Medical Physiology and Homeostasis Lecture Review

Vocabulary and key concept cards covering human physiology, homeostasis, neurobiology, the endocrine system, and cardiovascular basics from weeks 2 through 5.

Regulatory mechanisms

Functions of the body that work to maintain a dynamic constancy of the internal environment and are activated when there are deviations from the set point.

Tertiary structure

A protein structure held together by both weak chemical bonds between widely spaced amino acids and disulfide bonds between sulfur groups on cysteines.

Normal arterial blood pH

The physiological range of blood pH, which is $7.35-7.45$.

Alkalosis

A condition indicated by a blood pH higher than the normal range, such as $7.6$.

Integrating center

The part of a feedback loop that receives information from a sensor, directs the body's response, and sends information to the effector.

Disaccharide

A molecule formed when two monosaccharides are joined by a covalent bond.

Denaturation

The disruption of a protein's tertiary structure stabilization caused by changes in pH and temperature.

Intrinsics

Homeostatic regulatory mechanisms that are "built-in" to the organs being regulated.

Ketosis

A condition that occurs when stored fats are rapidly degraded by the body.

Prostaglandins

A class of fatty acids involved in the process of blood clotting.

Primary structure

The linear arrangement of amino acids within a protein molecule.

Effector

Generally a muscle or gland that increases or decreases its action to help restore homeostasis.

Optic disc

The area of the retina that contains no photoreceptors.

Myopia

A visual condition where the image is brought to focus anterior to the retina.

Varicosities

Swellings on postganglionic axons that contain neurotransmitters.

All-or-None principle

The phenomenon where depolarization occurs with the same amplitude of potential change once the threshold is reached in a neuron.

Sclera

The outermost layer of the eyeball.

Melanopsin

A pigment found in some ganglion cells of the retina that is sensitive to luminance and helps the hypothalamus regulate circadian rhythms.

Endocannabinoids

Retrograde neurotransmitters released from postsynaptic neurons that diffuse to the presynaptic neuron to inhibit neurotransmitter release.

Thyroxine

The hormone that provides the major regulation of basal metabolic rate, produced from iodine and tyrosine molecules.

Basal metabolic rate (BMR)

The metabolic rate of an awake, relaxed person, $12$ to $14$ hours after eating, at a comfortable temperature.

Thyroglobulin

The protein found in the colloid of a thyroid follicle.

Goiter

An enlarged thyroid gland that can be caused by iodine deficiency or autoantibodies in Graves’ disease.

Prehormones

Molecules secreted by endocrine glands that remain inactive until they are changed by their target cells.

Permissive effects

Actions of hormones that enhance the responsiveness of a target organ to a second hormone.

Synergistic effects

Actions that occur when two or more hormones work together to produce a particular result.

Antagonistic effect

An action where one hormone inhibits the secretion and action of another hormone or has an opposite effect.

Cretinism

A condition in children resulting in lethargy, shorter average height, mental retardation, and low body temperature.

Thromboxane A2 (TXA2)

A prostaglandin that promotes platelet aggregation in the body.

Prostacyclin (PGI2)

A molecule that prevents blood clotting and affects blood vessels.

Bundle of Hiss

The structure that conducts impulses from the AV node to the bundle branches and Purkinje fibers.

T wave

The component of an ECG that represents ventricular repolarization.