blood glucose

Question 1

what is a hormone

Answer 1

• a chemical messenger produced by an endocrine gland
• transported in the bloodstream to target organs where it exerts its functions
• destroyed by liver at the end of its action

Question 2

endocrine glands

Answer 2

• ductless glands that secrete hormones directly into the bloodstream which transports the hormones around the body
• adrenal gland: adrenaline
• pancreas (islets of langerhans): insulin and glucagon
• pituitary gland: several hormones including ADH

Question 3

role of glucose

Answer 3

• substrate for cellular respiration to produce ATP
• normal blood concentration: 90mg/100 ml
• held as reserves in the form of glycogen (in muscles and liver)
• quickly converted to glucose during prolonged physical activity

Question 4

homeostasis

Answer 4

• maintenance of a constant internal environment by an organism irrespective of changes in external environment
  e. g. negative feedback to regulate glucose levels of blood

Question 5

glucose regulation

Answer 5

Rise in blood glucose: (stimulus)

1. detected in the Islets of Langerhans of pancreas (receptor)
2. insulin is secreted by b-cells and transported in bloodstream to following sites (control centre)
3. liver and muscle: glucose converted to glycogen, cell respiration increases
   - liver and muscle cels are stimulated to increase uptake of glucose which is converted to glycogen –> oxidation of glucose by cellular respiration is increased (effector)
4. fall in blood glucose
5. normal blood glucose level of 90mg/100ml (output)
6. insulin secretion stops and insulin is excreted by kidneys

Fall in blood glucose: (stimulus)

1. detached by Islets of Langerhans
2. glucagon secreted by a cells which is transported in bloodstream to liver and muscle (control centre)
3. glucagon stimulates liver cells to convert glycogen to glucose and amino acids to glucose (effector)
4. rise in blood glucose
5. normal blood glucose level (output)
6. glucagon secretion stops and glucagon excreted by kidneys

Question 6

negative feedback

Answer 6

• mechanism of homeostasis

- a type of control in which the response counteracts the stimulus to achieve homeostasis

Question 7

diabetes

Answer 7

• high blood glucose concentration (urine contains glucose)
  Type 1:
• no cure
• body has attacked and destroyed the cells that make insulin
• cannot make insulin
• managed by taking the insulin to control blood sugar

Type 2:

• no cure but can be prevented and put into remission
• body doesn’t make enough insulin/insulin doesn’t work properly (body fails to respond to insulin stimulation)
• can be managed through medication, exercise and diet

Question 8

adrenaline

Answer 8

• adrenal gland secrets adrenaline when you are afraid, anxious or stressed
• prepares body for states of emergency
• responses that arise from secretion of adrenaline are temporary (short lived hormone)

effects:

• increases rate and depth of ventilation –> increases rate of uptake of oxygen by lungs
• increases rate of heartbeat and causes a rise in blood pressure –> oxygen and glucose are transported faster to the muscles
• constricts arterioles to the gut –> decreases digestive activities
• constructs arterioles in skin causing paleness –> channeling more blood to the muscles
• increase rare if blood clotting
• increases metabolic rate –> more energy is released from cellular respiration
• contracts hair muscles –> producing goosebumps
• increases blood glucose levels
• stimulates the liver to concert glycogen to glucose –> more glucose available for muscle concentration
• dilates pupils to enhance vision