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Chapter 16
Endocrine System
134
Anatomy
Undergraduate 2
02/08/2012

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Term
Endocrine system - overview
Definition
body's means by which it influence metabolic activities of cells by means of hormones
Term
Endocrine glands
Definition
pituitary, thyroid, parathyroid, adrenal, pineal, and thymus
Term
The pancreas and gonads also produce what other product?
Definition
Produce both hormones and exocrine
Term
Autocrines
Definition
chemicals that exert effect on the same cells that secrete them
Term
Paracrines
Definition
locally acting chemicals that affect cells other than those that secrete them
Term
What are hormones?
Definition
chemical substances secreted by cells into the extracellular fluids
Term
What are characteristics of hormones?
Definition
Regulate the metabolic functions of other cells, have lag times ranging from seconds to hours, tend to have prolonged effects, are classified as amino acid-based hormones, or steroid
Term
Eicosanoids
Definition
biologically active lipids with local hormone-like activity
Term
Types of Hormones
Definition
Amino acid based, steroid, Eicosanoids
Term
Amino-acid based hormone types
Definition
Amines, thyroxine, peptide, and protein hormones
Term
Steroids
Definition
gonadal and adrenocortical hormones
Term
Eicosanoids
Definition
leukotrienes and prostaglandins
Term
Target Cell Specificity: Overview
Definition
Hormones circulate to all tissue but only activate target cells. Target cells must have specific receptors to which the hormone binds. The receptors may be intracellular or located on the plasma membrane
Term
Three types of hormone interactions
Definition
Permissiveness, Synergism, Antagonism
Term
Permissiveness
Definition
one hormone cannot exert its effects without another hormone being present
Term
Synergism
Definition
more than one hormone produces the same effects on a target cell (multiply)
Term
Antagonism
Definition
one or more hormones opposes the action of another hormone (blocking)
Term
How is the release of hormone controlled?
Definition
Through a negative feedback system that varies with a narrow desirable rage based on blood levels
Term
What are hormones synthesized and released in response to?
Definition
Humoral stimuli, Neural stimuli, Hormonal stimuli
Term
Hypophysis
Definition
Pituitary gland
Term
How many lobes does the pituitary gland contain?
Definition
Two
Term
How many major hormones does the pituitary gland secrete?
Definition
Nine
Term
Neurohypophysis
Definition
Posterior lobe and the infundibulum
Term
Infundibulum
Definition
connecting stalk between hypothalamus and posterior lobe of pituitary
Term
What is the functiom of the neurohypophysis?
Definition
Receives, stores, and releases hormones from the hypothalamus
Term
Adenohypophysis
Definition
anterior lobe, made up of glandular tissue
Term
Function of the Adenohypophysis
Definition
Synthesizes and secretes a number of hormones
Term
Pituitary-Hypothalamic Relationships: Posterior Lobe - General info
Definition
Posterior lobe is a down growth of hypothalamic neural tissue. Has a neural connection with the hypothalamus (hypothalamic-hypophyseal tract)
Term
What does the nuclei of the hypothalamus synthesize?
Definition
Oxytocin and antidiuretic hormone (ADH)
Term
What happens to the hormones synthesized by the nuclei of the hypothalamus?
Definition
Transported to the pituitary
Term
What is the anterior lobe of the pituitary an out-pocketing of?
Definition
The oral mucosa
Term
Is there direct neural contact with the hypothalamus and the anterior lobe of the pituitary gland?
Definition
No
Term
Hypophyseal portal system
Definition
the vascular connection between the anterior pituitary and the hypothalamus
Term
What does the hypophyseal portal system consist of?
Definition
Primary capillary plexus, Hyophyseal portal veins, secondary capillary plexus
Term
The hypothalamus sends a chemical stimulus to the anterior pituitary: Release
Definition
Releasing hormones stimulate the synthesis and release of hormones
Term
The hypothalamus sends a chemical stimulus to the anterior pituitary: Inhibiting
Definition
Inhibiting hormones shut off the synthesis and release of hormones
Term
What are tropic hormones?
Definition
Hormones that produce indirect effects at organs
Term
Tropic hormones released by the Anterior Lobe of the Pituitary Gland
Definition
Growth Hormone (GH), Thyroid-stimulating hormone (TSH), Adrenocorticotropic hormone (ACTH), Follicle-stimulating hormone (FSH), Luteinizing hormone (LH), Prolactin (PRL)
Term
Function of the Tropic Hormones
Definition
Regulate the activity of other endocrine glands
Term
What is the posterior pituitary lobe made up of?
Definition
made of axons of hypothalamic neurons
Term
What does the posterior pituitary lobe store?
Definition
antidiuretic hormone (ADH, vasopressin) and oxytocin
Term
What does Antidiuretic hormone influence?
Definition
Water balance
Term
What does oxytocin stimulate?
Definition
Smooth muscle contraction in breasts and uterus
Term
What does thyroid hormone consist of?
Definition
Two related iodine-containing compounds. T4 and T3
Term
What is T4 called?
Definition
Thyroxine
Term
What is Thyroxine made up of?
Definition
Two tyrosine molecules plus four bound iodine atoms
Term
What is T3 called?
Definition
Triiodothyronine
Term
What is triiodothyronine made up of?
Definition
two tyrosines, and three bound iodine atoms
Term
What is Thyroid Hormone concerned with?
Definition
Glucose oxidation, Increasing metabolic rate, Heat production
Term
What does thyroid hormone play a role in?
Definition
Maintaining blood pressure, regulating tissue growth, developing skeletal and nervous systems, maturation and reproductive capabilities
Term
Synthesis of Thyroid Hormone: Step 1
Definition
Thyroglobulin is synthesized and discharged into the lumen of the follicle
Term
Synthesis of Thyroid Hormone: Step 2
Definition
Iodides (I-) are actively taken into the cell, oxidized to iodine (I2), and released into the lumen
Term
Synthesis of Thyroid Hormone: Step 3
Definition
Iodine attaches to tyrosine, mediated by peroxidase enzymes, forming T1 (monoiodotyrosine, or MIT) and T2 (diiodotyrosine, or DIT)
Term
Synthesis of Thyroid Hormone: Step 4
Definition
Iodinated tyrosines link together to form T3 or T4
Term
Synthesis of Thyroid Hormone: Step 5
Definition
Colloid is then endocytosed and combined with a lysosome where T3 and T4 are cleaved from thryoglobulin and diffuse into the bloodstream
Term
Which "T" is there generally more of?
Definition
More T2 than T1, more T4 than T3
Term
What produces Calcitonin?
Definition
The parafollicular cells of the thyroid
Term
What does calcitonin target?
Definition
The skeleton
Term
What is Calcitonin's function?
Definition
Inhibits osteoclast activity and release of calcium from the bone matrix. Stimulates calcium uptake and incorporation into the bone matrix
Term
How is calcitonin regulated?
Definition
A humoral (calcium ion concentration in the blood) negative feedback mechanism
Term
How are the cells of the parathyroid glands arranged?
Definition
In cords containing oxyphil and chielf cells
Term
What do the Chief (principal) cells secrete?
Definition
Parathormone (PTH)
Term
What is Parathormone's (PTH) function?
Definition
Regulates caclium balance in the blood
Term
What does PTH release do, basic?
Definition
Increases Ca2+ in the blood
Term
What does PTH release do, whole story>
Definition
Stimulates osteoclasts to digest bone matrix, enhances the reabsorption of Ca2+ and the secretion of phosphate by the kidneys, Increases absorption of Ca2+ by intestinal mucosa
Term
How is PTH release inhibited?
Definition
By rising Ca2+ levels in the blood
Term
Adrenal glands - General
Definition
paired, pyramid-shaped organs atop the kidneys
Term
Structurally and functionally the Adrenal Glands is what two glands in one?
Definition
Adrenal medulla and Adrenal cortex
Term
Adrenal Medulla
Definition
neural tissue that acts as part of the sympathetic nervous system
Term
Adrenal cortex
Definition
glandular tissue derived from embryonic mesoderm
Term
What does the adrenal cortex synthesize and release?
Definition
Steroid hormones called corticosteroids
Term
What are the three layers of the adrenal cortex?
Definition
Zona glomerulosa, Zona fasciculata, Zona reticularis
Term
Smooth muscle contraction in breasts and uterus through oxytocin stimulation is a result of what mechanism?
Definition
PIP-calcium second messenger
Term
What does the Zona gomerulosa produce?
Definition
Mineralcorticoids, chiefly aldosterone
Term
What does the Zona fasciculata produce?
Definition
Glucocorticoids, chiefly cortisol
Term
What does the Zona reticularis produce?
Definition
Gonadocorticoids, chiefly androgens
Term
What is the role of a Mineralocorticoids?
Definition
Regulation of electrolytes in extracellular fluids.
Term
Aldosterone
Definition
most important mineralocorticoid
Term
Aldosterone function
Definition
Maintains Na+ balance by reducing excretion of sodium from the body. Stimulates reabsorbtion of Na+ by the kidneys
Term
Aldosterone secretion is stimulated by:
Definition
Rising blood levels of K+, Low blood Na+, decreasing blood volume pressure
Term
Glucocorticoids (Cortisol): Helps the body resist stress by
Definition
Keeping blood sugar levels relatively constant. Maintaining blood volume and preventing water shift into the tissue
Term
Glucocorticoids (Cortisol): Cortisol provokes
Definition
Gluconeogenesis (formation of glucose from noncarbohyrdates), rises in blood glucose, fatty acids, and amino acids
Term
Excessive levels of glucocorticoids
Definition
Depress cartilage and bone formation, inhibit inflammation, depress the immune system, promote changes in cardiovascular, neural, and gastrointestinal function
Term
Gonadocorticoids (Sex hormones): Most secreted
Definition
Androgens, most important one is testosterone
Term
Androgens contribute to:
Definition
The onset of puberty. The appearance of secondary sex characteristics, sex drive in females
Term
After menopause what can androgens be converted into?
Definition
Estrogens
Term
Adrenal Medulla is made up of what cells?
Definition
Chromaffin cells
Term
What do Chromaffin eclls secrete?
Definition
Epinephrine and norepinephrine
Term
Secretion of epinephrine and norepinephrine causes:
Definition
Blood glucose levels to rise, Blood vessels to constrict, the heart to beat faster, blood to be diverted to the brain, heart, and skeletal muscle
Term
What role does epinephrine play with the heart?
Definition
The more potent stimulator of the heart and metabolic activities
Term
What is norepinephrine's more influential role?
Definition
Peripheral vasoconstriction and blood pressure
Term
endocrine
Definition
products are hormones, glandular, diffuses into blood stream
Term
exocrine
Definition
not hormones, leave through duct cells
Term
Pancreas - general info
Definition
triangular gland, with both exocrine and endcorine cells, located behind the stomach
Term
exocrine product of the pancreas
Definition
acinar cells produce an enzyme-rich juice used for digestion
Term
What are the pancreatic islets made up of?
Definition
Alpha cells and Beta cells
Term
What do the alpha cells of the pancreatic islets produce?
Definition
Glucagon
Term
What do the beta cells of the pancreatic islets produce?
Definition
Insulin
Term
Are the products produced by the pancreatic islets endocrinic or exocrinic?
Definition
Endocrinic
Term
Glucagon: Chemistry
Definition
A 29 amino acid polypeptide hormone that is a potent hyperglycemic agent
Term
What is glucagon's major target?
Definition
The liver
Term
What does glucagon promote?
Definition
Glycogenolysis, gluconeogenesis, release of glucose to the blood form liver cells?
Term
Glycogenolysis
Definition
breakdown of glycogen to glucose
Term
Gluconeogenesis
Definition
synthesis of glucose from lactic acid and noncarbohydrates
Term
Insulin: chemistry
Definition
a 51-amino acid protein consisting of two amino acid chains linked by disulfide bonds
Term
What is insulin first synthesized as?
Definition
Proinsulin
Term
How do we get insulin from proinsulin?
Definition
Proinsulin is excised by enzymes, releasing functional insulin
Term
What is insulin's role?
Definition
Lowers blood glucose levels, enhances transport of glucose into body cells, counters metabolic activity that would enhance blood glucose levels
Term
Regulation of Blood Glucose Levels: Rising blood glucose level: Step 1
Definition
Pancreas releases insulin
Term
Regulation of Blood Glucose Levels: Rising blood glucose level: Step 2
Definition
Insulin stimulates glucose uptake by cells and stimulates glycogen formulation in the liver
Term
Regulation of Blood Glucose Levels: Rising blood glucose level: Step 3
Definition
Blood Glucose returns to normal range
Term
Regulation of Blood Glucose Levels: Declining blood glucose level: Step 1
Definition
Pancreas releases glucagon
Term
Regulation of Blood Glucose Levels: Declining blood glucose level: Step 2
Definition
Glucagon stimulates glycogen breakdown in the liver
Term
Regulation of Blood Glucose Levels: Declining blood glucose level: Step 3
Definition
Blood glucose rises to normal range
Term
Diabetes mellitus results from...
Definition
hyposecretion or hypoactivity of insulin
Term
What are the three cardinal signs of Diabetes?
Definition
Polyuria, Polydipsia, Polyphagia
Term
Polyuria
Definition
huge urine output
Term
Polydipsia
Definition
excessive thirst
Term
Polyphagia
Definition
excessive hunger and food consumption
Term
Hyperinsulinism
Definition
excessive insulin secretion, resulting in hypoglycemia
Term
What are the female gonads?
Definition
Paired ovaries in the abdominopelvic cavity
Term
What hormones do the ovaries produce?
Definition
Estrogens and progesterone
Term
What are the female gonads responsible for?
Definition
Maturation of the reproductive organs, appearance of secondary sexual characteristics, breast development and cyclic changes in the uterine mucosa
Term
What are the male gonads?
Definition
Testes located in an extraabdominal sac (scrotum)
Term
What hormones do the male gonads produce?
Definition
Testosterone
Term
What is the role of testosterone?
Definition
Initiates maturation of male reproductive organs. Causes appearance of secondary sexual characteristics and sex drive, is necessary for sperm production. maintains sex organs in their functional state
Term
Pineal gland: Anatomy
Definition
Small gland hanging from the roof of the third ventricle of the brain
Term
What hormone does the pineal gland secrete?
Definition
Melatonin
Term
What is melatonin involved with?
Definition
day/night cycles
Term
At what point are melatonin levels highest?
Definition
middle of the night
Term
What physiological processes does melatonin affect?
Definition
ones that show rhythmic variations )decrease body temperature, induce sleep, suppress appetite)
Term
Thymus: anatomy
Definition
Lobulated gland located deep to the sternum
Term
What are the major hormonal products of the thymus?
Definition
Thymopoietins and thymosins
Term
What are thymopoietens and thymosins essential for?
Definition
The development of T lymphocytes (T Cells) of the immune system
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