Cardiovacular System (week 7) Flashcards
what is the cardiovascular system?
a closed system of the heart and blood vessels
—> the heart pumps blood
—> blood vessels allow blood to circulate to all parts of the body
what are the functions of the cardiovascular system?
transport oxygen, nutrients, cell wastes, hormones to and form cells and regulation of body temperature
how big is the heart?
size of a human fist, weighing less than a pound
where is the heart located?
in the thoracic cavity (the medial section of the thoracic cavity- i between the lungs in the inferior mediastinum)
describe the orientation of the heart
Apex (pointed region) is directed toward left hip and rests on the diaphragm
base (area where great blood vessels emerge) points toward right shoulder
how is the heart covered?
with a double walled sac called pericardium
- fibrous pericardium is loose and superficial
- serious membrane is deep to the fibrous pericardium and composed of 2 layers
what is fibrous pericardium layers composed of?
- parietal pericardium: outside layer that lines the inner surface of the fibrous pericardium
- visceral pericardium: next to the heart; also known as epicardium
* serious fluid fills the space between the layers of pericardium called pericardial cavity
describe and name the 3 walls of the heart
- epicardium: outermost layer of the heart wall; also known as the visceral pericardium
- myocardium: middle layer composed mostly of cardiac muscle (this muscle contracts)
- endocardium: inner layer known as endothelium
what are the 4 chambers of the heart?
- Atria (right and left): superior receiving chambers
- Ventricles (right and left): inferior discharging chambers
what is the role of the left and right Atria
- Atria (right and left): superior receiving chambers
- assist with filling the ventricles
- blood enters under low pressure from veins of the body
what is the role of the left and right ventricles
- Ventricles (right and left): inferior discharging chambers
- thick- walled pumps of the heart
- during contraction, blood is propelled into circulation
what is interatrial septum?
this section separates the two atria longitudinally
what is interventricular septum
this section separates the two ventricles longitudinally
what are 3 processes in the heart?
Heart functions as a double pump, pulmonary circulation and systemic circulation
what does the double pump process achieve in the heart?
right side works as the pulmonary circuit pump while left side works as the systemic circuit pump
what do arteries do to blood?
they carry blood away from the heart
what do veins do to blood?
they carry blood towards the heart
what is pulmonary circulation?
blood flows from right side of the heart to the lungs and back to the left side of the heart
in pulmonary circulation, where is blood pumped out of?
right side through the pulmonary trunk, which splits into pulmonary arteries and takes oxygen- poor blood to lungs
*oxygen- rich blood returns to the heart from the lungs via pulmonary veins
what is systemic circulation?
where oxygen- rich blood returned to the left side of the heart is pumped out into the aorta
blood returned to the right atrium via systemic veins, which empty’s blood into the superior or inferior vena cava
where does blood circulate in systemic circulation?
blood circulates to systemic arteries and to all body tissue
(T/F) does the left ventricle have thicker walls because it pumps blood to the body through the systemic circuit
True
what is the role of heart valves?
allow blood to flow in only one direction to prevent back flow
what are the two types of heart valves?
atrioventricular (av) valves and semilunar valves
where is atrioventicular (av) valves located?
between atria and ventricles
where are semilunar valves located?
between ventricle and arteries
when do valves open and close?
in response to pressure changes to the heart
what is the left av and right av valves called?
left av valve: bicuspid (mitral) valve
right av valve: tricuspid valve
when do the atrioventricular (av) valves open and close?
open during heart relaxation, when blood passively fills the chambers
closed during ventricular concentration
where do chordae tendineae anchor?
on the cusps to the walls of the ventricles
(T/F) does blood in the heart chambers nourish the myocardium?
false, the heart has its own nourishing circulatory system
what does the hearts own nourishing circulatory system consist of?
coronary arteries, cardiac veins, and coronary sinus
what are coronary arteries?
arteries that branch form the aorta to supply the heart muscle with oxygenated blood
- on the left: anterior interventricle artery and circumflex artery
- on the right: posterior interventricle artery and marginal artery
what are cardiac veins?
veins that drain the myocardium of blood
what are coronary sinus?
a large vein on the posterior of the heart; receives blood from cardiac veins
*blood empties into the right atrium via the coronary sinus
what is intrinsic conduction of the heart?
cardiac muscle that contracts spontaneously and can occur independently of nerve impulses
(Intrinsic conduction of the heart) how do contractions occur?
in a regular and continuous way
- atrial cells beat 60 times per minute
- ventricular cells beat 20-40 times per minute
** need a unifying control system- the intrinsic conduction system (nodal system)
what are the 2 systems regulate heart activity
- autonomic nervous system
2. intrinsic conduction system (nodal system)
what does the intrinsic conduction system (nodal system) do?
- sets the heart rhythm
- composed of special nervous tissue
- ensures heart muscle depolarisation in on direction (atria to ventricle)
- enforces a heart rate of 75 beats per minute
what are the components of the intrinsic conduction of the heart?
- sinoatrial (sa) node
- atrioventicular (av) node
- atrioventicular (av) bundle
- purkinje fibers
what is the sinoatrial (sa) node
the sa node is located in the right atrium- serves as the hearts pace maker
what is an atrioventricular (av) node?
a node at junction of the atria and ventricles
what is a atrioventricular (av) bundle
bundle of branches that are in the interventricular septum
what are purkinje fibers?
fibers that are spread within the ventricle wall muscles
what is the process of intrinsic conduction system of the heart?
- the sinoatrial node (SA node) starts each heart beat
- impulse spreads through the atria to AV node
- Atria contracts
- At the AV node, the impulse is delayed briefly
- impulse travels through the AV bundle, bundle branches and purkinje fibers
- ventricle contracts; blood is ejected from the heart
what is tachycardia
rapid heart rate, over 100 beats per minute
what is bradycardia
slow heart rate, less than 60 beats per minute
what is systole
contraction of the heart
what is diastole
relaxation of the heart
what is a electrocardiogram (ECG)
recording of electrical activity of the heart
*illustrates what is happening electrically in the atria and ventricles when they depolarise (contract) and relax (repoliarize)
what is a cardiac cycle?
refers to one complete heart beat, in which both atria and ventricles contract and then relax
what is the average heart rate?
approximately 75 beats per minute
what is the cardiac cycle length?
normally 0.8 seconds
what are the 5 stages of a heart beat?
- Atrial diastole (ventricular filling)
- Atrial systole
- Isovolumetric Contraction
- ventricular systole (ejection phase)
- isovolumetric relaxation
describe atrial diastole (ventricular filling)
- heart is relaxed (pressure in the heart is low)
- atrioventicular valves are open
- blood passively flows into the atria and into ventricles
- semilunar valves are closed
describe atrial systole
- ventricles remain in diastole
- atria contracts
- blood is forced into the ventricles to complete ventricular filling
describe isovolumetric contraction
- atrial systole ends; ventricular systole begins
- interventricular pressure rises
- AV valves close to prevent blood back flow into atria
- for a moment, the ventricles are completely closed chambers
describe ventricular systole (ejection phrase)
- ventricles continue to contract
- intraventricular pressure now surpasses the pressure in the manly arteries leaving the heart
- semilunar valves open
- blood is ejected from the ventricles
- atria are relaxed and filling with blood
describe isovolumetric relaxation
- ventricular diastole begins
- pressure in ventricles falls below that in the major arteries
- semilunar valves close to prevent blood back flow into the ventricles
- for another moment, the ventricles are completely closed chambers
- when atrial pressure increases above intraventricular pressure, the AV valves open
describe a lub heart sound
longer, louder heart sound causes by the closing of the AV valves
describe a dub heart sound
short, sharp heart sound caused by the closing of the semilunar valves at the end of the ventricular systole
what is cardiac output (o)?
amount of blood pumped by each side (ventricle) of the heart in 1 min
how do you calculate the cardiac output (o)?
product of stroke volume and heart rate
CO= HR x SV
what is the typical heart rate (hr)
typically 75 beats per minute
what is regulation of stroke volume?
60% of blood in ventricles (about 70ml) is pumped in each heart
venous return is important factor influencing the stretch of heart muscles
what is starlings law of the heart?
the critical factor controlling SV is how much cardiac muscle is stretched, called pre load
the more the cardiac muscle is stretched, the stronger the contraction
what are the 2 factors that influence preload?
- amount of venous return (volume of blood returning to the heart)
- length of time the ventricles are relaxed and filling (determined by heart rate)
what is contractility?
the ability of cardiac muscle tissue to generate tension
what is afterload?
the amount of pressure the ventricles must overdone to eject blood
state 3 factors modifying basic heart rate
- neural (ANS) control
- hormones and ions
- physical factors
describe the neural (ANS) control factor in modifying basic heart rate in detail
- sympathetic nervous system speeds heart rate
- parasympathetic nervous system, primary vagus nerve fibres, slow and steady the heart rat e
describe hormones and ions factor in modifying basic heart rate in detail
- enpinephrine and thyroxine speed heart rate
- excess or lack of calcium, sodium, and potassium ions also modify heart activity
describe the physical factors in modifying basic heart rate in detail
age, gender, exercise and body temperature influence heart rate
what are blood vessels?
form a closed vascular system that transport blood to the tissues and back to the heart
what are arteries and arterioles?
vessels that carry blood away form the heart
what are capillary beds?
vessels that play a role in exchanges between tissue and blood
what are venules and veins?
vessels that return blood toward the heart
how many layers (tunicas) are in the microscopic anatomy of blood vessels?
3 layers in blood vessels (except the capillaries)
what are the 3 layers (tunica) of blood vessels?
- tunica intima- forms a friction, reducing lining
- tunica media
- tunica externa- forms protective outermost covering
what is tunica intima made of ?
endothelium
what is tunica media made of?
smooth muscle and elastic tissue - controlled by sympathetic nervous system
what is tunica externa made of?
mostly fibrous connective tissue- supports and protects the vessel
what are the structural differences in arteries, veins and capillaries?
- arteries have a heavier, stronger, stretchier tunica media than veins to withstand changes in pressure
- veins have a thinner tunica media than artistes and operate under low pressure
- special capillary beds of the mesentery have pre capillary sphincters and a vascular shunt
what happens when precapillary sphincter is open?
blood flows through and exchanges with cells can occur
what happens when precapillary sphincter is closed?
blood flows through the shunt and passes cells in that region
what is the aorta
largest artery in the body
where does the aorta leave form the heart?
the left ventricle
what are the regions of the aorta?
ascending aorta: leaves the left ventricle
aortic arch: arches to the left
thoracic aorta: travels downward through the thorax
abdominal aorta: passes through the diaphragm into the abdominal pelvic cavity
what are vital signs
measurements of arterial pulse, blood pressure, respiratory rate, and body temperature
what is arterial pulse
alternate expansion and recoil of a blood vessel wall (the pressure wave) that occurs as the heart beats
what is blood pressure?
the pressure the blood exerts against the inner walls of the blood vessels
(the force that causes blood to continue to flow in the blood vessels)
what happens when the ventricles contract in the blood pressure gradient
blood is forced into elastic arteries close to the heart, blood flows along a pressure gradient (from high to low pressure)
(T/F) pressure decreases in blood vessels as distance from the heart increases in blood pressure gradient
true
(T/F) pressure is not high in the arteries, lower in the capillaries, and lowest in the veins
false, pressure is high
how is blood pressure measured
by measuring 2 arterial blood pressures
- systolic and diastolic
what is systolic?
pressure in the arteries at the ventricular contraction
what is diastolic?
pressure when ventricles relax
how is blood pressure expressed?
systolic pressure over diastolic pressure in millimetres of mercury (mm Hg)
what is the normal systolic pressure range?
110 to 140 mm Hg
what is the normal diastolic pressure?
70 to 80 mm Hg
what is the effects of various factors on blood pressure?
- arterial blood pressure (bp) is directly related to cardiac output and peripheral resistance
- neural effects: the autonomic nervous system
- renal factors: the kidneys
- temperature
- chemicals
- diet
what are the neural effects on blood pressure
- parasympathetic nervous system has little to no effect on blood pressure
- sympathetic nervous system promotes vasoconstriction (narrowing of vessels), which increases blood pressure
what is the renal factors on blood pressure?
- kidneys regulate blood pressure by alternating blood volume
- if blood pressure is too high, the kidneys release water in the urine
- if blood pressure is too low, the kidneys release renin to trigger formation of angiotensin II, a vasoconstrictor
- Angiotensin II stimulates release of aldosterono which enhances sodium (and water) reabsorption by kidneys
what is the temperature effects on blood pressure
- heat has a vasodilating effect
- cold has a vasconstricting effect
what are the chemical effects on blood pressure?
various substances can cause increase or decrease in BP
- epinephrine increases heart rate and blood pressure
what is the diet effect on blood pressure?
commonly believed that a diet low in salt, saturated fats, and cholesterol prevents hypertension (high blood pressure)
what is found between cells
interstitial fluid (tissue fluid)
how do substances move to and from to and from the blood and tissue cells?
through walls- exchange is due to concentration gradient
what are the various routes substances take entering or leaving the blood
- direct diffusion through membranes
- diffusion through intercellular clefts (goad between cells in the capillary walls)
- diffusion through pores of fenestrated capillaries
- transport via vesicles
what is fluid movement at capillary beds?
fluid movement out of or into a capillary depends on the difference between the 2 pressures
what are the 2 pressures in fluid movement at capillary beds
- blood pressure (forces fluid and solutes out of capillaries)
- osmotic pressure (draws fluid into capillaries)
(T/F) blood pressure is higher than osmotic pressure at the arterial end of the capillary bed
true
(T/F) blood pressure is higher than osmotic pressure at the venous end of the capillary bed false
false
