endocrine system Flashcards
Describe the function of endocrine glands within the human body (11)
- Pineal → melatonin (sleep regulation)
- The hypothalamus → maintains homeostasis by regulating a range of functions through the control of the pituitary.
- Anterior pituitary → the ‘’master gland’’, hormones control many other endocrine glands.
- Posterior pituitary → doesn’t produce its own hormones - ADH & oxytocin.
- Thyroid → TSH to enhance all necessary processes for the synthesis of thyroid hormones
- Parathyroid → PTH regulates calcium in the body.
- Thymus → produces hormones that support the development and maturation of T-cells
- Adrenal (inner) → noradrenaline & adrenaline - fight or flight
- Adrenal (outer) → cortisol & aldosterone - blood pressure and salt level regulation
- Pancreas → Insulin (lower blood glucose), Glucagon (increased blood glucose)
- Reproductive → Estrogen, progesterone & testosterone
How is high blood sugar regulated (6)
- Hypothalamus
- Pituitary
- pancreas - releases insulin
- liver-stimulated glycogen formation
- tissue-stimulated glucose uptake
- lower blood sugar
How is low blood sugar regulated (5)
- hypothalamus
- pituitary
- pancreas -glucagon
- liver - stimulates glycogen breakdown
- raised blood sugar
How is the stress response regulated (4)
- hypothalamus - CRH secretion
- anterior pituitary - ATCH
- adrenal gland - cortisol
- metabolic effects
What is the direct mechanism of action of the growth hormone (3)
- Growth hormone
- fat tissue
- direct effect
What is the indirect mechanism of action of the growth hormone (4)
- Growth hormone
- liver - IGF-1
- Bone
- indirect effect
How is prolactin release regulated, and what type of feedback control is it (7)
- hypothalamus - PRF & TRH
- anterior pituitary
- prolactin
- mammary glands
- suckling reflex
- hypothalamus - PRF & TRH
- Positive feedback
What are the types of hypothalamic hormones (6)
- dopamine
- TRH
- CRH
- somatostatin
- GHRH
- GnRH
What are the types of anterior pituitary hormones (6)
- prolactin
- TSH
- ACTH
- GH
- FSH
- LH
What are the types of adrenal hormones (2)
- Cortisol
- aldosterone
What is the classification of hormones (3)
- protein & peptide hormones
- Steroid hormones
- Amino acid derivatives
What is the concept of protein & peptide hormones (2)
- require exocytosis to be secreted
- triggered by an increase in extracellular calcium levels or cell depolarization
What is the concept of steroid hormones (3)
- derived from cholesterol (lipids)
- eliminated via inactivating metabolic transformations, urine or bile
- once made, diffuse out of the cell and do not require secretory mechanisms
What is the concept of amino acid derivative hormones (3)
- Thyroid hormones > derived from amino acid Tyrosine.
- serotonin and melatonin > tryptophan
- histamine > glutamic acid.
What are the patterns of hormone secretion (3)
- Episodic secretion - e.g. different at certain points of the day (morning, night, etc…) daily
- diurnal variation - e.g. female reproduction (menstrual cycle) monthly
- set point regulation - e.g. different at different points of the life cycle (birth, childhood, etc.…) over the years
What are the types of chemical signalling (9)
Synaptic:
- presynaptic cell releases hormones to receptor
- receptor becomes activated
- activated effector molecules enter the postsynaptic cell
Paracrine:
- presynaptic cell releases hormones to receptors on neighbouring cells
- receptors become activated
- activated effector molecules enter the neighboring postsynaptic cells
Endocrine:
- presynaptic cell releases hormones into the bloodstream
- hormones bind to receptors on a distant cell, activating it
- activated effector molecules enter the distant postsynaptic cell
What are the roles of the different hormone types (5)
- intracrine - receptors in the cell
- autocrine (local) - receptors on the outside of the same cell
- paracrine - adjacent cells
- endocrine (whole-body response) distant target cells
- neuroendocrine - neurosecretory cell releases hormones to distant target cells
What is the steroid hormone action (5)
- steroid hormone passes through the plasma membrane
- steroid hormone binds to a specific receptor protein in the cytoplasm or nucleus
- hormone-receptor complex enters the nucleus and binds to DNA, causing gene transcription
- Protein synthesis is induced.
- Protein is produced
What is the thyroxine hormone action (5)
- Thyroxine (T4) is secreted by the thyroid to the bloodstream, binding to transport proteins.
- In the target tissue, T4 is converted to T3 by deiodinases.
- T3 and some T4 enter target cells by diffusing through the membrane or transporter proteins.
- T3 binds to thyroid hormone receptors (THRs) in the nucleus.
- T3 triggers conformational change, initiating the transcription of target genes that regulate cellular processes.
What are ways in which peptide and steroid hormones interact to generate cellular responses (2)
- Peptide hormone → membrane receptor → second messenger → cellular response
- Steroid hormone → intracellular receptor → cellular response
