AnP Chapter 13 (LO2) Flashcards
Endocrine System
Consists of glands and clusters of hormone secreting cells in various organs including the brain, heart and small intestines
Hormones
chemicals that influence almost every cell and organ in the body
The endocrine system communicates through —– acting hormones placing it in charge of processes that happen more —– such as —-
The endocrine system communicates through slower acting hormones placing it in charge of processes that happen more slowly such as growth
Endocrine glands
Exocrine glands
Endocrine glands: ductless and secrete hormones directly into the blood
Exocrine glands: secrete to surface
Target cells
cells having receptors for that hormone
Specificity
a hormone that acts only on cells with recpetors specific to that hormone
Comparison of the endocrine and nervous systems
Endocrine system
Employs hormones to relay messages
Distributes hormones throughout the body via the bloodstream
Responds slowly to stimuli
Exerts long lasting effects
Adapts slowly to continual stimulation
Nervous system
Employs neurotransmitters to relay messages
Secretes neurotransmitters into tiny space of a synapse
Responds to stimuli quickly
Exerts short lived effects
Adapts quickly to continual stimulation
Pituitary gland
exerts more influence on body processes than any other endocrine gland
pea sized and sits under hypothalamus cradled the sella turica
Pituitary gland is 2 distinct glands: anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis)
Anterior pituitary
larger, consists of glandular tissue
Synthesizes and secretes a number of very important hormones under the direction of the hypothalamus
Releasing hormones
Inhibiting hormones
Releasing hormones: stimulate the anterior pituitary to secrete its hormones
Inhibiting hormones: suppress hormone secretion by the anterior pituitary
Hypophyseal portal system
a system of blood vessels that the neurons of the hypothalamus release their hormones into
Tropic (trophic):
hormones stimulate other endocrine cells to release their hormones
Thyroid stimulating hormone (thyrotropin)
stimulates the thyroid gland to secrete thyroid hormone
Growth hormone (somatotropin)
acts on the entire body to promote protein synthesis, lipid and carbohydrate metabolism and bone and skeletal muscle growth
Prolactin
stimulates milk production in the mammary glands in females
In males it may make the testes more sensitive to LH
Luteinizing hormone (LH)
a gonadotropin stimulates ovulation and estrogen and progesterone synthesis in females and the secretion of testosterone by the testes in males
Adrenocorticotropic hormone (ACTH)
stimulates the adrenal cortex to secrete corticosteroids
Follicle-stimulating hormone (FSH)
one of the gonadotropins-stimulate the production of eggs in the ovaries of females and sperm in the testes of males
Acromegaly
when the epiphyseal plates have already fused when the hypersecretion occurs cartilage will form new bone causing hands, feet, face and jaw to enlarge
Gonadotropin-releasing hormone
promotes secretion of FSH and LH
Thyrotropin-releasing hormone
promotes secretion of TSH
Corticotropin-releasing hormone
promotes secretion of ACTH
Prolactin-releasing hormone
promotes secretion of prolactin
Prolactin-inhibiting hormone
inhibits secretion of prolactin
Growth hormone- releasing hormone
promotes secretion of GH
Somatostatin
inhibits secretion of GH and TSH
Posterior pituitary
Made of neural tissue
Stores hormones synthesized by the hypothalamus
Hormones stored by the posterior pituitary are antidiuretic hormone (ADH) and oxytocin (OT)
Posterior pituitary How it works
The nerve fibers form the posterior pituitary originate in the hypothalamus
They hypothalamic neurons synthesize hormones which send down to the posterior pituitary to be stored
The posterior pituitary holds the hormones until stimulated by the nervous system to release them
Oxytocin
stimulates contraction of the uterus during childbirth
It also triggers the release of milk from the breasts during lactation
Antidiuretic hormone (ADH)
acts on the kidneys to reduce urine volume and prevent dehydration
Also called vasopressin
Hormone: GH: growth hormone (somatotropin)
- -target
- -principal effects
target
Throughout body including liver, bone, muscle and fat
principle effects
Growth and repair through the breakdown of proteins and fats
Hormone: PRL: Prolactin
- -target
- -principal effects
target
Mammary glands
effects
Milk secretion
Hormone: TSH: thyroid-stimulating hormone
- -target
- -principal effects
target
Thyroid gland
effects
Growth of the thyroid gland and secretion of thyroid hormone
Hormone: ACTH: adrenocorticotropic hormone
- -target
- -principal effects
target
Adrenal cortex
effects
Growth of and secretion of corticosteroids by the adrenal cortex
Hormone: FSH: follicle-stimulating hormone
- -target
- -principal effects
target
Ovaries; testes
effects
Female: growth of ovarian follicles and secretion of estrogen
Male: sperm production
Hormone: LH: luteinizing hormone
- -target
- -principal effects
target
Ovaries; testes
effects
Female: ovulation; maintenance of corpus luteum
Male: secretion of testosterone
Hormone:ADH: antidiuretic hormone
- -target
- -principal effects
target
Kidneys
effects
Water retention
Hormone:OT: oxytocin
- -target
- -principal effects
target
Uterus; mammary glands
effect
Stimulation of uterine contractions; stimulation of release of milk into ducts of mammary glands
anterior pituitary hormones include
GH: growth hormone (somatotropin)
PRL: Prolactin
TSH: thyroid-stimulating hormone
ACTH: adrenocorticotropic hormone
FSH: follicle-stimulating hormone
LH: luteinizing hormone
posterior pituitary hormones include
ADH: antidiuretic hormone
OT: oxytocin
Control of Pituitary Secretions
Releases hormones in phases or pulses
Central nervous system plays a role in controlling hormone secretion
Control of pituitary secretions by negative feedback
when the pituitary gland stimulates another endocrine gland ti secrete its hormone that hormone is then fed back to the pituitary telling it to stop further release of the tropic hormone
Pineal Gland
Produces melatonin
Tucked in the center of the brain on the roof of the brains third ventricle is the tiny, cone shaped pineal gland
Thymus
Secretes thymosin and thymopoietin which have roles in the immune system
Lies in the mediastinum just beneath the sternum
In children thymus gland Is large
Thyroid gland
Largest endocrine gland
Consists of two large lobes
Resides in the neck, just below the trachea where it is wrapped around the anterior and lateral portions of the trachea
can store hormones for later use
Isthmus
narrow band of tissue that connects the two lobes of thyroid gland
Thyroid follicles
tiny sacs that make up thyroid tissue
Thyroid colloid
thick fluid that fills each thyroid follicle
Sacs secrete 2 thyroid hormones
T3 (triiodothyronine) and T4 (Thyroxine)
Parafollicular cells
cells between the thyroid follicles that secrete the hormone calcitonin
Calcitonin
secreted when calcium levels rise, it triggers the deposition of calcium in bone thus promoting bone formation
Cretinism
condition characterized by retarded growth and sexual development, a low metabolic rate and mental retardation
Myxedema
swelling and firmness of the skin
Grave’s disease
results from a hypersecretion of TH that stimulates the bodys metabolism causing unexplained weight loss, increased heart rate, nervousness and exophthalmos
Exophthalmos
a protrusion of the eyeballs as a result of swelling of tissue behind the eye
Simple goiter
dietary deficiency of iodine
Parathyroid Glands
4 parathyroid glands located on the posterior surface of thyroid
Parathyroid hormone
secreted in response to low blood levels of calcium
Nerve and muscle function, blood clotting, cell membrane permeability, and the function of certain enzymes all depend on adequate calcium levels
PTH influence on bone
PTH inhibits new bone formation while stimulating the breakdown of old bone causing calcium to move out of bone and into the blood
PTH influence on kidney
PTH encourages the kidneys to reabsorb calcium while promoting the secretion of phosphate
Also prompts the kidneys to activate vitamin D necessary for intestinal absorption of calcium
PTH influence on intestines
after activation by the kidneys, vitamin D allows the intestines to absorb calcium from food; the calcium is transported through intestinal cells and into the blood
Regulation of Blood Calcium Levels
–Blood calcium excess
Blood calcium excess
Thyroid releases calcitonin
Calcium moves from blood to bone
Blood calcium levels decrease
Normal blood calcium levels
Regulation of Blood Calcium Levels
–Blood calcium deficiency
Blood calcium deficiency
Parathyroid releases PTH
Calcium moves from bones, kidneys, and intestines to blood
Blood calcium levels increase
Normal blood calcium levels
Triiodothyronine (T3) and Thyroxine (T4)
where its found
function
Most tissues
Increases rate of metabolism
Calcitonin
where its found
function
Bone
Increases deposition of calcium in bones lowering blood calcium levels
parathyroid hormone
where its found
function
Bone, kidneys
Increases blood calcium levels by increasing removal of calcium from bone reducing urinary excretion of calcium and increasing absorption of calcium by the intestines
Adrenal Glands
Perch on top of each kidney
Two distinct glands: adrenal medulla and adrenal cortex
Adrenal medulla
the inner portion, consists of modified neurons and functions as part of the sympathetic nervous system
Adrenal cortex
outer portion, 3 layers of glandular tissue and secretes corticosteroids
Corticosteroids
steroid hormones
Chromaffin cells
modified neurons that act as part of the sympathetic nervous system and secrete catecholamines
Catecholamines
prepare the body for physical activity by increasing heart rate and blood pressure
Adrenal medulla Boost glucose levels by:
Glycogenolysis: breaking down glycogen into glucose
Gluconeogenesis: converting fatty acids and amino acids into glucose
Zona glomerulosa
the outermost layer of the adrenal cortex
secretes glucocorticoids
Zona reticularis
the innermost layer of the adrenal cortex
secretes sex steroids
3 classes of hormones secreted by adrenal cortex
Mineralocorticoids:
Glucocorticoids:
Sex steroids
Mineralocorticoids:
aldosterone
aldosterone
the principal mineralocorticoids
Aldosterone acts on the kidneys to promote sodium retention and potassium excretion
In turn it also causes water retention
Glucocorticoids:
Cortisol:
Cortisol:
the principal glucocorticoids
Help the body adapt to stress and repair damaged tissue by stimulating the breakdown of fat and protein, converting fat and protein to glucose, and releasing fatty acids and glucose into blood
They have an anti inflammatory effect
They also suppress the immune system if secreted over a long term
Essential for maintaining a normal blood pressure
Sex steroids
Include a weak form of Androgen that is converted to the more potent androgen testosterone
Also includes small amounts of estrogen
Androgen
stimulate development of pubic and axillary hair and sustain sex drive in both sexes
hormone of adrenal medulla
Epinephrine
Norepinephrine
hormones of the adrenal cortex
Aldosterone
Cortisol
Adrenal androgens
Adrenal estrogens
hormone: epinephrine/norepinephrine
- -target
- -principal effect
Most tissues
Enhances the effects of the sympathetic nervous system
hormone: Aldosterone
- -target
- -principal effect
target
Kidney
effects
Promotes sodium retention and potassium excretion which leads to water retention
hormone: Cortisol
- -target
- -principal effect
target
Most tissues
effects
Stimulates the breakdown of fat and protein and the conversion of fat and protein to glucose; enhances tissue repair; anti inflammatory; in large amounts, inhibits the immune system
hormone: Adrenal androgens
- -target
- -principal effect
target
Sex organs
effects
Promotes growth of pubic and axillary hair; sex drive
hormone: Adrenal estrogens
- -target
- -principal effect
target
Sex organs
effects
Physiologically insignificant
Hypothalamic Pituitary Adrenal Axis
The amygdala signals the hypothalamus to activate the sympathetic nervous system and fight or flight response when a stressful event occurs
After 10 secs the initial surge of epinephrine begins to subside, the hypothalamic pituitary adrenal axis (HPA) axis is stimulated to help the body continue to cope
How it works Hypothalamic Pituitary Adrenal Axis
When stress continues the hypothalamus releases corticotropin releasing hormone (CRH)
CRH promotes the pituitary to release adrenocorticotropic hormone (ACTH)
ACTH travels to the adrenal cortex causing adrenal glands to secrete the glucocorticoid cortisol
Cortisol causing physiological changes design to give the body a burt of energy
Pancreas
Contains both endocrine and exocrine tissues
Majority acts like an exocrine gland
Lies just behind the stomach with its head tucked in the curve of the beginning of the small intestine and its tail reaching to the spleen
Acini
exocrine cells that secrete digestive enzymes into ducts that drain into the small intestine
Pancreatic islets (islets of Langerhans):
clusters of endocrine cells
Contain several different types of cells the main ones being alpha cells, beta cells, and delta cells
Alpha cells
Secrete glucagon
Gluconeogenesis between meals
Beta cells
Secrete the hormone insulin
After eating levels of glucose and amino acids in blood rise
Insulin
stimulates cells to absorb both of these nutrients from food causing blood glucose levels to fall
Delta cells
Secrete somatostatin
Inhibits release of glucagon, insulin and growth hormone
Somatostatin
A hormone that works within the pancreas to regulate the other endocrine cells
Regulation of Blood Glucose
Insulin and glucagon have opposite effects on levels of blood glucose which helps maintain blood glucose levels within normal range
how Regulation of Blood Glucose works
- After eating blood glucose levels rise as glucose flows from the digestive tract into the bloodstream
- High glucose levels stimulate beta cells of the pancreas to secrete insulin
- Insulin triggers two reactions:
- –It stimulates the cells to take up more glucose
- –It cause the liver to take up glucose and store it as glycogen
- –The combined result is that glucose levels return to normal levels - When blood glucose levels drop below a certain point the alpha cells of the pancreas release glucagon into the blood
- Glucagon stimulates the liver to break down stored glycogen into glucose which it then releases into the bloodstream
- –This causes the blood glucose level to rise
Diabetes
Results from an inadequate amount of insulin or from a diminished number of normal insulin receptors
Glycosuria
when excess glucose spills over into the urine
Polydipsia
kidneys produce more urine to flush out extra glucose
Polyphagia
people with untreated diabetes also experience continuous hunger
If left untreated the body begins to burn protein and fat for energy
Diabetic ketoacidosis
causing symptoms such as nausea, vomiting, fruity odor of the breath and possibly coma and death
Type 1 Diabetes
Average age at onset
Rate of onset
Percent of all diabetes
cause
Contributing factors
Treatment
Former name
Before age 30
Rapid
10%
Autoimmune condition in which the bodys antibodies attack the beta cells of thee pancreatic islets resulting in a deficiency of insulin
May be hereditary
Daily supplemental insulin, which may be administered by injection or via pump inserted under the skin in the abdomen
Juvenile-onset diabetes or insulin dependent diabetes mellitus
Type 2 Diabetes
Average age at onset
Rate of onset
Percent of all diabetes
cause
Contributing factors
Treatment
Former name
Usually after age 40
Gradual
90%
Cells become resistant to insulin in time the body stops producing enough insulin and the body can no longer use glucose effectively
Heredity combined with excess body weight. And sedentary lifestyle
Lifestyle change may control disease if not oral diabetic medications or insulin injections may be used
Maturity-onset diabetes or non-insulin dependent diabetes mellitus
hormone: glucagon
- target
- principal effects
target
-Primarily liver
effects
-Stimulates the break down of the stored form of glucose for release into the bloodstream
hormone: insulin
- target
- principal effects
target
-Most tissues
effects
-Stimulates the movement of glucose from the bloodstream into cells
hormone: Somatostatin
- target
- principal effects
target
-Pancreatic cells
effects
-Mainly helps regulate the secretion of other hormones of the pancreas
Gonads
Primary sex organs: Testes in males ovaries in females
Produce sex hormones
Estrogen
promotes the development of female characteristics and also contributes to the development of the reproductive system
Progesterone
helps maintain the uterine lining during pregnancy
secreted by the corpus luteum after ovulation
Certain cells in the body secrete other chemicals that help regulate function
Most significant is…
prostaglandins
prostaglandins
Made by cells throughout the body
Lipid molecules that integrate the activities of other cells
Released within the tissue where they are produced
Instead of influencing activities in distant organs prostaglandins influence activities of neighboring cells
Promote pain and fever, others act as vasodilators and vasoconstrictors
Involved in inflammation, blood clotting, uterine contraction, reproduction and digestion
