Heart Part 1 Flashcards
What does CVS transport?
oxygen and co2
water and nutrients
metabolities and hormones
Heat
Waste products.
Why is the CVS amazingly reliable?
over 2.5 billion beats in 70 years
Why is the heart remarkably flexible?
pump can vary output
Why does the hearts pump vary in output?
remarkably flexible
What are the CVS components?
Pump – the heart (nearly 100,000 beats / day)
* Pipes – the blood vessels
* Fluid in the system – the blood
* 2 circuits (circulation of blood)– The Pulmonary Circuit– The Systemic Circui
What are the two circuits in the heart?
- the pulmonary circuit
- the systemic circuit
What makes up the pulmonary circulation?
Heart
Lungs
Pulmonary artery
Pulmonary vein
What makes up systemic circulation?
Heart
Rest of body
Aorta (artery)
Vena cava (vein)
function of arteries?
carry oxygenated blood away from the heart (except pulmonary artery.
function of veins?
return deoxygenated blood to the heart, except pulmonary vein.
function of capillaries?
- sites of nutrient, metabolic products, and fluid exchange.
- Capillaries connect arteries to veins
What di capilleries connect?
Capillaries connect arteries to veins
what are the three layers of arteries.
1) an inner, single layer of endothelium - continuous with capillaries and veins and in contact with the blood.
2) a middle, thick layer of smooth muscle and elastic fibres (allows the arteries to stretch and contract)
3) an outer connective tissue coat (made up of mostly collagen fibres).
how do arteries regulate blood pressure?
arteries constrict and contract.
The smooth muscle fibres contract or dilate to adjust the size of
the calibre (internal diameter)
the anatomic structures of arteries are important in…
…regulating blood flow.
define calibre
internal diameter
in arteries, small changes in the vessel lumen can greatly affect…
…blood pressure and blood flow.
veins have the same…
… three layers as arteries.
why are the middle and outer layers of the veins much thinner than they are in arteries?
Because veins do not regulate blood pressure and
blood flow into capillaries as arteries do.
Because of a veins thinner layers, what happens to veins if not filled with blood?
they collapse
Because of the thinner layers, veins collapse if not
filled with blood – lower pressure. How to
overcome this?
Most veins have efficient valves to prevent back
flow of blood (not all veins are ‘that’ efficient)
Veins further away from the heart (e.g. lower limbs) rely more on…
…valves, ensuring that blood only flows in one direction.
Where is the internal jugular vein valve located (IJVV) ?
Situated just above the
termination of the internal
jugular vein
the Internal jugular vein valve is the only…
…valve between the heart and the brain
the Internal jugular vein valve prevents…
…cephalad flow of venous blood
- helps stop blood from flowing backward toward the head (cephalad) when there is increased pressure in the thoracic cavity or during activities like coughing.
If the Internal jugular vein valve does not function properly, what does this mean?
risk of increased intracranial pressure.
- accumulation of blood in the cranial cavity, which may affect brain function and lead to symptoms such as headaches, nausea
what makes up the walls of capillaries?
vascular endothelium
what comprises a capillary?
Comprise a single endothelial
layer – continuous with the
vascular endothelium of arteries
and veins
what do capillaries form?
dense networks (capillary beds) in the tissues
number of capillaries?
large number
why a large number of capillaries?
large surface area.
why a single endothelial layer in capilleries?
short diffusion distance – ideal for exchange
Output of the left ventricle is distributed so that…
… each part of the body receives a fresh blood supply.
The same arterial blood does not pass from…
…organ to organ.
what is O2 exchanged for?
O2 exchanged for CO2 in tissue cells.
Blood flow to brain at rest (ml/min)?
650 ml/min (13%) ml/min
Blood flow to heart at rest (ml/min)?
215 ml/min (4%)
Blood flow to skeletal muscle at rest (ml/min)?
1030 ml/min (20%)
Blood flow to skin at rest (ml/min)?
430 ml/min (9%)
Blood flow to kidney at rest (ml/min)?
950 ml/min (20%)
Blood flow to abdominal organs at rest (ml/min)?
1200 ml/min (24%)
Blood flow to other organs at rest (ml/min)?
525 ml/min (10%)
TOTAL blood flow to organs at rest (ml/min)?
5000 ml/min (100%)
describe walls of Abdominopelvic cavity?
Walls: abundant connective tissue with elastic properties
What is the heart ?
- A fist sized muscular organ
How many chambers does the heart contain?
4 chambers
What are the four chambers of the heart?
–Right and left atria
–Right and left ventricles
How many halves in the heart?
2 functional halves
What are the hearts two functional halves?
–Right side
–Left side
What are the two halves separated by?
septum (Interventricular septum)
is the left side of the heart o2 rich or o2 poor?
o2 rich
is the right side of the heart o2 rich or o2 poor?
o2 poor
why is blood pressure important?
unidirectional flow of blood
What do 4 one way heart valves ensure?
ensure the unidirectional flow of blood
What do pressure differences cause in terms of valves?
Pressure differences cause openings and closing of valves.
when pressure is greater in front of the valve, what happens?
it closes.
When pressure is greater behind the valve, what happens?
it opens.
Forward pressure gradient =
open
backward pressure gradient =
closed.
What is the function of atrioventricular valves?
prevent backflow from ventricles to atria.
Where is the tricuspid valve located?
between RA and RV
Where is the bicuspid valve located?
between LA and LV (sometimes called mitral valve).
What is the bicuspid valve sometimes called?
sometimes called mitral valve.
Chordae tendineae and papillary muscles play an
important role in…
… preventing backflow to atria.
What happens when papillary muscles contract?
Contraction of papillary muscles tenses chordae tendineae, holding
cusps closed.
whats the function of semi-lunar valves?
prevent backflow from major arteries to ventricles.
- pulmonary trunk into RV (pulmonary semi-lunar valve)
– Aorta into LV (aortic semi-lunar valve)
what do semi lunar valves act in?
act in a passive manner
semi lunar valves have no papillary muscles because
… arteries do not contract.
What is the left aortic sinus the origin of?
origin of the left coronary artery.
What is the right aortic sinus the origin of?
origin of the right coronary artery.
What is Mitral valve regurgitation?
Cusps of the mitral valve do not close properly, allowing
some blood to flow back into atrium during ventricular
contraction.
What are some causes of Mitral valve regurgitation?
Causes are congenital heart problems, infection, heart
attacks
What are symptoms of Mitral valve regurgitation?
Symptoms include shortness of breath, fatigue, oedema
Describe electrical system of the heart?
Sino-atrial node -> Internodal fibres -> Atrio-ventricular node -> AV bundles
(Purkinje fibres)
Left & right branches
what is the conduction velocity from SA node to Atrial muscles?
0.3 m/s (meters per second)
SA node produces electrical impulse to the …
… atrial muscles, causing them to contract
AV node produces electrical impulse to the …
ventricular muscles
what is the conduction velocity from AV node to ventricular muscles?
1.5 – 4.0 m/s
How can electrical activity of the heart be tracked?
with an ECG
ventricular repolarization = ?
T wave
atrial depolarization = ?
P wave
ventricular depolarization = ?
QRS wave
Examples of heart conditions diagnosed using ECG:
Enlargement of the heart
Congenital heart defects involving the conducting system
Arrhythmia
Coronary occlusion
Ischaemia
Abnormal position of the heart
Pericarditis or myocarditis
Cardiac arrest (in ER or ICU)
Electrolyte imbalances
Previous heart attacks
What is the pericardium?
double walled, fibrous sac, surrounds/encases the heart
What are the three layers of pericardium?
- fibrous pericardium (outermost layer)
- pericardial cavity
- serous pericardium (parietal layer + visceral layer (epicardium) (innermost)
WHat are the three layers of the heart wall?
epicardium (outermost) (visceral pericardium), myocardium (middle), and endocardium (innermost).
What are the characteristics of epicardium?
serous membrane including blood capillaries, lymph capilleries, and nerve fibres.
What are the functions of epicardium?
serves as a lubricative outer covering
What is myocardium?
cardiac muscle tissue separated by connective tissues and including blood capillaires, lymph capilleries, and lymph fibres.
Function of myocardium?
provides muscular contractions that eject blood from the heart chambers.
what are the characteristics of endocardium?
endothelial tissue and a thick subendothelial layer of elastic and collagenous fibres.
what is the function of endocardium?
serves a protective inner lining of the chambers and valves.
What is pericarditis?
inflammation of the pericardium
What is myocardium?
cardiac muscle
What are cardiac muscle cells also known as?
cardiocytes/cardiomyocytes
Cardiac muscle cells are unique to…….??
unique to the heart
what kind of muscle is cardiac muscle?
Striated Involuntary Muscle Tissue
is cardiac muscle voluntary or involuntary?
involuntary
is cardiac muscle smooth or striated?
striated.
cardiac muscle cells have….
… Numerous mitochondria (up to 40% of cell volume)
Humans are born with a set number of…
…cardiomyocytes
Humans are born with a set number of cardiomyocytes, which only…
…increase in size during childhood development into adulthood
Implications for heart disease?
– myocardial death
Recent evidence suggests cardiomyocytes are actually slowly …
… turned over, but less than 50% of the cardiomyocytes are replaced during a normal life span.
the different parts of the heart?
- Position of transverse pericardilal sinus
- Heart
- Fibrous pericardium
- Serous paericardium
- Pericadial cavity
Whats the serous fluid made of?
- Parietal layer
- Visceral layer.
What are adjacent cells joined at?
joined at intercalated discs.
2 types of membrane junctions
are present within an
intercalated disc which are?
- Desmosomes (mechanically
holds the cells together) - Gap junctions (allow action
potentials to spread from one
cardiac cell to adjacent cells)
Intercalated discs allow for?
Allows the entire muscle
mass of the atrium or
ventricle to contract almost simultaneously
(functional syncytium )
Define the cardiac cycle?
Sequence of events related to the blood flow
and blood pressure that occurs from the
beginning of one heartbeat to the beginning
of the next
What is the rhythm of the cardiac cycle controlled by?
Rhythm controlled by the cardiac conduction
system.
82
Using a stethoscope, it is possible to…
… listen to the heart. (auscultation).
what is the first sound heard in a stethoscope caused by?
Closure of the mitral (bicuspid or left AV) valve and the tricuspid (or right AV)
What does the first sound heard in a stethoscope indicate?
Beginning of ventricular
contraction (systole).
What is the second sound heard in the stethoscope caused by?
Closure of the aortic and
pulmonary (semilunar) valves.
What does the second sound heard in the stethoscope indicate?
Beginning of ventricular
relaxation (diastole)
Ausculation can be used as a…
… diagnostic tool
What does a murmur mean in heart sounds?
turbulent flow; often benign in children
What does a whistle mean in heart sounds?
stenotic valve; stiff and incompletely open
What does a swish mean in heart sounds?
valve insufficiency; does not close perfectly
