BMD 252 exam 2 study aid

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Endocrine System

Endocrine System

Integrated system of small organs exerting large effects on metabolic activity.

Hormone

Bloodborne chemical substances functioning as signaling (messenger) molecules.

Hypothalamus

Neuroendocrine organ producing and releasing hormones.

local acting hormones

prod. by several tissues (adipose, small intestine, stomach, kidneys, heart); not “true” hormones since action occurs close to site produced

Autocrines

Local acting hormones that exert effects on the same cells secreting them.

Paracrines

Local acting hormones that exert effects on nearby cells close to those secreting them.

Exocrine Glands

Glands that release substances through excretory ducts directly into adjoining areas.

Endocrine Glands

Glands that release hormones into local interstitial fluid, transported through the bloodstream.

Mixed Glands

Glands that have both endocrine and exocrine functions, such as the pancreas.

what are the three characteristics of all hormones?

regulates metabolic activity
exhibits lag time
must have prolonged effects

Amino-Acid Based Hormones

Most are protein hormones, including amines and polypeptides.

Steroid Hormones

Cholesterol-based hormones, such as corticosteroids.

Eicosanoids

Biologically active lipids with local hormone-like activity released by nearly all cell membranes.

are amino acid-based hormones water or lipid soluble?

water, cannot pass through cell membrane, thus relays external signal to internal messenger system

are steroid-based hormones water or lipid soluble?

lipid, readily pass through cell membrane, because hydrophobic cholesterol base molecule enables steroid hormones to pass through hydrophobic layer of phospholipid bilayer

what are the 5 effects hormones have on target cells?

Alters plasma membrane permeability (insulin)
Stimulates protein synthesis (promote anabolic actions)
Activates or deactivates enzyme
Induces secretory activity
Stimulates mitosis

peptide activation mechanisms

binds to extracellular receptors

steroid activation mechanisms

enters cell, binds to chaperone protein, complex migrates to nucleus, internal receptor ( i. Direct mechanism, stimulates transcription)

cAMP

Second messenger that mediates a cell-specific response in peptide hormone signaling.

ACTH receptors

found only on adrenal cortex cells

Thyroid hormone receptors

found on nearly all body cells, (includes adrenal cortex)

List 3 controlling factors of target cell activation.

-Hormone blood levels (concentration)
-Relative number of target cell receptors, TCRs
-Hormone receptor affinity (attractive force/binding strength)

Up-Regulation

Increase in the number of membrane receptors due to persistently low hormone levels.

Down-Regulation

Decrease in the number of membrane receptors due to persistently high hormone levels.

Negative Feedback System

Major feedback mechanism controlling hormone release.

Half-Life

Time required for a hormone level to decrease by 50%.

Permissiveness

One hormone cannot exert full effects without another being present.

Synergism

One hormone's effects are multiplied by the presence of another hormone.

Antagonism

One or more hormones oppose the action of another hormone.

Pituitary Gland

Bi-lobed gland connected to the hypothalamus, consisting of the neurohypophysis and adenohypophysis.

Neurohypophysis

Posterior pituitary composed of neural tissue that stores/releases hypothalamic-produced peptide hormones.

Adenohypophysis

Anterior pituitary composed of glandular tissue that produces/secretes several peptide hormones.

Thyroid Gland

Largest endocrine gland, involved in metabolism and calcium regulation.

Calcitonin

-Hormone produced by parafollicular
-Stimulates blood calcium uptake and storage by bone matrix
-Inhibits osteoclast activity to reduce bone resorption
-Action is short-lived but rapid

Parathyroid Hormone (PTH)

Hormone produced by parathyroid glands that regulates blood calcium levels.

Mineralocorticoids

Hormones that regulate electrolyte concentrations, such as aldosterone.

Glucocorticoids

Hormones that maintain blood sugar levels, such as cortisol.

Catecholamines

Hormones produced by the adrenal medulla, including epinephrine and norepinephrine.

Pancreas

exocrine/endocrine gland located behind stomach that produces digestive enzymes and glucose-regulating hormones.

Insulin

hypoglycemic Hormone that decreases blood glucose levels.

Glucagon

hypoglycemic Hormone that increases blood glucose levels.

Diabetes Mellitus (DM)

Chronic metabolic disorder caused by insulin deficiency. symptoms include hunger (polyphagia), thirst (polydipsia), and urination (polyuria)

Thymus

Gland that produces hormones involved in T cell maturation.

Pineal Gland

Produces melatonin, which regulates sleep-wake cycles.

Atrial Natriuretic Peptide (ANP)

Hormone produced by the heart that reduces blood pressure.

Erythropoietin

Hormone produced by the kidneys that stimulates red blood cell production.

Electrocardiogram (ECG/EKG)

Graphical representation of electrical activity in the heart.

Sinoatrial (SA) Node

Primary pacemaker of the heart, controlling heart rhythm.

Cardiac Output

Total blood volume pumped out of each ventricle in one minute.

Stroke Volume (SV)

Amount of blood ejected by the left ventricle during a single contraction.

Preload

Stretching of cardiac muscle cells during the filling phase of the ventricles.

Afterload

Pressure that the ventricles must overcome to eject blood.

Hemostasis

Process that prevents and stops bleeding.

Coagulation Cascade

Sequential activation of coagulation factors to form a blood clot.

Fibrinolysis

Breakdown of a blood clot to restore normal blood flow.

Heart Murmur

Extra or unusual heart sounds due to turbulent blood flow.

bound hormones

steroid hormones attach to blood carrier protein

free hormones

most peptide hormones lack carrier proteins (except thyroid hormone)

2 factors that determine the concentration of a hormone in the blood.

1. Rate of release
2. Speed of inactivation/body removal

List the 2 ways hormones can be removed from the body

1. Destroyed by liver or cells of actual target organ
2. Kidney/liver action

List 2 characteristics of blood hormone levels

a. Can be removed by target cell enzyme degradation or kidney/liver action (urine excretion)
b. Very low concentrations needed (µg to ng/mL… 10^-6 to 10^-9

Humoral

secreted in response to changing ion/nutrient blood levels (concentration)

Neural

direct nerve fiber innervation

Hormonal

hormone released by 1st gland causes 2nd gland to produce/release a different hormone

Neurohypophysis

downward growth of brain hypothalamic neural tissue; stores/releases oxytocin and ADH

Adenohypophysis

upward growth of oral mucosa w/ no direct hypothal. contact

Follicle cells

produce thyroglobulin, a protein from which thyroid hormone is produced

Parafollicular cells

produce another hormone called calcitonin
1. Involved in blood Ca2+ regulation
2. Very different from hormone

function of thyroid hormone

i. Helps maintain blood pressure
ii. Helps regulate tissue growth
iii. Skeletal and nervous system development
iv. Maturation and reproduction

Adrenal cortex

-outer glandular tissue makes up bulk of gland
-Mediates long term stress response, stimulated by ACTH released by anterior pituitary

Adrenal medulla

-inner nervous tissue acts as part of ANS sympathetic division
-Mediates short term stress response, stimulated by sympathetic preganglionic neurons

adrenal cortex layers from outside to inside

1. Zona glomerulosa
2. Zona fasciculata
3. Zona reticularis

Mineralocorticoids

-regulate extracellular fluid electrolyte concentrations by maintaining salt/water balancea.
-Released aldosterone maintains Na+/water balance
-Secretion is stimulated by dec. BP, inc. potassium and ACTH, renin release

Glucocorticoids

-keeps blood sugar levels relatively constanta.
-ACTH mostly stimulates cortisol production
-Increased during physical/emotional stress, strenuous activity, infection, injury to mobilize stored carbs/lipid

Posterior pituitary

ADH, Oxytocin

Anterior pituitary

GH, TSH, ACTH, FSH/LH, PRL

Gonadocorticoids

puberty onset, secondary sex characteristics, drive

Epinephrine

potent heart/metabolic activity stimulator

Norepinephrine

blood vessel constriction to inc. BP

Dopamine

precursor of both epi and norep

Exocrine products

digestive enzymes produced by acinar cells

Endocrine products

glucose regulatory hormones produced in islets of Langerhaans

Alpha cells

produce glucagon

Beta cells

produce insulin

normal glucose value

70-140

Hyperglycemic glucose value

>200

Hypoglycemic glucose value

<60

Type 1 diabetes

absolute insulin deficiency (hyposecretion) due to β-islet cell absence, destruction, or loss, insulin is required

Type 2 diabetes

relative insulin deficiency (hypoactivity) due to inc. insulin resistance, insulin is not required

Gestational diabetes mellitus (GDM)

due to high blood glucose levels in pregnant women w/o history of diabetes, may lead to type 2 DM

Gastrointestinal tract hormones

“local acting” digestive hormones

Placenta hormones

human chorionic gonadotropin (hCG) influences pregnancy course

Heart hormones

atrial natriuretic peptide (ANP) is a potent vasodilator, reduces BP, volume, and sodium concentration

Kidneys hormones

erythropoietin signals red blood cell production

Skin hormones

cholecalciferol, a VitD precursor

Adipose tissue hormones

leptin is involved in sensation of satiety, stimulates increase in energy expenditure

blood circulation starting and ending at heart

a. Moves away from the heart through a series of highly-branching arteries/arterioles
b. Reaches body tissues through nearby microscopic capillaries
c. Returns to heart through converging veins, moves on to lungs and then back to the heart

“blood travels in a closed circuit” meaning

a. Uninterrupted
b. Must travel this way or it will be lost to surrounding tissue spaces

Plasma

-fluid matrix that makes up 55% of whole blood, contains cellular elements
-fluid matrix that makes up 55% of whole blood, contains cellular elements
-. Formed elements: solid portion of blood containing RBCs, WBCs, and platelets

Hematocrit

relative percentage of RBCs (x%) when compared to total whole blood volume