Hormones
organic chemical messengers that are carried in the blood. most hormones are proteins but some are steroids (lipid - like organic compounds)
endocrine system
made up of a group of glands that produce hormones
Chemical coordination
using hormones to send a message from 1 part of the body to another. controlled by the nervous system
target organ
an organ that is affected by a specific hormone. the target organ has receptors for this specific hormone, allowing it to respond to the hormone.
endocrine glands
release secretions directly into the bloodstream to be carried to the target organ. capillaries around endocrine gland
exocrine gland
releases secretions via ducts, which carry them directly to the target organ or to outside of the body
negative feedback
if there is too much or too little hormone present for the body to function normally, this will cause changes to occur that will bring the hormone levels back to normal. this will ensure that a balance is always maintained in the body
Homeostasis
mechanism that maintains a stable/constant internal environment in the body, despite changes in the external environment
Glands in pituitary gland
1. Anterior lobe 2. Posterior lobe
anterior lobe
makes and secretes hormones
growth hormone
hormone secreted by anterior lobe of pituitary gland travels in blood and that controls growth of bones and muscles.
Prolactin
hormone secreted by anterior lobe of pituitary gland travels in blood to mammary glands and stimulates the production of milk
thyroid stumulating hormone
(TSH). hormone secreted by anterior lobe of pituitary gland travels in blood to thyroid gland to stimulate thyroid to produce thyroxin
Follicle - stimulating hormone
(FSH). hormone secreted by anterior lobe of pituitary gland travels through the blood to: - in females: ovaries to stimulate ovaries to produce eggs and oestrogen - in males: testes to stimulate testes to produce sperm
luteinising hormone
(LH). hormone secreted by anterior lobe of pituitary gland. controls the secretion of sex hormones
LH in females
travels in blood to the over to stimulate the ovary to produce oestrogen and progesterone
LH in males
travels in blood to testes to stimulate the testes to produce testosterone
posterior lobe
does not MAKE any hormones but relases hormones that are made by the hypothalamus
antidiuretic hormone
(ADH). hormone secreted by the posterior lobe of pituitary gland travels in blood to kidney. regulates the amount of urine produced, by controlling the amount of water absorbed back into the blood by the collecting ducts of the kidney
oxytocin
A hormone released by the posterior lobe of the pituitary gland travels in the blood to the uterus. stimulates the uterus to contract during labor
Dwarfism
under-secretion of GH in children. the body is short, with body parts in proportion
Gigantism
over-secretion of GH in children. the body is larger than normal
acromegaly
over-secretion of GH in adults . body of the adult will continually grow resulting in large facial bones, large hands and large feet
problems associated with pituitary gland
1. dwarfism 2. gigantism 3. acromegaly
where is the pituitary gland situated?
at the base of the brain. connected to the hypothalamus by a short stalk
where is the thyroid gland situated
across the trachea, below the larynx in front of the next
thyroid gland function
produces thyroxine hormone which controls metabolic rate and regulates growth and development of the body. thyroxine can only be made if iodine is present
Hypothyroidism
under-secretion of thyroxin. metabolic rate is low
cretinsim
hypothyroidism in children. results in reduced growth and development of the whole body
myxoedema
hypothyroidism in adults. resulting in thick skin in hands and feet. tongue is thick so person speaks slowly. slow mental and physical activities. weight gain
Hyperthyroidism
over secretion of thyroxin. causes Graves disease. metabolic rate increases and person loses weight quickly. hyperactive, high blood pressure, heart rate problems. buldging eyes (exophthalmia). can remove part of thyroid gland to fix the problem
Goitre
lack of iodine in body can cause thyroid gland to become enlarged and neck becomes swollen
Pancreas
- endocrine and exocrine gland - contains endocrine cells called Islets of Langerhans that secrete insulin and glucagon
islets or Langerhans
1. Alpha cells : secrete glucagon hormone 2. Beta cells : secrete insulin hormoneblood carries hormones to liver where hormones stimulate conversions
insulin
1. stimulates body cells to absorb glucose from blood and convert to energy (cellular respiration)2. converts excess glucose into glycogen (stored in liver and muscles)3. converts excess glucose into glycogen (stored in adipose tissue)insulin LOWERS glucose levels in the blood
Glucagon
converts glycogen in the liver into glucose glucagon raises the glucose levels in the blood
problems associated with the pancreas
1. Hyperglycaemia 2. Diabetes mellitus
hyperglycemia
too little insulin in blood resulting in high blood glucose levels. the body cells cannot use the excess glucose and the cells get damaged
diabetes mellitus
islets of langerhans don't produce enough insulin - diabetic. excess glucose in urine
adrenal glands
- 1 above each kidney - made up of two parts 1. adrenal cortex (outer)2. adrenal medulla (inner)
adrenal cortex
secrets aldosterone
adrenal medulla
secretes adrenalin
aldosterone
controls salt content (sodium ions) in the body and this allows water regulation to occur in the collecting ducts in the kidney
adrenalin
controls blood circulation and carbohydrate metabolism
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