,1-Endocrine System
The endocrine system: a scattered collection of ductless glands and individual cells
that secrete chemical messengers called hormones.
1.1-What is the difference between endocrine and exocrine glands?
• Endocrine glands secrete hormones directly into the bloodstream. These
hormones travel through the blood to target organs or cells. Examples
include the adrenal glands, pituitary gland, and thyroid gland.
• Exocrine glands secrete their products through ducts to an external or
internal surface (not directly into the blood). Examples include sweat
glands, salivary glands, and glands that produce digestive enzymes.
2-What is the function of the endocrine system?
Along with the nervous system, the endocrine system works to help regulate the
body and maintain homeostasis.
3-Comparion table of the nervous and the endocrine system
Nervous System Endocrine System
Initiates responses_____rapidly_______ Initiates responses_____slowly____
__short___-term duration responses __long___-term duration responses
Chemical messengers: Chemical messengers: Hormones
Neurotransmitters
, Act at ______specific______ locations Act at ____diffuse____ locations
determined by axon pathways determined by target cells that can be
anywhere blood reaches
Act over __very short______ distances Act over _long___ distances
4- What are the different types of endocrine glands?
Pure Endocrine Glands
• These glands primarily produce and secrete hormones as their main function.
• They are dedicated endocrine organs with no other major physiological roles.
• Examples discussed in your class include:
o Pituitary gland: Master gland controlling many other endocrine glands.
o Pineal gland: Produces melatonin, regulating sleep-wake cycles.
o Parathyroid glands: Regulate calcium levels in the blood.
o Thyroid gland: Produces thyroid hormones that regulate metabolism.
o Adrenal glands: Produce hormones like cortisol from the adrenal cortex.
Secondary Endocrine Glands
• These glands produce hormones but also have other major functions beyond
hormone secretion.
, • They are not solely endocrine organs; their endocrine role is part of a broader
physiological function.
• Examples from your class include:
o Pancreas: Primarily involved in digestion (exocrine function) but also secretes
insulin and glucagon (endocrine function).
o Gonads (ovaries and testes): Produce sex hormones but also have reproductive
functions.
o Hypothalamus: A neuroendocrine gland that links the nervous system to the
endocrine system by producing releasing hormones (like CRH) that regulate the
pituitary gland.
5-Which are the different types of possible stimuli for endocrine glands?
• Humoral Stimuli:
-Changing levels of ions/nutrients in the blood stimulate the endocrine gland
to release its hormone. The example below shows the parathyroid glands
(the 4 yellow circles) which release their hormone in response to changing
calcium levels in the blood and body.
• Neural Stimuli
-Hormone release is triggered by nerve signals from the nervous system.
The endocrine system: a scattered collection of ductless glands and individual cells
that secrete chemical messengers called hormones.
1.1-What is the difference between endocrine and exocrine glands?
• Endocrine glands secrete hormones directly into the bloodstream. These
hormones travel through the blood to target organs or cells. Examples
include the adrenal glands, pituitary gland, and thyroid gland.
• Exocrine glands secrete their products through ducts to an external or
internal surface (not directly into the blood). Examples include sweat
glands, salivary glands, and glands that produce digestive enzymes.
2-What is the function of the endocrine system?
Along with the nervous system, the endocrine system works to help regulate the
body and maintain homeostasis.
3-Comparion table of the nervous and the endocrine system
Nervous System Endocrine System
Initiates responses_____rapidly_______ Initiates responses_____slowly____
__short___-term duration responses __long___-term duration responses
Chemical messengers: Chemical messengers: Hormones
Neurotransmitters
, Act at ______specific______ locations Act at ____diffuse____ locations
determined by axon pathways determined by target cells that can be
anywhere blood reaches
Act over __very short______ distances Act over _long___ distances
4- What are the different types of endocrine glands?
Pure Endocrine Glands
• These glands primarily produce and secrete hormones as their main function.
• They are dedicated endocrine organs with no other major physiological roles.
• Examples discussed in your class include:
o Pituitary gland: Master gland controlling many other endocrine glands.
o Pineal gland: Produces melatonin, regulating sleep-wake cycles.
o Parathyroid glands: Regulate calcium levels in the blood.
o Thyroid gland: Produces thyroid hormones that regulate metabolism.
o Adrenal glands: Produce hormones like cortisol from the adrenal cortex.
Secondary Endocrine Glands
• These glands produce hormones but also have other major functions beyond
hormone secretion.
, • They are not solely endocrine organs; their endocrine role is part of a broader
physiological function.
• Examples from your class include:
o Pancreas: Primarily involved in digestion (exocrine function) but also secretes
insulin and glucagon (endocrine function).
o Gonads (ovaries and testes): Produce sex hormones but also have reproductive
functions.
o Hypothalamus: A neuroendocrine gland that links the nervous system to the
endocrine system by producing releasing hormones (like CRH) that regulate the
pituitary gland.
5-Which are the different types of possible stimuli for endocrine glands?
• Humoral Stimuli:
-Changing levels of ions/nutrients in the blood stimulate the endocrine gland
to release its hormone. The example below shows the parathyroid glands
(the 4 yellow circles) which release their hormone in response to changing
calcium levels in the blood and body.
• Neural Stimuli
-Hormone release is triggered by nerve signals from the nervous system.
