Chapter 18: Principles of Endocrinology; the Central Endocrine Glands
How does the endocrine system influence homeostasis?
The endocrine system regulates activities that require duration rather than speed.
Endocrine glands secrete hormones (Blood-borne Chemical messengers that act on
target cells located a long distance from the gland)
Hormonal control is directed at maintaining homeostasis.
Central endo glands are closely associated with the brain (Hypothalamus, Pituitary
gland & Pineal gland)
Hypothalamus and posterior pituitary gland release hormones essential for
maintaining water balance, giving birth, and breast feeding.
Hypothalamus also responsible for secretion of regulatory hormones that control
hormonal output of the anterior pituitary gland, which promotes growth and
influences nutrient homeostasis.
The Pineal gland creates a hormone that is important in establishing the body’s
natural rhythm.
General Principles of Endocrinology
Endocrinology: The study of the homeostatic chemical adjustments and other activities that
hormones accomplish
, Differences between Neurotransmitters and Hormones
Property Neurotransmitters Hormones
Conduction method Wired, released into Wireless, released into
synaptic cleft blood
Speed of info Rapid Slow
Duration of effect Brief Longer lasting
Type of action Voluntary or involuntary Involuntary
Target distance Target localised (cells Target distant often
connected to neuron)
Produced by Neurons Endocrine glands
Effect Stimulate postsynaptic Regulate their target organs
membranes
Similarities
- Chemical messengers
- Released from 1 cell to carry signal to a target cell elsewhere in body
- When target cell reached, specific response triggered in that cell
Classification of Hormones
- 2 distinct chemical groups: hydrophilic and lipophilic
- Amines- amino acid derivatives
- Hydrophilic
o Mainly peptide or protein hormones
o Catecholamines (amine hormone)
Derived from: tyrosine
Secreted by: adrenal medulla
How does the endocrine system influence homeostasis?
The endocrine system regulates activities that require duration rather than speed.
Endocrine glands secrete hormones (Blood-borne Chemical messengers that act on
target cells located a long distance from the gland)
Hormonal control is directed at maintaining homeostasis.
Central endo glands are closely associated with the brain (Hypothalamus, Pituitary
gland & Pineal gland)
Hypothalamus and posterior pituitary gland release hormones essential for
maintaining water balance, giving birth, and breast feeding.
Hypothalamus also responsible for secretion of regulatory hormones that control
hormonal output of the anterior pituitary gland, which promotes growth and
influences nutrient homeostasis.
The Pineal gland creates a hormone that is important in establishing the body’s
natural rhythm.
General Principles of Endocrinology
Endocrinology: The study of the homeostatic chemical adjustments and other activities that
hormones accomplish
, Differences between Neurotransmitters and Hormones
Property Neurotransmitters Hormones
Conduction method Wired, released into Wireless, released into
synaptic cleft blood
Speed of info Rapid Slow
Duration of effect Brief Longer lasting
Type of action Voluntary or involuntary Involuntary
Target distance Target localised (cells Target distant often
connected to neuron)
Produced by Neurons Endocrine glands
Effect Stimulate postsynaptic Regulate their target organs
membranes
Similarities
- Chemical messengers
- Released from 1 cell to carry signal to a target cell elsewhere in body
- When target cell reached, specific response triggered in that cell
Classification of Hormones
- 2 distinct chemical groups: hydrophilic and lipophilic
- Amines- amino acid derivatives
- Hydrophilic
o Mainly peptide or protein hormones
o Catecholamines (amine hormone)
Derived from: tyrosine
Secreted by: adrenal medulla
