The Endocine System Flashcards
What are the main components of the endocrine system?
Hypothalamus, pituitary gland, thymus, thyroid and parathyroid glands, pancreas, adrenal glands.
What is the chemistry of hormones?
Chemical messengers secreted by cells into extracellular fluid
Most are peptide hormones eg. Insulin
Some are steroid hormones eg. Sex hormones
What is the normal hormone change pathway?
Alters plasma membrane perm or membrane potential
Stimulates synthesis of proteins or regulatory molecules
Activates/deactivates enzymes
Secretory activity
What is the difference between fat soluble and water soluble hormones?
Fat soluble can pass through cell membranes and bind to receptor in cytoplasm, then complex enters nucleus -> transcription and translation.
What does target cell activation by hormone receptor interactions depend on?
- Blood levels of hormones
- Relative number of receptors
- Affinity - how well hormone binds
What are features of the pituitary gland?
Connected to hypothalamus by infundibulum.
2 major lobes.
What is the function of the posterior pituitary?
Releases neurohormones made by hypothalamus - oxytocin and ADH. S
Stored on posterior pituitary.
What is the function of the anterior pituitary?
Made of glandular tissue.
Releases/makes many hormones.
Summarise ADH.
Osmoreceptors in the hypothalamus monitor solute conc in blood, acts within kidney to increase water reabsorption using aquaporins.
Summarise oxytocin.
Strong stimulant of uterine contractions (childbirth).
What are features of the thyroid gland?
2 lateral lobes connected by isthmus.
Follicle cells produce thyroglobulin.
Parafollicular cells produce calcitonin.
Thyroxine needs iodine to regulate growth.
What are features of the adrenal glands?
Each gland functions independently.
Adrenal medulla and cortex
4 major mechanisms regulate aldosterone productions.
What are glucocorticoids?
Influence energy metabolism and help body adapt to intermittent food intake.
Cortisol = main one in humans.
What are features of the pancreas?
Endocrine and exocrine functions.
Acinar cells produce enzyme rich digestive juice, between these are islets of Langerhans.
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