Human Endocrine System
Chemical coordination
A slow process of communicating info throughout the body by way of hormones
Hormones are secreted by glands or tissue called endocrine glands
Endocrine system works with the nervous system
Hormone
An organic chemical substance (protein/steroid) secreted by endocrine gland
Mode of transport: blood stream
Goes to target organs where it regulates metabolic reactions
Do not last long (broken down by enzymes)
Target organ
Cells that respond to a given hormone have receptor sites for that hormone
Can be a single gland or organ or scattered throughout body
Endocrine gland
Vascular, ductless gland that secretes hormones which are transported to target organs
Exo- vs endocrine glands
- Exocrine: carried in ducts to where they are needed. Salivary glands,
liver, pancreas
- Endocrine: Ductless and carried in bloodstream to target organs
Endocrine Glands in body
, Hypothalamus
Part of brain situated under the pituitary gland
Secretes (amongst others) ADH (antidiuretic hormone)
Role
- Osmoreceptors in hypothalamus detect increase in osmolality (low water levels) of blood and
hypothalamus responds by releasing ADH
- ADH conserves water if body is dehydrated by causing water to be reabsorbed back into blood from
collecting ducts in kidney so less water is lost in urine
Pituitary gland
Chemical coordinator of most of the other endocrine glands (master gland)
Attached to hypothalamus by short stalk
Hormones secreted by pituitary:
1. TSH: Thyroid stimulating hormone
- Stimulates thyroid gland to secrete thyroxin
2. FSH: Follicle stimulating hormone
- Females: stimulates oogenesis in ovary
- Males: stimulates spermatogenesis in testes
3. LH: Luteinizing hormone
- Stimulates ovulation from ovary and formation of corpus luteum
4. Prolactin
- Stimulates production of milk after birth of baby for as long as they suckle
5. ACTH: Adrenocorticotropic hormone
- Stimulates adrenal cortex (top of kidney) to secrete cortisone & aldosterone
6. ICSH: Interstitial cell stimulating hormone
- Stimulates testes to produce testosterone
7. GH: growth hormone or STH: somatotrophic hormone
- Promotes skeletal and muscular growth by stimulating synthesis of proteins
Growth disorders
Hypersecretion: too much
Hyposecretion: too little
Chemical coordination
A slow process of communicating info throughout the body by way of hormones
Hormones are secreted by glands or tissue called endocrine glands
Endocrine system works with the nervous system
Hormone
An organic chemical substance (protein/steroid) secreted by endocrine gland
Mode of transport: blood stream
Goes to target organs where it regulates metabolic reactions
Do not last long (broken down by enzymes)
Target organ
Cells that respond to a given hormone have receptor sites for that hormone
Can be a single gland or organ or scattered throughout body
Endocrine gland
Vascular, ductless gland that secretes hormones which are transported to target organs
Exo- vs endocrine glands
- Exocrine: carried in ducts to where they are needed. Salivary glands,
liver, pancreas
- Endocrine: Ductless and carried in bloodstream to target organs
Endocrine Glands in body
, Hypothalamus
Part of brain situated under the pituitary gland
Secretes (amongst others) ADH (antidiuretic hormone)
Role
- Osmoreceptors in hypothalamus detect increase in osmolality (low water levels) of blood and
hypothalamus responds by releasing ADH
- ADH conserves water if body is dehydrated by causing water to be reabsorbed back into blood from
collecting ducts in kidney so less water is lost in urine
Pituitary gland
Chemical coordinator of most of the other endocrine glands (master gland)
Attached to hypothalamus by short stalk
Hormones secreted by pituitary:
1. TSH: Thyroid stimulating hormone
- Stimulates thyroid gland to secrete thyroxin
2. FSH: Follicle stimulating hormone
- Females: stimulates oogenesis in ovary
- Males: stimulates spermatogenesis in testes
3. LH: Luteinizing hormone
- Stimulates ovulation from ovary and formation of corpus luteum
4. Prolactin
- Stimulates production of milk after birth of baby for as long as they suckle
5. ACTH: Adrenocorticotropic hormone
- Stimulates adrenal cortex (top of kidney) to secrete cortisone & aldosterone
6. ICSH: Interstitial cell stimulating hormone
- Stimulates testes to produce testosterone
7. GH: growth hormone or STH: somatotrophic hormone
- Promotes skeletal and muscular growth by stimulating synthesis of proteins
Growth disorders
Hypersecretion: too much
Hyposecretion: too little
