Comprehensive Human Systems Overview: Cardiovascular, Respiratory, Digestive, Urinary, and Reproductive

These flashcards cover the anatomical structures, histological features, physiological functions, and key pathological conditions of the major human body systems discussed in the lecture notes.

Major Function of Transport (Cardiovascular)

Carries oxygen, nutrients, hormones, and wastes through the blood, specifically delivering $O_2$ to tissues and $CO_2$ to the lungs.

Pulmonary Circuit

The circuit where blood travels between the heart and lungs for the purpose of oxygenating deoxygenated blood.

Systemic Circuit

The circuit where oxygenated blood is supplied from the heart to the tissues of the body.

Myocardium

The cardiac muscle layer of the heart wall responsible for generating pumping force; it is thickest in the left ventricle for systemic circulation.

Epicardium

The outermost layer of the heart wall, also known as the visceral layer of the serous pericardium.

Endocardium

The innermost lining of the heart consisting of simple squamous epithelium that is in direct contact with blood.

Pericardium

A sac surrounding the heart composed of a tough outer Fibrous pericardium and a two-layered Serous pericardium (parietal and visceral layers).

Atria

The upper receiving chambers of the heart; the right receives blood from the body and the left receives blood from the lungs.

Ventricles

The lower pumping chambers of the heart; the right pumps blood to the lungs and the left pumps blood to the body.

Chordae tendineae

Often called "heart strings," these connect AV valves to papillary muscles to prevent the valves from inverting (backflow).

Tricuspid Valve

The right atrioventricular (AV) valve located between the right atrium and right ventricle, consisting of 3 cusps.

Mitral Valve

Also called the bicuspid valve, it is the left AV valve located between the left atrium and left ventricle and has 2 cusps.

Pulmonary Arteries (Exemption)

An exception to the general rule that arteries carry oxygenated blood; these carry deoxygenated blood from the heart to the lungs.

Myocardial Infarction (MI)

A blockage of the coronary artery leading to ischemia, myocardium necrosis, and the formation of scar tissue.

Hematocrit

The percentage of total blood volume occupied by formed elements, primarily red blood cells (RBCs), typically around $$45\%$.

Plasma

The straw-colored liquid portion of blood comprising approximately $55\%$ of total blood volume, mostly composed of water.

Buffy Coat

A thin white layer in centrifuged blood, making up less than $1\%$ of the volume, containing leukocytes (WBCs) and platelets.

Neutrophils

The most abundant white blood cell, characterized by a multilobed nucleus and pale lilac granules; they perform phagocytosis during bacterial infections.

Eosinophils

White blood cells with a bilobed nucleus and bright red/orange granules; they are involved in parasite defense and allergy response modulation.

Basophils

White blood cells with dark purple granules that obscure the nucleus; they release histamine to promote inflammation.

Monocytes

The largest white blood cells, featuring a kidney or U-shaped nucleus; they transform into macrophages for phagocytosis.

Spleen

The largest lymphoid organ; its white pulp monitors immunity while its red pulp removes old red blood cells.

Elastic Arteries

Also known as "conducting arteries," these are the largest arteries (e.g., aorta) with high elastic fiber content in the tunica media to act as a pressure reservoir.

Arterioles

Known as "major resistance vessels," these small arteries regulate blood pressure and flow through vasoconstriction or vasodilation.

Sinusoid Capillaries

The most permeable capillaries with large gaps, found in the liver, spleen, and bone marrow to allow for the passage of large proteins and cells.

Type II Pneumocyte

The cell in the alveoli responsible for producing surfactant to reduce surface tension and prevent alveolar collapse.

Respiratory Membrane

The very thin barrier where gas exchange occurs, composed of alveolar epithelium, a basement membrane, and capillary endothelium.

Trachea Histology

Lined with pseudostratified ciliated columnar epithelium and supported by C-shaped hyaline cartilage rings to prevent airway collapse.

Parietal Cells

Stomach cells responsible for the secretion of Hydrochloric acid ($HCl$) and intrinsic factor.

Chief Cells

Stomach cells that secrete pepsinogen for protein digestion.

Small Intestine Absorption Specializations

Structural adaptations including circular folds, villi, and microvilli (brush border) that exponentially increase surface area.

Proximal Convoluted Tubule (PCT)

The major site of reabsorption in the nephron, lined with simple cuboidal epithelium featuring an abundant microvilli brush border.

Transitional Epithelium

Also called urothelium, this tissue lines the ureters and urinary bladder, allowing them to stretch as they fill with urine.

Spermatogenesis

The process of sperm production in the seminiferous tubules starting at puberty, resulting in 4 sperm cells from one primary spermatocyte.

Oogenesis

The process of egg production starting during fetal development, resulting in 1 mature ovum and polar bodies.

Endometrium

The inner lining of the uterus which serves as the site for embryo implantation.