Biomed I: Chapter 11 Cardiovascular System

I hate cardio

What are the functions of the cardiovascular system?

to transport oxygen, nutrients, cell wastes, and hormones to and from cells

What is the size of the heart?

the size of a human fist, weighs less than 1 pound

inferior mediastinum

region in between the lungs/thoracic cavity, location of the heart

Orientation of the apex

directed toward the left hip and rests on the diaphragm

Orientation of the base

points toward the right shoulder

Pericardium

double-walled sac covering the heart

Fibrous pericardium

loose and superficial layer to the pericardium

Two layers of the serous membrane

parietal pericardium, visceral pericardium/epicardium

epicardium

outside layer of the walls of the heart, also called the visceral pericardium

myocardium

middle layer of the heart wall, mostly cardiac muscle

endocardium/endothelium

inner layer

Atria

superior receiving chambers of the heart, blood enters under low pressure

ventricles

discharging chambers, thick-walled pumps of the heart, during contraction blood is propelled into circulation

interartial septum

separates the two atria longitudinally

interventricular septum

separates the two ventricles longitudinally

Arteries

carry blood away from the heart

veins

carry blood toward the heart

double pump

right side works as the pulmonary circuit pump, left side works as the systemic circuit pump

Steps to Pulmonary circulation

\-blood flows from the right side of the heart to the lungs and back to the left side of the heart

\-blood is pumped out of the right side through the pulmonary trunk, which splits into pulmonary arteries and takes oxygen-poor blood to the lungs

\-oxygen-rich blood returns to the heart from the lungs via pulmonary veins

Steps to systemic circulation

\-oxygen-rich blood returned to the left side of the heart and is pumped out into the aorta

\-blood circulates to systemic arteries and to all body tissues

left ventricle has thicker walls because it pumps blood to the body through the systemic circuit

\-oxygen-poor blood returns to the right atrium via systemic veins, which empty blood into the superior or inferior vena cava

Heart valves

allow blood to flow in only one direction, to prevent backflow

atrioventricular valves

between the atria and ventricles

bicuspid/mitral valve

left atrialventricular valve

tricuspid

right atrioventricular valve

semilunar valves

\-between ventricle and artery

\-closed during heart relaxation

\-open during ventricular contraction

pulmonary semilunar valve

between a ventricle and pulmonary arterty

aortic semilunar valve

between a ventricle and aorta

Atrioventricular(AV) valves

\-cusps are anchored in place by chordae tendineae to the walls of the ventricles

\-opens during heart relaxation, when blood passively fills the chambers

\-closed during ventricular contraction

\-valves open and close in response to pressure changes in the heart

These valves have prssure put on them by the blood returning to the atria.

AV valves (question)

Blood in the heart chambers does not nourish the _________.

myocardium (question)

Parts of the heart’s nourishing circulatory system

\-coronary arteries

\-cardiac veins

\-coronary sinus

Cardiac Circulation

blood empties into the right atrium via the coronary sinus and does not nourish the myocardium

Coronary arteries

branch from aorta to supply the heart muscle with oxygenated blood

cardiac veins

drains the myocardium of blood

coronary sinus

a large vein on the posterior of the heart; receives blood from cardiac veins

two systems that regulate heart activity:

autonomic nervous system and intrinsic conduction system/nodal system

Sinoatrial node

starts each heartbeat

impulse spreads through the atria to the AV bundle, bundle branches, and Purkinje fibers

ventricles contract; blood ejected from heart

techycardia

rapid heart rate, over 100 beats per minute

Cardiac cycle

refers to one complete heartbeat, when both atria and ventricles contract and relax

Diastole

relaxation

average heart rate

\n 75 beats per minute

Length of cardiac cycle

0\.8 seconds

____ transfers blood to tissues and back from the heart

blood vessels in the closed vascular system

arteries and arterioles

vessels that carry blood away from the heart

capillary beds

vessels that are involved in exchanges between blood and tissue

tunica media

smooth muscle and elastic tissue

controlled by the sympathetic nervous system

tunica externa

forms protective outermost covering

mostly fibrous connective tissue

supports and protects the vessel

arteries

heavier, stronger, and stretching tunica media than veins to withstand pressure changes

smaller lumen

veins

thinner tunica media because they operate under low pressure

have valves to prevent backflow

larger lumen

skeletal muscle contracts and pushes blood in veins toward heart

capillaries

one layer thick, tunica intima

exchanges between blood and tissue

form capillary beds, networks that consist of:

vascular shunt and true capillaries

Bradycardia

slow heart rate, less than 60 beats per minutes

intrinsic conduction/nodal system

sets heart rhythm

composed of special nervous tissue

ensures heart muscle depolarization in one direction only (atria to ventricles)

enforces a heart rate of 75 beats per minute

autonomic nervous system

controls voluntary movement

Sinoatrial node

located in the right atrium

serves as the heart’s pacemaker

Atrioventricular node

at the junction of the aria and ventricles

atrioventricular bundle/bundle of his

in the interventricular septum with bundle branches

Purkinje fibers spread within the ventricle wall muscles

Systole

contraction

venules and veins

vessels that return blood toward the heart

tunica intima

layer of the blood vessels that is friction reducing

endothelium

microcirculation

blood flow through a capillary bed