Overview of the Endocrine System-18 Flashcards
What are examples of hormones in adipose tissues and GI tract?
GI- Gastrin, Gherkin and Glucagon
Adipose- Leptin
What is the difference between the connection in the endocrine and nervous system.
Endocrine system is wireless (travels in blood) and nervous system is wired (through wire like neurones)
What is the difference between the distance travelled in the endocrine and nervous system.
Hormones travel long distances in the bloodstream in the endocrine system whereas neurotransmitter diffuses a short distance in the nervous system.
What are the responding cells in the nervous system and endocrine system?
Endocrine- Communication depends on expression of specific receptors whereas in nervous system communication depends on anatomical relationship of neurons.
What is the difference between the speed and duration of the endocrine and nervous systems.
Endocrine can be quite rapid but can also be slow and longer lasting whereas nervous system is rapid and brief.
What processes do hormones regulate.
Homeostasis
Energy Metabolism
Growth and Development
Reproduction
Behaviour
What are the three different classes of hormones
Peptide- Composed of a chain of amino acids
Steroid- Derived from cholesterol
Amine- Amino acid derivatives
Where are different hormones synthesised and stored.
Peptide- Made in advance, stored in secretory vesicles.
Steroid hormones- Synthesized on demand from precursors
Amine hormones- Made in advance- stored in secretory vesicles
How are different hormones released from parent cells
Peptide- Exocytosis
Steroid- Simple diffusion
Amine- Exocytosis and transport proteins.
What are the half-lives of different hormones?
Peptide- Short
Steroid- Long
Catecholamines- short
Thyroid- Long
Where are receptors located for different hormones
Peptide- Cell membrane
Steroid- Cytoplasm or nucleus
Catecholamines- Cell membrane
Thyroid- Nucleus
What is the response to receptors of different hormones?
Peptide- Activators of secondary messengers and intracellular pathways.
Steroid- Activation of genes for transcription.
Catecholamines- Secondary messenger systems.
Thyroid- Activation of genes for transcription.
What is the general target response of the different hormones.
Peptide- Modification of existing proteins.
Steroid- Induction of new protein synthesis
Catecholamines- Modification of existing proteins.
Thyroid- Induction of new protein synthesis.
What are examples of each of the hormones.
Peptide- Insulin, parathyroid
Steroid- Estrogen, androgens, cortisol
Catecholamines- Adrenaline, Noradrenaline
Thyroid- Thyroxine(T4)
How do the different proteins travel in blood
Peptide- Dissolved in plasma
Steroid- bound to carrier proteins
Catecholamines- Dissolved in plasma
Thyroid- Bound to carrier proteins.
What factors control secretion of hormones
The concentration of ions or nutrients in plasma
Environmental changes
Neuronal activity
Other ‘releasing hormones, which are released from the hypothalamus and pituitary gland.
How does the hypothalamus regulate hormone release from the pituitary gland.
The hypothalamus receives signals from essentially all areas of the central nervous system
The hypothalamus produces ‘releasing’ and ‘inhibiting’ hormones, which act on the pituitary gland
The hypothalamus is thus a key link between the nervous system and the endocrine system
What is the function of the posterior pituitary?
Axons from the hypothalamic neurons enter the posterior pituitary
Hormones oxytocin and ADH are released from axon terminals, enter capillaries in the posterior pituitary and then released into general circulation.
Thus posterior pituitary releases hormones but does not synthesise them they are synthesised in the hypothalamus.
Function of the anterior pituitary.
Hormones released from hypothalamus move through portal veins into the anterior pituitary.
These hypothalamic hormones either stimulate or inhibit hormone release from cells in the anterior pituitary.
Hormones are released from anterior pituitary into general circulation.
Some anterior pituitary hormones control the secretion of hormones from other endocrine glands.
THUS HORMONES RELEASED FROM THE ANTERIOR PITUITARY ARE SYNTHESIZED IN THE ANTERIOR PITUITARY.
What is an example of a three hormone sequence.
Facilitates signal amplification from a small number of neurons in the hypothalamus to a large peripheral hormone signal.
What are examples of feedback regulation of hormone release.
- The biological response to a hormone can directly feedback to the gland that secretes that hormone. (Parathyroid hormone)
- The hormone itself can exert feedback regulation (thyroid hormones)
