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Endocrine Functions

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Endocrine System
consists of ductless endocrine glands scattered throughout the body
Hormones
chemical messengers
-go to target cells that contain receptor proteins for it
What are the 2 hormone categories in the endocrine system?
-hydrophylic
-lipophilic
What are the functions of the endocrine system?
-regulate organic metabolism and H2O and electrolyte balance
-induce adaptive changes to help body cope w/ stressful situations
-promote growth and development
-control reproduction
-regulate red blood cell production
-control circulation/digestion/absorption of food
Lipophilic Hormones
-nonpolar hydrophobic (water hating) lipid-loving
-include steroid and thyroid hormones
*can pass through the cell membrane
Hydrophylic
-polar hydrophilic (water loving) lipid-hating
-do not readily pass through the cell membrane
Second Messengers
messengers that communicate the info of hormones that cannot pass through the membrane
Tropic Hormones
-regulate hormone secretion by another endocrine gland
Endocrine Glands
-do not have ducts
-work w/ nervous system for control of bodily functions
-indirect link to tissue
-specificity
Exocrine Glands
-have ducts that carry their secretions to specific locations
-direct pathways
How do hormones bind to nuclear receptor proteins?
-lipid hormones travel in blood attached to carrier proteins
-they dissociate from carriers to pass thru plasma membrane of target
Chemical Classification of Hormones
-amine
-polypeptide
-glycoproteins
-steroids
Amines
hormones are derived from tyrosine or tryptophan (melatonin)
Polypeptides
amino acids maybe short chain or long chain
Glycoproteins
proteins combined to 1 or more CHO groups
Steroids
lipids derived from cholesterol (testosterone, estrogen, progesterone, cortisol)
Permissiveness
one hormone must be present in adequate amounts for full exertion of another hormone's effects
*if you release epinephrine in a cell and its affects make more binding sites for thyroid hormonesa
Synergism
-occurs when actions of several hormones are complimentary
-combined effects is greater than the sum of their separate effects
Antagonism
-occurs when one hormone causes loss of another hormone's receptors
-reduces effectiveness of second hormone
High blood levels cause...
hypertrophy
Low blood levels cause...
atrophy
What promotes growth, protein synthesis, and movement of amino acids into cells?
Growth Hormone (GH)
What stimulates thyroid to produce and secrete T4 & T3?
Thyroid Stimulating Hormone (TSH)
What stimulates adrenal cortex to secrete cortisol, aldosterone?
Adrenocorticotrophic Hormone (ACTH)
What stimulates growth of ovarian follicles & sperm production?
Follicle Stimulating Hormone (FSH)
What causes ovulation and secretion of testosterone in testes?
Luteinizing Hormone (HL)
What stimulates milk production by mammary glands?
Prolactin (PRL)
Posterior Pituitary
stores and releases 2 hormones produced in hypothalamus:
*Antidiuretic Hormone
*Oxytocin
Antidiuretic Hormone
-promotes H2O conservation by kidneys
-causes contraction of smooth muscles in arterioles
Oxytocin
-stimulates contractions of uterus during parturition (childbirth)
-stimulates contractions of mammary glands alveoli for milk ejection reflex
Thyroid Gland
secretes T4 & T3 which set BMR and are needed for growth and development
Effects of Thyroid Hormone...
-main determinant of basal metabolic rate
-influences synthesis and degradation of carbs, fat, & protein
-increase target-cell responsiveness to catecholamines
-increases heart rate and force of contractions
-essential for normal growth
-plays crucial role in normal development of nervous system
Hypoactive Thyroids
-an underactive thyroid
-slowing down of physical processes that result from insufficient thyroid hormone
-symptoms: fatigue, constipation, weight gain, low blood pressure
Hyperactive Thyroids
-rapid metabolism resulting from oversupply of thyroid hormone
-symptoms: anxiety, insomnia, weight loss, diarrhea, high blood pressure
Islets of Langerhans
-scattered clusters of endocrine cells in pancreas
-contain alpha, beta, & delta cells
Beta Cells
site of insulin synthesis & secretion in response to high blood glucose
Alpha Cells
produce glucagon
Delta Cells
pancreatic site of somatostatin synthesis: monitors bloods glucose & regulates insulin & glucagon activities (most impotant in regulating fuel metabolism)
Diabetes Mellitus
-most common of all endocrine disorders
-prominent feature is elevated blood glucose levels
-2 major types: Type I & Type II
Type I Diabetes
lack of insulin secretion
Type II Diabetes
normal/even increased insulin secretion but reduced sensitivity of insulin's target cells
Mineralocorticoids
-found in adrenal glands
-mainly aldosterone
-influence mineral balance specifically Na+ and K+ balance
Glucocorticiods
-found in adrenal glands
-primarily cortisol
-major role in glucose metabolism, protein and lipid metabolism
Dehydroepiandosterone
-male sex hormone
Adrenal Medulla
-activated during fight/flight response; releases epinephrine
-causes: increased respiratory rate, increased HR & cardiac output, general vasoconstriction which increases venous return, glycogenolysis & lipolysis
General Adaption Syndrome
-stress induced, nonspecific response
-causes ACTH & cortisol release
-affects physiology negatively
Autocrine Regulators
-produced and act within same tissue of an organ
-control gene expression in target cells
Paracrine Regulators
-autocrines produced in one tissue and act on different tissues in same organ
Cytokines
any # of substances that are secreted by specific cells of the immune system
Growth Factors
promote growth and cell divition
Neutrophins
provides trophic support for normal and regenerating neutrons
Why do hormones want to work with specific target cells?
specificity
What is a hormone that is chemically combined with a protein and carb?
glycoprotein
What are the 2 lobes of the pituitary glands?
anterior and posterior
What are some of the affects of the anterior and posterior pituitary glands?
-sex
-protein synthesis
-metabolism
Where are adrenal glands located?
above the kidneys