Endocrine System
Download
Report
Transcript Endocrine System
Endocrine System
Overall Functions
Regulatory System
Maintains homeostasis internally
Responds to environmental changes
Growth and development
Reproduction
Glands
Exocrine e.g. salivary glands
Endocrine e.g. Thyroid gland
Hormone
Definition: A chemical messenger carried
by bloodstream and made by endocrine
glands.
Structure
Transport in body
Action of hormones
Target cell
Receptors
– Plasma membrane
– Within target cell
Second messenger (cAMP)
Activation of genes
Relationships
To other hormones
To nervous system
Controls
Negative Feedback
Releasing hormones and Inhibiting
hormones from Hypothalamus
PITUITARY GLAND
(Hypophysis)
Location – in sella turcica of sphenoid bone
Hormones of the
Adenohypophysis
Gonadotropins
– FSH = Follicle Stimulating Hormone
– LH/ICSH = Luteinizing hormone in female,
Interstitial cell stimulating hormone in male
Adenohypophysis
TSH = Thyroid stimulating hormone
ACTH = Adrenocorticotropic hormone
GH = Growth hormone
Prolactin
MSH = Melanocyte stimulating hormone
(endorphins)
Adenohypophysis
Controls
Inhibiting hormones and Releasing
hormones
Brain
Negative feedback
Neurohypophysis
Infundibulum (hypothalamic-hypophyseal
tract)
ADH = Antidiuretic hormone = Vasopressin
Oxytocin
Thyroid Gland
Location
Histology
Follicles, colloid
Thyroid hormones
Thyroid hormone
Iodine
T4 (thyroxine – 90%)
T3 (thriiodothyronine – 10%)
TBG (thyroid binding globulin)
Function
Controls
Thyroid Hormone Synthesis
Tyrosine + Iodine Monoiodotyrosine
+ Iodine Diiodotyrosine
2 Diiodotyrosine Tetraiodothyronine =
T4 = Thyroxine
Thyroid Hormone Synthesis
1 Diiodotyrosine + 1 mono…
Triiodothyronine = T3
Thyroid gland
Calcitonin
Parafollicular (C) Cells
Decreases Ca and P
Controls
Parathyroid glands
Location
PTH (Parathromone)
Increases Ca and decreases P
Controls
Adrenal gland
Location
Adrenal Medulla
Chromaffin cells
Epinephrine (80%)
Norepinephrine (20%)
Action
Release
Adrenal gland
Adrenal Cortex
Mineralocorticoids
– Zona glomerulosa
– Aldosterone (90%)
– Na reabsorption, K excretion in kidneys
Aldosterone
Release/Controls
Renin, Angiotensin
K/Na levels
ACTH, CRH
Adrenal cortex
Glucocorticoids
– Zona fasciculata
– Conserves and supplements energy
– Anti-inflammatory
– Release/Controls
ACTH, CRH,
Stress
Adrenal cortex
Sex hormones
– Zona reticularis
Pancreas
Location
Endocrine AND Exocrine
Pancreatic islets = Islets of Langerhans
Insulin
Beta cells
Lowers blood glucose
Controls
Glucagon
Alpha cells
Raises blood glucose
Controls
Somatostatin
Delta cells
Inhibits GH release
Controls
Blood glucose levels
GI
ANS
Gonads
Testes make androgens
Ovaries make estrogen and progesterone
TO BE DISCUSSED LATER
Pineal Gland
Location
– Roof of third ventricle in brain
Melatonin
– Decreases reproductive activity
Thymus
Location
– Mediastinum, above heart
Puberty
Immunity
Thymic Hormone stimulates T cell
maturation
Prostaglandins
Fatty acids
Localized hormones
Functions vary