AP 2 4.1: Anatomy of the Heart and Vessels

Question 1

Introduction to the Cardiovascular System

Answer 1

Every cell of the human body must be supplied with oxygen and nutrients and must rid itself of waste. These requirements are met by a circulatory system that transports these materials between cells and their surrounding environment.

Question 2

cardiovascular system

Answer 2

The cardiovascular system is a closed circulatory system because the fluid contents are pumped from the heart throughout the body and back to the heart. Cardio means heart, and vascular means vessels. Therefore, the cardiovascular system includes the study of the muscular heart, blood vessels, and blood. The functions of the cardiovascular system include transporting gases, nutrients, and wastes throughout the body. Secondly, the cardiovascular system prevents the loss of blood from ruptured vessels through clotting mechanisms. Finally, the cardiovascular system fights the invasion of the body by foreign pathogens.

Question 3

heart

Answer 3

The heart is a fist-sized cone-shaped muscular organ located in the pericardial cavity in the anterior portion of the mediastinum between the lungs, The heart has four one-way valves that regulate the flow of blood

Question 4

thoracic cavity

Answer 4

The thoracic cavity is separated by the mediastinum in the middle, between the two lateral pleural cavities (which each contain a lung).

Question 5

pericardium

Answer 5

The heart is enclosed in a tough, thick sac called the pericardium, which protects the heart and anchors it to the diaphragm. The inner and outer layers of the pericardium are covered by a smooth layer of endothelium. A special lubricating fluid between the layers allows the heart to slide around with very little friction.

Question 6

myocardium

Answer 6

The bulk of the heart, called the myocardium, is composed mainly of cardiac muscle and is the layer that contracts. The myocardium muscle fibers are highly branched and attached by collagen connective tissue fibers, which link all parts of the heart together.

Question 7

endocardium

Answer 7

The heart is lined with a white sheet of endothelium called the endocardium, which is continuous with the blood vessel linings.

Question 8

septum

Answer 8

The heart has four chambers separated into a right and left set by a partition called the septum

Question 9

atria

Answer 9

The two upper receiving chambers are called the atria. The atria are smaller than and not as muscular as the ventricles, which must force the blood through vessels to distant parts of the body.

Question 10

ventricles

Answer 10

two-lower pumping (sending) chambers are called the ventricles.

Question 11

fossa ovalis

Answer 11

There is a shallow depression on the septum separating the atria called the fossa ovalis. The fossa ovalis marks the place of an opening between the atria, which is present in all developing fetuses. It allows fetal blood to move directly from right to left atrium, bypassing the undeveloped lungs. The fossa ovalis closes during birth so that the lungs can receive oxygen once the baby is born.

Question 12

pulmonary valve

Answer 12

The pulmonary valve controls the flow leaving the right ventricle into the pulmonary trunk.

Question 13

aortic valve

Answer 13

The aortic valve controls the flow of blood out of the left ventricle into the aorta. The aortic valve is stronger than the pulmonary valve because of the increased blood pressure needed to send blood pumping to the entire body.

Question 14

mitral valve

Answer 14

The mitral valve (bicuspid) controls the flow of blood from the left atrium into the left ventricle.

Question 15

tricuspid valve

Answer 15

The tricuspid valve controls the flow of blood from the right atrium into the right ventricle.

Question 16

three types of blood vessels

Answer 16

The three types of blood vessels used to transport the blood throughout the body are: the arteries (which carry blood away from the heart), veins (which carry blood back to the heart), and capillaries (which exchange materials with tissues).

Question 17

Arteries

Answer 17

Arteries are elastic, thick-walled vessels that can expand and contract to accommodate the larger blood volume flowing from the heart at the end of each heartbeat. Large arteries expand and recoil to help the heart pump blood through the systemic circulation.

Question 18

arterioles

Answer 18

Small arteries called arterioles are constricted and dilated by muscles controlled by the sympathetic and parasympathetic nervous system, which control blood pressure. Contracting the arterioles increases the blood pressure through decreasing the available volume. Relaxation of the arterioles decreases blood pressure as the volume increases. Arterioles are the vessels primarily responsible for providing differing levels of peripheral resistance (varying blood pressure) to blood flow depending on the external and internal conditions affecting the body.

Question 19

Veins

Answer 19

are thinner-walled vessels that are under less pressure from the heart. For this reason, veins do not have pulses. Arteries, not veins, have palpable (able to be felt) pulses. Veins have internal valves that open toward the heart and close at the end of a heartbeat to prevent blood from flowing backward as the blood is returned to the heart. Veins have compliance, which means stretch with little recoil. Because of their compliance, veins have the largest amount of blood in the cardiovascular system.

Question 20

lumen

Answer 20

The opening in the center of a vessel is called the lumen. Arteries and veins throughout the body contain three layers: the tunica externa, tunica media, and tunica intima. The thickness of the layers depends on the location in the body.

Question 21

tunica externa

Answer 21

The tunica externa (adventitia) is the most superficial layer of a vessel, which helps to anchor the vessel to the surrounding structures.

Question 22

tunica media

Answer 22

The tunica media is the middle muscular layer of a vessel has an external elastic membrane, a layer of smooth muscle, and a layer of internal elastic membrane.

Question 23

tunica intima

Answer 23

The tunica intima layer of a vessel contains a layer of subendothelial tissue and a layer of endothelium.

Question 24

capillaries

Answer 24

The branching of arterioles causes formation of even narrower tubes called capillaries (Figure 4.5). Capillaries are interconnected to form capillary beds, which perform the exchange of materials with the cells of the body.

Question 25

venules

Answer 25

The blood is collected from the capillary beds by small veins called venules, many of which join to form a vein that returns the blood to the heart.

Question 26

left coronary artery

Answer 26

The left coronary artery runs toward the left side of the heart and divides into the anterior interventricular branch and the circumflex branch.

Question 26

Blood Supply to the Heart

Answer 26

There are also two artery systems (left and right coronary arteries), which arise from the base of the aorta and supply oxygen and nutrients to the heart tissues

Question 27

anterior interventricular branch

Answer 27

The anterior interventricular branch supplies blood to both ventricles

Question 28

right coronary artery

Answer 28

The right coronary artery runs toward the right side of the heart and divides into the posterior interventricular artery and the marginal artery, which supply the right atrium and right ventricle

Question 29

circumflex branch

Answer 29

The circumflex branch supplies the left atrium and left ventricle

Question 30

Blood Supply to the Body

Answer 30

Once the blood leaves the heart, it leaves through the aorta and spreads throughout the body.

Question 31

aortic arch

Answer 31

The aortic arch turns posteriorly and becomes the descending aorta.

Question 32

thoracic aorta

Answer 32

The thoracic aorta is in the thoracic cavity above the diaphragm.

Question 33

abdominal aorta

Answer 33

The descending aorta becomes the abdominal aorta below the diaphragm.

Question 33

inferior vena cava

Answer 33

The inferior vena cava returns deoxygenated blood from the lower body,

Question 34

major vessels

Answer 34

The major vessels are typically named for the region of their location or where it supplies blood.

Question 34

superior vena cava

Answer 34

The inferior vena cava returns deoxygenated blood from the lower body, and the superior vena cava returns blood to the heart from the upper body

Question 34

brachiocephalic trunk

Answer 34

For example, the brachiocephalic trunk (Figure 4.9) is the first branch off the aortic arch. The brachiocephalic trunk supplies blood to the right arm and neck. (Brachio means arm, and cephalic means relating to the head.)

Question 34

internal carotid arteries

Answer 34

The internal carotid arteries arise from the common carotid arteries in the neck.

Question 34

Circle of Willis

Answer 34

The Circle of Willis is also known as the cerebral arterial circle. The Circle of Willis has a unique feature of providing alternate circulation in case one of the arteries becomes blocked. The alternate circulation is important because neurons must be continuously supplied with oxygen or they will die within minutes.

Question 34

vertebral arteries

Answer 34

Two vertebral arteries rise superiorly along both sides of the spinal cord joining to form the basilar artery at the base of the pons. The basilar artery branches into the left and right posterior cerebral arteries.

Question 34

major arteries and veins have matching

Answer 34

Some major arteries and veins have matching names if running together in a parallel location. For example, the right and left subclavian arteries and the right and left subclavian veins parallel each other on the left and right sides of the body. The figure below labels the major branches to and from the heart

Question 34

posterior communicating arteries

Answer 34

The posterior communicating arteries connect to the left and right internal carotid arteries.

Question 34

anterior cerebral arteries

Answer 34

The anterior cerebral arteries are branches off the middle cerebral arteries.

Question 34

middle cerebral arteries

Answer 34

The internal carotid arteries terminate in the left and right middle cerebral arteries.