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108 Cards in this Set

  • Front
  • Back

Name the functions of the endocrine system.

1. metabolism and tissue maturation


2. ion regulation


3. water balance


4. immune system regulation


5. heart rate and blood pressure regulation


6. control of blood glucose and other nutrients


7.control of reproductive function


8. uterine contraction and milk release

What are the two main differences between the endocrine system and the nervous system?

1. endocrine system is amplitude-modulated whereas nervous system is frequency-modulated


2. the response of target tissues to hormones is usually slower and of longer duration than that of neurons

Definition: chemical substances secreted by cells into the interstitial fluid and diffuse into the blood

hormones

Hormones act on specific tissues called __________. They have lag times from a few _____ to _____. Hormones also tend to have prolonged effects.

target tissues


seconds


hours

What are the four protein groups of hormones?

proteins, glycoproteins, polypeptides, and amino acid derivatives

What are the two lipid groups of hormones?

steroids and fatty acid derivatives

What controls the secretion of most hormones?

negative feedback

What are the three mechanisms by which hormone secretion from endocrine tissue is regulated?

1. changes in extracellular concentration of non-hormones substances


2. stimulation by the nervous systems


3. stimulation by a hormone from another endocrine tissue

TRH is released from the ______ and stimulates _____ release from the ______. Then ____ travels in the blood to stimulate the ______ gland to release ______ hormones. These hormones have a negative feedback effect on the _______ and the ______.

hypothalamus


TSH


anterior pituitary gland


TSH


thyroid


thyroid


hypothalamus


anterior pituitary gland

________ hormones do not bind the plasma proteins and/or readily diffuse out of the blood. They are quickly ____________ or taken up by tissues. They regulate activities that have a _____ and a ______. Examples include _____, _____, ______.

water-soluble


broken down by enzymes


rapid onset


short duration


proteins


epinephrine


norepinephrine

______ and ______ hormones are not easily removed from the blood. They produce a _____ effect.

lipid-soluble


thyroid


prolonged

Hormones either leave the blood to reach ______ or are excreted by the _____ or _____.

target tissues


kidneys


liver

Definition: receptors that span the plasma membrane; bind to water-soluble or large-molecular-weight hormones

membrane-bound receptors

Definition: receptors in the cell cytoplasm of nucleus; bind to lipid-soluble hormones

intracellular receptors

What is the main function of intracellular receptors?

To activate genes for protein or enzyme synthesis

What are the functions of the membrane-bound receptors?

1. act on G proteins to open or close ion channels and activate existing enzymes


2. alter the activity of intracellular enzymes to activate existing enzymes

What are the three subunits of G proteins?

alpha, beta, gamma

What are the active and inactive states of G proteins?

GDP - inactive


GTP - active

What is the function of G proteins?

To produce responses when activated by membrane-bound receptors

Name three hormones that activate G proteins.

LH, FSH, TSH, oxytocin, ADH, calcitonin, PTH, glucagon, epinephrine

What are the steps in the process of G protein activation?

1. Hormone binds to a membrane-bound receptor


2. Receptor is altered and G protein binds to it. GTP replaces GDP alpha subunit


3. G protein separates from the receptor. GTP alpha subunit separates from G protein.


4. Hormone separates from its receptor. GTP's phosphate is cleaved and the remaining GDP binds to the G protein.

How does the GTP alpha subunit induce a cell response?

It binds to a Ca+2 ion channel, causing it to open. Ca+2 flows in and binds to calmodulin which produces a cell response.



If its an enzyme, the GTP binds to the enzyme and activates it. The enzyme converts ATP to cAMP and 2PPi. cAMP is a intracellular modulator and activates protein kinases.

How do intracellular enzymes activated by a membrane-bound receptor initiate a cell response?

1. they synthesize intracellular mediators


2. they add phosphate groups to intracellular enzymes, which alters their activity

Why do intracellular mediator mechanisms act so rapidly?

They work on already existing enzymes to produce a cascade effect

How do intracellular receptors work?

1. Hormone diffuses through the membrane and binds with a receptor.


2. Receptor-hormone complex diffuses into the nucleus where it activates genes.


3. mRNA is produced.


4. mRNA initiates the production of certain proteins that produce the response

Intracellular mechanisms are _____-acting because _________________.

slow


time is required to produce mRNA and protein

Steroid hormones are _______. They travel in the blood _______.

water-soluble


attached to protein carriers

The pituitary gland secretes at least __ hormones that regulate numerous body functions and other glands. The hypothalamus regulates ______ activity through _____ and ______.

9


pituitary gland


hormones


action potentials

The posterior pituitary is called the _________. It develops from the ______ and connects to the hypothalamus by the ______.

neurohypophysis


floor of the brain


infundibulum

The anterior pituitary is called the ______. It develops from the _______.

adenohypophysis


roof of the mouth

The _______________ connects the hypothalamus and the anterior pituitary. Hormones are produced in the ________. Through this, the hormones ____ or _____ hormone production in the anterior pituitary.

hypothalamohypophyseal portal system


hypothalamic neurons


inhibit


stimulate

The _______________ connects the hypothalamus and the posterior pituitary. Hormones are produced in the ________. The hormones move down the _______ and are secreted from the ______.

hypothalamopophyseal tract


hypothalamic neurons


axons of the tract


posterior pituitary

What two hormones does the neurohypophysis store/secrete and what do they do?

Anti-diuretic hormone (ADH): promotes water retention by the kidneys


Oxytocin: promotes uterine contractions during delivery and causes milk ejection in lactating women

Name 4 hormones that the anterior pituitary releases.

growth hormone (GH)


thyroid-stimulating hormone (TSH)


adrenocorticotropic hormones (ACTH)


melanocyte-stimulating hormone (MSH)


luteinizing hormone (LH)


follicle-stimulating hormone (FSH)


prolactin

GH stimulates growth in ________ and is a regulator of _____. It stimulates the uptake of ____ and their ________, the breakdown of ____ and the synthesis of _____, and the production of _________ (which promote ____ and ____ growth).

most tissues


metabolism


amino acids


conversion into proteins


fats


glucose


somatomedins


bone


catrilage

GH secretion increases in response to ______, ____, and an increase in certain ______. It is regulated by _____ and ______.

low blood glucose


stress


amino acids


growth hormone-releasing hormone (GHRH)


growth hormone-inhibiting hormone (GHIH)

The pituitary gland is located in the _____ of the _____ bone.

sella turcica


sphenoid

The _____ is the largest gland in the body and is connected by a median tissue mass called the _____. It is composed of _____ that produce the glycoprotein ______. Other endocrine cells, called the __________, produce the hormone ______.

thyroid


isthmus


follicles


thyroglobulin


parafollicular cells


calcitonin

Thyroid hormones consist of two _____-containing compounds: __________ (90%) and __________ (10%).

iodine


triiodothyronine (T3)


tetraiodothyronine (T4)

Name the release origin, function, and target tissue of ADH.

Origin: posterior pituitary


Target Tissue: kidney


Function: increased water reabsorption

Name the release origin, function, and target tissue of oxytocin.

Origin: posterior pituitary


Target Tissue: uterus; mammary glands


Function: increased uterine contractions; increased milk expulsion

Name the release origin, function, and target tissue of GH.

Origin: anterior pituitary


Target Tissue: most tissues


Function: increased growth

Name the release origin, function, and target tissue of TSH.

Origin: anterior pituitary


Target Tissue: thyroid gland


Function: increased thyroid hormone secretion

Name the release origin, function, and target tissue of ACTH.

Origin: anterior pituitary


Target Tissue: adrenal cortex


Function: increased glucocorticoid hormone secretion

Name the release origin, function, and target tissue of MSH.

Origin: anterior pituitary


Target Tissue: melanocytes in skin


Function: increased melanin production in melanocytes (makes skin darker)

Name the release origin, function, and target tissue of LH.

Origin: anterior pituitary


Target Tissue: ovaries/testes


Function: ovulation and progesterone production; testosterone synthesis and sperm cell production

Name the release origin, function, and target tissue of FSH.

Origin: anterior pituitary


Target Tissue: follicles in ovaries; seminiferous tubes


Function: follicle maturation and estrogen secretion; sperm cell production

Name the release origin, function, and target tissue of prolactin.

Origin: anterior pituitary


Target Tissue: ovaries and mammary glands


Function: milk production; increased response of follicle to LH and FSH

Name the release origin, function, and target tissue of GHRH.

Origin: hypothalamus


Target Tissue: anterior pituitary


Function: increased GH secretion

Name the release origin, function, and target tissue of GHIH.

Origin: hypothalamus


Target Tissue: anterior pituitary


Function: decreased GH secretion

Name the release origin, function, and target tissue of TRH.

Origin: hypothalamus


Target Tissue: anterior pituitary


Function: increased thyroid-stimulating hormone secretion

Name the release origin, function, and target tissue of CRH.

Origin: hypothalamus


Target Tissue: anterior pituitary


Function: increased adrenocorticotropic hormone secretion

Name the release origin, function, and target tissue of GnRH.

Origin: hypothalamus


Target Tissue: anterior pituitary


Function: increased secretion of LH and FSH

Name the release origin, function, and target tissue of PIH.

Origin: hypothalamus


Target Tissue: anterior pituitary


Function: decrease prolactin secretion

Name the release origin, function, and target tissue of PRH.

Origin: hypothalamus


Target Tissue: anterior pituitary


Function: increased prolactin secretion

How are thyroid hormones synthesized?

1. iodides are taken up into the cell, oxidized to iodine, and released into the lumen.


2. thyrogobulin is synthesized and discharged into the lumen


3. iodine attaches to tyrosine via peroxidase enzymes (thyroglobulin) and forms T1 and T2


4. iodinated tyrosines link together to form T3 and T4.

How are T3/T4 stored?

They are stored within the thyroid follicles as part of thyrogobulin (2-4 month supply).

How is thyroid hormone released into the bloodstream?

Thyrogobulin is brought in by endocytosis and combined with a lysosome, which cleaves T3/T4 and they diffuse into the bloodstream.

What are the functions of T3/T4?

-increase the rate of glucose, fat, and protein metabolism in many tissues


-increase body temperature


-help maintain BP


-help regulate tissue growth


-help in development of skeletal an nervous systems


-help with maturation and reproductive capabilities

How is thyroid hormone regulated?

-TRH from the hypothalamus increases TSH secretion


-increased TSH from anterior pituitary increases thyroid hormone secretion


-increased thyroid hormone have a negative feedback on TSH and TRH

Parafollicular cells secrete ______. This hormone is directly regulated by _________ levels. When levels drop, the hormone levels ______. When levels rise, the hormone levels ______. This hormone targets the ______ to inhibit ______ activity and the release of _____ from the _______. It also stimulates ______ uptake and incorporation into the ________.

calcitonin


blood calcium


drop


rise


skeleton


osteoclast


calcium


bone matrix


calcium


bone matrix

Definition: tiny glands embedded into the posterior aspect of the thyroid

parathyroid glands

The parathyroid glands secrete a polypeptide hormone called _____. This hormone is essential in regulating _____________ (much more so than ______). This hormone ______ the release of ____ from bones into blood by increasing the number of _______. A decrease in ______ levels stimulates the release of this hormone.

PTH


calcium balance in the blood


calcitonin


increases


calcium


osteoclasts


calcium

In addition to regulating blood calcium levels, PTH also promotes calcium reabsorption by the _____ and the formation of _______ by the _____.

kidneys


active vitamin D


kidneys

Active vitamin D increases _______ absorption by the ______.

calcium


intestine

Definition: paired, pyramid-shaped organs that sit on top of the kidneys

adrenal glands

The adrenal glands are divided into two parts: the _________ (inner area) and the ________(outer area).

adrenal medulla


adrenal cortex

The adrenal medulla arises from the same cells that give rise to __________ neurons. The adrenal cortex is _____ tissue derived from the embryonic ______. It is composed of 3 layers called ______, _____, ______. Structurally and functionally, they are three glands in one.

postganglionic sympathetic


glandular


mesoderm


zona glomerulosa


zona fasciculata


zona reticularis

Approximately 80% of the hormones released by the adrenal medulla is ______ and 20% is _____. Secretion of these hormones prepares the body for physical activity by increasing _____, increasing the use of ______ and _____ by skeletal muscle, increasing ___ and force of ________, causing _______ in the skin and viscera, and causing _______ in the skeletal and cardiac muscle.

epinephrine


norepinephrine


blood glucose levels


glycogen


glucose


HR


contraction


vasoconstriction


vasodilation


Epinephrine and NE are released from the adrenal medulla in response to what stimuli?

emotions


injury


exercise


stress


low blood glucose levels

The adrenal cortex synthesizes and releases ____ hormones called ________.

steroid


corticosteroids

Name what hormones each of the layers of the adrenal cortex produce.

zona glomerulosa: mineralocorticoids (aldosterone)


zona fasciculata: glucocorticoids (cortisol)


zona reticularis: gonadocorticoids (androgens)

What are the main functions of mineralocorticoids and which is the most important one?

-regulate electrolytes in extracellular fluids


-aldosterone

What is the function of aldosterone?

-maintains sodium balance by reducing excretion of sodium from the body


-stimulates reabsorption of sodium by the kidneys


-decreases potassium and H+ levels in the blood

What is aldosterone secretion stimulated by?

-rising blood levels of potassium


-low blood sodium


-decreasing blood volume or pressure

What are the main functions of glucocorticoids and which is the most important one?

-help the body resist stress by keeping blood sugars constant


-maintain blood volume and prevent water shift into tissue


-cortisol

What are the functions of cortisol?

-promotes gluconeogenesis


-rise in blood glucose, fatty acids, and amino acids

Definition: formation of glucose from non-carbohydrates

gluconeogenesis

What are the negative effects of excessive levels of glucocorticoids?

-depress cartilage and bone formation


-inhibit inflammation


-depress the immune system


-promote changes in cardiovascular, neural, and gastrointestinal function


How is cortisol secretion regulated?

-CRH is released from the hypothalamus in response to stimuli and travels to the anterior pituitary


-anterior pituitary is stimulated to release ACTH


-ACTH stimulates the release of cortisol from the adrenal cortex


-cortisol has a negative feedback on CRH and ACTH

What are the main functions of gonadocorticoids and which is the most important one?

-onset of puberty, appearance of secondary sex characteristics, sex drive in females


-testosterone

Androgens can be converted to ______ after _____.

estrogens


menopause

Definition: a triangular gland which has both exocrine and endocrine cells; locate behind the stomach

pancreas

In the pancreas, the ____ cells produce an enzyme-rich juice used for digestion (_____ product). The ______ (islets of ______) produces hormones (______ products). The islets contain two major cells types: alpha and beta. Alpha cells produce ____ and beta cells produce _____.

acinar


exocrine


pancreatic islets


Langerhans


endocrine


glucagon


insulin

The target tissues of insulin are _____, _____, ______, and the _____ in the ______. The function of insulin is to maintain _______ by increasing the uptake of _____ and _______ by cells.

liver


adipose tissue


muscle


satiety center


hypothalamus


blood glucose levels


glucose


amino acids

Glucose is used for ______. It is stored as ______ and converted into _____. Amino acids are used to __________.

energy


glycogen


fats


synthesize proteins

Low levels of insulin promote the formation of ________ by the ______.

ketone bodies


liver

The target tissue of glucagon is mainly the ______. It causes the breakdown of ____ to _____ and stimulates the synthesis of ______ from ______. The ______ releases glucose into the blood.

liver


glycogen


glucose


glucose


amino acids


liver

What causes insulin levels to increase of decrease?

Increase: elevated blood glucose levels, increase in some amino acids, parasympathetic stimulation, gastrointestinal hormones


Decrease: sympathetic stimulation (somatostatin)

What causes glucagon levels to increase or decrease?

Increase: low blood glucose levels, certain amino acids, sympathetic stimulation


Decrease: somatostatin (inhibits both glucagon and insulin)

What happens are eating a meal?

1. high glucose --> stimulates insulin, inhibits glucagon/cortisol/GH/Epi


2. insulin increases uptake of glucose, amino acids, and fats


3. after some time, glucose levels drop


4. insulin decreases, other hormones increase


5. glucose is released from tissues and liver


6. use of glucose by tissues decreases


7. adipose tissues release fatty acids and ketones, which most tissues use for energy

What happens after exercise?

1. sympathetic activity increases Epi and glucagon --> release of glucose from liver into blood


2. uptake of glucose by muscle --> low blood sugar levels --> stimulates Epi, glucagon, GH, and cortisol secretion


3. increase in fatty acids and ketones in blood which are used for energy

The testes secrete ______. This hormone initiates the __________, causes appearance of _______ and _____, is necessary for _______, and maintains ____ in their functional state.

testosterone


maturation of male reproductive organs


secondary sex characteristics


sex drive


sperm production


sex organs

Ovaries secrete ______ and _______. This hormone is responsible for the __________, appearance of _______, _____ development, and cyclic changes in the _________.

estrogens


progesterone


maturation of reproductive organs


secondary sexual characteristics


breast


uterine mucosa

Definition: small, pinecone-shaped structure located superior and posterior to the thalamus

pineal body

What is the secretary product of the pineal body? What is its function?

melatonin - inhibits reproductive maturation, regulates sleep-wake cycles

How is melatonin secretion stimulated?

1. light entering the eye stimulates neurons


2. signals are sent to hypothalamus


3. hypothalamus transmits signals through sympathetic system to pineal body


4. decrease in light increases pineal stimulation/melatonin levels; increase in light decreases pineal stimulation/melatonin levels

Definition: lobulated gland located deep in the sternum

thymus

What are the major hormonal products of the thymus and what are their functions?

thymopoietins and thymosins - essential for the development of T lymphocytes of the immune system

What are some of the hormones of the gastrointestinal tract and what are their functions?

gastrin, secretin, and cholecystokinin - regulate digestive function

What hormone is secreted by the kidneys and what are it's functions?

erythropoietin - stimulates red blood cell production

What hormone is secreted by the placenta and what are it's functions?

human chronic gonadotropin - essential for the maintenance of pregnancy

Definition: chemical signals that locally affect cells of the same type as the cell producing the agent

autocrine agents

What are some examples of autocrine agents?

prostaglandins, thromboxanes, prostacyclins, and leukotrienes

Definition: chemical signals that locally affect cells of a different type than the cell producing the agent

paracrine agent

What are some examples of paracrine agents?

growth factors, clotting factors, and histamine

How do autocrine/paracrine chemical signals differ from hormones?

-they are not secreted from discrete endocrine glands


-they have local effects rather than systemic effects


-they have functions that are not understood in all cases

As a person ages, there is a gradual ______ in the secretion ____ of most, but not all, hormones. Some decreases are secondary to gradual decreases in _________.

decrease


rate


physical activity