Case 3A Hormonal regulation
Learning goals
What are the different types of hormones?
Hormones are used to communicate by the endocrine system. They are chemical signals that
are secreted into the blood and distributed in the body.
Hormones are chemical messengers secreted by cells into extracellular fluids. They are
produced in the endocrine glands, such as pituitary, adrenal, pineal, thyroid and parathyroid
gland.
A final scheme divides hormones in three main chemical classes:
Peptide hormones: Composed of linked amino acids
Steroid hormones: All derived from cholesterol
Amino acid-derived hormones: Modifications of single amino acids
A hormone typically produces one or more of the following changes:
• Alter plasma membrane permeability or membrane potential, or both, by opening
and closing ion channels.
• Stimulates the synthesis of enzymes and other proteins within the cell.
• Activates or deactivates enzymes
• Induces secretory activity
• Stimulates mitosis
In general hormones act on receptors in 2 ways:
1. Water-soluble hormones (all amino-acid based hormones except for thyroid
hormone) act on receptor in the plasma membrane. These receptors are usually
coupled via regulatory molecules called G-proteins to one or more intracellular
second messengers which mediate the target cell’s response
Cyclic AMP signalling mechanism
PIP-calcium signalling mechanism
2. Lipid soluble hormones (steroids and thyroid hormone) act on receptors inside the
cell (either the nucleus or in the cytoplasm), which directly activate genes.
, Different signalling: Endocrine, autocrine, neuroendocrine, paracrine
What is the secretion and production place of hormones?
The primary production place of hormones are the posterior/anterior pituitary,
hypothalamus, thyroid gland, adrenal gland, pancreas, adipose tissue and the GI tract
Posterior pituitary/hypothalamus: Oxytocin and ADH
Anterior pituitary:
o Growth hormone(GH): growth promoting effects mediated indirectly by IGFs
o Thyroid stimulating hormone (TSH): stimulates thyroid gland to release
thyroid hormone
o Adrenocorticotropic hormone (ACTH): promotes release of glucocorticoids
and androgens
o Follicle stimulating hormone (FSH): in females stimulates ovarian follicle
maturation and oestrogen production; in males stimulates sperm production
o Luteinizing hormone (LH): in females triggers ovulation and stimulates
ovarian production of oestrogen and progesterone, in males promotes
testosterone production
o Prolactin (PRL): promotes lactation
Thyroid gland: Thyroxine and triiodothyronine
o Parathyroid hormone: Increases Ca absorption
Learning goals
What are the different types of hormones?
Hormones are used to communicate by the endocrine system. They are chemical signals that
are secreted into the blood and distributed in the body.
Hormones are chemical messengers secreted by cells into extracellular fluids. They are
produced in the endocrine glands, such as pituitary, adrenal, pineal, thyroid and parathyroid
gland.
A final scheme divides hormones in three main chemical classes:
Peptide hormones: Composed of linked amino acids
Steroid hormones: All derived from cholesterol
Amino acid-derived hormones: Modifications of single amino acids
A hormone typically produces one or more of the following changes:
• Alter plasma membrane permeability or membrane potential, or both, by opening
and closing ion channels.
• Stimulates the synthesis of enzymes and other proteins within the cell.
• Activates or deactivates enzymes
• Induces secretory activity
• Stimulates mitosis
In general hormones act on receptors in 2 ways:
1. Water-soluble hormones (all amino-acid based hormones except for thyroid
hormone) act on receptor in the plasma membrane. These receptors are usually
coupled via regulatory molecules called G-proteins to one or more intracellular
second messengers which mediate the target cell’s response
Cyclic AMP signalling mechanism
PIP-calcium signalling mechanism
2. Lipid soluble hormones (steroids and thyroid hormone) act on receptors inside the
cell (either the nucleus or in the cytoplasm), which directly activate genes.
, Different signalling: Endocrine, autocrine, neuroendocrine, paracrine
What is the secretion and production place of hormones?
The primary production place of hormones are the posterior/anterior pituitary,
hypothalamus, thyroid gland, adrenal gland, pancreas, adipose tissue and the GI tract
Posterior pituitary/hypothalamus: Oxytocin and ADH
Anterior pituitary:
o Growth hormone(GH): growth promoting effects mediated indirectly by IGFs
o Thyroid stimulating hormone (TSH): stimulates thyroid gland to release
thyroid hormone
o Adrenocorticotropic hormone (ACTH): promotes release of glucocorticoids
and androgens
o Follicle stimulating hormone (FSH): in females stimulates ovarian follicle
maturation and oestrogen production; in males stimulates sperm production
o Luteinizing hormone (LH): in females triggers ovulation and stimulates
ovarian production of oestrogen and progesterone, in males promotes
testosterone production
o Prolactin (PRL): promotes lactation
Thyroid gland: Thyroxine and triiodothyronine
o Parathyroid hormone: Increases Ca absorption
