Endocrine System Flashcards
How does the endocrine system regulate homeostasis ?
By slow, long-lasting chemical signalling
What do hormones secreted from glands act on?
target organs via circulatory system.
What does the endocrine system need to be activated by ?
The nervous system
What are the 2 different mechanisms that glands function through ?
1 - ENDOCRINE
2. EXOCRINE
Where does the endocrine secrete hormones snd what’s its target ?
- Secretion into BLOOD
- Action on distant target
Where does the exocrine mechanisms secrete hormones ?
Secretion through duct to skin or into lumen outside body
Whats the endocrine system scheme function ?
1) sense internal change
2) Integrate sensory information
3) Respond by acting on other body systems.
What do glands release hormone in response to ?
Internal change
What is the hypothalamus ?
Brain area with various physiological functions important for maintaining homeostasis by linking nervous and endocrine systems
What are 3 functions of the hypothalamus ?
1- Integrates sensory input
2- Coordinates appropriate physiological responses
3- Regulates hormone release from pituitary gland and other glands all over body
How are hormones classified ?
According to function and structure
Whats a tropic and non tropic hormone ?
TROPIC HORMONE -
-Regulates production / secretion of another hormone in a gland
NON-TROPIC HORMONE -
- Has a direct effect on target organ
What are 3 structures of hormones ?
PEPTIDE - Most hormones are amino acids
AMINES - Derived from the amino acid tyrosine
STEROIDS - Derived from the lipid cholesterol
How are peptides released into the blood ?
1) Peprohormone precursor is translated and packaged into vesicles
2) PEPROHORMONE - PROHORMONE - HORMONE
3) Hormone packaged into secretory vesicles and stored in cytosol
4) Vesicles fuse with plasma membrane and release hormone into blood
How is the hormone amine released into the blood ?
1- Synthesised from the amino acid tyrosine by specific enzymes
2- Packaged into secretory vesicles and stored until release
3- Vesicles fuse with plasma membrane and release hormone into blood.
What are the 3 different ways that catecholamines are synthesised, stored and released ?
- Dopamine
- Noradrenaline
- Adrenaline
How is steroids synthesised, stored and released ?
1- Synthesised from the lipid cholesterol by specific enzymes
2- diffuse across plasma membrane into blood once synthesised
3- Can be converted into different hormones once in blood or at target
Via what pathways does cholesterol give rise to many hormones ?
Via several enzymatic synthesis pathways.
What does the way a hormone is transported through the circulation depend on ?
Their solubility characteristics
What hormones are water-soluble and where are they located ?
- Peptide, some amines
- FREE in blood or binding to plasma proteins
What hormones are lipid-soluble and where are they located ?
-Steroid, some amines
- Bound to plasma proteins
in what location do hormones circulate in the blood ?
The whole body
Explain how hormones only have specific effects ?
They only act in certain organs
Explain how hormones induce a response within a cell ?
Hormones bind to a specific RECEPTOR on cells in target organs. Hormone binding to its receptor induces a response within cell
What are the two types of hormone receptors ?
Membrane receptors
Internal receptors
What are membrane receptors and what do they bind ?
- GPCR or kinase-linked
- bind peptides, catecholamines, or some steroids
Where do hormones bind on membrane receptors ?
Hormone binds to receptor on outside of plasma membrane
What responses does binding on membrane receptors cause ?
-Enzyme activation
- Change in protein synthesis
What hormones bind to internal receptors ?
Most steroids, thyroid hormone
What internal receptor do hormones bind to ?
Cytosol