Cardiovascular system I & II Flashcards
What does the cardiovascular system consist of?
The heart, arteries, capillaries and veins
Which circuit carries deoxygenated blood to the lungs?
Pulmonary circuit
What circuit sends oxygenated blood to all body cells?
Systemic circuit
Which vein carries deoxygenated blood back to the heart from the body?
Superior vena cava
What artery carries oxygenated blood from the heart around the body?
Aorta
What layer encloses the heart?
The pericardium
Wha are the two layers of the pericardium?
The outer= fibrous pericardium
(Tough connective tissue)
Inner = visceral pericardium
What is the visceral pericardium known as?
Epicardium
At the base of the heart, the visceral pericardium folds back to become what?
Parietal pericardium (lines the fibrous pericardium)
What is the name of the potential space between the parietal and visceral pericardia?
Pericardial cavity
What is between the parietal and visceral pericardium?
Serious fluid to prevent friction
In front of the visceral pericardium what is there?
Myocardium
What is the in front of the myocardium?
Endocardium
Layers of the heart wall from the inside out
Endocardium Myocardium Epicardium (visceral pericardium) Pericardial cavity Parietal pericardium Fibrous pericardium
Which layer houses blood capillaries and coronary arteries?
Visceral pericardium (epicardium)
Inferior vs superior vena cava
Inferior vena cava brings deoxygenated blood from the lower half of the body back to the heart
Superior vena cava brings deoxygenated blood from the upper half of the body back to the heart
Which chamber do the superior and inferior vena Cavae bring blood back to?
Right atrium
Which chambers pump blood away from the heart?
Left and right ventricles
Which chambers receive blood returning back to the heart?
Left and right atria
Which chambers have thicker walls? Why?
Ventricles
More muscular to pump blood further
What divides the right and left chambers?
A septum
What prevents backflow of blood from ventricles to atria?
Atrioventricular valve
Which at valve is tricuspid and which is bicuspid?
Right- tricuspid
Left- bicuspid
Bicuspid vs tricuspid
Bicuspid (left) has two cusps
Tricuspid (right) has three cusps
What attaches to cusps?
Chordae tendineae (heart strings)
What are chordae tendineae attached to?
Papillary muscles in the inner heart wall that contract during ventricular contraction to prevent blood back flow
What prevents back flow?
Muscles in ventricular wall called papillary muscles are attached to chordae tendineae and contract when the ventricles contract to pull the valve shut and prevent backflow
What does the coronary sinus do?
Drains blood from the myocardium into the right atrium
Which of the ventricles has a thicker wall?
Left ventricle (pumps blood around entire body not just to lungs) higher pressure needed
At the pulmonary trunk between the ventricles and the pulmonary artery there is what?
Pulmonary valve (semilunar valve) to prevent blood backflow
The right ventricles pump blood where?
Lungs via pulmonary veins
What are the two AV valves called?
Bicuspid (left) = mitral valve
Tricuspid (right)
The semilunar valves are known as what?
Left ventricle to aorta= aortic valve (to around the body)
Right ventricle to pulmonary artery=pulmonary valve (to lungs)
How many divisions of pulmonary vein return to the left atrium?
4
How many divisions of the aorta go around the body?
3
Where does blood return to the right atrium from?
Vena cava (both) from body And coronary sinus from myocardium
What causes blood to move from right atrium to right ventricle?
Right atrium contracts increasing pressure in atrium so tricuspid AV valve is forced open and blood flows down pressure gradient into ventricle.
What causes the tricuspid AV valve to close?
The ventricle contracts closing it (papillary muscles pull heart strings which shut it)
right ventricle contracts and then what happens?
Tricuspid valve closes
Pressure in ventricle increases
Semilunar (pulmonary) valve opens
Blood flows into pulmonary artery to lungs
What leads into pulmonary arteries?
Pulmonary trunk
Oxygenated blood from the lungs returns to where?
Left atrium through pulmonary veins
When the left atrium contracts what happens?
Left bicuspid (mitral) valve opens Blood pressure in atrium increases and blood flows into ventricles through mitral valve
Left ventricle contracts causing what?
Mitral valve closes due to papillary muscles and heart strings.
Blood pressure increases in ventricles and semilunar (aortic valve) opens
Blood flows into aorta to the body
What arteries supply blood to the heart itself?
Left and right Coronary arteries
First branches of the aorta
Branches of the coronary arteries feed what?
Capillaries of the myocardium
When does blood in vessels in the heart flow best?
During relaxation periods (diastole) because contraction (systole) closes the vessels
What drains blood from the heart muscle?
Cardiac veins which lead to coronary sinuses, these empty blood into the right atrium
What are auricles?
Appendages to increase the volume of the atria
What is atrial systole?
When both atria are contracting in unison.
Ventricular systole
When both ventricles are contracting
Diastole
When the whole heart briefly relaxes
When is pressure highest in the atria?
When atria are contracting
What forces the AV valves to open?
Higher pressure in the atria than in the ventricles
When do the semilunar valves close?
When pressure in the ventricles is lower than in the arterial pressure, the semilunar valves close
Which valves are open during atrial systole?
AV valves (mitral=left=bicuspid) (right=tricuspid)
What causes heart sounds?
Vibrations in heart tissue as the valves close
The first sounds is as the ventricles contract and AV valves close
The second sounds is as ventricles relax and aortic and pulmonary valves close
What causes the abnormal murmur sound?
Valve damage
What is the functional syncytium and where are they?
A mass of merging fibres as a unit
One exists in the atria (atrial syncytium) the other in the ventricles (ventricular syncytium)
What separates the syncytia?
The fibrous skeleton of the heart
What are the two types of cardiac cells?
Electrical cells (conductile) Myocardial cells (contractile)
Which cells are conductile?
Electrical cardiac cells
Which cells are contractile in the heart?
Myocardial cardiac cells
What are electrical cardiac cells for and how are they distributed?
1) they make up the conduction system of the heart
2) they’re distributed in an orderly fashion through the heart
Three properties of electrical cardiac cells?
Automaticity
Excitability
Conductivity
Where are myocardial cells in the heart?
They make up the muscular walls of the atria and ventricles
What are two specific properties of myocardial cardiac cells?
Contractability
Extensibility
What does specialised cardiac muscle tissue do in the cardiac conduction system?
Conducts impulses throughout the myocardium
What makes up the sinoatrial node?
Self exciting mass of specialised cardiac muscle cells
What is the sinoatrial (SA) node also known as
The pacemaker
Where is the SA node (pacemaker) located?
The posterior right atrium
What generates the impulses for a heart beat?
The SA node (pacemaker)
What’s special about the cardiac muscles that make up the pacemaker (SA node)?
They are self-exciting (self exciting cells)
Where does the impulse (created by the pacemaker) spread to after being generated in the posterior right atrium?
They spread to the atrial syncytium
What happens when the impulse spreads to the atrial syncytium?
The atria contract
Where does the impulse spread to after the atrial syncytium?
Junctional fibres leading to the atrioventricular node (AV node) in the septum
Where is the atrioventricular node located?
In the septum
What allows the atria to contract simultaneously?
The delay through the junctional fibres
Where does the electrical impulse spread to after the AV node?
To branches of the AV bundle and down the interventricular septum (between ventricles)
What branches off the bundle branches?
Purkinje fibres
Where do purkinje fibres lead to?
The ventricular wall and papillary muscles
What do purkinje fibres stimulate in the ventricular wall?
Contraction on papillary muscles as the ventricles contract
Where does the electrical impulse for contraction start and finish?
Starts in the SA node
Finishes in the ventricular syncytium
What does an electrocardiogram record?
The electrical changes that occur in the cardiac cycle
What 5 types of blood vessel are there in the cardiac system?
Arteries Arterioles Capillaries Venules Veins
Centre of a blood vessel
Lumen
What makes artery walls adapted for high blood pressure?
Thick muscular, elastic walls to withstand high blood pressure
Why do veins have valves?
To prevent back flow of blood in slow blood pressure
What is the outside layer of blood vessels called?
Tunica externa
What branches off from an arteriole to individual cells?
Capillaries
What does a sphincter do between arterioles and capillaries?
It adjusts blood flow from arterioles into smaller capillaries
Why are capillary membranes porous?
For tissue fluid formation
What is the name of the fluid in the extravascular space around capillaries?
Interstitial fluid
What four forces operate across capillary membranes?
Plasma colloid osmotic pressure
Capillary hydrostatic pressure
Interstitial fluid hydrostatic pressure
Interstitial fluid colloid osmotic pressure
When is arterial pressure highest?
When ventricles are contracting
When is arterial pressure lowest?
When ventricles relax
What is used to measure blood pressure?
A sphygmomanometer
What 4 factors influence arterial pressure?
Cardiac output
Blood volume
Peripheral resistance (friction between walls of blood vessels and blood)
Blood viscosity (thickness)
Stroke volume x heart rate =
Cardiac output
Cardiac output x peripheral resistance =
Blood pressure
What increases stroke volume and cardiac output?
Stronger ventricular contraction
What detects change in BP
Baroreceptors
If baroreceptors detect raised BP from raised cardiac output what happens?
Sensory impulses sent to cardiac centre Parasympathetic impulses to heart SA node inhibited Heart rate decreases BP decreases
Other than heart contraction, what 3 factors affect venous blood flow?
Skeletal muscle contraction
Breathing movements
Vasoconstriction
What are the two circuits in the double circulatory system?
Pulmonary circuit
Systemic circuit
What is the foramen ovale?
An opening of the septum between the two atria in a fetal heart that closes at birth
What is the ductus ateriosus
A short broad vessel in the fetus that connects the pulmonary artery with the aorta to bypass to lungs
What is the ductus venous?
A vein in the fetus passing through the liver connecting the left umbilical vein with the inferior vena cava
What does the foramen ovale become after birth?
Fossa ovalis
What does the ductus venous become after birth?
Ligamentum venosum
What does the ductus arteriosus become after birth?
Ligamentum arteriosum
What does the P wave represent?
Depolarisation of the atria
What does the QRS complex represent?
Depolarisation is the ventricles
What does the T wave represent?
Repolarisation of the ventricles
Functional syncytium
Cardiac muscles work together
