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endocrine system

the body's chemical communication system; a set of glands that secrete hormones into the bloodstream

endocrine glands

structures of the endocrine system that release hormones into the bloodstream

neuroendocrine cells

neurons that release their secretions into the bloodstream. A hybrid between Neurons and Endocrine cells

Target Organs

organs that respond to a particular hormone

pituitary gland

The endocrine system's most influential gland. Under the influence of the hypothalamus, this gland regulates growth and controls other endocrine glands.

anterior pituitary gland

The part of the pituitary gland whose secretions are controlled by the hypothalamic hormones. Not connected to the hypothalamus by neurons, opting for blood vessel connections

posterior pituitary gland

This is made up of nervous tissue/neurons and stores and secretes 2 hormones made by the hypothalamus. Connected to the hypothalamus by neurons

hypophysial portal system

a system of blood vessels in the brain that connects the hypothalamus with the anterior pituitary. Its main function is to transport and exchange hormones between the two glands.

hypothalamo-hypophyseal tract

neural connection between the hypothalamus and the posterior pituitary

follicle-stimulating hormone (FSH), luteinizing hormone (LH), Thyroid-Stimulating hormone (TSH), Adrenocorticotropic Hormone (ACTH), Prolactin, and Growth Hormone

The 6 hormones that the Anterior Pituitary Gland secretes

Antidiuretic Hormone (ADH) and Oxytocin

The 2 hormones that the Posterior Pituitary Gland secretes

pineal gland

gland that secretes melatonin

Thymus

Gland in the thoracic cavity above the heart where T lymphocytes mature. It shrinks as we age.

thyroid gland

produces hormones that regulate metabolism, body heat, and bone growth. Surrounds the trachea at the neck.

Calcitonin

Hormone that lowers blood calcium levels

C cells

Cells that secrete calcitonin

parathyroid glands

small pea-like organs that regulate calcium and phosphate balance in blood, bones, and other tissues. Located on the thyroid gland.

adrenal glands

a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.

adrenal medulla

Part of the Adrenal glands that secretes epinephrine and norepinephrine

adrenal cortex

The outer section of each adrenal gland. Secretes cortisol, aldosterone, and sex hormones

Glycogenolysis

breakdown of glycogen to glucose

Gluconeogenesis

The formation of glucose from noncarbohydrate sources, such as amino acids.

Cortisol

stress hormone

Aldosterone

"salt-retaining hormone" which promotes the retention of Na+ by the kidneys.

Androgens

male sex hormones that are produced in the adrenal glands

Estradiol

Female sex hormones that are secreted by the adrenal glands

Pancreas

Organ that regulates the level of sugar in the blood

pancreatic islets

parts of the pancreas that have endocrine functions

alpha cells

cells that produce glucagon

beta cells

cells that secrete insulin

delta cells

secrete somatostatin (growth hormone-inhibiting hormone)

PP cells

secrete pancreatic polypeptide

Gonads

ovaries and testes

Testosterone

Male sex hormone

Estrogen

Female sex hormone

steroid hormones

Hormones that are derived from cholesterol, produced by gonads and adrenal cortex, function by binding to DNA to alter gene transcription

Monoamines

hormones derived from a single amino acid

peptide hormones

hormones composed of short chains of amino acids

transport proteins

A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane.

bound hormone

a hormone attached to a transport protein

unbound hormone

a hormone that is not attached to a transport protein

Preproinsulin

Protein cleaved to become proinsulin which is cleaved to become insulin

signal amplification

turns one signal molecule into multiple second messenger molecules

up-regulation

target cells form more receptors in response to the hormone

down regulation

target cells lose receptors in response to the hormone

synergistic effect

interaction of two or more hormones that results in a greater effect than when the hormones are working alone

permissive effect

first hormone allows action of second hormone

antagonist effect

one hormone opposes the action of another hormone

Stress response

the physical and emotional reactions to a stressor. This involves elevated levels of epinephrine and cortisol.

alarm reaction

First stage of the GAS, during which the body mobilizes its resources to cope with a stressor.

stage of resistance

Second stage of the GAS, during which the body adapts to and uses resources to cope with a stressor.

stage of exhaustion

Third stage of the GAS, during which the body depletes its resources in responding to an ongoing stressor.

Paracrine

Referring to a secreted molecule that acts on a neighboring cell.

Autocrine

term for hormones that act on same cells that secrete them

hyposecretion

abnormally decreased secretion

diabetes insipidus

antidiuretic hormone is not secreted adequately, or the kidney is resistant to its effect

hypersecretion

abnormally increased secretion

Pheochromocytoma

a benign tumor of the adrenal medulla that causes the gland to produce excess epinephrine

Cushing's syndrome

caused by prolonged exposure to high levels of cortisol

diabetes mellitus

insulin is not secreted adequately or tissues are resistant to its effects

polyuria

excessive urination

polyphagia

excessive hunger

polydipsia

excessive thirst

Pulmonary Circuit

Circuit that carries blood to the lungs for gas exchange and returns it to the heart

systemic circuit

Circuit of blood that carries blood between the heart and the rest of the body.

cardiomyocytes

cardiac muscle cells

Intercalcated discs

The division between neighboring cardiac muscle cells that has 3 distinct features

interdigitating folds

folds that interlock with each other, and increase the surface area of contact. Looks like the bottom of a carton of eggs.

mechanical junctions

made from strong proteins that bind adjacent cardiomyocytes together at the intercalated disks, and prevent them from tearing apart as the heart beats. Composed of the fascia adherens and the desmosomes.

electrical junctions

Gap junctions that allow ions to flow between cells - can electrically stimulate neighbors

SA node (sinoatrial node)

Pacemaker of the heart. Sets the heartbeat rate, located in the right atrium, and causes the atria to contract

AV node (atrioventricular node)

region of the heart between the right atrium and right ventricle from which electrical impulses spread to the ventricles during a heartbeat

AV bundle (bundle of His)

fibers in the heart that relay a nerve impulse from the AV node to the ventricles

Subendocardial Conducting Network (Purkinje fibers)

fibers in the ventricles that transmit impulses to the right and left ventricles, causing them to contract

Systole

Contraction of the heart

Diastole

Relaxation of the heart

sinus rhythm

normal heartbeat triggered by the SA node

nodal rhythm

if SA node is damaged, heart rate is set by AV node, 40 to 50 bpm

arhythmia

Absence of normal cardiac rhythm

Electrocardiogram (ECG)

recording of the electrical changes that occur in the myocardium during a cardiac cycle

P wave

Wave that represents when the SA node produces a signal that spreads through the atria, causing it to depolarize.

QRS complex

Small downward deflection, a tall shark peak, and a final downward deflection. It is produced when the signal from the AV node spreads through the myocardium and depolarized the muscle. This is also the time of Atrial Repolarization and diastole.

PR interval

Represents the time it takes for the cardiac impulse to travel from the atria to the ventricles

QT interval

indicates how long the ventricles remain depolarized

ST segment

represents the end of ventricular depolarization and the beginning of ventricular repolarization. This is where blood id pumped out of the ventricles

T wave

represents ventricular repolarization and diastole

ventricular fibrillation

the rapid, irregular, and useless contractions of the ventricles

atrial fibrillation

rapid, random, ineffective contractions of the atrium

congestive heart failure

A condition resulting from the heart's inability to pump out all the blood that returns to it; blood backs up in the veins leading to the heart, causing an accumulation of fluid in various parts of the body

cardiac cycle

A complete heartbeat consisting of contraction and relaxation of both atria and both ventricles

ventricular filling

Phase of the cardiac cycle in which the ventricles expand, their pressure drops, and the AV valves open and blood flows into the ventricles.

isovolumetric contraction

refers to the short period during ventricular systole when the ventricles are completely closed chambers and no blood has been pumped out yet.

ventricular ejection

as ventricular pressure rises and exceeds pressure in the arteries, the semilunar valves open and blood is ejected

isovolumetric relaxation

period when all four valves are closed and ventricular blood volume does not change

Cardiac Output (CO)

measurement of the amount of blood ejected per minute from either ventricle of the heart

CO (Cardiac Output) \= HR (heart rate) X SV (Stroke Volume)

The Cardiac Output Equation

cardiac reserve

difference between resting and maximal CO

Tachicardia

abnormally rapid heart rate

Bradycardia

abnormally slow heartbeat

positive chronotropic agents

factors that raise the heart rate