Endocrine System

endocrine gland

a ductless gland from which secretions (hormones) are released directly into the blood

hormone, paracrine, neurotransmittors, autocrine

What are the four major types of intercellular communication?

hormone

Type of intercellular communication produced in one area which are then transported by blood to affect cells in another area to act in areas of low concentration

paracrine

Type of intercellular communication produced in one cell then transported in extracellular fluid to affect adjacent cells

neurotransmittors

Type of intercellular communication that functions as paracrine communication within the nervous system

autocrine

Type of intercellular communication produced by and affecting the same cell

hormones

_____________ target ONE of the following functions":

1. metabolism

2. mineral balance

3. water balance

4. energy production and maintenance

5. reproductive control

chemical composition, source, physiological action

What are three ways that hormones can be classified?

chemical composition

Hormones classified by __________________ can be steroids or amine/polypeptide/protein

source

Hormones classified by ________________ can be pituitary or non-pituitary

physiological action

Hormones classified by __________________ can be growth, reproduction, stress, mineral balance, etc.

protein

___________ hormones are synthesized as pre-hormones then processed (undergoing several modifications) in the rough endoplasmic reticulum and Golgi apparatus to become mature hormones which are then stored in secretory vesicles until needed

secretory vesicles

Where are protein hormones stored after synthesis and maturation?

prehormones

Protein hormones are synthesized as ______________ before undergoing modifications in the rough ER and Golgi to mature

Ca, ATP

Secretion of protein hormones is mediated by what (2)?

hydrophilic, can

Most protein hormones are _____________ (hydrophilic, hydrophobic) and ________ (can, cannot) travel dissolved in the blood

cell surface

Protein hormone receptors are on the _______________ and trigger a cascade of second messenger enzymes, eventually carrying the signal to the nucleus

as needed

Steroid hormones are synthesized ___________ from cholesterol stored in the liver

lipophilic, can, cannot

Steroid hormones are _____________ and _____ (can, cannot) diffuse across the membrane, but _________ (can, cannot) be stored in granules

steroid

Because they are lipophilic, __________ hormones must be bound to a carrier protein to be transported in the blood

carrier

Because they are lipophilic, steroid hormones must be bound to a __________ protein to be transported in the blood

affinity, specificity, albumin

Lipophilic steroid hormones transported in the blood are bound to either (1) specific binding proteins that have a high _______ and __________ for the hormone or (2) non-specific binding to ___________

biologically active

Only about 1% of steroid hormones are free hormone circulating through the blood, but this small proportion represents the ________________ hormone

cytoplasm/nucleus

Steroid hormone receptors are located in the ______________________ and do not require secondary messengers

can

Steroid hormones are lipophilic so free hormone _______ (can, cannot) diffuse across the plasma membrane

rapidly cleared

Protein hormones are _____________ from circulation by peptidases that cleave the hormones or by being excreted in the urine

slow clearance

Steroid hormones have __________________ from circulation because they are reduced then conjugated with sulfates or glucuronides to make them water soluble so they can be excreted in urine

production

Degradation of both protein and steroid hormones is relatively constant, so their blood concentration reflects the rate of _______________ and release

feedback loop

The concentration of something is sensed leading to the up- or downregulation of an endocrine product

negative

Most feedback loops are _________ (positive/negative)

negative

_____________ feedback loops function to maintain homeostasis by sensing an adequate concentration then turning off a stimulatory sequence

positive

_____________ feedback loops generally result in an end outcome

long

______ feedback loops target organ response by feeding back to any part of the loop

short

_______ feedback loops target an intermediate hormone feeding back to a prior step in the loop

increased, increased

As a result of a productive parathyroid tumor, you would expect the concentration of parathyroid hormone to be ______________ and the concentration of Ca to be ___________

*Note: parathyroid hormone stimulates the release of calcium from bone stores

increased, decreased

As a result of a dietary Ca deficiency, you would expect the concentration of parathyroid hormone to be ______________ and the concentration of Ca to be ___________

*Note: parathyroid hormone stimulates the release of calcium from bone stores

decreased, increased

As a result of Vitamin D toxicosis, you would expect the concentration of parathyroid hormone to be ______________ and the concentration of Ca to be ___________

*Note: parathyroid hormone stimulates the release of calcium from bone stores and Vitamin D stimulates uptake of calcium from the GI tract

finer

Long feedback loops often have short components as well because redundancy helps build in ________ control

true

True or False: Long feedback loops may involve multiple hormones

hypothalamus

The ________________ serves as the connection between the two major controlling systems in the endocrine system: hormones and the nervous system

pituitary

The hypothalamus functions to influence the _______________ gland, telling it to produce tropic hormones that drive other organs to produce hormones and hormones that have direct effects

neuro

The posterior pituitary has __________hypophysis functions

oxytocin

Hormone secreted by the posterior pituitary gland which stimulates milk letdown, smooth muscle contraction at parturition, and maternal behavior and bonding

vasopressin (antidiuretic hormone, ADH)

Hormone secreted by the posterior pituitary gland which enhances water retention by the kidney and increases blood pressure by contraction of vascular smooth muscle

oxytocin, vasopressin (antidiuretic hormone, ADH)

What two hormones are produced by the posterior pituitary gland (neurohypophysis)?

adeno

The anterior pituitary has __________hypophysis functions

posterior

Pars nervosa makes up the ___________ pituitary gland

anterior

Pars distalis and pars intermedia make up the ____________ pituitary gland

hypothalamic releasing

The anterior pituitary contains several cell types, each specialized for secreting a single hormone (thyrotropin releasing hormone, growth hormone releasing hormone, growth hormone, thyroid stimulating hormone, luteinizing hormone, etc), control of which is regulated by _________________________ hormones

posterior

Diabetes insipidus occurs as a result of a problem with the ______________ pituitary gland, in which a lack of antidiuretic hormone (ADH, vasopressin) causes the kidneys to struggle to retain water, leading to polyuria (increased urination) and increased thirst and water intake to maintain blood volume

growth hormone (GH)

Hormone secreted by the anterior pituitary gland which stimulates the growth of bones and breakdown of fat (lipolysis)

liver, increase, increase

Growth Hormone from the anterior pituitary gland acts on the ___________ to:

1. _______________ gluconeogenesis in order to increase blood glucose

2. _______________ insulin resistance in order to increase blood glucose

3. Secrete insulin-like growth factor (IGF, somatomedin)

insulin-like growth factor (IGF, somatomedin)

When the liver is acted on by Growth Hormone, it secretes ___________________ which acts as a negative feedback

anterior

Pituitary dwarfism is usually caused by failure of pars distalis to completely develop, causing a deficiency in Growth Hormone and other ___________ pituitary hormones, leading to slow growth, retention of the puppy coat, abnormal development of testes/ovaries, abnormal dentition, a high/shrill bark, and a shortened lifespan

hyper

Acromegaly is a disease caused by a pituitary tumor causing ______secretion of Growth Hormone, leading to uncontrolled/poorly controlled diabetes due to increased gluconeogenesis and insulin resistance and broad head and underbite due to increased bone growth

anterior

Thyroid stimulating hormone (TSH) is a hormone produced by the ____________ pituitary gland which stimulates the thyroid to produce T3 and T4 which have a negative feedback to the hypothalamus and pituitary gland

T4

____ is the main hormone produced by the thyroid gland

both

Is T3, T4, or both biologically active thyroid hormones in the body?

T3

While T4 is the main thyroid hormone produced, it is metabolized to ____ by kidney and liver

thyroglobulin

When the T4 thyroid hormone is produced, it is placed into colloid and stored in the follicular lumen, attached to _________________ with high affinity and high specificity, until it is needed. Then it is absorbed, split from __________________, and secreted into the bloodstream

lipophilic

Thyroid hormones are _____________ and therefore must bind to a thyroid binding globulin for transport, interacting with the NUCLEUS rather than surface receptors

thyroid

The ____________ performs several actions to INCREASE metabolism including:

1. Increasing oxygen uptake and use which enhances heat production

2. Increasing glucose absorption from the gut and enhancing its movement into cells

3. Facilitating growth along with growth hormone

4. Enhancing lipolysis (which can lead to hypercholesterolemia)

5. Enhancing neural function

6. Enhancing cardiac function

feline hyperthyroidism

Thyroid disorder causing weight loss, increased appetite, hyperactivity, changes in coat, and heart murmurs in cats

canine hypothyroidism

Thyroid disorder causing weight gain, lethargy, heat-seeking behavior, and changes in the coat/alopecia of dogs

zona glomerulosa

Outermost layer of the adrenal gland cortex which secretes mineralocorticoids

zona fasciculata

Middle layer of the adrenal gland cortex which secretes glucocorticoids

zona reticularis

Innermost layer of the adrenal gland cortex which secretes sex steroids and glucocorticoids

medulla

Part of the adrenal gland that secretes catecholamines like epinephrine and norepinephrine for postganglionic sympathetic-like responses

cortex

Part of the adrenal gland related to the anterior pituitary gland which produces steroid hormones

cortisol

____________ produced by the adrenal cortex works as a negative feedback to the hypothalamus and anterior pituitary

cortisol

The major glucocorticoid hormone which:

1. Increases hepatic gluconeogenesis and decreases peripheral glucose uptake to INCREASE blood glucose

2. Redistributes fat into the liver and abdomen, creating the pot-bellied appearance

3. Induces protein catabolism, further creating the pot-bellied appearance

4. Suppresses the immune system which increases our susceptibility to infections

5. Increases water excretion which increases our urination and thirst

corticosterone

Less potent glucocorticoid which has anti-inflammatory functions

circadian rhythm, night

Glucocorticoid levels follow our 24 hour __________________, leading them to be the highest and lowest at _________

canine hyperadrenocorticism

Also known as Cushing’s Disease, this elevated levels of glucocorticoids causes thin, scaly skin, hair loss, increased urination and thirst, and a pot-bellied appearance

anti-inflammatory

Glucocorticoids are used therapeutically as ___________________ drugs, but the feedback pathways are delicate and slow to up- or downregulate so chronic use of such medications must be tapered off slowly

cortisol, corticosterone

What glucocorticoids are produced by the zona fasiculata of the adrenal cortex?

aldosterone

What mineralcorticoid is produced by the zona glomerulosa of the adrenal cortex?

aldosterone

Hormone produced by the zona glomerulosa of the adrenal cortex which acts on renal tubules to retain Na/water and excrete K/H+ to effect electrolyte and acid-base balance

low, low, high

Primary control of aldosterone secretion is not from the anterior pituitary gland, but instead its production is stimulated by:

1. ______ blood pressure

2. ______ plasma Na concentration

3. ______ plasma K concentration

retention (increases blood pressure)

Aldosterone affects the renal tubules by increasing Na and water _____________ (retention, excretion)

excretion (decreases plasma K, increases blood pH)

Aldosterone affects the renal tubules by increasing K and H+ ______________ (retention, excretion)

macula densa

specialized group of kidney cells that sense sodium chloride levels in the distal tubule and regulate glomerular filtration and renin release

juxtaglomerular apparatus

_____________________ cells produce renin in response to low blood pressure

macula densa

Renin is increased when cells in the _________________ sense low Na concentrations

renin

________ converts angiotensinogen to angiotensin I, the first molecule required to stimulate the production of aldosterone

angiotensin converting enzyme (ACE)

________________________ converts angiotensin I to angiotensin II, the second molecule required to stimulate the production of aldosterone

angiotensin II

______________ acts on the adrenal cortex to produce aldosterone, which functions to return blood pressure to normal levels by retaining Na and water and excreting K and H+

antidiuretic hormone (ADH, vasopressin)

In addition to aldosterone, angiotensin II also stimulates secretion of _______________ to increase water retention to aid in returning blood pressure to normal parameters

renin-angiotensin-aldosterone system

Low blood pressure and low plasma Na concentration act on the adrenal cortex via the _____________________________, whereas increased plasma K concentrations act DIRECTLY on the adrenal cortex to produce aldosterone and does not rely on this system

blood

The adrenal medulla has different cell types to produce each hormone (epinephrine, norepinephrine), and releases these catecholamines into the __________ rather than the synaptic cleft

epinephrine

Both epinephrine and norepinephrine act on the same receptors, but ______________ is more potent

fight or flight

Catecholamines (epinephrine, norepinephrine) target tissues with various receptors (alpha 1, alpha 2, beta 1, beta 2) and the corresponding response depends on which receptors are present in varying numbers and which catecholamine is binding the receptor. They trigger ____________________ responses including:

1. Increased blood glucose - glycogenolysis, lipolysis, gluconeogenesis

2. Increased heart rate/contractility

3. Decreased GI contractility

4. Pupil dilation

5. Shunting blood from viscera to muscles

hypoglycemia, acute stress, severe blood loss

What are three common triggers of secretion of catecholamines (epinephrine, norepinephrine) by the medulla of the adrenal gland?

islets of langerhans

The endocrine portion of the pancreas

glucagon

Alpha cells in the Islets of Langerhans (endocrine pancreas) secrete _____________

insulin

Beta cells in the Islets of Langerhans (endocrine pancreas) secrete _____________

somatostatin

D cells in the Islets of Langerhans (endocrine pancreas) secrete _____________

pancreatic polypeptide

F cells in the Islets of Langerhans (endocrine pancreas) secrete _____________

insulin

Pancreatic hormone that acts to decrease blood glucose by moving nutrients from the blood into cells:

1. Glucose stored in the form of glycogen

2. Fatty acids stored in the form of triglycerides

3. Amino acids stored in the form of proteins

increased blood glucose

What is the main stimulus for production of insulin?