Exam 2 Review: Chapters 19, 20, & 21

Vocabulary-style flashcards covering the anatomy and physiology of blood vessels, the lymphatic system, and the mechanisms of innate and adaptive immunity.

Capacitance vessels

A term referring to veins because they contain a large portion of the blood volume.

Elastic arteries

Pressure reservoirs that expand and recoil as blood is ejected from the heart.

Muscular arteries

Also known as distributing arteries; they deliver blood to specific body organs.

Arterioles

Commonly called resistance vessels; their diameter determines blood flow into capillary beds.

True capillaries

The actual exchange vessels in a capillary bed where gas and nutrient exchange occurs.

Precapillary sphincter

A cuff of smooth muscle fibers surrounding the root of each true capillary that regulates blood flow into the bed.

Venous valves

Folds of the tunica intima that prevent blood from flowing backward; they resemble the semilunar valves of the heart.

Blood flow ($F$)

The volume of blood flowing through a vessel, an organ, or the entire circulation in a given period.

Resistance

The amount of friction blood encounters as it flows through vessels; primary sources include blood viscosity, vessel length, and vessel diameter.

Laminar flow

The normal, quiet blood flow where blood stays in "lanes," moving faster in the middle and slower at the edges.

Turbulent flow

A flow pattern that occurs when pathways narrow or meet fatty plaques, greatly increasing resistance.

Pulse pressure

The difference between systolic pressure and diastolic pressure.

Mean arterial pressure (MAP)

The pressure that propels blood to the tissues throughout the cardiac cycle.

Vasomotor center

A part of the cardiovascular center in the medulla oblongata that controls blood vessel diameter.

Baroreceptors

Sensory receptors located in the carotid sinuses and aortic arch that detect changes in blood pressure by sensing stretch.

Chemoreceptors

Sensors in the aorta and neck arteries that respond to low $pH$, high $CO_2$, or low $O_2$ by triggering vasoconstriction and increased cardiac output.

Atrial natriuretic peptide (ANP)

A hormone produced by the atria that lowers blood pressure by causing vasodilation and promoting the excretion of $Na^+$ and water.

Renin-angiotensin-aldosterone mechanism

The indirect renal mechanism for long-term blood pressure regulation triggered by a drop in arterial blood pressure.

Tissue perfusion

The flow of blood through body tissues for nutrient/oxygen delivery and waste removal.

Angiogenesis

A long-term autoregulation process where the number of blood vessels in a region increases or existing vessels enlarge.

Syncope

Fainting; typically occurs when Mean Arterial Pressure (MAP) falls below $60\,mm Hg$.

Capillary hydrostatic pressure ($HP_c$)

The pressure that forces fluid through capillary walls, typically measuring $35\,mm Hg$ at the arterial end.

Colloid osmotic pressure ($OP$)

The force created by large molecules like albumin that are unable to leave the capillary, drawing water back into the blood.

Net filtration pressure (NFP)

Calculated value considering all forces acting on a capillary bed; positive results indicate filtration and negative results indicate reabsorption.

Hepatic portal system

A unique venous drainage system where blood from the digestive system passes through the liver before entering general circulation.

Lacteals

Specialized lymphatic capillaries in the intestinal mucosa that absorb and transport dietary fats (chyle).

Right lymphatic duct

Drains lymph from the right upper limb and the right side of the head and thorax.

Thoracic duct

Receives lymph from the majority of the body, including the left side of the head, thorax, and everything below the diaphragm.

Lymphocytes

The primary cells of the adaptive immune system, existing as either T cells or B cells.

Macrophages

Voracious phagocytic cells that destroy foreign substances and help activate T cells.

Primary lymphoid organs

The sites where lymphocytes originate and mature, specifically red bone marrow and the thymus.

MALT

Mucosa-associated lymphoid tissues found in the tonsils, Peyer’s patches, and appendix to protect body entries.

Tonsillar crypts

Breaks in the tonsil epithelium that invite pathogens in to interact with lymphocytes and build immune memory.

Peyer’s patches

Aggregated lymphoid nodules found on the wall of the distal portion of the small intestine.

Blood-thymus barrier

A structure in the thymus that prevents developing T cells from being prematurely activated by antigens.

Lysozymes

Antibacterial enzymes found in saliva, respiratory mucus, and lacrimal secretions.

Opsonization

The process of coating pathogens in opsonins (antibodies or complement) to provide "handles" for phagocytes to bind to.

Natural killer (NK) cells

Large granular lymphocytes that can lyse cancer cells and virus-infected cells by detecting abnormalities like a lack of "self" MHC proteins.

Exudate

Fluid containing clotting factors and antibodies that enters tissues during the inflammation process.

Leukocytosis

An increase in the number of white blood cells in the bloodstream, often in response to inflammation.

Diapedesis

The process by which phagocytes squeeze through the walls of capillaries and enter the interstitial space.

Chemotaxis

The movement of phagocytes toward a site of injury following a chemical trail.

Interferon

Proteins produced by virus-infected cells that help uninfected neighboring cells resist viral infection.

Complement

A group of about 20 bloodborne proteins that, when activated, enhance inflammation and can directly lyse target cells.

Membrane attack complex (MAC)

A structure formed by complement proteins that creates a pore in a target cell's membrane, causing it to lyse.

Pyrogens

Chemicals released by leukocytes and macrophages that act on the hypothalamus to raise body temperature (fever).

Humoral immunity

Also called antibody-mediated immunity; based on antibodies circulating in the blood and lymph.

Cellular immunity

Cell-mediated immunity where lymphocytes themselves defend the body against targets like infected or cancerous cells.

Haptens

Partial antigens that are not immunogenic on their own but can cause a hypersensitivity reaction if they bind to body proteins.

Immunocompetence

The ability of a lymphocyte to recognize and bind to its one specific antigen.

MHC proteins

Cell surface proteins (Class I and II) that present antigens to T cells for recognition.

Clonal selection

The activation of a lymphocyte when it encounters its first antigen, leading to rapid proliferation.

IgM

The first antibody class secreted by plasma cells during the primary immune response; potent agglutinator.

IgG

The most abundant antibody in plasma; main antibody of secondary responses and the only class to cross the placenta.

Cytotoxic T (Tc) cells

Activated CD8 cells that directly attack and kill infected or cancerous self-cells using perforins and granzymes.