Lecture: The Cardiac System Flashcards
What are the two layers of pericardium?
Parietal (inner) and Visceral (outer)
What is the role of the pulmonary circuit?
Carries blood to and from gas exchange surfaces of lungs
What is the role of the Systemic Circuit?
Carries blood to and from the body
Blood alternates between which 2 circuits?
The pulmonary and the Systemic
What are the 3 types of blood vessels?
- Arteries 2. Veins 3. Capillaries
What is the role of arteries?
Carry blood away from the heart
What is the role of veins?
Carry blood to the heart
What is the role of capillaries
Networks between veins and arteries
Capillaries exchange materials between what two things?
Blood and Tissues
What materials do capillaries carry between blood and tissues?
dissolved gases, nutrients, wastes
What are the 4 chambers of the heart?
The Right and Left atria, The Right and Left ventricle
What occurs in the Right atrium?
Collects blood from the systemic circuit
What occurs in the Right ventricle?
Pumps blood to the pulmonary circuit
What occurs in the Left atrium?
Collects blood from the pulmonary circuit
What occurs in the Left ventricle?
Pumps blood to the systemic circuit
Where do the great veins and arteries gather?
The base of the heart
What is the ‘pointed tip’ of the heart
The apex
What surrounds the heart?
The pericardial sac
Where does the heart ‘sit’
Between two pleural cavities in the mediastinum
What is the ‘outer’ layer of the pericardium?
The parietal pericardium
What is the ‘inner’ layer of the pericardium?
The Visceral pericardium
Where is the pericardial cavity?
Between the visceral layers
Where is the pericardial fluid?
Inside the pericardial cavity
What is the purpose of pericardial fluid?
To prevent friction on the heart as it pumps
What is the pericardial sac made of?
Fibrous Sac
What qualities differentiate the cardiac muscle?
- It is branched 2. It contains intercalated disks 3.
Which part of the heart has THIN walls?
The Atria
Which part of the wall is flexible and expandable?
The outer auricle
What is the coronary sulcus?
Divides the atria and the ventricles
What part of the heart separates the right and left ventricles?
Anterior inter ventricular sulcus and posterior interventricular sulcus
What contains the blood vessels of cardiac muscle?
Anterior inter ventricular sulcus and posterior interventricular sulcus
Between which ribs does the heart ‘sit’?
Approx between 2-6
What 3 parts make up the heart wall?
The epicardium, the myocardium, and the endocardium.
Which layer of the heart is the muscular wall?
The myocardium (middle layer)
The atrial myocardium wraps around what?
The great vessels
Which layer of the heart is made of simple squamous epithelium?
The Endocardium or inner layer
What connects cardiac muscle cells?
Intercalated disks
What is secured by desmosomes?
Intercalated disks
What conveys the FORCE of contraction in cardiac muscle?
Intercalated disks
Intercalated disks are linked by what?
Gap junctions
Describe the nucleus of a cardiac muscle cell:
Single and central
Muscle cells are abundant in what?
Mitochondria (25% of total cell volume)
What is the role of the Interatrial septum?
Separates the atria
What is the role of the Interventricular septum?
Separates ventricles
What valves connect the right atrium to the right ventricle and the left atrium to the left ventricle?
The AV valves
Which valves contain the bicuspid and tricuspid valves?
The AV valves
Which valves permit blood flow from atria to the ventricles?
The AV valves
Where do the Superior and Inferior Vena Cava open to?
The right atrium
The right atrium receives blood from the head neck and upper limbs and chest via what valve?
The Superior vena cava
The right atrium receives blood from the trunk viscera and lower limbs via what valve?
The Inferior vena cava
Other than the vena cava, how does blood enter the right atrium?
Via the coronary sinus
What returns blood to the coronary sinus?
Cardiac veins
Where is the foramen ovale?
The right atrium
What happens to the foramen ovale after birth?
It closes and becomes the fossa ovalis.
What does the foramen ovale connect?
The two atria
Where are the pectinate muscles located?
The right atrium
What do chordae tendinae attach?
Papillary muscles to the right ventricle
What is the role of the chordae tendinae?
Prevents the valve from opening backwards.
Which valve is the RIGHT AV valve
The tricuspid valve
The tricuspid valve opens from ____ to _____
Right Atrium to Right Ventricle
What is the role of the tricuspid valve?
To prevent back flow
What is Trabeculae carneae?
Muscular ridges on internal surface of right and left ventricle
What is the role of the motor band on the Trabeculae carnae?
coordinates contractions of cardiac muscle cells
Where is the Conus arteriosus and where does it lead?
Superior end of right ventricle. Leads to pulmonary trunk
Pulmonary trunk divides into what?
2 left and right pulmonary arteries
Blood passes through what when passing from the right ventricle to the pulmonary trunk?
Through the pulmonary valve
Which valve has 3 semilunar cusps?
The pulmonary valve
What veins deliver blood to the left atrium?
Left and right pulmonary veins
Through what valve does blood pass from the left atrium to the left ventricle?
The LEFT AV valve (mitral, biscupid)
Which chamber of the heart is the most powerful?
The left ventricle
Which ventricle lacks a moderator band?
The left ventricle
The aortic valve connects which chamber to what?
The left ventricle to the ascending aorta
What are the 3 parts of the aorta?
The ascending aorta the aortic arch and the descending aorta
Which ventricle is pouch shaped and which ventricle is round?
Right: pouch shaped Left: round
Which valves close due to blood pressure during ventricular contraction
Atrioventricular Valves (AV)
What prevents the valves from swinging into atria
Papillary muscles tensing the chordae tendineae
Which 2 valves make up the semi lunar valves?
Pulmonary and aortic tricuspid valves
Which valves receive no muscular support?
The semi lunar valves
The semi-lunar valves prevent back flow from where?
The pulmonary trunk (pulmonary) and aorta (aortic) into ventricles.
What are the aortic sinuses?
They are sacs that prevent valve cusps from sticking to the aorta
Where are the aortic sinuses?
At the base of the ascending aorta.
What causes the semilunar valves to close?
The cusps fill with blood
What structure provides physical support cardiac muscle fibers?
the Cardiac (Fibrous) Skeleton
What supplies the heart itself with blood?
Left and right coronary arteries and cardiac veins
Where do the coronary arteries orginate?
The aortic sinuses.
2 main branches of the coronary artery are?
The circumflex artery and the Anterior interventricular artery
What is the role of the Great cardiac vein?
Drains blood from area of anterior interventricular artery into coronary sinus
What is the role of the Anterior cardiac veins
Empties blood into the right atrium
What is the role of the posterior middle and small cardiac vein?
Empty into great cardiac vein or coronary sinus
In what order to the parts of the heart contract when beating?
The atria, followed by the ventricles.
What are the 2 types of cardiac muscle cells?
- Conducting system (coordinates heartbeat) 2. Contractile cells (produces contractions that propel blood)
What stimulates the contraction of the heart?
Electrical impulses
What is Automaticity?
Automatic muscle contractions
What are the 3 structures of the conducting system?
- Sinoatrual (SA) node 2. Atrioventricular (AV) node 3. Conducting cells (throughout myocardium)
What is prepotenial?
Resting potential of conducting cells.
What node establishes the heart rate?
SA node depolarizes, establishing heart rate.
How many action potentials are generated by the SA Node per minute?
80-100
What slows the heart rate?
Parasympathetic stimulation
How many action potentials are generated by the AV node per minute?
40-60
Which node is in the posterior wall of the right atrium?
The SA node
Which node contains pacemaker cells?
The SA node
Where is the AV node located?
The floor of the right atrium
Which node receives impulses from the SA Node?
The AV node
Where does atrial contraction begin?
The AV node
How long is the delay at the AV node?
100 msec
Where is the AV bundle?
The septum
Where does the AV bundle lead impulses?
The moderator band and left and right bundle branches
Where do Purkinje fibers receive impulses from?
The AV bundle
How does ventricular contract begin?
The purkinje fibers distribute impulse through the ventriclular myocardium as the atrial contraction completes.
What is Bradycardia?
Abnormally slow heart rate
What is Tachycardia?
Abnormally high heart rate
What is Electrocardiogram?
A device that uses electrodes to record of electrical events in the heart and detect Abnormal patterns and diagnose damage
What is ectopic pacemaker?
An excitable group of cells that causes premature heart beat outside the normally functioning SA node of the heart.
What is denoted by the P wave on an EKG?
Atria depolarizes
What is denoted by the QRS complex on an EKG?
Ventricles depolarize
What is denoted by the T wave on an EKG?
Ventricles depolarize
Where does the P-R interval start and end on an EKG?
Starts at atrial depolarization and ends at the start of the QRS complex
Where does the Q-T interval start and end on an EKG?
Starts and ventricular depolarization and ends at ventricular repolarization.
What is the resting potential of a ventricular cell?
About 90mV
What is the resting potential of an atrial cell?
About 80mV
What is the difference between Absolute refractory period and Relative refractory period?
- Long, cardiac muscle cells can NOT respond 2. Short, response depends on degree of stimulus
Length of cardiac action potential in ventricular cell?
250-300 msecs
What ion increases to produce contraction of cardiac muscle?
Calcium Ions
What 3 steps provide aerobic energy for the heart?
- Mitochondrial breakdown of fatty acids and glucose 2. Oxygen from hemoglobin 3. Cardiac muscles store oxygen in myoglobin
What is a cardiac cycle?
Includes contraction and relaxation of 1 heartbeat
What is systole?
Contraction of the heart
What is Diastole?
Relaxation of the heart
Blood pressure does what during systole?
Rises
Blood pressure does what during diastole?
Falls
How long is the cardiac cycle and what bpm does it produce?
800 msecs, 75 bpm
What parts of the cardiac cycle shorten when the heart rate increases?
All parts but especially diastole.
