Physiology (1) Complete Review Flashcards

This set covers all major physiological systems including tissues, muscular, nervous, cardiovascular, respiratory, digestive, renal, reproductive, immune, and endocrine systems as detailed in the lecture transcript.

Physiology

The study of tissues and groups of cells that are similar in structure and perform common or related functions.

Epithelial Tissue

Sheets of cells or epithelium that line the outside of the body, organs, or cavities, providing sensory support, secretion, and absorption.

Tight Junctions

Closely packed junctions in epithelial tissue that prevent mechanical injuries, pathogen entry, and fluid leakage.

Apical Surface

The side of the epithelium that faces the lumen or outside of an organ, often featuring microvilli or cilia.

Simple Squamous Epithelium

A single flat layer of cells functioning in material exchange via diffusion, found in blood vessels and lung air sacs.

Simple Columnar Epithelium

A single layer of brick-shaped cells specialized for secretion and absorption, often found in the intestines and fallopian tubes.

Pseudostratified Columnar Epithelium

A single layer of cells varying in height and nuclei position that appears multilayered, often forming mucus membranes in the respiratory tract.

Transitional Epithelium

Multilayered tissue made from different cell types that supports expansion and contraction in the urinary bladder and ureters.

Microvilli

Microfilament-based projections that increase a cell’s surface area for absorption and secretion, forming a brush border.

Cilia

Microtubule-based projections that move together to sweep out dust and mucus from the respiratory tract.

Merocrine Secretion

A secretion type where products are released by exocytosis from vesicles fusing with the cell membrane.

Apocrine Secretion

A type of secretion where a portion of the cell is pinched off to release the product.

Holocrine Secretion

Secretion characterized by the complete rupture and death of a gland cell to release the whole amount of its product.

Desmosomes

Cellular junctions that connect adjacent cells and allow them to move together as a unit.

Gap Junctions

Pores made of six connexons that allow for sharing of cytosol substances and ion-based communication between cells.

Mesenchyme

A loose and fluid embryonic tissue from which all connective tissues develop.

Fibroblasts

Resident cells in connective tissue proper that secrete fiber proteins.

Collagenous Fibers

Tough protein fibers in the extracellular matrix that provide strength and flexibility.

Dense Connective Tissue

Tissue rich in collagenous fibers with a small ground substance-to-fiber ratio, found in tendons and ligaments.

Chondrocytes

Specialized cells that secrete collagen and chondroitin sulfate to form cartilage.

Sarcomere

The basic structural and contractile unit of skeletal muscle, bounded by Z lines.

Sarcoplasmic Reticulum

A modified endoplasmic reticulum in muscle fibers that stores a high concentration of $Ca^{2+}$ ions.

Sarcolemma

The modified cell membrane of a muscle fiber capable of distributing action potentials through T-tubules.

Intercalated Discs

Specialized junctions containing gap junctions that synchronize contractions in cardiac muscle.

Astrocytes

Glial cells that nourish neurons, repair damage, and help form the blood-brain barrier (BBB).

Saltatory Conduction

The efficient transmission of electrical signals in myelinated neurons where the signal hops between Nodes of Ranvier.

Resting Potential

The electrical potential difference across a neuronal membrane at rest, typically $-70\,mV$, maintained by the $Na^{+}/K^{+}$ ATPase pump.

Threshold Value

The specific voltage level, usually $-55\,mV$ to $-40\,mV$, required to trigger an action potential at the axon hillock.

Depolarization

The process where voltage-gated $Na^{+}$ channels open, allowing an influx of sodium ions and raising the membrane potential.

Repolarization

The process where $Na^{+}$ channels close and $K^{+}$ channels open, allowing potassium efflux to lower the membrane potential.

Neurotransmitters

Chemical signals released from the synaptic bouton into the synaptic cleft to transmit messages to the postsynaptic cell.

Systole

The portion of the cardiac cycle characterized by ventricular contraction and blood ejection from the heart.

Diastole

The portion of the cardiac cycle where the heart muscles relax and the chambers fill with blood.

Sinoatrial (SA) Node

The natural pacemaker of the heart located in the right atrium that initiates electrical impulses.

Surfactant

A fluid secreted by Type II pneumocytes that lowers surface tension in the alveoli to prevent collapse.

Tidal Volume ($TV$)

The volume of air inhaled and exhaled during a normal, relaxed breath.

Vital Capacity ($VC$)

The maximum volume of air that can be inhaled and exhaled, calculated as $TLC - RV$.

Chyme

The mixture of partially digested food and gastric juice formed in the stomach.

Pepsin

An active protein-digesting enzyme in the stomach activated by the presence of hydrogen chloride ($HCl$).

Bicarbonate ($HCO_{3}^{-}$)

A basic substance released by the pancreas and salivary glands to neutralize acidity.

Bile

A substance produced in the liver and stored in the gallbladder that emulsifies fat globules for digestion.

Podocytes

Epithelial cells lining Bowman’s capsule that form a filtration barrier against large particles and negative ions.

Aldosterone

A steroid hormone from the adrenal cortex that stimulates $Na^{+}$ reabsorption and $K^{+}$ excretion in the distal convoluted tubule.

Innate Immunity

Nonspecific defense mechanisms, such as skin and mucus membranes, that are always active but do not target specific invaders.

Adaptive Immunity

Specific immune response that targets particular pathogens and develops memory for faster subsequent responses.

B Cells

Agranulocytes that mature in the bone marrow, reside in the spleen/lymph nodes, and produce antibodies for humoral immunity.

Cytotoxic T-Cells ($CD8^{+}$)

T-cells that kill virally infected or cancerous cells by responding to antigens presented on MHC Class I molecules.

MHC Class I

Molecules found on all nucleated cells that display endogenous antigens to the immune system.

Interferons

Proteins produced by virally infected cells that signal neighboring cells to decrease viral protein production and permeability.

Thyroxine ($T_{4}$)

A lipid-soluble thyroid hormone containing four iodine atoms that regulates the basal metabolic rate.

Calcitonin

A peptide hormone from the thyroid gland that lowers blood calcium levels by increasing osteoblast activity and kidney excretion.

Parathyroid Hormone (PTH)

A hormone that raises blood calcium levels by stimulating bone breakdown and kidney reabsorption.