The Cardiovascular System

Vocabulary flashcards covering major cardiovascular system concepts from the lecture notes.

Cardiovascular system

A closed system of the heart and blood vessels that delivers oxygen and nutrients and removes carbon dioxide and other wastes.

Heart

Organ located in the thorax between the lungs; apex directed toward the left hip; about the size of a fist.

Pericardium

Double serous membrane consisting of visceral (next to the heart) and parietal layers with serous fluid between them.

Epicardium

Outer heart wall layer; also the parietal pericardium portion in this context.

Myocardium

Middle heart wall layer composed mostly of cardiac muscle.

Endocardium

Inner heart wall layer composed of endothelium.

Atria

Receiving chambers of the heart; right atrium and left atrium.

Ventricles

Discharging chambers of the heart; right ventricle and left ventricle.

Bicuspid valve (mitral valve)

Left atrioventricular valve between the left atrium and left ventricle.

Tricuspid valve

Right atrioventricular valve between the right atrium and right ventricle.

Pulmonary semilunar valve

Semilunar valve between the right ventricle and the pulmonary trunk.

Aortic semilunar valve

Semilunar valve between the left ventricle and the aorta.

Chordae tendineae

Fibrous strands (heart strings) that anchor AV valve cusps to papillary muscles to prevent backflow.

Conduction system

Intrinsic system that sets the heart’s pace and coordinates contraction without nerve impulses.

Sinoatrial node (SA node)

Pacemaker of the heart; initiates electrical impulses with the fastest rate.

Atrioventricular node (AV node)

Delays and relays electrical impulses from atria to ventricles.

Atrioventricular bundle (Bundle of His)

Pathway for conducting impulses from the AV node through the interventricular septum.

Purkinje fibers

Network delivering impulses to the ventricles to cause contraction.

Cardiac cycle

Events of one complete heartbeat, including atrial systole, ventricular systole, and diastole.

Isovolumetric contraction

Phase when ventricles contract but all valves are closed, so no volume change.

Isovolumetric relaxation

Phase when ventricles relax but all valves are closed, so no volume change.

Ventricular filling

Phase during which blood flows from atria into ventricles, mainly during diastole.

Cardiac output

Volume of blood pumped by each ventricle per minute; CO = heart rate × stroke volume.

Stroke volume

Volume of blood pumped by a ventricle with each contraction.

Heart rate

Number of heartbeats per minute.

Starling’s law of the heart

The greater the stretch of cardiac muscle before contraction, the stronger the contraction.

Parasympathetic regulation of heart rate

Vagal activity that decreases heart rate.

Sympathetic regulation of heart rate

Nerves and hormones that increase heart rate and contractility (eg, epinephrine, thyroxine) during stress or exercise.

Epinephrine

Adrenal hormone that increases heart rate and contractility.

Thyroxine

Thyroid hormone that increases heart rate and metabolic rate.

Hepatic portal circulation

Blood from the GI tract to the liver via the hepatic portal vein and associated vessels for processing.

Capillary exchange

Movement of substances between blood and tissues by diffusion, endocytosis/exocytosis, and filtration; true capillaries are exchange vessels.

True capillaries

Capillaries where oxygen and nutrients diffuse to tissues and wastes diffuse into blood.

Vascular shunt

Direct connection between an arteriole and a venule bypassing true capillaries.

Tunica intima

Innermost layer of a blood vessel, consisting of endothelium.

Tunica media

Middle layer of a blood vessel with smooth muscle; controlled by the sympathetic nervous system.

Tunica externa

Outer fibrous connective tissue layer of a blood vessel.

Arteries

Blood vessels that carry blood away from the heart; have thick walls and small lumens relative to veins.

Veins

Blood vessels that carry blood toward the heart; have larger lumens and often valves to prevent backflow.

Capillaries

Tiny vessels with walls one cell thick where diffusion occurs between blood and tissues.

Circle of Willis

Arterial ring at the base of the brain supplying cerebral circulation.

Fetal circulation

Circulation in which foramen ovale, ductus arteriosus, and ductus venosus redirect blood away from nonfunctional fetal lungs.

Foramen ovale

Opening in the fetal heart that directs blood from the right to the left atrium.

Ductus arteriosus

Fetal vessel that connects the pulmonary trunk to the aorta, bypassing the lungs.

Ductus venosus

Fetal vessel bypassing the liver by directing blood from the umbilical vein to the inferior vena cava.

Umbilical vein

Blood vessel carrying oxygenated blood from the placenta to the fetus.

Umbilical arteries

Blood vessels carrying deoxygenated blood from the fetus to the placenta.

Pulse

Pressure wave of blood produced by the heart’s contraction, palpable at various arteries.

Pulse points

Common locations to feel the pulse: temporal, facial, carotid, brachial, radial, femoral, popliteal, posterior tibial, dorsalis pedis.

Blood pressure

Measurement of the pressure in large arteries; systolic is peak during contraction, diastolic is minimum during relaxation.

Systolic pressure

Peak pressure in arteries during ventricular contraction.

Diastolic pressure

Minimum pressure in arteries during ventricular relaxation.

Normal blood pressure range (notes)

Systolic around 140–110 mm Hg and diastolic around 80–75 mm Hg.

Factors influencing blood pressure

Blood volume, cardiac output, peripheral resistance, neural and hormonal controls, temperature, and posture.

Capillary diffusion mechanisms

Direct diffusion, intercellular clefts, fenestrations, and vesicular transport enabling exchange between blood and tissues.

Development of the heart

Embryo starts as a simple tube; by week 4 pumps; by week 7 becomes a four-chambered organ with few changes after.