endocrine system chapter 45. endocrine system regulation & communication blood system glands...
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Endocrine system Regulation & communication Blood system Glands (ductless) Hormones (chemicals) Target tissues
Both systems (overlap) Neurohormone Released by the nervous system Into blood stream (ADH)
Norepinephrine Chemical involved in both Nervous system (cleft) Endocrine system (adrenal gland)
Both systems Neural control of endocrine system Hypothalamus Regulates hormonal secretion of the
anterior pituitary Glands derived from nervous tissue Adrenal medulla, posterior pituitary
& pineal gland
Local regulators Paracrine Messages between neighboring cells 1. Cytokines
Regulate immune system 2. Growth factors
Regulate cell growth 3. NO
Vasodilation (local blood vessels)
Local regulators 4. Prostaglandins 20-carbon fatty acid Derived from lipids in plasma
membrane Found in many organs Released into interstitial fluid
Local regulators 4. Prostaglandins A. Immune system
inflammation B. Reproductive system
Labor Semen
C. Digestive system Inhibit gastric secretions Increase gut motility
Local regulators D. Respiratory system
Some cause dilation Some cause constriction
E. Circulatory system Platelets
F. Urinary system Renal vasodilation Increased excretion
Hormone types 1. Polypeptide
Short, <100 aa, insulin, ADH 2. Glycoprotein
>100 aa, carbohydrate attached, FSH, LH 3. Amines
Tyrosine & tryptophan Adrenal medulla (NE, Epinephrine) Thyroid (T3 & T4
Pineal (Melatonin)
Hormone types 4. Steroids
Lipids from cholesterol Testosterone Estradiol, progesterone Aldosterone, cortisol
Mechanism of regulation 1. Enter the cell Lipophilic Lipid soluble 2. Do not enter the cell Lipophobic Water soluble
Mechanism of regulation 1. Lipophilic (Steroids, thyroxine) Not water soluble Plasma attached to protein carriers Target cell-release carrier Cross plasma membrane Bind receptor protein (+/- nucleus) Hormone receptor binds DNA Protein synthesis
Mechanism of regulation
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Mechanism of regulation 2. Lipophobic or too large Bind receptors on target cell
membrane A. Triggers second-messenger system cAMP IP3/Ca+2
B. Causes change in an ion channel
Mechanism of regulation
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Thyroid Neck 2 lobes/isthmus T4 (tetraiodothyronine) thyroxine T3 (triiodothyronine) Regulates metabolism in the body Calcitonin Stimulates Ca2+ uptake into bones Decreases serum Ca+2
Parathyroid glands Neck 4 small glands on top of thyroid PTH (parathyroid hormone) Increase in blood calcium levels Stimulates osteoclasts Break down calcium phosphate crystals Stimulates kidneys to reabsorb Ca2+
Activates Vitamin D
Pancreas Abdomen behind stomach Islets of Langerhans Insulin ( cells) Decreases blood glucose levels Stores in glycogen (liver/muscle) & fat
(adipose cells) Glucagon ( cells) Increases glucose blood levels
Ovaries Abdomen Estrogen Secondary female characteristics Menstruation Progesterone Prepares/maintains pregnancy
Adrenal glands Small glands on top of kidneys 1. Adrenal cortex Outer layer 2. Adrenal medulla Inner layer
Adrenal glands Adrenal cortex A. Corticosteriods Cortisol (glucocorticoid) Increases serum levels of glucose Gluconeogenesis Converts aa to glucose Exercise or fasting
Adrenal glands B. Mineralcorticoids Aldosterone Stimulates kidneys to reabsorb Na+1
Stimulates kidneys to eliminate K+1
C. Gonadocorticoids Androgens Sex characteristics
Adrenal glands Adrenal medulla Catacholamines Epinephrine/norepinephrine Increased heart rate, BP, glucose
blood levels, Dilation of bronchioles Decreased blood flow to skin and gut
Pituitary gland (hypophysis) In the brain Hangs by a stalk from hypothalamus 1.Anterior Adenohypophysis Developed from epithelial tissue 2. Posterior Neurohypophysis Developed from the neural tissue Nerve axons from hypothalamus end here
Anterior pituitary gland All hormones stimulate growth in
target organs Tropins A. GH (growth hormone) Somatotropin Stimulates muscle growth (bone)
Anterior pituitary gland B. ACTH Adrenocorticotropic hormone Corticotropin Stimulates adrenal cortex (cortisol) C. TSH Thyroid-stimulating hormone Thyrotropin Stimulates thryroid to produce thyroxine
Anterior pituitary gland D. LH Luteinizing hormone Stimulates ovulation & lining of
uterus Stimulates testes to produce
testosterone
Anterior pituitary gland E. FSH Follicle stimulating hormone Stimulates the egg development Development of sperm F. Prolactin Stimulates mammary glands to
produce milk
Anterior pituitary gland G. MSH Melanocyte-stimulating hormone Causes darkening of skin in some
fish, amphibians & reptiles
Posterior pituitary gland A. ADH Antidiuretic hormone (vasopressin) Stimulates water retention in the
kidneys B. Oxytocin Milk ejection from mammary glands Stimulates uterine contractions in
labor
Pineal gland Small mass of tissue located near
center of brain Synthesizes & secretes melatonin
(modified aa) Regulates functions related to day
and night Seasons
Hypothalamus
Spinal cord
Posteriorpituitary
Cerebellum
Pinealgland
Anteriorpituitary
Hypothalamus
Pituitarygland
Hypothalamus
Thalamus
Cerebrum
Hypothalamus control Posterior pituitary (direct) Stimulation in hypothalamus Causes release of hormone from
axon in pp ADH released increased blood
osmolality Oxytocin released due to baby
suckling
Hypothalamus
Posteriorpituitary
Anteriorpituitary
Neurosecretorycells of thehypothalamus
Hypothalamus
Axon
HORMONE OxytocinADH
Kidney tubulesTARGET Mammary glands,uterine muscles
Hypothalamus control Controls release of AP hormones Neurons in Hypothalamus secrete
releasing or inhibiting hormones Anterior Pituitary (negative
feedback)
thyroid
Cold
Pathway
Stimulus
Hypothalamus secretesthyrotropin-releasinghormone (TRH )
Example
Sensoryneuron
Neurosecretorycell
Bloodvessel
+
Anterior pituitary secretesthyroid-stimulatinghormone (TSHor thyrotropin )
thyroid
Cold
Pathway
Stimulus
Hypothalamus secretesthyrotropin-releasinghormone (TRH )
Neg
ativ
e fe
edb
ack
Example
Sensoryneuron
Neurosecretorycell
Bloodvessel
Anterior pituitary secretes thyroid-stimulatinghormone (TSHor thyrotropin )
Targetcells
Response
Body tissues
Increased cellularmetabolism
–
Thyroid gland secretes thyroid hormone (T3 and T4 )
–
Anterior pituitary
Hypothalamicreleasing andinhibitinghormones
Neurosecretory cellsof the hypothalamus
HORMONE
TARGET
Posterior pituitary
Portal vessels
Endocrine cells ofthe anterior pituitary
Pituitary hormones
Tropic effects only:FSHLHTSHACTH
Nontropic effects only:ProlactinMSH
Nontropic and tropic effects:GH
Testes orovaries
Thyroid
FSH and LH TSH
Adrenalcortex
Mammaryglands
ACTH Prolactin MSH GH
Melanocytes Liver, bones,other tissues
Problems Thyroid Graves disease Over production of thyroxine Cretinism To little thyroxine in children Leads to delayed skeletal and
mental growth
Problems Growth hormone (anterior
pituitary) Gigantism too much hormone Pituitary dwarfism to little hormone Acromegaly to much hormone
after growth plates are fused