the endocrine system chapter 36. endocrine glands

The Endocrine System

Chapter 36

ENDOCRINE GLANDS

ENDOCRINE SYSTEM:

Set of hormone secreting glands within an animal’s body

ENDOCRINE GLAND:

Is a ductless gland that makes & secretes specific chemical messengers (hormones) into the blood

EXOCRINE GLAND:

Secretes their chemicals into ducts that carry them to their destination eg sweat gland, salivary gland, gastric gland

HORMONE:

Is a chemical messenger secreted by an endocrine gland into the blood which distributes it through out the body altering the activity of specific target tissues

GLAND HORMONE FUNCTION

pituitary ADHAnti diuretic hormone

Growth hormone

Thyroid stimulation hormone TSH

Increases H2O absorption in the kidney

Speeds up growth

Causes thyroid gland to secrete thyroxine increasing cell metabolism

GLAND HORMONE FUNCTION

Pituitary

Thyroid

Gonad stimulating hormone GSH

Thyroxine

Stimulates gonads (ovaries & testes) to secrete sex hormones

Regulates metabolism, growth & development

GLAND HORMONE FUNCTION

Adrenal

Pineal

Pancreas

Adrenaline

Melatonin

insulin

Prepares the body for emergency responses

Controls body rhythms

Regulates the amount of sugar in the blood

GLAND HORMONE FUNCTION

Thymus

Ovaries

Testes

Parathroids

Thymosine

Oestrogen& progesterone

Testosterone

Parathorome

Matures WBC

Controls sexual development

Controls sexual development

Controls release of Ca from bones into blood plasma

Differences between endocrine & nervous systems

NERVOUS SYSTEM ENDOCRINE SYSTEM

Electrical – chemical message

Chemical message

Carried by nerves Carried by blood

Impulses target specific sites

Messages can be sent to many regions in the body

Response is fast acting

Response is slow acting

Effects are short term Effects are long term

Growth Hormone

Deficiency Symptoms:Lower than normal height, immature face

Excess symptoms:Over enlargement of body tissue including

bones in hands, feet, face & skull

Corrective measures: (for deficiency)Injections of growth hormone

Hormone Supplements– know 2

1. Growth hormone can be used as a body building supplement

2. Oestrogen can be used to regulate the menstrual cycle

3. Insulin in the treatment of diabetes4. HRT hormone replacement therapy

to reduce the effects of the menopause

Negative feedback control of thyroxine levels – HIGHER LEVEL ONLY

1. When the level of thyroxine is LOW, thyroid releasing hormone TRH is produced by the hypothalmus

2. This causes the release of thyroid stimulating hormone TSH in the pituitary

3. TSH stimulates the secretion of thyroxine

4. When the amount of thyroxine reaches a certain level, the hypothalmus stops secreting TRH

5. When the level of thyroxine falls again the cycle repeats

6. This is an example of a negative feedback mechanism

THYROXINE control – Feedback