hormonal control

Question 1

what is involved in extracellular communication?

Answer 1

the endocrine system, the nervous system, and chemical messengers
extracellular communication is the communication between cells

Question 2

what do chemical messengers do?

Answer 2

they produce effects on target cells

there are lots of types of chemical messengers, neurons, endocrine and neurosecretory

Question 3

what is the role of hormones?

Answer 3

they maintain the internal enviroment (homeostasis)

they regualte energy metabolism, growth, development and reproduction

Question 4

what does an endocrine hormone do?

Answer 4

its secreted by endocrine glands into the blood and carried by the blood to specific target tissues or organs
these act as receptors and are subject to feedback control

Question 5

what is the name of the hydrophilic hormone family?

Answer 5

peptide hormones

• theyre made up of chains of amino acids and are <50 amino acids
• amine hormones [adrenaline]
• theyre not soluble in lipids and the receptor for them is on the plasma membrane (generally) as they cannot travel through it

Question 6

what is the family of hormones which is hydrophobic?

Answer 6

steroid hormones
- derived from cholesterol and is soluble in lipids
the receptor is in the cytosol as they can travel through the plasma membrane

Question 7

what are hormone receptors?

Answer 7

theyre receptors specific to one messenger

Question 8

what is it essential for endocrine glands to have?

Answer 8

they have to have mechanisms that ‘switch-on’ hormone secretion when its required and ‘switch-off’ hormone secretion when it isn’t

Question 9

what are the types of stimulation endocrine glands have?

Answer 9

hormonal stimulation- hormones relased by one gland confluence the secretion of other hormones e.g. trophic hormones

humoral stimulation- blood levels of ions = nutrients, bile and other components stimulate hormone release

neural stimulation- nerve fibres activate hormone relase

Question 10

what are the 2 pituritary glands?

Answer 10

posterior pituitary gland (neuropophysis)- contains nerve endings of neurons originating in the hypothalamus

anterior pituitary gland (adenohypophysis) - synthesised trophic hormones that control the secretion of other hormones

Question 11

what are the names of 2 primary hormones secreted by the thyroid gland?

Answer 11

T3 and T4

Question 12

what is iron deficiency disease?

Answer 12

• cretinism is the most extreme manifestation of iodine deficiency
• it causes mental retardation, reduction of physical growth and deaf-mutism
• this can be caused by inadequate dietary iodine intake (150 mcg/day)
  this can also be duw to maternal iodine deficiency during pregnancy and in many countries salt is now fortified with iodine to prevent this

Question 13

what is the regulation of thyroid hormones?

Answer 13

almost all cells need exposure to thyroid hormones for normal function, they increase metabolic rate for thermoregulation and regulating O2 consumption
they also increase basal activity of th cardiovascular system, stimulate growth and development

Question 14

what is hypothyroidism?

Answer 14

its low levels of thyroid hormones

it causes weight gain, lethargy and oedema (swelling due to fluid accumulation)

Question 15

what is hyperthyroidism?

Answer 15

its high levels of thyroid hormones

it causes weight loss, sweating and eye abnormalities

Question 16

whta is graves disease?

Answer 16

its hyperthyroidism

TSI- thyroid stimulting immunoglobin which mimics the action of thyroid stimulating hormone

Question 17

what is insulin?

Answer 17

its produced by the pancreas and was discovered in 1922 by Fredrick Banting and Charles Best
its a protein made up of 51 amino acids

Question 18

what are the stages of the regulation of insulin secretion?

Answer 18

its a negative feedback loop
start 
- increase in blood glucose
- beta cells of the pancreas
- increase in insulin secretion
- cells throughout the body 
- increase in glucose uptake 
- decrease in blood glucose

then it restarts

Question 19

what are normal blood glucose levels?

Answer 19

4-5.9mmol/l (before meals)

7.8mmol/l 2hrs after a meal

Question 20

what is hyperglycemia?

and what are the symptoms?

Answer 20

its high blood glucose
>11mmol/l
symptoms: being thirsty, polyuria (frequent urination), tiredness and can go to diabetic coma

Question 21

what is hypoglycemia?

Answer 21

its low blood glucose
<2.5mmol/l
symptoms; dizziness, drowsy, confused, diabetic coma

Question 22

what type I diabetes?

Answer 22

its caused by a loss of insulin secreting cells often caused by the body producing antibiotics which attack the beta cells in the pancreas
it requires daily injections of insulin and can cause long term complications like cardiovascular disease, damage to eye (retinopathy), damage to kidneys (nephropathy) and damage to nerves (neuropathy)