Chapter 10: Spreading the Love: The Circulatory System Summary

Circulatory System

The system involves blood, blood vessels, and the heart.

It is also called the closed double system

The system is closed because blood is contained in the vessels and the heart.

The system is double because it contains two cavities and circuits separated by the septum.

• The two circuits include:
  • The pulmonary circuit which moves blood into and out of the lungs to exchange gases. It receives blood from the right side of the heart and transports it to lung capillaries through the pulmonary artery.
  • The systemic circuit retains a constant body tissue environment using the oxygen-rich blood.

The heart walls

• The wall of the heart has three layers.
• The epicardium contains a connective tissue that is fibroelastic together with adipose tissue. It is also referred to as the visceral pericardium.
  • The pericardium contains two parts: the fibrous pericardium found outside nd the serous membrane(parietal pericardium) close to the heart.
  • A pericardial space is located between the parietal and the fibrous pericardium and it contains pericardial fluid which reduces irritation during systole.
• The myocardium is found under the epicardium and contains cardiac muscle tissue bundles.
• The endocardium is the inner lining of the heart and contains simple squamous endothelial cells.

The Heart Chambers

Atria

• They receive blood returning into the heart.
• They contain a principal cavity and an auricle.
• The left atrium is smaller than the right atrium.

• The openings that are directed to the right atrium include:
  • Superior vena cava which lacks a valve and passes blood from the head, upper extremities, and thorax into the atrioventricular opening.
  • Inferior vena cava moves blood from the lower extremities and the trunk into the fosa ovalis located in the interatrial septum.
  • Coronary sinus opens between atrioventricular opening and inferior vena cava.
  • Atrioventricular opening.
  • The fosa ovalis

Ventricles

• They are the heart’s pumping chambers.
• They accept blood from atria and force it to the body or lungs.
• The right ventricle pumps blood to the lungs.
• The right ventricle is located on the sternocostal surface of the heart.
• The pulmonary artery joins to the right ventricle at the conus arteriosus.
• Relaxation of the ventricle allows blood to flow back to the ventricle and closes valves.
• The tricuspid valve surrounds the AV.
• Left ventricles from the heart apex.
• It has thicker walls than the right ventricle by three times.
• It contains the bicuspid valves.
• The aortic semilunar valves protect the aorta opening.
• Aortic sinuses are found between the aortic wall and the cusps.

The conduction system of the heart

• The sinoatrial node: This is the heart’s pacemaker.
  • It is found at the right atrium and vena cava junction.
  • It generates electrical impulses that move atrial muscles and makes atria to contact.
• Atrioventricular node: It begins from the sinoatrial node.
  • It passes impulses to the atrioventricular node.
• Atrioventricular bundle: it receives impulses from the atrioventricular node.
  • It divides into two and moves to the interventricular septum.
• Purkinje fibers: It receives pulses that promote the contraction of ventricles.

Blood vessels

• They are divided into three.
  • Arteries transport blood from the heart. They contain oxygenated blood.
  • Veins transport blood into the heart. They contain deoxygenated blood.
  • Capillaries transport blood into venules from arterioles.

Fetal circulation

It helps in the transfer of nutrients and oxygen to the fetus from the mother.

Umbilical arteries help to transfer materials to the mother.

Umbilical arteries include the ductus venosus and the umbilical vein.

Umbilical vein transports fetal blood.

The vein branches in the liver to form ductus venosus which enters the vena cava and the blood is delivered to the heart.

Revision

cardiovascular system
Consists of the heart, arteries, veins and capillaries. It functions as a transport system for oxygen, nutrients, hormones, enzymes and cellular wastes to and from the body cells.

Four Chambers of the Heart
left/right atrium, right/left ventricle

receiving chambers
left and right atrium

discharging chambers
left and right ventricle

epicardium (visceral pericardium)
The outermost layer of the wall of the heart that is a thin and transparent layer composed of serous tissue and mesothelium

aorta
The largest artery in the body. It begins as it exits from the left ventricle of the heart and arches to the left as the aortic arch and heads down along spine becoming thoracic aorta and abdominal aorta.

aortic semilunar valve
found in the opening where the ascending aorta leaves the left ventricle.

arteries
Blood vessels that carry blood away from the heart.

arterioles
small arteries that delivery blood to the capillaries.

ascending aorta
leaves the left ventricle of the heart.

auricle
Increases the volume of the atrium, external appendage of the atrium.

bicuspid (mitral valve)
atrioventricular valve between the left atrium and the left ventricle. It has two cusps and is the only valve like this.

semilunar valves
two arteries that leave the heart (ascending aorta and pulmonary trunk) and prevent blood from flowing back into the pumping chamber.

chordae tendineae
connect the pointed ends of the flaps or cusps to the papillary muscles in the ventricles of the heart. known as ‘heart strings’

coronary arteries
Supply the walls of the heart with oxygenated blood.

coronary circulation
supplies the blood to the myocardium of the heart.

coronary sinus
drains the blood from most of the vessels that supply the walls of the heart with blood.

coronary sulcus
groove separating the atria from the ventricles externally.

descending thoracic aorta
part of the aorta located in the thorax.

diastole
phase of relaxation of the heart.

endocardium
third and innermost layer of the wall of the heart. It is a thin layer of endothelium that overlies a thin layer of connective tissue, and acts as a lining for the myocardium, covering the valves of the heart and the chordae tendieae of the valves.

fibrous pericardium
outermost layer of the pericardial sac

heart
major pumping organ of the cardiovascular system.

inferior (posterior) vena cava
brings blood to the heart from the lower parts of the body

left atrium
one of upper receiving chambers of the heart.

left pulmonary artery
carries blood to the left lung.

left ventricle
one of the lower discharging chambers of the heart

myocardium
Second layer of the wall of the heart that makes up the bulk of the heart of cardiac muscle tissues. Arranged in interlacing bundles and responsible for the contraction of the heart.

papillary muscles
connect the pointed ends of the flaps or cusps to small conical projections in chordae tendineae “heart strings”

pericardial sac
parietal pericardium made up of two layers; fibrous pericardium and serous pericardium

pulmonary semilunar valve
found in the opening where the pulmonary trunk exits the right ventricle.

pulmonary trunk
the artery that leaves the right ventricle.

pulmonary veins
enter the left atrium of the heart.

right atrium
one of the upper receiving chambers of the heart.

right pulmonary artery
carries blood to the right lung.

right ventricle
lower discharging chamber of the heart.

serous pericardium
Thin, delicate, and innermost layer of the pericardial sac; parietal layer of the pericardial sac; continuous with large blood vessels and outermost layer of the heart’s wall.

superior (anterior) vena cava
brings blood from the upper parts of the body to the right atrium of the heart.

systole
phase of hearts contraption

thoracic aorta
name given to aorta in the thorax

tricuspid valve
valve between the right atrium and right ventricle.

veins
blood vessels that carry blood to the heart.

Name the three parts of the circulatory system
Heart blood blood vessels

What kind of blood cell carries oxygen
Red blood cell

Name the three types of blood cells
Red blood cells white blood cells platelets

Describe the function of each type of blood cell
Red blood cell transports oxygen throughout the body
White blood cell fights against injury and disease
Platelets start the blood clotting process

What is the main function of the circulatory system
To transport blood oxygen and nutrients throughout the body

Name the three types of blood vessels and state their function
Veins carry blood to the heart
Arteries carry blood away from the heart
Capillaries is where gas exchange takes place, forms network of tubing between the arterioles and venules

Why does the pulmonary artery have blood filled with carbon dioxide in it
The pulmonary arteries carry deoxygenated blood from the heart to the lungs were it will release CO2 and pick up oxygen during respiration

Why does the pulmonary vein have blood filled with oxygen in it
The pulmonary veins carry oxygenated blood to the heart from the lungs so that it may be directed to the rest of the body

What prevents blood from flowing backwards
Bicuspid and tricuspid valves

Veins carry blood in which direction
To the heart

What is blood mostly made up of
Blood plasma white blood cells red blood cells and platelets

What is the part of blood that causes clotting
Platelets

What is the name of the smallest type of blood vessel
Capillary

How many chambers does a mammaLian heart have
Four

What are the upper chambers of the heart called
Atriums

What are the lower chambers of the heart called
Ventricles

What is the wall that separates the chambers of the heart called
Septum

What is another name for the circulatory system
Cardiovascular system

Blood brings what two things to the cells of the body
Oxygen and nutrients

Blood picks up what materials from the cells of the body
Carbon dioxide water and waste products

Trace the flow of blood through the heart
1)blood enters heart at superior and inferior vena cava
2) blood circulates through the right atrium
3)blood passes through tricuspid valve
4) blood enters right ventricle
5)heart pumps blood through pulmonary semilunar valve
6) blood branches through pulmonary artery left and right 7)blood goes to lungs
8) blood picks up oxygen and comes back through pulmonary veins 9) blood reenters the heart the left atrium
10) blood travels through bicuspid valve
11) blood travels to left ventricle
12) blood is pumped through the aortic semilunar valve
13) blood passes into aorta
14) blood either exits aorta or passes through thoracic aorta to body organs and cells

Define blood-pressure explain the difference between systolic pressure and diastolic pressure
Blood pressure is the pressure the blood exerts against the inner walls of the blood vessels the force that keeps blood circulating
Systolic is pressure in arteries when arteries contract
Diastolic is pressure at artery relaxation

Explain the difference in the function of the systemic and pulmonary circulation
Systemic is the pathway between the left and right sides of the heart
Pulmonary is the blood pathway between the right side of the heart to the lungs and back to the left side of the heart

What are the two major heart sounds and what causes them
Lub-atrioventricular valves are surrounding fluid vibrations as valves close at beginning of ventricular systole
Dubb- closure of aortic and pulmonary semilunar valves at beginning of ventricular diastole(last longer)

What are three factors that are important in promoting venous return of blood
Respiratory pump skeletal muscle activity larger lumens of veins with valves

Explain what a stroke is
When blood flow to part of the brain is blocked or stop

Explain how capillaries exchange oxygen and nutrients the CO2 and waste materials
Diffusion everything moves from a high concentration to low

Name three different factors that increase heart rate
Sympathetic nervous system hormones exercise and decreased blood volume

Define pulse
The rate at which your heart beats

List several factors that can cause a heart attack
Blood vessels get blocked by plaque high blood pressure lack of physical activity poor blood cholesterol