Topic 3: Cardiovascular System Flashcards
How many times will the heart contract throughout an average human lifespan?
3 billion times
When does the heart start beating?
in the utero at three weeks
Why does the cardiovascular system develop early?
the embryo needs to be able to move nutrients and waste products early in development
What are the three components of the cardiovascular system?
- the heart
- the blood vessels
- blood
What is the function of the heart?
serves as a pump to move the blood throughout the body
What is the function of the blood vessels?
serve as passageways for the movement of blood
What are the two types of vascular loops?
- pulmonary
- systemic
What is the function of the blood?
travels throughout the body into two vascular loops
What is the function of the pulmonary vascular loop?
pulmonary circulation vessels carrying blood between the heart and the lungs
What is the function of the systemic vascular loop?
systemic circulation vessels carrying blood between the heart and the other organ systems
Where is the heart located in the body?
resides in the center of the thoracic cavity and it is surrounded by the pericardium
What are the three layers of the heart?
- epicardium (outer)
- myocardium - muscle of the heart, contracts to create heartbeats
- endocardium (inner)
What are the four chambers of the heart?
- two ventricles
- two atria
What are the functions of the two ventricles?
- muscular left ventricle pushes blood throughout the body
- the right ventricle pushes blood to the lungs
What are the functions of the two atria?
- smaller, thinner-walled chambers on top of the more muscular ventricles
- receive blood returning from the body (right atrium) or lungs (left atrium)
- hold the blood and then pump it into the ventricles
What is the movement of de-oxygenated blood?
- oxygen-poor blood enters the RIGHT atrium from the large veins known as the VENA CAVAE
- from the right atrium, blood flows through the right AV valve into the RIGHT VENTRICLE
- From the right ventricle, blood flows through the PULMONARY SEMILUNAR VALVE to the PULMONARY ARTERY to the lungs
- the right side of the heart pumps blood from the systemic circulation to the pulmonary circulation
What is the movement of oxygenated blood?
- oxygenated blood returns from the lungs and enters the LEFT atrium via the PULMONARY VEINS
- from the left atrium, the blood flows through the mitral valve into the LEFT VENTRICLE
- the left ventricle pumps the blood through the AORTIC SEMILUNAR VALVE to the AORTA and then throughout the body
- the left side of the heart pumps blood rom the pulmonary circulation to the systemic circulation
VEINS do not always carry _ blood and ARTERIES do not always carry _ as is often though
DE-OXYGENATED, OXYGEN-RICH
What is the blood flow in the circulatory system (overall)?
- in pulmonary circulation, all blood flows through the lungs
- in systemic circulation, the blood flows to various organs systems in a series of parallel paths
How do tissues receive blood?
- blood does not pass from tissue to tissue
- each tissue receives freshly oxygenated blood directly
How many directions does blood move?
blood flows in one direction only from atrium to ventricle
What prevents blood from going back in the wrong direction?
a series of VALVES located in several places; valves open in response to pressure form one direction only
When pressure is _ behind the valve, the valve _
greater, opens
When pressure is _ in front of the valve, the valve _
greater, closes
What makes the heartbeat sound?
when valves slam shut
What are the valves that control blood flow between the atria and ventricles?
the RIGHT AND LEFT ATRIOVENTRICULAR VALVES or AV VALVES
What is the TRICUSPID valve?
the right AV valve that has three leaflets
What is the BICUSPID valve?
the left AV valve that has two leaflets
What are the two leaflets at the bicuspid valve?
the left AV valve; MITRAL VALVE
Where is the SEMILUNAR VALVES?
there are two between the ventricles and the arteries into which the blood is pumped
What are the two SEMILUNAR valves?
- aortic semilunar valve
- pulmonary semilunar valve
Where is the aortic semilunar valve?
between the LEFT VENTRICLE and the AORTA
Where is the pulmonary semilunar valve?
between the RIGHT VENTRICLE and the PULMONARY ARTERY
Why are the SEMILUNAR valves SEMILUNAR?
each leaflet is cup-shaped-like a half moon
What are the normal heart sounds?
“lub-dub”
What is S1 (“lub”)?
a resonating sound caused by blood pressure against the atrioventricular valves (sound is the result of the closing of AV valves)
What is S2 (“dub”)?
a snapping sound when the ventricles relax and blood in the arteries flows back toward the ventricles (closing of semilunar valves)
What is the cardiac cycle?
the cycle of heart muscle alternately contracting and relaxing
What are the three periods of the cardiac cycle?
- diastole (relaxation period)
- atrial systole
- ventricular systole
What happens in diastole?
at the beginning of the cycle, the heart is completely relaxed, with blood entering both the left and right atria
What happens in atrial systole?
as the heartbeat begins, the atria contract. This forces the blood from the atria into the ventricles
What happens in ventricular systole?
the atria relax during ventricular systole. The ventricles remain contracted for a measurable time, and then the entire heart returns to diastole
In atrial systole, the AV valves are _, semilunar valves are _
open, closed
In ventricular systole, the AV valves are _, semilunar valves are _
closed, open
What causes blood pressure?
- blood volume does not change during the cardiac cycle
- force generated by the left ventricle results in a change in blood pressure from the relaxed state
What is the expression for blood pressure?
systolic pressure/diastolic pressure (ex. 120/80mmHg)
What is systolic pressure?
the force with which left ventricle pushes blood through the circulatory system
What is diastolic pressure?
the force the blood exerts on the walls of the circulatory system hile the heart is relaxed
What is normal blood pressure?
90-120 (systolic), 60-80 (diastolic)
What is high blood pressure?
140/90mmHg
What happens at maximum pressure?
when ventricles are contracting, systolic pressure, 120 mm Hg
What happens at minimum pressure?
when ventricles are relaxing, diastolic pressure, 80 mm Hg, minimum pressure is never zero
What is pulse pressure (PP)?
SP - DP
What is mean pressure (MAP)?
weighted average of pressure
What value is MAP closest to?
diastolic because time spent in diastole is greater than time spent in systole
What is the expression for MAP?
DP + (PP/3)
What are the two types of blood flow?
- laminar flow
- turbulent flow
What is laminar flow?
blood flowing smoothly, it makes almost no sound (ex. water flowing in a garden hose is quiet)
What is turbulent flow?
blood flow is restricted, it bounces around, it creates sounds as it hits the sides of the vessel (ex. a kinked hose will vibrate and make noise)
What is a sphygmomanometer?
inflatable cuff attached to a pressure gauge. Used with a stethoscope
How does a sphygmomanometer work?
- cuff wrapped around upper arm and inflated with air
- pressure compresses brachial artery and can be varied to prevent or permit blood flow
- turbulent blood flow can be detected with a stethoscope, whereas smooth laminar flow and no flow are inaudible
What happens when cuff pressure >120 mm Hg?
- no blood flows through the vessel
- no sound is heard because of no flow
What happens when cuff pressure is between 120 and 80 mm Hg?
- blood flow through the vessel is turbulent whenever blood pressure exceeds cuff pressure
- first sound is heart at peak systolic pressure
- intermittent sounds are heard as blood pressure due to turbulent spurts of flow cyclically exceeds cuff pressure
What happens when cuff pressure is <80 mm Hg?
- blood flows through the vessel in smooth, laminar fashion
- the last sound is heard at minimum diastolic pressure
- no sound is heard thereafter because of uninterrupted, smooth, laminar flow
What are the patterns of sounds (5)?
- no sound is heard because of no flow
- the first sound is heart at peak systolic pressure
- intermittent sounds are heard as blood pressure due to the turbulent spurts of flow cyclically exceeds cuff pressure
- the last sound is heart at minimum diastolic pressure
- no sound is heart thereafter because of uninterrupted, smooth, laminar flow
What happens to cuff pressure during the patterns of sounds?
- cuff pressure above 120; artery is pinched closed: no blood flow, no blood flowing by stethoscope, no sound heard
- cuff is loosened to allow blood flow
- when cuff pressure is between 120 and 80, there is turbulent flow. sound is heart in stethoscope every time pressure in artery exceeds cuff pressure (pink shading)
- pressure in cuff is equal to the lowest pressure in the artery
- cuff is so loose (below diastolic pressure) that sounds are no longer heard
What are the 5 components of the heart (without neuronal input)?
- sinoatrial node
- atrioventricular (AV) node
- atrioventricular (AV) bundle
- right and left bundle branches
- purkinje fibers
What are the 5 steps of heart beating and contraction without neuronal input?
- the SA note initiates the heartbeat by initiating an electrical signal that passes from cell to cell through the right and left atria, causing both to contract
- the AV node (atrioventricular) in the base of right atrium slows the signal down so the ventricles get the signal a bit later so they contract after the atria
- the AV bundle sends the signal to the ventricles
- the bundle branches send the signal to the two ventricles to they contract together
5.the purkinje fibers send the signal to all of the cells of the ventricles
What is an electrocardiogram?
measures the electrical currents generated by cardiac muscle at the skin surface
What two points need to be remembered in an ECG analysis?
- the ECG is a recording of that portion of the cardiac signal that actually reaches the surface of the body-not the direct recording of the electrical activity of the heart
- the ECG is the summed activity of many cells-not a single electrical signal in a single cell at a single point in time
What are the parts of an ECG?
- P wave
- QRS complex
- T wave
- P-R interval
- Q-T interval
- T-P interval
What is the P wave?
represents the depolarization of the ATRIA (beginning of their contraction)
What is the QRS complex?
represents the depolarization of the VENTRICLES (atria, also repolarizing (end of their contraction)).
What is the T wave?
represents the repolarization of the VENTRICLES
What is the P-R interval?
AV nodal delay
What is the Q-T interval?
time during which ventricles are contracting and emptying
What is the T-P interval?
time during which ventricles are relaxing and refilling
What are the three types of blood vessels?
- arteries
- capillaries
- veins
What are the three layers of artery/vein walls?
- endothelium, the inner layer
- smooth muscle and elastic tissue in the middle
- connective tissue makes up the outside layer
How thick are the walls of capillaries?
one-cell layer thick
What type of valves do veins have?
one-way valves (much like the heart)
As blood flows through the body, the pressure _ so that at the veins, the pressure is almost _ as blood is returned to the heart
drops, zero
What do capillaries form?
networks called “capillary beds”
What do arterioles lead to?
capillaries, the smallest blood vessels
What is structure of capillaries?
a single layer of endothelial cells; small gaps between adjacent cells form pores
What is the function of the capillary pores?
small water-soluble substances are exchanged between the plasma and the interstitial fluid by passing through the water-filled pores
What can pass through the capillary wall?
- small water-soluble substances
- lipid-soluble substances
- proteins
How do small water-soluble substances pass through the capillary wall?
are exchanged between the plasma and the interstitial fluid by passing through the water-filled pores
How do lipid-soluble substances pass through the capillary wall?
are exchanged across the capillary wall by passing through the endothelial cells
How do proteins pass through the capillary wall?
moved across are exchanged by vesicular transport
How do plasma proteins pass through the capillary wall?
cannot escape from the plasma across the capillary wall
What happens during ultrafiltration at the ARTERIOLE end?
high blood pressure in the capillaries forces water into tissues. Large plasma proteins do not leave the blood as they cannot pass through the pores. Blood pressure > Osmotic pressure
What happens during reabsorption at the VENULE end?
as blood passes through capillaries, the pressure drops and the osmotic pressure increases. Most of the water then flows back into the blood at the venous end of the capillary. Osmotic pressure > Blood pressure
How does blood leave the capillaries and move toward the heart?
- larger vessels called venules
- veins
What pressure does blood move through the veins?
lower pressure, to blood continues to flow toward the heart
What are four reasons blood continues to flow toward the heart at low pressures?
- fluids flow more easily from smaller vessel to a larger one
- venous valves prevent backflow of blood
- skeletal muscles surrounding veins “push” blood toward the heart
- respiratory pump enhances venous return
The pressure surrounding the chest veins is _ than the pressure surrounding the veins in the extremities and abdomen
lower
What does the pressure surrounding the chest veins and extremities and abdomen cause?
- establishes an externally applied pressure gradient on the veins, which drives blood toward the heart (ex. a vacuum that sucks blood back into the thoracic cavity); works even when lying down
What is blood composed of?
a liquid portion, the plasma, and a solid portion, the formed elements, which are mainly cells
How does blood maintain homeostasis (4)?
- forms clots to prevent blood loss at injuries
- patrol the body to destroy pathogens
- plasma contains hormones, nutrients, and gases (CO2/O2) that need to be transported to specific areas of the body
- transports heat between the body core and the skin
What is plasma?
the liquid portion of the blood, comprising 46 to 63% of total blood volume
What is plasma composed of?
- 92% water
- 7% dissolved proteins
- 1% electrolytes, nutrients, and wastes
What is the function of plasma proteins?
(albumin) maintain blood’s osmotic pressure, so that water remains inside the vessels instead of diffusing into tissues
What are examples of of plasma electrolytes?
(ions): sodium and potassium
What are examples of plasma nutrients?
carbohydrates and amino acids
What are examples of plasma wastes?
urea, CO2, and lactic acid
What percent of blood cells are red and white?
99.9% are red blood cells and 0.1% are white blood cells
Where did red blood cells originate from?
a common stem cell in the red bone marrow
What are red blood cells?
(erythrocytes) membrane bound sacs of hemoglobin that carry oxygen
How many hemoglobin are in red blood cells?
about 200 million hemoglobin molecules
What type of atom does hemoglobin contain?
each molecule contains 4 atoms of iron (bound to heme co-factor)
What is the function of hemoglobin?
picks up oxygen where the O2 is high, and releases O2 where O2 is scarce
What do red blood cells arise from?
reticulocytes (an immature red blood cell)
Can red blood cells repair themselves? Why?
they cannot repair themselves when damaged because red blood cells have no nuclei
How are damaged red blood cells removed?
- circulate about 120 days before they need to be removed from the circulatory system
- spleen and liver remove and recycle these cells
How many red blood cells are broken down per second?
about 2 million red blood cells are broken down per second; the need to be replaced at the same time
What controls the rate at which red blood cells are replaced?
hormones: low O2 in the blood stimulates the kidneys to make erythropoietin
What is erythropoietin?
a hormone that stimulates red blood cell production
What is erythropoietin used for?
- increase athletic performance: “blood doping”
- legal: train at higher elevations to stimulate red blood cell production
- illegal: blood-transfusions; inject commercial erythropoietin
