A&P: Blood Vessels/Vasculature

Flashcards on Blood Vessels/Vasculature

Pulmonary Circuit

Between the heart and lungs.

Systemic Circuit

Between the heart and the rest of the body.

Arteries

Transport blood away from the heart.

Veins

Transport blood to the heart.

Capillaries

Microscopic, single cell walled, perfuse the tissues, respiration.

Tunica intima (interna)

Innermost layer of a vessel.

Tunica media

Middle muscle layer of a vessel.

Tunica adventitia (externa)

Outermost layer of a vessel.

Elastic Arteries

HUGE vessels that stretch to accommodate massive pressures and constrict to move blood. Tunica media has elastic fibers.

Muscular Arteries

Medium vessels; tunica media has more muscle than elastic arteries. Can constrict and relax to adjust blood pressure.

Arterioles

Microscopic vessels. End of arteriole at capillary junction.

Metarteriole

End of arteriole at capillary junction.

Precapillary sphincter

Between metarteriole and capillary. Regulate blood flow into tissue.

Venules

Microscopic; area where group of capillaries reunite; no tunica media.

Medium-sized Veins

2-9mm lumen; tunica media thinner than found in arteries; under less pressure than arteries; tunica intima forms valves.

Large Veins

Thick tunica adventitia; superior and inferior vena cava, jugular vein.

Continuous Capillaries

Plasma membranes intact; diffusion occurs only at intercellular clefts.

Fenestrated Capillaries

Plasma membrane has small holes (fenestrations=“windows”); greater diffusion: neurological areas, small intestines, kidneys.

Sinusoids

Plasma membrane has larger fenestrations and intercellular clefts; cells can cross through: spleen, bone marrow, liver.

Capillary bed

The network of capillaries branching from a single metarteriole

Collateral arteries

Different arteries perfusing the same capillary bed

Anastomoses

Generic term: a connection

Arterial anastomoses

Connections between arteries to provide collateral circulation

Arteriovenous anastomoses

Connections between arteriole and venule to bypass the capillary bed.

Thoroughfare channel

Arteriole to metarteriole to thoroughfare channel to venule -has capillaries coming off metarteriole and thoroughfare channel to create capillary bed.

Pre/post capillary sphincters

Determine perfusion of capillary bed

Skeletal muscle pump

Skeletal muscles contract and squeeze veins, valves cause one-way flow to return blood to heart

Respiratory pump (thoraco-abdominal pump)

Diaphragm contracts causing decreased thoracic pressure (causes inhalation), abdominal intravascular pressure is greater than thoracic pressure, thus this enhances venous return to the thorax from the abdomen

Vascular Resistance

Resistance to blood flow in the vessels due to friction

Systemic vascular resistance (SVR) (also: PVR: Peripheral Vascular Resistance)

Total combined resistance in the entire vascular system

Proprioceptors

In muscles during exercise

Baroreceptors

In vasculature determining pressure

Chemoreceptors

Blood pH, O2, CO2

Atrial natriuretic peptide

Stretch receptors (type of proprioceptor) in atria determine increased pressure due to increased atrial stretching

Systolic

Ventricular systole (contraction) and overcomes afterload (the pressure the heart must overcome in order to expel blood)

Diastolic

Ventricular diastole (rest) and is the minimum pressure in the artery

Pulse Pressure

Difference between systolic and diastolic pressures