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Endocrine system
the body's second great regulatory system  * An integrated system of small organs that involve the release of extracellular signaling molecules known as hormones 
What does the endocrine system do?
-regulates cellular activities by means of chemical messengers called hormones -these hormones can act at site independent of secretion and have short and long-term regulatory functions 
How does this differ from the nervous system?
1. neurons directly innervate tissue 2.stimulation is direct and immediate 
Major endocrine organs
1. Hypothalamus: has neural and endocrine functions and releases hormones  2.Pituitary Gland: storage and regulation site for secretion of other hormones  3.Thyroid  and Parathyroid  4.Pancreas 5. Adrenal Glands  6. Gonads 7. Other Tissues
Other Tissues and Organs that produce hormones
adipose cells pockets of cells in wall of small intestine (leptin and secretin) stomach (gastrin and HCL) kidneys Heart
Hormones
chemical messengers secreted by cells into extracellular fluids that affect other parts of the body
Hormones Function
1. alters membrane permeability  2. regulates metabolic activity 3. Activates/deactivates/ inhibits 4. enzyme activity  5. Stimulates mitosis 
Characteristics of Hormones
-lag times ranging from seconds to hours -Tend to have prolonged effects
Classification of Hormones
1. Amino acid-based: 1 or more amino acids (most are water soluble except thyroid hormones) 2. Steroids: derived from cholesterol (no WS ex: adrenal and gonadal glands) 3.Eicosanoids: biologically active lipids with LOCAL hormones-like activity 
Autocrines and Paracrines
autocrines: chemicals (not hormones) that exert effects on the same cells that secrete them  Paracrines: locally acting chemicals (not hormones) that affect cells other than those that secrete them
Amino Acids
Amines Peptides Protein hormones
Steroids
gonadal (ex: testosterone) adrenocortical hormones
Eicosanoids (not really hormones)
leukotrienes prostaglandins 
How do hormones exert a biological effect of tissue?
RECEPTORS are vital for activation  1. membrane bound (surface): water soluble 2.Intracellular (inside cell): not soluble 
Why do the same hormones affect some tissues/organs differently ?
Target Cell Specificity 
How do we regulate Hormones activity 
1. Hormones concentration: rate of release and inactivation and removal based on volume  2. Receptor Concentration: cells can increase or decrease the number of receptors expressed
1/2 life 
the time required for a hormone's blood level to decrease by half
How are hormones removed from blood?
degrading enzymes -kidneys and liver
Three Types of Hormone Interaction
1. Permissiveness: one hormone cannot exert effects w/o another (ex: GH and thyroid hormone) 2.Synergism: more than one hormone produces same effect on target cells 3. Antagonism: one or more hormones opposes action of another (insulin and glycogen)
How are Endocrine Hormones regulated?
1. Humoral Stimulus: capillary blood (Ca2+/ glucose) stimulates secretion of hormones (PTH increases Ca2+ levels/liver> glucose/ pancreas> insulin) 2. Neural stimulation: regulated by direct nervous system input (adrenal medulla--> E and NE) 3.Hormonal regulation: regulated by hormones …
Hypothalamus
-midbrain -connects to pituitary gland by infundibulum (stalk) and is located within cave-like bone called ?
Neurohypophysis
1. posterior lobe (neural tissue) 2. and infundibulum 
How does hypothalamus connect to posterior/ anterior pituitary gland?
posterior: nerves/ neurons --> strictly storage anterior: no neural connection just VASCULAR
Adenohypophysis 
anterior lobe made out of glandular tissue 
Hypophyseal Vein Portal System
1. primary capillary plexus (infundibulum) 2. Hypophyseal plexus  3.Secondary capillary plexus (where anterior pituitary hormones are secreted)
Anterior pituitary Gland
REAL pituitary gland: synthesizes and secretes a number of hormones 1. Growth hormones 2. thyroid stimulating hormone 3. adrenocorticotropic hormone  4. Gonadotropins 5. Prolactin
Growth Hormone
-produced by somatotropic cells of anterior lobe -stimulates most cell division; specifically target bone and skeletal muscle -promotes protein synthesis and encourages use of fats for fuel -most effects are mediated by Insulin-like growth factors (IGFs)
GH is regulated by Antagonistic hypothalamic hormones
-Growth hormone-releasing hormone (GHRH): stimulates anterior pituitary gland to release GH (positive biofeedback) -Growth hormone-inhibiting hormone (GHIH): produced by hypothalamus inhibits anterior pituitary from releasing GH (neg. feedback)
Directs effects of GH
1. anti-insulin actions : releases glucose from liver by breaking down glycogen and stopping cells from reuptake  2. Increases lypolysis: breaking down fats for energy 3. Liver and other tissues: like insulin-growth factors (IGFs)
Indirect effects of GH
1.GH acts through IGFs to indirectly increase cartilage formation and skeletal bone growth 2.Increases protein synthesis and cell growth
GH deficiency
Infant= hypoglycemia Childhood=pituitary dwarfism (muscles and bones) Adult=loss of lean tissue mass (more fat) ; not as much of an effect because epiphyseal plate is closed
GH excess
childhood=pituitary gigantism (up to 8ft) adults=Acromegaly (enlargement of extremities)
Thyroid Stimulating Hormones (TSH)
-stimulates normal development of secretory activity of thyroid  -triggered by hypothalamic peptide thyrotropin-releasing hormone (TRH) -rising blood levels of thyroid hormone act on pituitary gland & hypothalamus to block release of TSH (neg. feedback)
Adrenocorticotropic Hormone (ACTH)
-stimulates adrenal cortex to release corticosteroids (cortisol) -triggered by hypothalamic corticotropin-releasing hormone (CRH) in daily rhythm -Internal and external factors such as fever, hypoglycemia, and stressors can trigger release of CRH
Gonadotropins
1. follicle stimulating hormone FSH: stimulates gamete (egg or sperm) production 2.Lutenizing hormone (LH): promotes production of gonadal hormones (estrogen and testosterone) *triggered by gonadotropin-releasing hormone (GnRH) during/after puberty
Negatuve feedback of gonadotropins
testosterone, progesterone, and estrogen will inhibit the hypothalamus from releasing GnRH
Deficiency of gonadotropins?
failure of sexual maturation and possible infertility
LH & FSH is females/males
F- LH & FSH cause maturation of ovarian follicle; LH alone triggers ovulation (expulsion of egg from follicle) and promotes synthesis and release of estrogens and progesterone  M-LH stimulates interstitial cells of testes to produce testosterone
Prolactin 
-in females stimulates milk production by breasts -triggered by hypothalamic prolactin-releasing hormone (PRH) -inhibited by prolactin-inhibiting hormone (PIH) or dopamine (neg. feedback) -blood levels rise toward end of pregnancy and suckling
Deficiency/overproduction in Prolactin
deficiency-poor milk production overproduction males=impotence and breast enlargement  females=inappropriate milk production
The Posterior Pituitary Gland
1.oxytocin and ADH
oxytocin 
-stimulates uterine contraction -positive feedback mechanism -triggers milk ejection "LET DOWN" reflex -"cuddle hormone" --> may have role in sexual arousal
ADH (antidiuretic hormone)
-helps to avoid dehydration -prevents urine formation -osmoreceptors -high osmolarity= ADH preserves water -low osmolarity=ADH not released causing water loss ALCOHOL inhibits ADH release and causes copious urine output 
Diabetes Insipidus (ADH deficiency)
abnormal increase in urine output, fluid intake and often thirst  -symptoms: dilute urine; increased urinary frequency (nocturia ) and enuresis (involuntary  urination during sleep) Cause: death of ADH producing cells in hypothalamus
ADH Overproduction
-syndrome of inappropriate ADH production (SIADH) -symptoms:hypoatremia:not enough sodium in the body fluids outside the cells;  elevated urine osmolality -excessive sodium in urine causes: hypovolemia (low blood volume);ADH-secreting tumor
Thyroid Gland
-anterior neck -butterfly shape -very vascularized (carotid arteries)  -two lobes (isthmus connects)
Hormones of Thyroid Gland
1. Thyroid hormone 2. Calcitonin 
Thyroid hormone
follicle cells-->produce thyroglobulin--> need iodine (3 atoms) to produce thyrozine (T4) and T3 parafollicular cells(outside)--> make calcitonin  1.Glucose oxidation 2.increasing metabolic rate 3. heat production 
Thyroid Hormone plays a role in ...
1. maintaing BP 2.Regulates tissue growth (everywhere but RBCs) 3.Developing skeletal and nervous systems 4.maturation and reproductive capabilities  5.Permissive hormone (w/ GH)
Cretinism (children)
Symptoms: low metabolic rate, growth retardation, developmental delay Caused: lack of iodine in maternal diet or genetic factors
Myxedema (adults)
Symptoms: low metabolic rate, skin and tissue disorder usually due to severe prolonged hypothyroidism , dry skin and extrememly tired
Goiter
-swollen thyroid gland due to lack of iodine in diet and over production of thyroglobulin 
Graves disease
-hyperthyroid disorder/ autoimmune disease -Symptoms: inflammation of tissues around eyes causing swelling and bulging (exophthalmos); high metabolic rate; sweating;rapid and irregular heart beat; nervousness; weight loss; protruding eye balls
Calcitonin 
-regulates calcium level  -humoral stimulus -Calcium in blood stream-->inhibits osteoclast activity which keeps calcium in bones and reduces it in the blood -lack of calcium in blood means calcitonin won't work (neg. feedback)
Parathyroid Gland
-4 glands total -cells are arranged in cords containing oxyphil and chiefs cells -Chief cells secrete PTH 
Parathyroid Hormones
-raises blood calcium levels (antagonistic to calcitonin) -no connection in production just antagonistic in function -Humoral Function (neg. biofeedback ) calcium levels up in blood then parathyroid hormone will NOT be released
Target Organs of Parathyroid Hormone 
1. bone 2. intestine 3. Kidney: increases Ca2+ reabsorption and promotes activation of Vit D which increases calcium absorption from fluid
Hyperparathyroidism 
rare and usually results from a parathyroid gland tumor  -calcium is leached from bones and it causes them to soften and deform 
Hypoparathyroidism
-PTH deficiency -usually follows parathyroid gland trauma or removal -hypocalcemia -results in tetany (loss of sensation, muscles twitches, and convulsions) -Untreated can lead to paralysis and death
Adrenal (Suprarenal) Gland
-2 Glands in 1 1. Adrenal medulla: neural tissue that acts as part of SNS  2. Adrenal cortex: secretes steroid hormones 
Adrenal Cortex 
-Synthesizes and releases steroid hormones called corticosteroids  1. zona glomerulosa --> mineralocorticoids (aldosterone) 2. zona fasciculata --> glucocorticoids (cortisol) 3. zona reticularis--> gonadocorticoids (androgens)
Mineralocorticoids (Aldosterone Regulation)
*essential function is to regulate electrolyte (mineral salt) concentrations in extracellular fluids particular Na+ and K+
Primary Regulators 
1. Blood volume/pressure is low /  K+ levels are high  2. kidneys to release Renin which produces Angiotensin II 3. zona glomerulosa of adrenal cortex secretes aldosterone 4. Targets kidney tubules  5. absorp. of Na+ / increased excretion of K+ 6.blood volume/pressure increases
Other Factors: ACTH
1. Stress 2. hypothalamus secretes MORE corticotropin-releasing hormone (CRH)  3. anterior pituitary releases ACTH into blood 4.zona glomerulosa releases aldosterone  5. kidney tubules/absorop. Na+ and excretion of K+ 6. BP up (to deliver nutrients)
Other Factors: Atrial Natruiretic Peptide (ANP)
1. Blood pressure/volume high 2. heart 3. Atrial natriuretic peptide (ANS)-- inhibitory effect 4.zona glomerulosa of adrenal cortex releases aldosterone  5. kidney tubules 6.increased absorp. of Na+ and excretion of K+ 7.BP increases

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