THE ENDOCRINE SYSTEM
Anatomy And Physiology: The Foundation Series
HIGH YIELD – NOTES AND POINTS
Gland covered – Hypothalamus, pituitary, thyroid,
Adrenal, thyroid, pineal
1
Prepared by – Sanyogita (Nursing Note)
,Exocrine Glands:
These are the glands that produce secretions and release them outside the body or into specific body
cavities.
These glands possess a duct system; therefore, they are also called duct glands.
There are three types of exocrine glands based on the mode of secretion:
(A) Merocrine (Eccrine)
These glands release their secretions without any loss of cellular material.
Examples: Salivary glands, sweat glands, pancreatic glands.
(B) Apocrine
These glands release secretions along with the apical part (upper portion) of the cell cytoplasm.
Examples: Modified sweat glands, mammary glands.
(C) Halocrine
In these glands, the secretion consists of the entire cell, which breaks down and disintegrates to release
its contents.
Examples: Sebaceous glands (oil glands), ceruminous glands (earwax glands).
Endocrine System:
Definition: It is a system responsible for maintaining homeostasis (internal balance or stability).
Function: It provides a long-term response during stress or crisis.
➢ Note: The Nervous System (NS) provides short-term and rapid responses.)
Components: The endocrine system consists of glands and hormones
▪ Hormones act as chemical messengers.
2
Prepared by – Sanyogita (Nursing Note)
, Hormone:
Definition: A hormone is a chemical messenger that carries specific messages to target cells or organs.
Mechanism: Hormones act on cellular receptors (located either on the cell surface or inside the cell)
to perform specific cellular activities.
❖ Classification of Hormones (According to Receptor Location)
Hormones are classified into three types based on the location of their receptors:
Protein derivatives Steroids Tyrosine
Pituitary Adrenal cortex Thyroid hormone
Pancreatic Placental Adrenal medulla
Pineal Estrogen
Parathormone Progesterone
Calcitonin
Receptor Locations (Visual Summary)
1.Protein Derivatives: Receptors are located on the cell membrane.
2.Steroid Hormones: Receptors are located in the cytoplasm.
3.Tyrosine Derivatives: Receptors are located in the nucleus.
Hypothalamus:
Master of the Master Gland: It controls the Pituitary gland, which is known as the Master Gland.
“Commander-in-Chief”: It regulates the entire endocrine system.
❖ Note: Structurally, the hypothalamus is a part of the brain (nervous tissue) and acts as a link
between the nervous system and the endocrine system.
Function: It helps in the secretion of regulatory hormones (releasing and inhibiting hormones) that act
directly on the Pituitary gland.
There are seven hormones secreted by the Hypothalamus that regulate the Anterior Pituitary Gland:
1) GHRH (Growth Hormone Releasing Hormone)
2) GHIH (Growth Hormone Inhibiting Hormone / Somatostatin)
3) PRH (Prolactin Releasing Hormone)
4) PIH (Prolactin Inhibiting Hormone / Dopamine)
3
Prepared by – Sanyogita (Nursing Note)
Anatomy And Physiology: The Foundation Series
HIGH YIELD – NOTES AND POINTS
Gland covered – Hypothalamus, pituitary, thyroid,
Adrenal, thyroid, pineal
1
Prepared by – Sanyogita (Nursing Note)
,Exocrine Glands:
These are the glands that produce secretions and release them outside the body or into specific body
cavities.
These glands possess a duct system; therefore, they are also called duct glands.
There are three types of exocrine glands based on the mode of secretion:
(A) Merocrine (Eccrine)
These glands release their secretions without any loss of cellular material.
Examples: Salivary glands, sweat glands, pancreatic glands.
(B) Apocrine
These glands release secretions along with the apical part (upper portion) of the cell cytoplasm.
Examples: Modified sweat glands, mammary glands.
(C) Halocrine
In these glands, the secretion consists of the entire cell, which breaks down and disintegrates to release
its contents.
Examples: Sebaceous glands (oil glands), ceruminous glands (earwax glands).
Endocrine System:
Definition: It is a system responsible for maintaining homeostasis (internal balance or stability).
Function: It provides a long-term response during stress or crisis.
➢ Note: The Nervous System (NS) provides short-term and rapid responses.)
Components: The endocrine system consists of glands and hormones
▪ Hormones act as chemical messengers.
2
Prepared by – Sanyogita (Nursing Note)
, Hormone:
Definition: A hormone is a chemical messenger that carries specific messages to target cells or organs.
Mechanism: Hormones act on cellular receptors (located either on the cell surface or inside the cell)
to perform specific cellular activities.
❖ Classification of Hormones (According to Receptor Location)
Hormones are classified into three types based on the location of their receptors:
Protein derivatives Steroids Tyrosine
Pituitary Adrenal cortex Thyroid hormone
Pancreatic Placental Adrenal medulla
Pineal Estrogen
Parathormone Progesterone
Calcitonin
Receptor Locations (Visual Summary)
1.Protein Derivatives: Receptors are located on the cell membrane.
2.Steroid Hormones: Receptors are located in the cytoplasm.
3.Tyrosine Derivatives: Receptors are located in the nucleus.
Hypothalamus:
Master of the Master Gland: It controls the Pituitary gland, which is known as the Master Gland.
“Commander-in-Chief”: It regulates the entire endocrine system.
❖ Note: Structurally, the hypothalamus is a part of the brain (nervous tissue) and acts as a link
between the nervous system and the endocrine system.
Function: It helps in the secretion of regulatory hormones (releasing and inhibiting hormones) that act
directly on the Pituitary gland.
There are seven hormones secreted by the Hypothalamus that regulate the Anterior Pituitary Gland:
1) GHRH (Growth Hormone Releasing Hormone)
2) GHIH (Growth Hormone Inhibiting Hormone / Somatostatin)
3) PRH (Prolactin Releasing Hormone)
4) PIH (Prolactin Inhibiting Hormone / Dopamine)
3
Prepared by – Sanyogita (Nursing Note)
