Unit 4: Endocrine Physio Flashcards by Sasha K.

Define “hormone,” and “target cell”.

Hormone- chemical secreted by a cell(s) into the blood for transport to a target where it acts in low concentrations to affect growth/homeostasis/metabolism

target cell- a cell that has a receptor, therefore has ability to bind to the hormone and recognize its presence

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Compare and contrast between endocrine and exocrine glands.

endocrine glands are ductless and can only secrete cellular signals in the form of a hormone

exocrine glands can secrete many different molecule types and they will move through a duct to destination

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Compare and contrast between the endocrine and the nervous systems

endocrine system
~cellular signal starts out as a chemical; chemical is carried by bloodstream to a target cell [also being carried to all other cells but only recognized by target cells with receptors]
~signal is transported to selected target cells that respond to the presence of the endocrine hormone
~slower response time (secretion of endocrine cell into blood, transportation takes time, response)
~chemical signal is an endocrine hormone

nervous system
~bulk of message is carried electrically down neuron length
~signal delivery much faster
~signal is distributed only to terminal synapse (more localized/targeted)
~chemical signal is a neurotransmitter

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Describe the different mechanisms of endocrine tissue control.

A. Nervous (ex- adrenal medulla)

B. Humoral (ex- blood glucose level)

C. Hormonal (ex- hypothalamic releasing hormones)

D. Feedback (via any above mechanisms)

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Describe the different chemical classifications used to describe hormones.

A. Water soluble/ membrane impermeable
i. Polypeptide (amino acid derived)
ii. Catecholamine (amino acid derived)
[cannot enter cell, can only interact with target cells exteriorly]

B. Water Insoluble/ membrane permeable
i. steroid
ii. thyroid hormones (amino acid dervied)
[require some carrier within the blood]

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Describe the steps in the cAMP second messenger system.

What type of hormone (chemical classification) uses this activation system?

Water soluble hormones (they cannot cross membrane)- polypeptides & catecholamine

1) signal molecule binds to G protein linked receptor, activating G protein

2) G protein turns on Adenylyl cyclase (an amplifier enzyme)

3) Adenylyl cyclase converts ATP into Cyclic AMP (cAMP)

4) cAMP activates protein kinase A

5) Protein kinase A phosphorylates other proteins, leading to cellular response in target cell

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Describe the steps in the calcium second messenger system.

What type of hormone (chemical classification) uses this activation system?

Also used by water soluble/ membrane impermeable hormones- polypeptides & catecholamine

1) signal molecule activates the receptor and associated G protein

2) G protein activates phospholipase C (Pl-C, an amplifier enzyme)

3) Pl-c converts membrane phospholipids into ip3, which diffuses into cytoplasm

4) Ip3 causes release of calcium from organelles, creating a calcium signal

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Describe the steps in target cell activation by steroid hormones.

Hormone bound to receptor becomes active & can move into nucleus and attach to DNA

when attached to DNA at a promoter site, DNA segment can make copies of itself in form of mRNA

mRNA is shuttled out into cytoplasm and used for protein synthesis

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Describe the steps in target cell activation by thyroid hormones.

Hormone is bound to plasma carrier protein

Binding to a target cell activates the prehormone (T4 > T3)

T3 moves in nucleus and binds to receptor protein that is attached to DNA; binding will trigger RNA production which will be used for protein synthesis

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Describe the process of up and down regulation and its significance.

Target cell property

Up regulation- Some will at their tonic level of hormone exposure have very little responsiveness (not many receptors for a hormone), but as hormone levels rise, the cells produce more receptors > cell is more responsive to hormone

up-regulation can also occur when hormone levels decline [increasing sensitivity to lower hormone levels]

Down regulation- ex) insulin in diabetic; target cells decrease # receptors if hormone levels rise if they are chronically elevated [receptors removed and become less sensitive to hormone]
~can also occur if hormone levels drop

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Name each of the lobes of the pituitary and describe the structure (origin) of each lobe.

3 main zones

~posterior pituitary [made of neural tissue] AKA neurohypophysis; produces 2 meaningful hormones

~intermediate pituitary [tiny sliver in the center of the gland]; secretes one hormone

~anterior pituitary [6 cell types- epithelial cells that secrete 7 hormones]

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Describe the relationship between the hypothalamus and the anterior pituitary.

The hypothalamus releases neurohormones that affect the anterior pituitary

[the neurohormones will stimulate or inhibit anterior pituitary cells]

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Identify all of the hormones produced by the anterior pituitary and the general function of each.

How many regulate the function of another endocrine gland?

Prolactin: more dramatic role in females; act on glandular breast tissue to stimulate milk production
Growth hormone: acts on multiple tissue types to stimulate growth
thyroid stimulating hormone (TSH): stimulated thyroid gland (follicular cells of the gland)
Adrenocorticotropic hormone (ACTH): targets adrenal cortex
Follicle stimulating hormone (FSH): follicle growth within the ovary
Leutanizing hormone (LH): triggers ovulation

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Describe the relationship between the hypothalamus and the posterior pituitary

The hypothalamus synthesizes the hormones stored and released by the posterior pituitary [ADH, oxytocin]

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Identify the hormones secreted by the intermediate and posterior pituitary and describe the general function of each

Posterior pituitary [2]
~Anti diuretic hormone ADH: stimulates increased reabsorptive potential of collecting duct by increasing water permeability with aquaporins [decreased urine]

~Oxytocin: smooth muscle stimulator resulting in smooth muscle contraction

intermediate pituitary [1]
~Melanocyte stimulating hormone MSH: stimulates melanocytes [found in skin- pigment]- minimal role

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Describe the endocrine and exocrine structure of the pancreas.

99% exocrine structure
~pancreatic acinar cells: secrete protein/lipid/carb digesting enzymes, buffering agents down the ductwork into small intestine for digestion

1% endocrine structure
~pancreatic islets (of Langerhans) [ductless]
~insulin & glucagon production

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Identify the different cell types of the endocrine pancreas and their products.

Beta cells produce insulin

Alpha cells produce glucagon

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Describe the function of insulin on cells in general, on liver tissues, on adipose tissues and on skeletal muscle tissues.

General- increases cellular uptake of blood glucose [lowering blood glucose]

Liver & skeletal muscle tissue: convert glucose into glycogen for storage [glycogenesis] may be shorter term

adipose tissue: glucose converted into triglyceride molecules [lipogenesis] longer-term conversion

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Describe the function of glucagon on cells in general, on liver tissues, on adipose tissues and on skeletal muscle tissues.

General- antagonistic to insulin in metabolism effect; increases blood glucose levels

Liver & skeletal muscle tissue: converts glycogen or other non-carb molecules to glucose [glycogenolysis]

Adipose tissue: lipolysis; no change in blood glucose; release of ketones into blood (fuel source in absence of glucose)

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Distinguish between type I (IDDM) and type II (NIDDM) diabetes mellitus.

Type 1: very severe; [juvenile onset]; due to early autoimmune error that kills all beta cells; deficient in insulin production

Type 2: Adult onset; response of target cells which are down-regulating and not responding to insulin as much as they should; typically due to diet that leads to chronically elevated insulin levels > down-regulation

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Compare and contrast between diabetes mellitus and diabetes insipidus.

diabetes mellitus: lack/abnormal insulin action

diabetes insipidus: lack of vasopressin (ADH)

Both marked by frequent urination [polyurea]

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What are the cardinal symptoms of diabetes mellitus (three P’s)? Explain how each symptom comes about.

Polyphagia- extreme hunger

Polyuria- increased urination (due to increased osmotic conc. of filtrate caused by hyperglycemia)

Polydipsia- extreme thirst

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Identify the different hormones of the thyroid gland, their specific origin and their general function.

Secretes 2 key hormones

triiodothyronine T3
thyroxine T4

^ both responible for regulating metabolic rate; role in negative feedback loop; become self-regulatory; dependent on iodine

[insufficient iodine> leads to large thyroid gland]

[also calcitonin, but not as important]

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Identify the hormone of the parathyroid gland and its general function.

Parathyroid hormone

targets mainly kidneys & bone

Kidneys: reabsorption of Ca2+ calcium [increases blood calcium & decreases urinary excretion of calcium]

Bone: dissolution of calcium phosphate crystal> increases blood calcium [negative feedback]

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Identify the different hormones of the adrenal gland, their specific origin and their general functions.

Adrenal cortex - 3 zones Zona glomerulosa: mineralocorticoid AKA ALD [Na reabsorption, K secretion] Zone fasciculata: glucocorticoids [ex) cortisol- blood glucose regulation, anti-inflammation] Zona reticularis: sex hormones (testosterone, etc, but not as much as in sex organs) Adrenal medulla (core) Norepinephrine: neurotransmitter produced & secreted by post-ganglionic sympathetic neurons Epinephrine Dopamine

__________ ________ are glands that release a secretion into interstitial space; then the molecule can migrate and enter the bloodstream [ductless glands]

endocrine glands

________ ______ always have ducts; products are secreted into a duct> moves through to duct to a destination (internal or external space)

exocrine glands

Endocrine glands secrete :

cellular signals [chemicals]; transported in blood- unique label of hormone

Exocrine glands can secrete :

various molecules such as enzymes, buffers, acids, protein water mix, etc...

While exocrine glands can secrete several molecule types, endocrine glands only secrete:

cellular signals in the form of hormones

Hormones are named as such if found in the:

blood

________ _____ is a cell that has a receptor and, therefore can bind to the hormone and recognize its presence

target cell

which cell is the target cell is determined by:

the cells, not by the hormone or endocrine gland

the _________ __________ produces and secretes the endocrine hormone

endocrine tissue

the endocrine hormone is transported by way of:

blood

The thyroid gland produces predominantly the prehormone:

Thyroxine (T4)

Thyroxine doesn't do anything; it needs to be converted to its active form by removing 1 iodine:

triiodothyronine (T3)

Testosterone is not fully functional; it is a pre hormone and needs to be converted into:

DHT to be functional

Vitamin D3 is a prehormone and converted to its functional form:

Dihydroxyvitamin D3

Some hormones are produced and secreted in a pre hormone format and activated at:

their target cells

Some other hormones are produced and stored in an inactive form and are converted to active form once secreted, but as a consequence:

2 pieces are secreted such as with insulin

A classic example of a polypeptide:

insulin

for water-soluble hormones, when released from endocrine tissue, they can migrate :

right through interstitial fluid and enter plasma without a carrier or any restrictions

Water insoluble hormones will be secreted and diffuse into the blood; then they must meet with a:

plasma carrier to trap them there, or else they will move right out of the blood

For water insoluble hormones, what might the plasma carrier be?

plasma protein albumin globulins

thyroid hormones contain:

iodine

What is a synergistic effect?

Hormone A produces response in target cell Same target cell responds to hormone B Hormones A and B if present at the same time, produce more dramatic response in target cell [they add to each other's effect]

What is a permissive effect?

Target cell may not response to hormone A unless hormone B is also present [1 hormone must be present for 2nd hormone to produce any effect]

what is an antagonistic effect?

1 hormone may counter effect of 2nd hormone

endocrine glands secrete chemicals that act as :

cellular signals

An _______ gland secretes it products without a duct

endocrine

In the cAMP second messenger pathway, ATP is used for:

the substrate that the enzyme reconfigures to form cAMP

Illustrated above is a cylclic-AMP (cAMP) second messenger pathway used by membrane impermeable hormones. Identify all components

A- receptor protein B/C- G-proteins D- adenylate cyclase E- cAMP

The production and secretion of hormones by endocrine tissues may be regulated by all of the following EXCEPT: stimulation by hormones from other endocrine tissues nervous system stimulation of the endocrine tissue voluntary regulation directly responding to concentrations of "humoral" factors in the blood stimulation by hormones that are produced by the nervous system

voluntary regulation

When a hormone is secreted so that plasma levels of the hormone remain chronically elevated, the likelihood of ________ is increased

down regulatory effects

Cholesterol is a precursor for the synthesis of

aldosterone

Thyroid hormones act on target cells by binding to :

cytoplasmic receptors resulting in activation of specific segments of the DNA

True or false- All hormones that are derived from (aka made of) amino acids are water soluble.

False

Neurohormones are hormones produced by :

neurons and secreted from their terminals into interstitial fluid > bloodstream

Hypothalamic neurohormones are either

releasing or inhibiting

What is the target of hypothalamic neurohormones?

anterior pituitary

A releasing hormone stimulates the __________ to release hormones

anterior pituitary

An inhibitory hormone :

inhibits the anterior pituitary from releasing hormones

ADH and oxytocin are produced by the hypothalamic neurons, but secreted:

from posterior pituitary

99% of the pancreas is ___________ in nature

exocrine

Beta cells within pancreatic islets are responsible for:

insulin production [they are humorally sensitive cells responding to blood sugar level changes]

Alpha cells produce:

glucagon [also respond to blood glucose]

Literally what insulin does is :

stimulates permeability [to glucose, so it can move into the cells]

What are the 2 parts of the adrenal gland?

1. cortex (outer layer); divided into 3 segments (zonas)- produce different steroid hormones 2. Medulla- core segment in the center ~produces catecholamines (epinephrine, norepinephrine, dopamine..)

The adrenal cortex produces and secretes _____________ (in addition to many other hormones) in both males and females.

testosterone

Insulin is secreted from:

Beta cells of the pancreatic islets (islets of Langerhans)

The endocrine gland that is a modified sympathetic ganglion is the

adrenal medulla

Insulin is secreted by __beta cells __ in response to:

high blood sugar

Antidiuretic Hormone (ADH) is secreted from:

the posterior pituitary

The pituitary portal system transports releasing and inhibiting hormones _______. from where to where?

from the hypothalamus to the anterior pituitary

What are the 3 main symptoms of insulin lack (as would occur in diabetes mellitus type I)?

polyuria [excessive pee] polyphagia [hunger] polydipsia [thirst]

Polyuria- increased urination due to increased :

osmotic concentration of filtrate caused by hyperglycemia [type 1 diabetic]

Why do type 1 diabetics experience polyphagia?

When blood glucose levels are high, the body's cells may not be able to effectively take in glucose for energy due to insufficient insulin production The cells, lacking the necessary energy, signal the brain that the body needs more fuel, leading to increased feelings of hunger.

Why do type 1 diabetics experience polydipsia?

The increased urination caused by the elimination of glucose in the urine leads to dehydration. Dehydration triggers the sensation of thirst as the body attempts to replenish lost fluids.

which cells do NOT respond to insulin? [only 4]

epithelial lining of nephron & intestines RBC CNS neurons

what is the renal threshold for blood glucose?

Blood glucose concentrations exceed 180 mg/dL

The real job of insulin and glucagon is to regulate blood glucose levels in a way so :

cells have access to glucose

Osmotic diuresis is increased urination due to the presence of :

substances in the fluid filtered by the kidneys

Which of the following exhibits endocrine functionality: heart kidney intestines stomach testis and ovaries pancreas

all of the above exhibit endocrine functionality

When insulin levels are increased, what also occurs? 3 things increase:

increased fat formation increased cellular uptake of glucose increased glycogen formation

Which of the following is NOT dependent on insulin for glucose uptake? red blood cells fat cells epithelial cells of the nephron CNS neurons intestinal epithelial cells

red blood cells epithelial cells of the nephron CNS neurons intestinal epithelial cells

Which of the following is dependent on insulin for glucose uptake? red blood cells fat cells epithelial cells of the nephron CNS neurons intestinal epithelial cells

fat cells