FINALS: ENDOCRINE SYSTEM Flashcards
- Second messenger system of the body
- Uses chemical messages (hormones) that are released into the blood
ENDOCRINE SYSTEM
Hormones control several major processes:
- Reproduction
- Growth and development
- Mobilization of body defenses 4. Maintenance (homeostasis)
- Regulation of metabolism
- Comes from a Greek word meaning “to arouse”
- Produced by specialized cells (secrete hormones into extracellular fluids)
HORMONES
____ transfers hormones to target sites
Blood
Chemical classification of hormones:
Amino acid-based hormones (proteins, peptides, amines)
Steroids (cholesterol)
Prostaglandins (highly active lipids)
- Hormones affect only certain tissues/organs (target cells or organs)
- Target cells must have specific protein receptors
- Hormone binding influences the working of the cells
MECHANISM OF HORMONE ACTION
Effects caused by hormones:
- Changes in plasma membrane permeability/electrical state
- Synthesis of proteins, such as enzymes
- Activation/inactivation of enzymes 4. Stimulation of mitosis
- Promotion of secretory activity
- Diffuse through the plasma membrane of target cells
- Enter the nucleus
- Bind to a specific protein within the nucleus
- Bind to specific sites on the cell’s DNA
- Activate genes that result in synthesis of new proteins
Direct Gene Activation: Steroid Hormone Mechanism
- Hormone binds to a membrane receptor & it does not enter the cell
- Sets off a series of reactions that activates an enzyme catalyzing a reaction that produces a second messenger molecule
- Oversees additional intracellular changes to promote a specific response
Second-Messenger System: Nonsteroid Hormone Mechanism
Hormone levels in the blood are maintained by ____.
negative feedback
- A stimulus/low hormone levels in the blood triggers the release of more hormones
- Hormone release stops once an appropriate level in the blood is reached
CONTROL OF HORMONE RELEASE
Endocrine glands are activated by other hormones
Hormonal stimulus
Changing blood vessels of certian ions stimulate hormone release
Humoral stimulus
Nerve impulses stimulate hormone release
Nerve stimulus
- Approximately the size of a pea
- Hangs by a stalk from the hypothalamus
- Protected by the sphenoid bone
PITUITARY GLAND
Has 2 functional lobes pituitary gland
Anterior Pituitary
Posterior Pituitary
glandular tissue
Anterior Pituitary
nervous tissue
Posterior Pituitary
“Master endocrine gland”
- Releases 6 hormones (2 affect non-endocrine targets & 4 stimulate other endocrine glands [tropic hormones])
Anterior Pituitary
Proteins (or peptides)
Act through second-messenger systems Regulated by hormonal stimuli, mostly negative feedback
Anterior Pituitary
Not an endocrine gland, acts only as a storage area for hormones made by hypothalamic neurons
Posterior Pituitary
Posterior Pituitary released what 2 hormones?
- Oxytocin
- Antidiuretic hormone (ADH) or vasopressin
Hormonal release of the anterior pituitary is controlled by releasing hormone & inhibiting hormones produced by hypothalamus
HYPOTHALAMUS
- Found at the base of the throat
- Consists of 2 lobes & a connecting isthmus
THYROID GLAND
THYROID GLAND PRODUCES 2 HORMONS:
- Thyroid hormone (major metabolic hormone)
- Calcitonin
- Tiny masses on the posterior of the thyroid
- Chief cells secrete parathyroid hormone (chemical class: peptide) Stimulate osteoclasts to remove calcium from bone
Stimulate the kidneys & intestine to absorb more calcium
Raise calcium levels in the blood
PARATHYROID GLANDS
Sit on top of the kidneys
ADRENAL GLANDS
ADRENAL GLANDS 2 GLANDS:
Cortex
Medulla
outer glandular region; produces 3 major groups of steroid hormones (corticosteroids)
cortex
inner neural tissue region;
produces catecholamines (epinephrine & norepinephrine)
medulla
Flattened organ that measures about 12.515 cm (5-6 in.) in length, located in the curve of the duodenum
PANCREATIC ISLETS
Pancreas is a mixed gland. T or F?
True
Pancreatic islets (islet of Langerhans)
Chemical class: protein
4 Cell Types in the Pancreatic Islets
ALPHA (A) CELLS
BETA (B) CELLS
DELTA (D) CELLS
F CELLS
17% of pancreatic islet cells & secrete glucagon
ALPHA (A) CELLS
70% of pancreatic islet cells & secrete insulin
BETA (B) CELLS
7% of pancreatic islet cells & secrete somatostatin
DELTA (D) CELLS
6% of pancreatic islet cells & secrete pancreatic polypeptide
F CELLS
A small, cone-shaped gland found hanging from the roof of the 3rd ventricle of the brain
PINEAL GLAND
Secretes melatonin
PINEAL GLAND
Chemical class: amine Contribute to the setting of the body’s biological clock
Peak levels is at night & lowest levels is during daylight (noon)
May have other as-yet-unsubstantiated functions
MELATONIN
- Located posterior to the sternum, between the lungs
- Largest in infants & children
THYMUS GLAND
Produces thymosin
THYMUS GLAND
Chemical class: peptide
Promotes maturation of some types of WBCS
May retard aging process
Important in developing the immune system
THYMOSIN
Produce sex cells and sex hormones that are identical to those produced by adrenal cortex cells
GONADS
2 GONADS
- Ovaries
- Testes
Stimulates corpus luteum in ovary to continue production of estrogens
& progesterone maintain pregnancy
Human chorionic gonadotropin (hCG)
Maintain pregnancy; help prepare mammary glands to secrete milk
Estrogen and progesterone
Works cooperatively with estrogen & progesterone in preparing the breasts for lactation
Human placental lactogen (hPL)
Causes the mother’s pelvic ligaments & the pubic symphysis to relax & become more flexible, which eases birth passage
Relaxin
- Excessive urine output due to hyposecretion of ADH
- Person is continually thirsty & drink huge amounts of water
DIABETES INSIPIDUS
Hyposecretion of GH during childhood slows bone growth, & the epiphyseal plates close before normal height is reached
PITUITARY DWARFISM
- Hyposecretion of GH during childhood, an abnormal increase in the length of long bones
- Acromegaly: hyposecretion of GH occurs after long-bone growth has ended
GIGANTISM
hyposecretion of GH occurs after long-bone growth has ended
Acromegaly
Hyposecretion of FSH or LH in both males and females
STERILITY
Enlargement of thyroid gland that results when the diet is deficient in iodine
GOITER
- Congenital hypothyroidism
- Hyposecretion of thyroid hormones that is present at birth, causes severe mental retardation & stunted bone growth
CRETINISM
- Hypothyroidism occurring in adults
- Occurs 5xmore often in females
- Hallmark: edema
MYXEDEMA
- Most common form of hyperthyroidism
- Autoimmune disorder in which the person produces antibodies that mimic the action of TSH
- Enlarged thyroid & exophthalmos (protruding eyes)
GRAVE’S DISEASE
Too little parathyroid hormone-leads to a deficiency of blood Ca2+, leading to twitches, spasms & tetany of skeletal muscle
HYPOTHYROIDISM
- Hyposecretion of glucocorticoids & aldosterone
- Majority of cases are autoimmune disorders, characterized by a peculiar bronze tone of skin
ADDISON’S DISEASE
- Overproduction of hormone aldosterone by adrenal glands
- Excessive water & sodium are retained, leading to high blood pressure & edema.
HYPERTHYROIDISM
- Hyposecretion of cortisol by the adrenal cortex
- Causes include a tumor of the adrenal gland that secretes cortisol, or a tumor elsewhere that secretes ACTH, which in turn stimulates excessive secretion of cortisol.
CUSHING’S SYNDROME
- Hypersecretion of the sex hormones, regardless of sex
- In females: beard develops & masculine pattern of body hair distribution occurs
MASCULINIZATION
- Inability to produce/use insulin
- Blood glucose level is high & glucose “spills” into the urine(glucosuria)
- Hallmarks: polyuria, polydipsia, & polyphagia
DIABETES MELLITUS
- Often results when a diabetic injects too much insulin
- Main symptom: hypoglycemia
HYPERINSULINISM
2 MECHANISM OF HORMONE ACTION
DIRECT GENE ACTIVATION: STEROID HORMONE MECHANISM
SECOND-MESSENGER SYSTEM: NONSTEROID HORMONE MECHANISM
The endocrine part secretes hormones, whereas the exocrine part secretes digestive enzymes
Pancreas
Organs in the body with the richest blood supply are the ____
endocrine glands
some portion secretes hormone, but other parts produce oocytes (female sex cells) or sperm cells (male sex cells)
Ovaries & testes
6 TYPES OF HORMONE ACTION
ENDOCRINE
PARACRINE
AUTOCRINE
JUXTACRINE
EXOCRINE
NEUROENDOCRINE
is secreted in one location (ducts) and released into blood circulation.
ENDOCRINE
is secreted in endocrine cells and released into interstitial space.
PARACRINE
is secreted in endocrine cells and sometimes released into interstitial space; binds to specific receptor on cell of origin resulting to self-regulation of its function.
AUTOCRINE
is secreted in endocrine cells and remains in relation to the plasma membrane; acts on immediately adjacent cells by direct cellto-cell contact.
JUXTACRINE
is secreted in endocrine cells and released into the lumen of gut.
EXOCRINE
is secreted in the neurons and released from nerve endings; interacts with receptors of cells at distant site.
NEUROENDOCRINE
AKA adenohypophysis, 3 parts are derived embryonically from the hypophyseal pouch
Anterior pituitary (glandular tissue)
3 PARTS OF ANTERIOR PITUITARY
Pars distalis
Pars tuberalis
Pars intermedia
❖ Accounts for 75% of the adenohypophysis and has a thin fibrous capsule
❖ Main components are cords of well-stained endocrine cells interspersed with fenestrated capillaries and supporting reticular connective tissue
Pars distalis
❖ A smaller funnel-shaped region surrounding the infundibulum of the neurohypophysis
❖ Most of the cells are gonadotrophs (synthesize & secrete luteinizing hormone [LH] & follicle-stimulating hormone [FSH])
Pars tuberalis
❖ A narrow zone lying between the pars distalis and the pars nervosa
❖ Contains basophils (corticotrophs: releases adrenocorticotropic hormone [ACTH]), chromophobes, and small, colloid-filled cysts
Pars intermedia
AKA neurohypophysis
Posterior pituitary (nervous tissue)
Retains many histologic features of brain tissue and consists of a large part, the pars nervosa, and the smaller infundibulum stalk attached to the hypothalamus
Posterior pituitary (nervous tissue)
Neuroendocrine organ because aside from neural functions, it also produces and releases hormones
HYPOTHALAMUS
Accounts for 75% of the adenohypophysis and has a thin fibrous capsule
Pars distalis
Main components are cords of well-stained endocrine cells interspersed with fenestrated capillaries and supporting reticular connective tissue
Pars distalis
A smaller funnel-shaped region surrounding the infundibulum of the neurohypophysis
Pars tuberalis
Most of the cells are gonadotrophs (synthesize & secrete luteinizing hormone [LH] & follicle-stimulating hormone [FSH])
Pars tuberalis
A narrow zone lying between the pars distalis and the pars nervosa
Pars intermedia
Contains basophils (corticotrophs: releases adrenocorticotropic hormone [ACTH]), chromophobes, and small, colloid-filled cysts
Pars intermedia
stimulates the secretion of thyroid hormones from the thyroid gland
TSH
thyroid hormone with 4 iodine atoms
Thyroxine
contains 3 iodine atoms
Triiodothyronine
outer glandular region; produces 3 major groups of steroid hormones (corticosteroids)
cortex (adrenal gland)
has 3 concentric zones in which the cords of epithelial steroid-producing cells are arranged somewhat differently, and which synthesize different classes of steroid hormones:
cortex (adrenal gland)
3 concentric zones of adrenal cortex:
Zona glomerulosa
Zona fasciculata
Zona reticularis
Zona glomerulosa:
mineralocorticoids
Zona reticularis:
androgen
Zona reticularis:
androgens
Secreted by the outer layer of the adrenal cortex, helps regulate blood volume & blood levels of K+ & Na+
Zona glomerulosa
Zona glomerulosa Major hormone:
aldosterone
Zona fasciculata Major hormone:
cortisol
Zona reticularis Major hormone:
testosterone
Primarily binds to receptor molecules in the kidney, but also affects the intestine, sweat glands, & salivary glands
✓ Small amounts are secreted in both males & females.
✓ Adult males: secreted by the testes.
Causes Na+ & water to be retained in the body & increases the rate at which K+ is eliminated
Aldosterone
Increases the breakdown of proteins & lipids & increases their conversion to forms of energy the body can use
Reduces the inflammatory & immune responses.
Response to stressful conditions: secreted in larger than normal amounts, aids the body by providing energy sources for tissues
cortisol
✓ Secreted by the middle layer of the adrenal cortex, helps regulate blood nutrient levels.
Zona fasciculata
✓ Secreted by the inner layer of the adrenal cortex, stimulate the development of male sexual characteristics
✓ Small amounts are secreted in both males & females.
✓ Adult males: secreted by the testes.
Causes Na+ & water to be retained in the body & increases the rate at which K+ is eliminated
❖ Zona fasciculata:
glucocorticoids ✓ Secreted by the middle layer of the adrenal cortex, helps regulate blood nutrient levels.
✓ Major hormone: cortisol Increases the breakdown of proteins & lipids & increases their conversion to forms of energy the body can use
Reduces the inflammatory & immune responses.
Response to stressful conditions: secreted in larger than normal amounts, aids the body by providing energy sources for tissues
❖ Zona reticularis: androgens ✓ Secreted by the inner layer of the adrenal cortex, stimulate the development of male sexual characteristics.
✓ Adult females: influence the female sex drive.
✓ If secretion is abnormally high: exaggerated male characteristics develop in both males & females
Zona reticularis
AKA adrenaline, principal hormone
epinephrine
AKA noradrenaline, released in small amounts
norepinephrine
Both hormones are released in response to stimulation by the sympathetic nervous system (fight-orflight hormones)
epinephrine and norepinephrine
Acts on several tissues to cause entry of glucose into cells and promotes decrease of blood glucose content
Insulin
Acts on several tissues to make energy stored in glycogen and fat available through glycogenolysis and lipolysis; increases blood glucose content
Glucagon
Inhibits release of other islet cell hormones through local paracrine action; inhibits release of GH and TSH in anterior pituitary and HCl secretion by gastric parietal cells
Somatostatin
Stimulates activity of gastric chief cells; inhibits bile secretion, pancreatic enzyme and bicarbonate secretion, and intestinal motility
Pancreatic polypeptide
hyposecretion of ADH, usually caused by a brain tumor, head trauma, or brain surgery that damages the posterior pituitary or the hypothalamus
Neurogenic DI
the kidneys do not respond to ADH & the ADH receptors may be nonfunctional, or the kidneys may be damaged
Nephrogenic DI
a skeletal disorder caused by an overproduction of parathyroid hormone from the overactive parathyroid glands
Osteitis fibrosa cystica
swollen “moon” face, redistribution of fat to the abdomen and the
posterior neck (causing a “buffalo hump”), easy bruising, and poor wound healing.
“Cushingoid signs”
insulin is absent
Type I Diabetes Mellitus
insulin is deficient
Type II Diabetes Mellitus
fatty acid metabolites or ketones or ketone bodies are organic acids that when they accumulate in the blood
Ketoacidosis
▪ Autoimmune
hypothyroidism
▪ Chronic Autoimmune Thyroiditis ▪ Increase TSH ▪ Antibody present: Anti-TPO (thyroid peroxidase)
▪ Symptoms: a more common cause of goiter
Hashimoto’s disease
Decrease T3 and T4; Increase TSH
Primary Hypothyroidism
increase T3 and T4; Decrease
Primary Hyperthyroidism
▪ Fluid retention = decreased urine volume
▪ ADH excess
▪ Marked by headache and disorientation due to brain edema, weight gain, and decreased solute concentration is the blood.
▪ SIADH management requires restricting fluids and carefully monitoring blood sodium levels
Syndrome of inappropriate ADH secretion
(SIADH)
▪ Presence of excessive body & facial hair in a male pattern, especially in women.
▪ May be due to excess androgen production due to tumors/drugs.
Hirsutism
pituitary gland, adrenal medulla, pineal gland
Ectoderm
adrenal cortex
Mesoderm
thyroid gland, parathyroid gland, pancreas, thymus
Endoderm
Thymus size begins to decrease, & thymic tissue is replaced by adipose & areolar connective tissue
AFTER PUBERTY
is brought about by lack of efficiency of the ovaries
Menopause
