hormonal control Flashcards
what is involved in extracellular communication?
the endocrine system, the nervous system, and chemical messengers
extracellular communication is the communication between cells
what do chemical messengers do?
they produce effects on target cells
there are lots of types of chemical messengers, neurons, endocrine and neurosecretory
what is the role of hormones?
they maintain the internal enviroment (homeostasis)
they regualte energy metabolism, growth, development and reproduction
what does an endocrine hormone do?
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
what is the name of the hydrophilic hormone family?
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
what is the family of hormones which is hydrophobic?
steroid hormones
- derived from cholesterol and is soluble in lipids
the receptor is in the cytosol as they can travel through the plasma membrane
what are hormone receptors?
theyre receptors specific to one messenger
what is it essential for endocrine glands to have?
they have to have mechanisms that ‘switch-on’ hormone secretion when its required and ‘switch-off’ hormone secretion when it isn’t
what are the types of stimulation endocrine glands have?
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
what are the 2 pituritary glands?
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
what are the names of 2 primary hormones secreted by the thyroid gland?
T3 and T4
what is iron deficiency disease?
- 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
what is the regulation of thyroid hormones?
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
what is hypothyroidism?
its low levels of thyroid hormones
it causes weight gain, lethargy and oedema (swelling due to fluid accumulation)
what is hyperthyroidism?
its high levels of thyroid hormones
it causes weight loss, sweating and eye abnormalities
whta is graves disease?
its hyperthyroidism
TSI- thyroid stimulting immunoglobin which mimics the action of thyroid stimulating hormone
what is insulin?
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
what are the stages of the regulation of insulin secretion?
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
what are normal blood glucose levels?
4-5.9mmol/l (before meals)
7.8mmol/l 2hrs after a meal
what is hyperglycemia?
and what are the symptoms?
its high blood glucose
>11mmol/l
symptoms: being thirsty, polyuria (frequent urination), tiredness and can go to diabetic coma
what is hypoglycemia?
its low blood glucose
<2.5mmol/l
symptoms; dizziness, drowsy, confused, diabetic coma
what type I diabetes?
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)
