A set of hormone secreting glands within the body of an animal
What is the function of the Endocrine System?
Homeostasis, communication and response to stimuli
What is a hormone?
A hormone is a chemical messenger (protein) secreted by an endocrine gland into the bloodstreamand carried to a target organ where it causes a response
What is an endocrine gland?
An endocrine gland is a ductless gland, produces & secretes hormones directly into the bloodstream, eg thryoid - thyroxine
What is an exocrine gland?
An exocrine gland has ducts, secretes directly to site of actioneg salivary glands- saliva- salivary ducts-mouth
Differences between Nervous System and Endocrine System?
1. Nervous isfaster2. Nervous shorter in duration
3. Nervous stops quicker
4.Nervous response is much more local
5.Nerve 'messages' are conducted electrically, endocrine chemically
Pituitary (master) gland?
1. Growth hormone - stimulates growth
2. Prolactin- stimulates milk formation in mammary glands
3. Pituitary- muscle contractions at birth, milk ejection
Melatonin - natural sleep, enhances immunity
GHRF- stimulates pituitary to produce growth hormone
Thryoxine- controls metabolism
Adrenaline- emergency response
Islets of Langerhans (pancreas)?
Insulin- stimulates the uptake of glucose from blood, maintains blood sugar level
Oestrogen- female 2ndary characteristics, graafian follicle formation, control menstrual cycle.Progesterone- maturation of uterine lining, prep for pregnancy
Testosterone- male 2ndary characteristics, sperm
Thryoid Gland in detail?
2. Regulation of metabolic rate, growth and development
3. Iodine is needed for thryoxine formation
4. Iodine is absorbed from blood by active transport
Thryoxine Deficiency? HYPOthryoidism
Underactivity of thyroid gland. Insufficient thyroxine. Cretinism in kids-poor, stunted growth/dwarfism & poor brain development.Myxoedema in adults- fatique, low energy, reduced resistence to disease, sluggishness, reduced metabolic rate-weight gain. Lack of iodine can cause this
Thryoxine EXCESS? HYPERthyroidism
Overactivity of thyroid gland. Overproduction of thyroxine. Raised metabolism, greater appetite, weight loss, restlessness, protruding eye- Graves DiseaseDrugs suppress thyroid gland, or surgically remove part of the gland, radioactive iodine to destroy part of gland
Regulation of Thyroid action?
TSH ( thyroid stimulating hormone)Released in blood, causes gland to produce thyroxine.
If thyroxine level is correct- tsh not produced-no more thyroxine produced. Correct level of thyroxine has a NEGATIVE effect- Negative feedbackBelow normal thyroxine level-tsh made- more thyroxine produced-thryoxine level correct it switches off
Insulin for diabetes-under-secretion of insulin- allows glucose to enter cells from the bloodGrowth hormone for potential cretinism?