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Hormones and Homeostasis
Physiological variables that need to be within certain limits:
1) blood pH
2) Body temperature
3) Blood Co2 levels
4) Water balance within tissues
5) Blood glucose concentration
Negative feedback mechanism is the physiological process that brings back a value to its set point
(body temp back to 37 degree Celsius). Negative feedback functions to keep a value within the
narrow range that is considered normal for homeostasis.
The endocrine system has a lot of glands that produce a lot of hormones. Each hormone is
transported by the bloodstream, from the gland of production to the target organ (cels in the body
that are influenced by that particular hormone)
Endocrine system glands:
1) pituitary gland
2) Pineal gland
3) Hypothalamus
4) Thyroid
5) Pancreas
6) Ovaries / testes
Each hormone has a specific gland that produces and secretes it into the blood capillaries. Not all
body cells are influenced by any one hormone but those cells that are by one hormone are called
target tissues of the hormone.
Some hormones (leptin) have very specific n limited target tissues wherever others (insulin) have a
broader range.
Thyroxin-
• Produced by thyroid gland
• Butterfly shaped, located in the neck
• Created by amino acid + iodine
• Exists in two forms- T4 and T3 (numbers indicate the no. Of iodine within the structure)
• Both forms enter target cells (almost all cells in the body) and T4 form is typically converted into
T3.
• T3 enters the nucleus of the cells and cats as a transcription regulator
• Leading an increase in mRNA and thus results into an increase in proteins.
• These increase in proteins lead to an increase in the cell metabolism
• therefore, a cell under the influence of thyroxin will have a greater need for oxygen
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Hormones and Homeostasis
Physiological variables that need to be within certain limits:
1) blood pH
2) Body temperature
3) Blood Co2 levels
4) Water balance within tissues
5) Blood glucose concentration
Negative feedback mechanism is the physiological process that brings back a value to its set point
(body temp back to 37 degree Celsius). Negative feedback functions to keep a value within the
narrow range that is considered normal for homeostasis.
The endocrine system has a lot of glands that produce a lot of hormones. Each hormone is
transported by the bloodstream, from the gland of production to the target organ (cels in the body
that are influenced by that particular hormone)
Endocrine system glands:
1) pituitary gland
2) Pineal gland
3) Hypothalamus
4) Thyroid
5) Pancreas
6) Ovaries / testes
Each hormone has a specific gland that produces and secretes it into the blood capillaries. Not all
body cells are influenced by any one hormone but those cells that are by one hormone are called
target tissues of the hormone.
Some hormones (leptin) have very specific n limited target tissues wherever others (insulin) have a
broader range.
Thyroxin-
• Produced by thyroid gland
• Butterfly shaped, located in the neck
• Created by amino acid + iodine
• Exists in two forms- T4 and T3 (numbers indicate the no. Of iodine within the structure)
• Both forms enter target cells (almost all cells in the body) and T4 form is typically converted into
T3.
• T3 enters the nucleus of the cells and cats as a transcription regulator
• Leading an increase in mRNA and thus results into an increase in proteins.
• These increase in proteins lead to an increase in the cell metabolism
• therefore, a cell under the influence of thyroxin will have a greater need for oxygen
Find more resources on this topic on
