Chapter 18 - The Endocrine System Detailed Study Notes

Direct Communication

Local; Exchanges ions and molecules between cells across gap junctions

Paracrine Communication

Local; cells release chemical mediators called paracrine into extracellular fluid to communicate with neighboring cells for localized control

Autocrine Communication

Local: effects the same type of cell that secretes them

Endocrine Communication

Long distance; Hormones that are released into tissue and enter the bloodstream while altering metabolic activity in many organs

What communication has the ability to affect any tissue with target cells?

Endocrine Communication

Target Cells

Have receptors that can bind to and read hormonal messages

Synaptic Communication

Local; neurons release neurotransmitters at the synapse, allows high speed messages to reach specific destinations and ideal for crisis management

What is endocrine’s communication type?

Slower pace but long lasting the hormones circulate to target cells

What is nervous system communication type?

Shorter term but extremely fast and allows action potentials through neurons across synapses

Exocrine Cells

Release secretions into ducts

Amino Acid derivatives

Protein that Contain Tyrosine and tryptophan

What are the derivatives of amino acid tyrosine?

Thyroid Hormone, Catecholamines that contain epinephrine,norepinephrine, and dopamine

What are the derivatives of amino acid tryptophan?

Serotonin and melatonin

What are peptide hormones?

Chains of amino acids strung together; molecules that change to active hormones and then secreted

What are glycoproteins?

Large Proteins that contain more than 200 amino acids long that have carbohydrate side chains

What are polypeptides and proteins?

Hormones secreted by the hypothalamus,heart,thymus, digestive, pancreas, posterior lobe, and pituitary gland

What are short chain polypeptides?

Short protein that contains 9 amino acids long such as ADH and OXT

What are small proteins?

Less than 200 amino acid such as insulin, growth hormone, and prolactin

What are Eicosanoids?

Derived from arachidonic acid, paracrine that can coordinate localized cellular activities and affects enzyme processes

What are steroid hormones?

Derived from cholesterol, such as testosterone, progesterone estrogens and calcitriol

What are free hormones?

Diffuse out of bloodstream and bind to receptors on target cells, and broken down by enzymes in the blood or interstitial fluids

What are bound hormones?

Functional for longer being they attach to special transport proteins in the blood. Which include thyroid and steroid hormone

What are extracellular receptors?

Located on outer surface of plasma membrane, binds to hormones that are not lipid soluble and unable to penetrate the plasma membrane.

What are intracellular receptors?

Located within the cell and bind to hormones that can cross the plasma membrane

What is a steroid hormone?

Lipid soluble, therefore can cross the cell membrane without receptor

What is a thyroid hormone?

Can cross cell membrane from transport mechanism and bind to receptor on mitochondria or nucleus

What is down regulation?

Hormone triggers a decrease in the number of hormone receptors, when hormones are high cells become less sensitive to that hormone

What is up regulation?

Absence of hormone triggers an increase in number of hormone receptions, when levels of certain hormone are low cells become more sensitive to hormone

What is a tropic hormone?

Triggers another hormone

What is adrenocorticotropic hormone(ACTH)?

Released due to corticotropin releasing hormone CRH

What is Prolactin?

Released due PRH and stimulates mammary gland development & milk production

What is Growth Hormone?

Stimulates livers cells to release somatomedins that stimulate tissue growth by causing cells to increase their uptake of amino acids

ADH(Antidiuretic Hormone)

Causes kidneys to retain water

Oxytocin (OXT)

Non-tropic hormone, stimulates contraction in females

Calcitonin

Helps lowers concentration Ca2+ in body fluids, promotes Ca2+ excretions by kidneys, Decreases the activity of osteoclasts

Adrenal glands

Stores lipids especially cholesterol and fatty acids and manages steroid hormones and produces epinephrine and norepinephrine

Adrenal Cortex

Produces minealcorticoids and aldosterone. Stimulates conservation of sodium ions, water, and elimination of potassium ions

Pineal Gland

Synthesize hormone melatonin in response to a decrease in light

Pancreas

Contains both endocrine cells and exocrine cells

Alpha a Cells

Produces glucagon when blood glucose levels decrease, mobilizes energy reserves

Beta B cells

Produces insulin when blood glucose levels increase

Delta Cells

Produces somatostatin

PP cells

Produces pancreatic polypeptide

Diabetes Mellitus

Develop intense thirst to replace water that is lost in the urine