Endocrine System, Sarina RIvera Period 2
Major functions of the endocrine system
Maintains Homeostasis
Made up of cells, tissues, & organs
Hormones act on target cells & diffuse into the blood stream
Endocrine glands secrete hormones into body fluids
Paracine secretions (affect neighboring cells)
Autocrine cells (only affect secretory cells)
2 Major Types of Glands
Exocrine: secretes products into duct, outside internal
Endocrine: secretes hormones into body fluids to affect target cells
Major endocrine glands/organs and their functions
Pituitary Gland
Thyroid Gland
Parathyroid Gland
Adrenal Gland
Pancreas Gland
Pineal Gland
Reproductive Gland
Kidney's
Thymus
Anterior
Posterior
glandular epithelial tissue
located around blood vessels
enclosed in a capsule of collagenous connective tissue
part of nervous system
made up of axons of neurons of hypothalamus
stores hormones made by hypothalamus
releases hormones into blood, responding to nerve impulses from hypothalamus
Releasing & Inhibiting hormones (controlling secretion)
Hypophyseal portal Viens carry hormones in bloodstream
specific cells are stimulated to continue/stop releasing hormones.
Hormones
Hormones
Growth Hormone (GH):
body cells grow & reproduce
cells use carbohydrates & fats
GHRH releasing hormones, released by hypothalamus
increasing the amount being secreted, (GHIH) inhibiting hormones, inhibits secretion.
Prolactin (PRL)
increases milk production
controlled by Prolactin Releasing Factor (PRL) & Prolactin Inhibiting Hormone from hypothalamus
Thyroid-Stimulating Hormone (Thyrotropin or TSH)
controls secretion of hormones in thyroid gland
TRH (releasing) stimulates the release of TSH
Blood concentration increases, secretions of TRH & TSH decrease
Adrenocorticotrophic Hormone (ACTH)
Gonadotrophins
secretion of certain hormones from adrenal cortex
regulated by corticotropin-releasing Hormone (CRH) from hypothalamus
stress can increase CRH, which increases ACTH secretion
FSH & LH affect male (testis) & female (ovary) gonads
In males, LH is known as interstitial-cell stimulating hormone (LCSH)
Antidiuretic Hormone (ADH)
allows kidney's to conserve water
regulated by hypothalamus based on water in body fluids
osmoreceptors detect changes in osmotic pressure
high levels caused vasoconstriction of blood vessels, balancing blood pressure when dehydrated
Insufficient ADH = Diabetes Inspididus
Oxytocin (OT)
contracts muscles in uterine Wall during childbirth
forces milk-letdown into ducts from milk glands
stretching of uterus (pregnancy) creates release of oxytocin
Release is controlled by positive feedback.
located below larynx
2 broad lobes connected by an isthmus
contains follicles with colloid (stores hormones)
2 hormones help caloric intake
1 hormone regulates wood calcium growth & bone growth
Hormones
iodine-containing hormones
Thyroxine/Tetraidothyroine
Triiodothyronine
both regulate metabolism of carbohydrates, lipids, & proteins
determines basal metabolic rate (BMR) caloric intake
essential for growth development & nervous system growth
released by hypothalamus & pituitary gland
Calcitonin
released y extrafollicular cells
lowers blood levels of calcium & phosphate ions when too high
increases calcium deposition in bones by inhibiting osteoclasts & stimulating osteoblasts
increases calcium excretion by kidneys into urine
regulated by blood concentration of calcium.
located posterior of thyroid gland
Hormone
Parathyroid Hormone (PTH)
increases blood calcium ion concentration, decreasing phosphate ion concentration
stimulates bone resorption by osteoclasts, releasing calcium into blood.
makes kidney's conserve calcium
activates vitamin D by kidney's, increasing absorption of calcium in intestines
negative feedback involving blood calcium levels regulates PTH
contains a inner medulla & outer cortex, shaped like a pryamind
cortex makes up most of gland
made up of post-ganglionic neurons, connects to sympathetic nervous system
consist of epithelial cells in three layers
outer (glomerulosa)
middle (fasiculata)
inner (reticularis) zone
Hormones
Aldosterone
mineralocorticoid
regulated minerals/electrolytes
causes kidney's to conserve sodium ions & water to excrete potassium ions
responded to decreasing blood volume & pressure, detected by kidney
Cortisol
glucocorticoid, regulates glucose metabolism
created by cells in middle layer of cortex
restricts protein synthesis, increasing blood amino acids
increases use of fatty acids for energy & decreasing of glucose
liver cells produce glucose
Sex hormones
produced in the inner zone
mainly male hormones (adrenal/androgens)
secretes hormones as an endocrine gland & digestive juice into digestive tract as exocrine gland
hormones control level of blood glucose
Hormones
Glucagon
increases blood level (glucose)
breakdown of glycogen
change of non-carbohydrates into glucose by liver
negative feedback releases/controls glucagon
low blood glucose levels creates secretion of glucagon
Insulin
Decreases the blood level of glucose by allowing the liver to form glycogen
allows adipose cells to store fat
negative feedback releases/controls insulin
high blood glucose creates the release
Near upper portain of thalamus
produces melatonin
regulation of circadian rhythms
released at night but suppressed during day
located between lungs behind the sternum
produces thymosins
larger in children, shrinks with age.
ovaries produce estrogen & progesterone
placenta produces gonadotrophins
testes produce testosterone
produce erythropoietin fro blood cell produciton
Compare and contrast steroid vs. non-steroid hormones
Steroid Hormones
obtained from cholesterol
pass through cells membrane
carried through bloodstream
loosely bound to plasma proteins
protein receptors: located inside the target cell
Hormones Receptor Complex binds with DNA & activates specific genes
Non-steroid Hormones
Receptors are in the target cell membranes, contain binding site & activity site
first messenger
second messenger are chemicals responding to binding of hormone
signal transduction
Homeostatic mechanisms of hormone regulation (negative and positive feedback)
Negative feedback
sensitive to concentration of the substance it regulates
allows hormones to remain constant
controls hormone release
doe not allow more secretion, hormone secretion decreases
hormone level increase, applying effects
concentration hormone levels decrease, that's when glands secrete more again
Positive Feedback
has no limits to secretion
increases secretions levels
Diseases associated with the endocrine system
Growth Hormone Imbalances
Pituitary Dwarfism: GH Deficiency during Childhood
Gigantism: GH over secretion during childhood
Acromegaly: GH over secretion during adulthood
Thyroid Disorders
Parathyroid Disorders
Hypothyroidism
under activity in thyroid gland
creates low metabolic rate, fatigue, & weight gain in adults
poor growth for infants
Hyperthyroidism
over activity of thyroid gland
creates high metabolic rates, restlessness, overeating adults
can lead to eye prostitution (exopthalamia)
Hypoparathyroidism
low PTH
due to surgical removal/ injury to glands
decrease in blood calcium
Hyperparathyroidism
High PTH
maybe due to parathyroid tumor
increase of blood calcium
Adrenal Disorders
Addison Disease
hypersecretion of glucorticoids & mineralocorticoids
Crushing Syndrome
Hypersecretion of cortical hormones
Pancreas Disease/disorders
Diabetes Mellitus
Lack of insulin, inability of cells to recognize insulin
High Blood Glucose, harms eyes, heart, kidneys, & peripheral nerves
Interrupts metabolism of carbohydrates, fats, & proteins
glucose entry into body is impaired
Type 1 diabetes (Insulin-Dependent Diabetes Mellitus, IDDM)
autoimmune disorder
beta cells are destroyed
insulin production decreases/stops
Type 2 Diabetes (Non-Insulin Dependent, NIDDM)
Insulin produced but is not recognized by cells