Chapter 17 A&P 2 Endocrine System
Oxytocin (OT) (Posterior Pituitary Hormone)
(blank) has a variety of reproductive functions in situations ranging from intercourse to breast-feeding. It surges in both sexes during sexual arousal and orgasm, possibly aiding in the propulsion of semen through the male reproductive tract and stimulating uterine contractions that help transport sperm up the female tract. (blank) also functions in feelings of sexual satisfaction and emotional bonding between partners. In child birth it stimulates labor contractions and in lactating mothers, it stimulates the flow of milk from deep in the mammary gland to the nipple. May also promote bonding between the mother and infant.
Prolactin (PRL)
(blank) is secreted by pituitary cells called lactotropes. The hormone and these cells are named for the role in lactation. During Pregnancy, the lactotropes increase greatly in size and number, and (blank) secretion rises proportionately, but it has no effect of the mammary glands until after woman gives birth. Then, it stimulates them to synthesize milk
Growth Hormone (GH) or Somatotropin (inhibits growth)
(blank) is secrted by somatotropes, the most numerous cells of the anterior pituitary. the pituitary produces at least a thousand times as much (blank) as any other hormone. General effect of (blank) is to stimulate mitosis and cellular differentiation and thus promote tissue growth throughout the body.
Negative Feedback
(the brake that reverses or stops production)- Increased target organ hormone levels inhibit the release of hormones
Peptide Hormones
3 to 200 or more amino acids. the two posterior pituitary hormones, oxtocin and antidiuretic hormone
Anterior Pituitary galnd
3/4 of gland, has no nervous connection to the hypothalamus but is linked by a complex of blood vessels called HYPOPHYSEAL PORTAL SYSTEM. hormones secreted by hypothalamus control the (blank)
Hypothalamic Hormones
6 regulate the anterior pituitary and 2 are stored in the posterior pituitary.
Pancreatic Islets have 3 main cell types
A Cells- secrete glucagon B Cells- secrete insulin, promotes the syntheis of glycogen ,fat, and protein thereby promoting the storage of excess nutrients for later use and enhancing cellular growth and differentiation D Cells- Secrete Somatostatin ( Growth Hormone) concurrently with the release of insulin by the beta cells. Somatostatin inhibits the secretion of stomach acid.
Target Organ or target cells
A cell or organ acted upon by nerve fiber , hormone, or other chemical messenger
Steroids
Aldosterone, Androgens, Calcitriol, Corticosterone, Cortisol, Estrogens Progesterone
Hormones
All hormones are made from either cholesterol or amino acids , with carbohydrate added in the case of glycoproteins
Cholesterol or Amino Acids with carbohydrates
All hormones are made up of
Half-Life
All hormones have a half-life, which is the time required for 50% of the hormone to be cleared from the blood. GH is short-lived; its half-life is only 6 to 20 minutes.
Hyperglycemic hormone
Any hormone that raises blood glucose conentration
Steroid Hormone
Are derived from cholesterol, include sex steroids(estrogen, progesterone, and testerone) produced by the testes and ovaries. and corticosteroids produced by the adrenal glands (such as cortisol, aldosterone and dhea)
GH & IGF are responsible for:
Carbohydrate Metabolsim- ( ) also has a glucose-sparing effect. Its role in mobilizing fatty acids reduces the dependence of most cells on glucose so they will not compete with the brain, which is highly glucose-dependent. ( ) also stimulates glucose syntheisis by the liver
Neuroendocrine Cells
Cells that act like neurons in many respects, but like endocrine cells they release their secretions into the bloodstream.
Gonadtropins
Collectively , FSH (Follicle-Stimulating Hormone) and LH (Luteinizing Hormone) they target the ovaries and testies
Neuroendocrine reflexes
Controls the posterior pituitary , release of hormones in response to nerve signals
Steroids (physiology)
Derived from cholesterol and are hydrophobic, they easily pass through the cell membrane. Consist of estrogen, progesterone, testosterone, cortisol, corticosterone, aldosterone, dhea and calcitriol
Monoamines
Dopamine, Epinephrine, Melatonin, Norepinephrine, , thyroid hormone
GH & IGF are responsible for:
Electrolyte Balance- ( ) promotes NA+ , K+ and CL- retention by the kidneys, enhances Ca2+ absorption by the small intestine, and makes these electrolytes available to the growing tissues.
Polypeptide
Except for dopamine the releasing and inhibiting hormones produced by the hypothalamus
GH continued
Fluctuates greatly over the course of a day. It rises 20 nanograms per milliliter of blood plasma (ng/ml) or higher during the first 2 hours of deep sleep, and may reach 30ng/ml in response to vigorous exercise
Hypothalamus
Forms the floor and walls of the third ventricle of the brain. It regulates primitive functions of the body ranging from water balance and thermoregulation to sex drive and child birth
GH continued
GH Level declines gradually with age. It averages about 6 ng/ml in adolescence and one-quarter of that in very old age.
Exocrine Glands
Glands that secrete hormones by ducts
LH (Luteinizing Hormone)
In females it stimulates ovulation, the release of an egg. After ovulation the follicle becomes yellowish body called the corpus luteum. (blank) also stimulates the corpus luteum to secrete progesterone, a hormone import in pregnancy. In males (blank) stimulates the testess to secrete testosterone.
Gap Junction
Join single-unit smooth muscle, cardiac muscle, epithelial and other cells to each other. Enable cells to pass nutrients, electrolytes and signaling molecules directly from the cytoplasm of one cell to the cytoplasm of the next through pores in their plasma membrane
Thyroid Gland
Largest adult gland to have purely endocrine function. Composed mostly of thyroid follicles. Follicular cells of the thyroid secrete mainly the hormone thyroxine. Thyroid gland also produces triiodothyronine.
GH & IGF are responsible for:
Lipid Metabolism- to provide energy for growing tissues, ( ) stimulates adipocytes to catabolize fat and release fatty acids and glycerol into the blood. ( ) makes it unnecessary for cells to consume their own proteins. This is called protein-sparing effect
Estradiol
Main adrenal estrogen.
Dehydroepiandrosterone
Major Androgen
Skin
Major Hormone: 1, 25 dihydroxyvitamin D3 Primary Target: Small Intestine Primary Effect: Stimulates absorption of Ca2+
Pituitary, Posterior
Major Hormone: Antidiuretic hormone, oxytocin Primary Target: Kidneys and blood vessels , uterus and mammary glands. Primary Effect: Antidiuretic hormone promotes water retention and vasoconstriction; oxytocin stimulates contraction of uterus and mammary secretory units
Heart
Major Hormone: Atrial Natriuretic hormone Primary Target: Kidneys Primary Effect: Promotes excretion of Na+ in the urine
Adrenal Medulla
Major Hormone: Epinephrine Primary Target Organs: Heart, bronchioles, and blood vessels. Primary Effect: causes adrenergic stimulation
Kidneys
Major Hormone: Erythropoietin. Primary Target: Bone Marrow Primary Effect: Stimulates red blood cell production
Ovaries
Major Hormone: Estradiol-17b and progesterone Primary target: Female reproductive tract and mammary glands Primary Effect: Maintains structure of reproductive tract and promotes secondary sex characteristics
Stomach
Major Hormone: Gastrin Primary Target: Stomach Primary Effect Stimulates acid secretion
Adrenal cortex
Major Hormone: Glucocorticoids, Aldosterone Primary Target: Liver and muscles, kidneys Primary Effect: Glucocorticoids influence glucose metabolism; aldosterone promotes Na+ retention , K+ excretion
Islets of Langerhans (Pancreas)
Major Hormone: Insulin, Glucagon Primary Target: Many organs Liver and adipose tissue Primary effect: Insulin promotes cellular uptake of glucose and formation of glycogen and fat; glucagon stimulates hydrolysis of glycogen and fat
Adipose Tissue
Major Hormone: Leptin Primary target:hypothalamus Primary Effect: Suppresses Appetite
Pineal Gland
Major Hormone: Melatonin Primary Target: Hypothalamus and anterior pituitary Primary Effect: Affects secretion of gonadotrophic hormones
Parathyroid glands
Major Hormone: Parathyroid Hormone Primary Target: Bone, Small Intestine, and kidneys Primary Effect: Increases Ca2+ concentration in blood
Hypothalamus
Major Hormone: Releasing and inhibiting Hormones. Primary Target Organ: Anterior Pituitrary Primary Effect: Regulates secretion of anterior pituitary hormones
Small Intestine
Major Hormone: Secretin and cholecystokinin Primary Target: Stomach, Liver, and Pancreas Primary Effect: Inhibits gastric motility and stimulates bile and pancreatic juice secretion
Liver
Major Hormone: Somatomedins (gh) Primary Target: cartilage Primary Effect; stimulates cell division and growth
Testes
Major Hormone: Testosterone Primary Target: Prostate, seminal vesicles, and other organs Primary Effect: Stimulates secondary sexual development
Thymus
Major Hormone: Thymopoietin Primary Target: Lymph Nodes Primary Effect: Stimulates white blood cell production
Pituitary, Anterior
Major Hormone: Trophic Hormones (TSH, FSH, LH, PRL, ACTH, GH Primary Target: Endocrine Glands and other organs Primary Effect: Stimulates growth and development of target organs; stimulates secretion of other hormones
Thyroid Gland
Major hormone: Thyroxin and triiodothyronone; calcitonin Primary Target: most organs Thyroxine and triiodothyronine promote growth and development and stimulate basal rate of cell respiration(basal metabolic rate or bMR); calcitonin may participate in the regulation of blood Ca2+ levels
Five most important corticosteroids fall into three categories (Produced by the adrenal cortex)
Mineralocorticoids-which regulat body's electrolyte balance. Glucocorticoids- which regulate the metabolism of glucose and other organic fuels. Sex Steroids- various developmental and reproductive functions
Anterior Pituitary
Most hormones of the anterior pituitary are polypeptides or glycoproteins
Aldosterone
Most significant mineralocortocoid and is produced only by the zona glomerulosa. It helps the kidneys retain sodium body fluids and excrete potassium in the urine. aldosterone helps to maintain blood volume and pressure
Function as both neurotransmitters and hormones
Norepinephrine, dopamine, and antidiurectice hormone. When released by a nerve cell its a neurotransmitter but when its released by an endocrine cell its a hormone
Peptides
Oligopeptides, Polypeptides, glycoproteins
Placenta
Organ performs many functions in pregnancy, including fetal nutrition and waste removal. It also secretes estrogen , progesterone and otehr hormones that regulate pregnancy and stimulate development fo the fetus and the mothers mammary glands
Thymus
Plays a role in endocrine, lymphatic, and immune. Located in the mediastinum superior to the heart. The (blank) is a site of maturation for certain white blood cells call t cells which are important for immune function. The blank secrets several hormones: thymopoietin, thymosin and thymulin) that stimulate the development of other lymphatic organs
GH & IGF are responsible for:
Protein Synthesis- tissue growth require protein synthesis and needs two things: amino acids for building material, and messenger RNA9mrNA) for instructions. ( )also supports protein catabolism
Hypothalamus, other brain centers
Regulates anterior pituitary secretions
Parathyroid glands
Secrete parathyroid hormone in response to hypocalcemia. PTH raises blood calcium levels.
Adrenocorticotropic Hormone (ACTH) or corticotropin
Secreted by cells call corticotropes. Its target organ and the basis for its name is the adrenal cortex. (blank) stimulates the adrenal cortex to secrete hormones called glucocorticoids, which regulate glucose, protein and fat metabolism and are important in the body's response to stress
Thyroid-Stimulating Hormone (TSH)
Secreted by pituitary cells called thyrotropes. It stimulates growth of the thryoid gland and the secretion of thyroid hormone, which has widespread effects on metabolic rate, body temperature and other functions
Involution
Shrinkage of a tissue or an organ by autolysis
Releasing Hormones
Six hormones that stimulate the pituitary to release hormones
Oxycotin (OT) and Antidiurectic hormone (ADH)
Stored and released by the posterior pituitary. ( ) comes mainly from neurons in the right and left paraventricular nuclei of the hypothalamus and ( ) comes mainly from the supraoptic nuclei.
Adrenal Cortex
Surrounds the medulla on all sides. Produces more than 25 steroid hormones, known collectively as the corticosteroids or corticods. Only 5 corticosteroids are secreted in physiological significant amounts.
Pituitary Gland
Suspended from the floor of the hypothalamus by a stalk and housed in a depression of the sphenoid bone. Composed of the anterior and posterior pituitary gland both with different functions
Steroids
Synthesized from cholesterol and differ mainly in the functional groups attached to the four-ringed steroid backbone
Positive Feedback
The accellerator that increases or amplifies ) - stretching of uterus increases OT release, causes contractions , causing more stretching of uterus, etc
Homeostasis
The body's ability to detect change, activate the mechanisms that oppose it, thus maintain stable internal conditions
Adrenal Cortex has three layers of tissue which differ in histology and hormone output
Zona Glomerulosa- produces mineralcorticoids Zona Fasciculata- Produces glucocoticoids and androgens Zona Reticularis- Produces glucocorticoids and androgens
IGF-I
accelerates bone growth at the epiphyseal plates. It stimulates the multiplication of chondrocytes and osteogenic cells as well as protein deposition in the cartilage and bone matrix. In adulthood it stimulates osteoblast activity and appositional growth of bone; thus, it continues to influence bone thickening and remodeling
Adrenal Medulla
acting as both an endocrine gland an ganglion of the sympathetic nervous system.
Cortisol
also known as hydrocortisone and is the glucocorticoid, but the adrenals also secrete a weaker one called cortiosterone.
Hypoglycemic hormone
any hormone that lowers blood glucose levels
Neurotransmitters
are released by neurons, diffuse across a narrow synaptic cleft, and bind to receptors on the surface of the next cell.
Paracrines
are secreted by one cell, diffuse to nearby cells in the same tissue, and stimulate their physiology. Some call them local hormones.
Androgens
are the primary adrenal sex steroids, but the adrenals also produce small amounts of estrogen. Sex hormones come from both the zona fasciculata and zona reticularis
(ADH) Antidiuretic Hormone (Posterior Pituitary Hormones)
blank increases water retention by the kidneys, reduces urine volume, and helps prevent dehydration. (blank) also functions as a brain neurotransmitter and is usually called arginine vasopressin (aVP) in the neuroscience literature. Causes vasoconstritction
Posterior Pituitary
composed of nervous tissue. Connected to the hypothalamus by nerve fibers. Nerve fibers arise from certain cell bodies in the hypothalamus , pass down the stalk as a bundle called the hyopthalamo-hypophyseal tract and connect to the (blank)
Liver cells
defy classification, neither exocrine or endocrine, secrete bile and hormones
GH (Growth Hormone)
does not have a targeted effect but is widespread throughout the body. It effects cartilage, bone , muscle and fat. It exerts its effects both directly and indirectly. ( ) also induces the liver and other tissues to produce growth stimulants called insulin-like growth factors(IGF-I) and (IGF-II) also known as somatomedins, which then stimulate other target cells
IGF half life
has a life of about 20 hours
Pituitary Gland & hypothalamus
have a more wide-ranging influence than any other part of the endocrine system.
Hormones
in the strict sense, are chemical messengers that are transported by the bloodstream and stimulate physiological responses in cells of another tissue or organ, often a considerable distance away. Certain blank produced by the pituitary gland in the head, for example, act on organs as far away as the pelvic cavity.
Monoamines
include dopamine, epinephrine, norepinephrine, melatonin, and thyroid hormone( first three are catecholamines)
Pineal Gland
is attached to the roof of the third ventricle of the brain, beneath the posterior end of the corpus callosum. Larger in children than shrinks as an adult. May play a role in establishing 24-hour circadian rhythms. Synthesizes melatonin
Thyroid hormone
is secreted in response to TSH from the pituitary gland. Primary effect of TH is to increase the body's metabolic rate.
Insulin
large peptide hormone.
Glucose -sparing effect
neurotransmitters such as epinephrine are said to be glucose sparing in which they use fat as primary energy
Pancreatic Islets
secrete hormones vital importance especially in the regulation of glycemia.
FSH ( Follicle-Stimulating Hormone)
secreted by pituitary cells. In the ovaries it stimulates the secrtion of ovarian sex hormones and the development of the bubblelike follicles that contain eggs. In testes it stimulates sperm production
GH continued
secretion rises sharply in response to trauma , physical or emotional stress, hypoglycemia (low blood sugar) , and other conditions. small peaks occur after high-protein meals, but a high carbohydrate meal tends to supress GH secretion.
Hormones fall into three chemical classes
steroids, monoamines and peptides
norepinephrine and glucagon
stimulate the liver to break down glycogen and release glucose.
Endocrinology
study of the endocrine system(glands, tissues and cells that secrete hormones)
Negative feedback inhibition
the pituitary stimulates another endocrine gland to secrete its hormone, and that hormone feeds back to the pituitary or hypothalamus and inhibits further secretion of the pituitary hormoen
Inhibiting Hormones
those that suppress pituitary secretion
