The heart Flashcards
What does the cardiovascular system consist of?
Heart, blood and blood vessels
Where is the heart situated?
Between the lungs in the thoracic cavity, between the vertebral column and the sternum.
What are the 4 compartments of the heart?
- right atrium
- left atrium
- right ventricle
- left ventricle
What is the membrane that surrounds and protects the heart called?
Pericardium
The pericardium is made up of two layers. What are they?
- fibrous pericardium - the dense outer layer that protects and anchors the heart
- serous pericardium - thin, delicate double layer that lubricates the heart
There are 3 major layers of the heart wall. What are they?
(EME OR ‘EMMY’)
- epicardium
- myocardium (cardiac muscle tissue)
- endocardium
Arteries always take blood in what direction (in relation to the heart)?
Away from the heart (oxygen rich blood)
The pulmonary trunk divides the right and left pulmonary arteries and carries blood to where?
The lungs
Blood passes from the left atrium into the left ventricle via which valve? (hint: two cusps)
Bicuspid valve
Which chamber of the heart is the thickest?
Left ventricle
(it needs to pump blood greater distances at higher pressure)
Blood passes from the left ventricle to the ascending aorta via which valve?
Aortic valve
Valves ensure a one-way flow of blood. They open and close in response to what?
Pressure changes
The tricuspid and bicuspid valves are together known as the atrioventricular valves. Why is this?
Because they are located between an atrium and a ventricle.
The aortic and pulmonary valves are together known as what?
Semilunar valves
(crescent moon-shaped cusps)
What are the two closed circulation circuits? Which sides of the heart are associated with each?
- Pulmonary (right is the pump)
- Systemic (left is the pump)
Deoxygenated blood returns to the heart (right atrium) via 3 main veins. What are they?
- Superior vena cava
- Inferior vena cava
- Coronary sinus
Cardiac Myofibrils are bundles of fibre that make up specialised muscle cells of the heart.
They contain less sarcoplasmic reticulum and need WHAT from extracellular fluid for contraction?
Calcium
What are autorhythmic fibres?
Cardiac muscle cells that are self-excitable
(i.e. generate spontaneous action potentials that then trigger heart muscle contractions)
What are the two main functions of autorhythmic fibres?
- They act as a pacemaker
- Form the cardiac conduction system
Order the main components of the conduction system.
- Right and left bundle branches
- Atrioventricular (AV) Node
- The Sinoatrial (SA) Node
- Purkinje Fibers
- Bundle of His
- Sinoatrial node (SA)
- Atrioventricular node (AV)
- Bundle of His
- Bundle branches
- Prukinje Fibers
SABBP
What are the 3 main steps in the action potential of a heart contractile fibre?
- Depolarisation (Na+ inflow)
- Plateau (Ca2+ inflow and K+ outflow)
- Repolarisation (Ca2+ channels close)
Pressure and volume change throughout the cardiac cycle. During a cycle, atria and ventricles alternately contract and relax, forcing blood from high to low pressure areas.
A cardiac cycle consists of three phases. What are they?
- Atrial systole
- Ventricular systole
- Relaxation period (diastole)
Cardiac output equals the stroke volume multiplied by the heart rate.
What is stroke volume?
The volume of blood ejected by the ventricle each contraction.
Changing heart rate is the body’s principal short-term way of controlling cardiac output and blood pressure.
What are the main factors that affect heart rate?
> Neural Factors
E.g. Sympathetic/parasympathetic impulses; Baroreceptors detect changes in blood pressure and send information to the cardiovascular centre…
> Hormones and Ions
E.g. Epinephrine, norepinephrine…
> Other Factors:
E.g. Age, gender, physical fitness and temperature
