Summary Life Sciences: The Human Endocrine System

LIFE PROCESSES IN PLANTS AND ANIMALS
HUMAN ENDOCRINE SYSTEM
ENDOCRINE SYSTEM
- Made of: glands that produce + secrete hormones into blood
- Purpose: constant internal environment is maintained (homeostasis)
- Controls: growth + development; chemical reactions (metabolism); balance of water + salts
(osmoregulation); + reproduction

Gland:
- Group of cells specialised to produce + secrete specific chemical substance (eg. Hormone)
- 2 types:
Endocrine (within) Exocrine (without)
- Secrete hormones they produce into blood - Secrete chemical substances they produce into
duct = carries them to part of body they are
needed
- Have no ducts (ductless glands) Eg.
*ducts: tubes that connect one part of body to another • Digestive glands
• Salivary glands
• Sweat glands

Eg.
• Pituitary gland
• Thyroid gland

Hormone:
- Chemical substance produced + secreted in small amounts into bloodstream by endocrine
glands
- Transfer info from one set of body cells (somatic cells) to another = coordinates functions of
parts of body
- Controls: function of specific organ in body (target organ)

, Nervous vs endocrine system:
Nervous system Endocrine system

• Neurons • Glands

• Info transmitted in form of nerve impulses • Info transmitted in form of hormones

• Nerve impulses travel along nerve fibres • Hormones travel in blood

• Info travels quickly • Info travels slowly

• Affects the action of effectors (muscles/glands) • Affects the action of target organs

• Effect of nerve impulse does not last long • Effect of hormone can last for long time