MD2001 Flashcards
Endocrine system
- Second integrative control system in the body
- Slower to act than nervous system
- Actions mediated by hormones
Endocrine glands
No ducts, hormones secreted and released directly into blood from extracellular fluid
Classes of hormones
Proteins
Steroids modified cholesterol)
Amino acid derivatives
Paracrine secretion
- Polypeptides diffuse over short distance (hormones into interstitial fluid and binds to receptor on nearby cell)
- Cell to cell communication (induce changes in adjacent cells)
- Important in embryogenesis & influence developmental change
Glands
Hypothalamus Pituitary gland Thymus Pancreas Testis Ovary Adrenal gland Parathyroid glands Thyroid gland Pineal gland
Hormones secreted by anterior lobe of pituitary (adenohypoplysis)
Growth hormones Thyroid stiumlating hormones Adrenocorticotropic hormones FSH LH Prolactin
Hormones secreted by posterior lobe of pituitary (neurogyoiogysis)
ADH
Oxytocin
Consists neural tissue, secretes hormones secreted by neurosecretory cell in hypothalamus, transported via neural axons in stalk to posterior lobe of pituitary
Pituitary adenoma (tumour)
Gigantism
Acromegaly (abnormal growth or hand, feet & face)
Enlarged hands/feet after puberty
Thyroid gland
Anterior to trachea
Hormones secreted by follicular cells, stored as larger molecule
Thyroglobulins in colloid (T3&T4 - regulate rate of metabolism, growth & development, sensitivity of cells to hormones)
Thyroid gland
Anterior to trachea
Hormones secreted by follicular cells, stored as larger molecule
Thyroglobulins in colloid (T3&T4 - regulate rate of metabolism, growth & development, sensitivity of cells to hormones)
Parafollicular C cells - calcitonin (stimulate osteoblast)
Disorders: overeactive / understactive
Parathyroid glands
Develop from wall of pharynx
2 pair of glands
Posterior aspect of thyroid
Produce parathyroid hormones (stimulate osteoclast - break down bone matrix to increase calcium level)
Adrenal glands
Cortex:
- 3 layer of epithelial cell:
Zona glomerulosa - mineralcoticoids: Aldosterone
Zona fasciculata - glucocorticoids: Cortisol
Zona reticular - sex steroids: Androgens
Medulla:
Neural crest cells - Developed from neuroctoderm
- Contains chromaffin cell, produce catecholamines (epinephrine, dopamine, norepinephrine)
Produce steroid hormones (connection with SNS - fight/flight)
Abnormalities: Cushing syndrome
Pancreas
Exocrine & endocrine gland
Develop as continue growth of gut lube
Associated with development of gallbladder
Exocrine (Pancreatic acini produce pancreatic amylase; disorder: pancreatitis)
Endocrine (Islets of Langerhans produce hormones; alpha = glucagon & beta = insulin; diabetes mellitus)
GI Tract
Gastrin
Kidney
Renin
