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73 Cards in this Set

  • Front
  • Back
The endocrine system
Second controlling system of the body "slow acting" control system, uses chemical messengers that are released into the blood
Endocrine system hormones control what processes?
Reproduction, Growth and development, mobilization of body defenses, maintenance of much of homeostasis, regulation of metabolism
How hormones work
1. Hormones are produced by specialized cells
2. Cells secrete hormones into extracellular fluids
3. Blood transfers hormones to target sites
4. These hormones regulate the activity of other cells
Hormone chemical classifications
Amino acids, Steroids, Prostaglandins
Amino acid classifications
Proteins, peptides, amines
Proteins
Multiple chains of amino acids
Peptides
Single chain of amino acids
Amines
Modified single or double amino acids
Steroids
Made from cholesterol, include many different hormones including testosterone and estrogen
Prostaglandins
Made from highly active lipids, have local effects on reproductive function, blood pressure, etc..
Mechanisms of Hormone action
Hormones affect only certain tissues or organs,Target cells must have specific protein receptors, Hormone-binding alters cellular activity
Effects caused by hormones
1. Changes in plasma membrane permeability or electrical state
2. Synthesis of proteins, such as enzymes
3. Activation or inactivation of enzymes
4. Stimulation of mitosis
5. Promotion of secretory activity
Two mechanisms in which hormones act
Direct gene activation, and second-messenger system
Process of direct gene activation
1. Steroid hormone moving through the blood enters interstitial fluid
2. Passes through the plasma membrane
3. Steroid binds to a receptor in the nucleus
4. Creates hormone-receptor complex which attatches to DNA
5. Initiates transcription (making mRNA)
6. mRNA transported out of the nucleus
7. Ribosomes use mRNA to create proteins
8. Proteins go to almost everything
Process of second messenger system
1. Blood in the interstitial fluid bind to its receptor in plasma membrane
2. Receptor activates enzymes in the plasma membrane
3. Enzymes are then activated that create the second messenger
4. Cyclic AMP is the second messenger (inside cells) (hormone was first messenger)
5. Second messenger creates many cellular effects
How hormone release is controlled
Mainly controlled by negative feedback, A stimulus or low hormone levels in the blood triggers the release of more hormone, Hormone release stops once an appropriate level in the blood is reached
Hormonal stimulation of Endocrine glands
Hormones are main stimuli
Neural stimulation of endocrine glands
Nerve impulses (action potentials) stimulate hormone release, most are under the control of the sympathetic nervous system
Hierarchy of hormone release
Hypothalamus--> Hormones--> Pituitary--> Hormones--> Endocrine glands
Humoral stimulation of endocrine glands
Changing blood levels of certain ions stimulate hormone release, relates to homeostasis of ions and molecules
Humoral
indicates various body fluids such as blood and bile
Major endocrine organs
Pituitary gland
Thyroid gland
Parathyroid glands
Adrenal glands
Pineal gland
Thymus gland
Pancreas
Gonads (Ovaries and Testes)
Hypothalamus
Pituitary gland location
Hangs by a stalk from the hypothalamus in the brain, rests in the “sella turcica” a saddle shaped bone,
Protected by the sphenoid bone
Lobes of the pituitary gland
Anterior pituitary and posterior pituitary
Anterior pituitary gland
Glandular tissue, true endocrine gland
Posterior pituitary gland
Nervous tissue, extension of the hypothalamus (neurons)
Hormones of the anterior pituitary gland
Growth hormone, Prolactin, Thyroid-stimulating hormone (thyrotropic hormone) TSH,
Adrenocorticotropic hormone ACTH, Two gonadotropic hormones
Characteristics of all anterior pituitary hormones
Proteins (or peptides), Act through second-messenger systems, Regulated by hormonal stimuli, mostly negative feedback
Growth hormone (GH) disorders
Pituitary dwarfism results from hyposecretion of GH during childhood
Gigantism results from hypersecretion of GH during childhood
Acromegaly results from hypersecretion of GH during adulthood
Hormones produced by hypothalamus
Oxytocin and Antidiuretic hormone, released by cells in the posterior pituitary
Posterior pituitary
neural tissue, extension of the hypothalamus, almost completely composed of axon terminals
Pituitary–Hypothalamus Relationship
Hormonal release is regulated by releasing and inhibiting hormones produced by the hypothalamus,These hormones are transported to neurosecretory cells of the posterior pituitary
Thyroid gland location
Found at the base of the throat
Consists of two lobes and a connecting isthmus
Thyroid gland function
Produces two hormones:
Thyroid hormone and
Calcitonin
Thyroid hormones
Major metabolic hormone, T3 & T4, small hormones made from two tyrosine amino acids with iodine atoms attached, t3= 3 iodines, t4= 4 iodines
Thyroid gland is stimulated by what?
TSH (thyroid stimulating hormone), releases more thyroid hormones and gets bigger
Goiter
A thyroid gland disorder, swollen thyroid gland, the thyroid trys to make up for a lack of dietary iodine, throid gland swells in result
T4
Thyroid hormone, 99% of hormone produced by the thyroid, T4 turns into T3 at target tissues for a stronger effect
Effect of T3 and T4
Regulate (increase) metabolic rate, also important in development (of children). Necessary for reproductive function
Follicular cells
produce thyroid hormones (stored in follicles as colloid)
Parafollicular cells
produce calcitonin
Cretinism
Caused by hyposecretion of thyroxine, Results in dwarfism during childhood
Myxedema
Caused by hypothyroidism in adults
Results in physical and mental slugishness
Graves’ disease
Caused by hyperthyroidism
Results in increased metabolism, heat intolerance, rapid heartbeat, weight loss, and exophthalmos
Parathyroid glands
Tiny masses on the posterior of the thyroid, Secrete parathyroid hormone (PTH)
Adrenal glands
Sit on top of the kidneys, has two regions, the adrenal cortex and the adrenal medulla
Adrenal cortex
Outside of medulla, stimulated by ACTH, Has three layers
Adrenal medulla
inner neural tissue region
Three layers of adrenal cortex
Zona glomerulosa (produces mineralocortocoids), Zona fascicula (produces glucocorticoids), Zona Reticularis (produces sex hormones)
Hormones of the adrenal cortex
Mineralocorticoids, Glucocorticoids, sex hormones
Production of mineralocortocoids
Production stimulated by renin and aldosterone, Production inhibited by atrial natriuretic peptide (ANP)
Mechanism of action (aldosterone)
Low blood pressure:
1. Causes release of renin from the kidneys
2. Which causes angiotensin to be turned into angiotension II
3. Which causes release of aldosterone
4. Effects of aldosterone: Blood sodium levels increase, H2O in blood increases
5. Water retained in blood causes blood pressure to increase
Zona reticularis
Sex hormone production, important for female sex drive, involved in first hormones in adolesence
Addison’s disease
Results from hyposecretion of all adrenal cortex hormones
Bronze skin tone, muscles are weak, burnout, susceptibility to infection
Hyperaldosteronism
May result from an ACTH-releasing tumor
Excess water and sodium are retained leading to high blood pressure and edema
Cushing’s syndrome
Results from a tumor in the middle cortical area of the adrenal cortex
“Moon face,” “buffalo hump” on the upper back, high blood pressure, hyperglycemia, weakening of bones, depression
Masculinization
Results from hypersecretion of sex hormones,
Beard and male distribution of hair growth
Hormones of the Adrenal Medulla
Epinephrine (adrenaline)
Norepinephrine (noradrenaline)
Purpose of hormones in the adrenal medulla
These hormones prepare the body to deal with short-term stress (“fight or flight”) by
Increasing heart rate, blood pressure, blood glucose levels
Dilating small passageways of lungs
Adrenal medulla
Actually an extension of the nervous system
Adrenal medulla composition
composed of axon terminals of nerves in the sympathetic nervous system
Pancreatic islets
Produce the hormones insulin and glucagon
Alpha cells
Secrete glucagon, works with insulin to maintain blood glucose homeostasis
Beta cells
Secrete insulin, works with glucagon to maintain blood glucose homeostasis
Glucagon
Glucose--> Whats the difference?
Glycogen
Glucagon- hormone
Glucose- Sugar
Glycogen- Storage molecule
Pineal Gland location
Found on the third ventricle of the brain
Pineal gland function
Secretes melatonin, establishes sleep/wake cycle, coordinates fertility
Thymus gland location
Located posterior to the sternum, largest in infants and children
Thymus gland function
Produces thymosin, this is where white blood cells congregate
Gonads
Ovaries and testes
Ovaries
produce eggs, produce estrogen and progesterone
Testes
Produce sperm, produce androgens
Function of placenta
Produces hormones that maintain the pregnancy
Some hormones play a part in the delivery of the baby
Produces human chorionic gonadotropin (hCG) in addition to estrogen, progesterone, and other hormones