rate
• adrenal gland histology

  A) capsule

  B) cortex

  C) medulla

  D) blood vessel

  
• pancreas location


  below stomach
• Exocrine function of pancreas

  Release pancreatic juices containing enzymes. Arranged around acini that are grouped around tubules that join to form a pancreatic duct that leads to the small intestines where enzymes are required. Sodium hydrogen carbonate is also deposisted
• why is sodium hydrogen carbonate deposited with pancreatic juice in the small intestines?

  neutralises extreme stomach acid so it doesn’t denature enzymes in pancreatic juice.
• endocrine function of pancreas

  Islets of langerhan have 2 forms. Alpha cells that produce glucagon. Beta cells that produce insulin.
• glucagon function 


  glycogen -> glucose
• insulin function


  glucose -> glycogen
• Why is hypoglycaemia bad

  There is not enough glucose for respiration
• why is hyperglycaemia bad

  causes a change in cell behaviour and water potential
• is blood glucose constant

  no it is always fluctuating as there is a time delay between release of enzyme and change in blood sugar
• pancreas structure

  A) pancreatic duct

  B) lobule

  C) acinus

  D) tubule

  E) islet of Langerhans

  F) bile duct

  G) duodenum

  
• how is sodium hydrogen carbonate deposited with pancreatic juice

  via bile duct from gall bladder
• glycogen


  a carbohydrate storage molecule for mammals produced in the liver
• glucagon


  a hormone that triggers the conversion of glycogen to glucose when blood sugar is low , produced by the pancreas
• how to decrease blood sugar levels

  respiration

  glycogenesis
• how to increase blood sugar levels

  glycogenolysis

  gluconeogenesis

  consume glucose containing substance
• glycogenesis


  turning glucose to glycogen in the liver
• glycogenolysis


  turning glycogen to glucose
• gluconeogenesis


  making glucose from lipids and amino acids