Kin 163- Ch 6. Cardiovascular System
Intrinsic control of the heart allows what type of rhythm? What 2 nodes play a role in Intrinsic Control? What other structures play a role in intrinsic control?
- Autorhymaticity= the ability of the cardiac muscle to start its own impulse for contraction at regular intervals -Sinoatrial Node + Atrioventricular Node SA node: Is the "Pacemaker" of cardiac contraction. It makes up specialized nervous tissue INITIATES Atrial Systole AV Node: delays the impulse by 1/10 of a second This allows the Atria to contract before the ventricles -Purkinje fibres: these fibres quickly spread the impulse so the ventricles contract in synchronization
What do the following mean: -horizontal length of wave -height of wave -short wave vs large wave
- horizontal: time - height: amount of electrical activity and amount of cardiac muscle contraction and relaxation -short: it is a rapid contraction or relaxation
A client you have suffers from hypertension and asks why aerobic training makes the work of their heart easier at rest? How do you explain this to your client
-Aerobic training decreases resting BP -Decreased resting BP makes it easier for your left ventricle to pump blood -It develops less force to eject blood
The heart is encased in what membranous structure? What is it made up of (the different names for the layers). What fluid is secreted and where does it come from? What is the main function of the serous fluid?
-It is encased in the PERICARDIUM - 4 layers: 1) Fibrous pericardium 2) Parietal layer of serous pericardium 3) Pericardial cavity- has the serous fluid 4. EPICARDIUM- Visceral layer of serous pericardium The serous fluid is secreted by the epicardium into the pericardial cavity The serous fluid is secreted because it reduces friction on the heart wall.
For Extrinsic control, what structures influence the heart rate?
-Parasympathetic and Sympathetic Branches of the Nervous System (Spinal Cord) 1. Parasympathetic Nerve Fibres: -DECREASE HEART RATE -Acetylcholine released at SA + AV Nodes 2. Sympathetic Nerve Fibres: -INCREASE HEART RATE -Nonrepinephrine released at SA + AV nodes 3. Endocrine Glands: -Secrete the nonrepinephrine from adrenal gland which INCREASE heart rate "flight or fight" 4. If nonrepinephrine is released at a slow rate, "BRADYCARDIA" occurs. The heart rate is slowed down.
What is ejection fraction?
-Ratio of EDV : SV -EDV (amount of blood able to pump out of left ventricle)
Name the receiving chambers of the heart
-Small, thin walled, contribute little to the population of blood 1. Right Atrium receives deoxy blood from inferior and superior vena cava 2. Left atrium receives oxy blood from lungs by left pulmonary vein
Discuss mechanisms of increased venous return and oxygen delivery during exercise
-pressure in the veins is LOW compared to arteries -have a low pressure gradient - veins store ~65% of blood volume so are storage reservoirs of capacitance blood vessels
arterial-venous oxygen difference (a-v O2 diff)
1) Amt of O2 per 100ml of arterial blood "entering" a tissue MINUS amt of O2 per 100ml of venous blood "leaving" a tissue >(amt of O2 arterial blood entering tissue - amount of O2 venous blood leaving tissue) 2) During exercise, more O2 is taken out of blood = Increases a-vO2 diff 3)Referred as diff in blood leaving LV, and amt of blood returning to right atrium A) At rest: ~5ml O2 per 100 ml of blood B) During exercise: ~15ml O2 per 100 ml of blood
Explain how oxygen delivery to muscle is increased during physical activity
1) Venoconstriction -constricting of veins by sympathetic stimulation -only effective in tissues other than skeletal muscle, not enough sympathetic stimulation in skeletal muscle 2) Muscle Pump is rhythmic muscle contractions propelling blood back to the heart (venous return to heart) -muscle squeezes together during contraction and forces blood back to heart, 1 way valves in the veins prevent backflow 3) Respiratory Pump -changes in intrathoracic and intraabdominal pressure during expiration and inspiration, this allows blood in those cavities towards the heart a) Inspiration= intrathoracic pressure decreases, intraabdominal pressure increases b)Exhalation- intrathoracic pressure increases, intraabdominal pressure decreases
functions of blood
1) deliver essential substances to tissue such as oxygen and nutrients 2) remove metabolic by-products from tissue such as carbon dioxide and lactate
What 2 structures separate the atria and ventricles?
1. Atria- Interatrial septum 2. Ventricles- Interventricular septum
Name the 2 major type of valves, give 2 examples for each
1. Atrioventricular Valves- are between atrium and ventricle ex: Tricuspid and Bicuspid valve 2. Semilunar valves - are between the ventricles and major arteries ex: Aortic semilunar and Pulmonary semilunar
Can you think of any examples that would increase or decrease blood flow
1. Blood Viscosity Increased viscosity= increased resistance= blood flow decreases 2. Total blood vessel length longer the vessel= greater the resistance= blood flow decreases 3. *Blood vessel diameter greatest influence on resistance radius increases, resistance decreases, blood flow increases LAMINANT FLOW if radius decreases, resistance increaeses, blood flow decreases TURBULENT FLOW
Which arteries supply blood to the heart? What type of blood is supplied? Is this blood at high or low pressure?
1. Coronary arteries branch off the aorta and supply the blood to the heart (myocardium) 2. Oxygenated blood is supplied 3. Blood pressure is highest in the aorta, THEREFORE it is very high in the coronary arteries supplying the heart.
How can someone increase Q (Cardiac Output)?
1. HR affects Q Directly 2. Stroke Volume= EDV(ml)- ESV(ml) EDV: End Diastolic Volume Is the Blood in ventricles at end of diastole If EDV increases, SV increases ESV: End Systolic Volume Blood in ventricles at end of systole A SO: increase blood in ventricles after diastole (relaxation) OR decrease blood in ventricles after systole (contraction) or B: Frank Starling Mechanism -Increased venous return stretches/preloads the ventricle this then.... - Increases contractile force of the ventricle which then.... - Decreases End Systolic Volume - Increases Stroke Volume
Describe the various waves, intervals and segments in a electrocardiography reading 1. P Wave 2. QRS Complex 3. T Wave 4. P-R Interval 5. S-T segment 6. Q-T Interval
1. P Wave- atrial contracts 2. QRS Complex- ventricle contraction 3. T Wave- ventricle relaxes 4. P-R Interval- atrial contraction to ventricular contraction 5. S-T segment- ventricular contraction to relaxation 6. Q-T Interval- Beginning of ventricular depolarization through ventricular repolarization
Describe the composition of blood
1. Plasma - can decrease ~10% during exercise due to sweat - can increase by 10% through adaptation to endurance training - 90% water, 7% plasma proteins, 3% other 2. Hematocrit -99% red blood cells -1 % other a) Red Blood Cells -transport O2 via hemoglobin -produced in bone marrow -nucleus removed to stop reproduction -lifespan= 4 months -destruction & production are balanced i. Hemoglobin: consist of protein (globin) & and iron containing pigment (heme) necessary for binding of O2
3 characteristics of Myocardial muscle fibres ...
1. high mitochondrial density 2. extensive capillary network 3. aerobic energy for contraction
How much blood is typically pumped out of the heart?
60% of the "blood that is available" is pumped out of heart
Increase in Heart Relaxation (EDV) & Decrease in Heart Contraction (ESV) leads to
=Increased Stroke Volume =Increased Cardiac Output during activity
Increase in pressure difference =
=increase in blood flow
What is the Frank-Starling mechanism?
A greater EDV will increase ventricle contractile strength leading to increase stroke volume Because: -myocardium will be stretched more because there is a greater volume. -Sacromeres in myocardium will increase in length -results in an increased sensitivity to Ca2+ =A STRONGER CONTRACTION
If both training and hypertension increase the size of the left ventricular wall thickness, why would hypertension be considered bad?
A thickened heart ventricle wall increases risk of heart attack, failure and cardiac death. Hypertension= high blood pressure therefore heart works hard to pump blood to rest of body
Describe the function of the AV Valves
AV Valves Open 1) The atrium is filled with blood returning to the heart. This causes pressure against the AV Valves forcing the AV Valve to open. 2) As the ventricles fill, the AV Valves will stay open. The atria will further contract forcing even more blood into the ventricles AV Valves Close 1) The ventricles contract forcing blood against the AV Valve cusps. Therefore the AV Valves close. 2) *** Papillary muscles contract and chordae tendinae tighten, this prevents the valve flaps from everting into the atria
How do the right and left coronary arteries communicate?
Anastomosis Anastomosis is the intercommunication between the 2 arteries. It makes sure blood is flowing to the area even if one artery becomes blocked.
What is the largest artery in the body?
Aorta
Name the parts of the heart
Arterial Blood -left atrium -bicuspid valve -left ventricle - aortic semilunar valve Venous blood -Right atrium -tricuspid valve -right ventricle -pulmonary semilunar valve
What is the cardiac cycle?
Constant series of contractions and relaxations of the chambers. Diastole and Systole Atrial Diastole, Atrial Systole, Ventricle Systole, Ventricle Diastole 2 types of controls: Intrinsic Control and Extrinsic: Intrinsic: Autorhythmaticity, SA Nodes, AV Nodes, Purkinje Fibres Extrinsic: Parasympathetic Nerve Fibres, Sympathetic Nerve Fibres, Acetylycholine, Nonrepinephrine, Endocrine glands, adrenal glands, Bradycardia
Factors affecting redistribution of blood Vasoconstriction
Decrease in radius of blood vessels more resistance to blood flow forcing blood flow to other tissues
Describe oxygen delivery to tissue
Depends on: 1. amount of O2 tissue takes out of blood flowing by it 2. amount of blood flowing by the tissue Constant at rest During exercise: 1. O2 taken from blood is increased by ACTIVE muscle 2. Blood delivered to active muscle is increased
Endurance training increases EDV. How does this effect SV and HR during training.
EDV- amount of blood that is able pump out of left ventricle If EDV increases during endurance training, HR increases SV increases
What is the equation for Ejection Fraction?
EF= Blood being pumped out of heart / amount of blood available to be pumped out of left ventricle EF= SV/EDV
Distinguish between cardiovascular training adaptations due to endurance and strength training
Endurance -decrease in BP -Increase in SV >>due to plasma at first >>increased LV filling >>increase in LV hypertrophy Strength/Resistance: -increase in LV hypertrophy >>Q is maintained against increased BP -little to no increase in LV filling
Left ventricle adaptation to training Endurance Training: Strength Training:
Endurance Training: -Increase in EDV (blood filling) -Increase in wall thickness Strength Training: - increase is L.V. mass is due to increase in wall thickness
T/F Coronary, branches only to the right side of the heart
False: Branches to both right and left sides. Left Coronary Artery Right Coronary Artery
Blood flows from areas of _________ pressure to _________ pressure.
High to Low
Would the shape of the ECG complex change during exercise in a healthy heart?
In a healthy heart the QRS complex will experience minimal shortening, but will increase in height a little bit.
Factors affecting redistribution of blood: Vasodilation
Increase in radius of blood vessels Less resistance to flow, increase in blood flow to tissue
When training, Stroke Volume Increases, during what type of training does EDV increase with?
Increases during endurance training
Describe cardiac output in trained and untrained people
It is the same but the components are little different Trained= Low HR, High SV Untrained is the opposite.
What happens to the R-R Interval during exercise
It will decrease due to the increase in heart rate (Remember R-R interval is the time between the beats)
When starting aerobic training or weight training the following occurs to the plasma volume
It will reduce because there is an increase in BP which is forcing fluid out of blood not the cellular components Hemoconcentration will occur where blood plasma reduces and there is then an increase in hematocrit (formed elements such as RBCs)
Which ventricle produces greater force? why? what would need to change regarding the coronary circulation?
Left ventricle -it is thicker and muscular because it pumps blood at a higher pressure -pumps to the rest of the body vs the right ventricle pumps to the lungs -the left ventricle pumps to the aorta which pumps the coronary circuit, therefor pressure in the coronary arteries is VERY high.
What would an increase in EF signify? What would a decrease in EF signify?
Low E.F. can lead to heart failure/ cardiomyopathy High E.F hypertrophic cardiomyopathy.
What is the average amount of blood pumped/min by the heart? In men? In Women?
Men: 72 bpm x 70ml = 5L/min Women: 75 bpm x 60ml= 4.5 L/min
The bicuspid valve is also known as the _____ valve
Mitral
Diagnostic tests using ECG, a depression of the ST segment indicates what?
Myocardial ischemia When there is decreased blood flow resulting in insufficient oxygen delivery to the myocardium muscle.
What is the cardiac muscle called? Main function?
Myocardium -to contract and generate force -initiates impulse (autorhythmaticity) -has intercalated discs- leaks in membrane, the discs separate cardiac muscle fibres allowing impulse to spread and contraction to occur. -syncytial contraction- is when the myocardial muscle fibres contract simultaneously
Aerobic and weight(strength) training can reduce resting BP in both ________________ and ___________________ individuals
Normotensive & Hypertensive individuals
Factors affecting redistribution of blood
Parallel Circuitry, vasodilation, vasoconstriction, precapillary sphincters
Acute effect on weight training causes a ___________ of plasma volume by ____-____%.
Plasma volume decreases by 0-22%
Over time prolonged ENDURANCE exercise will result in plasma volume __________ by____-____%
Plasma volume decreases by 10-20%
Chronic effects of longe term endurance training on -plasma volume -EDV,SQ, Q -Blood transport, performance, temperature
Plasma volume increases 10-20% Increases EDV, SV, Q Improved blood transport & performance Temperature regulated
Describe the electrical events in the heart in relationship to pressure in the left ventricle, the volume of blood in the left ventricle and the position of the heart valves. QRS Wave
Pressure: High Vol of Blood: Ventricle is filled with blood and will push it through the pulmonary trunk Position of Heart Valves: Bicuspid Mitral Valve Closed Aortic Semilunar Valve Open
Describe the electrical events in the heart in relationship to pressure in the left ventricle, the volume of blood in the left ventricle and the position of the heart valves. T Wave
Pressure: Low Vol of Blood: ventricle empty Position of Heart Valves: Bicuspid Mitral Valve closed Aortic Semilunar Valve Closed
Describe the electrical events in the heart in relationship to pressure in the left ventricle, the volume of blood in the left ventricle and the position of the heart valves. P Wave
Pressure: Low to High Volume of Blood: Increasing as atrial is emptying out Position of Heart Valve: Bicuspid Mitral valve: Open Aortic Semilunar Valve Closed
Identify factors contributing to cardiac output
Q= Amount of blood pumped per minute by heart (L/min or mL/min) SV= Amount of blood pumped per contraction of the ventricles (Stroke Volume) HR- Heart Rate (bpm)
What is the equation for finding Q (amount of blood pumped per minute by heart)?
Q= HR(bpm) x SV(ml)
Describe how the following factors are altered during exercise: Q, a-vO2 diff
Q= increases linearly a-vO2= increases linearly
What is rate of flow inversely proportional to
Resistance as resistance goes up, rate of (blood) flow goes down
Describe the function of Semilunar valves
Semilunar Open - As ventricles contract, this increases intraventricular pressure forcing blood up against the semilunar valves. Therefore the Semilunar valves open, Semilunar Close -As the ventricles relax, and intraventricular pressure falls, blood flows back from the arteries, this fills the cusps of the semilunar valves, and forces them to close.
Extrinsic control of the heart
Structures that influence heartrate are not part of the heart but part of the CNS.
Name the 2 main phases of the cardiac cycle
Systole is the contraction phase meaning blood is pumped out of chamber Diastole is the relaxation phase, blood filling chamber
Define Systolic BP and Diastolic BP What is typical BP? Where is it usually measured? Why is it beneficial to have low pressure at capillaries
Systolic BP: Highest pressure occuring during systole Diastolic BP: Lowest pressure occuring during diastole Typical BP is 120/80 mmHg (Systole/Diastole) Measured at brachial artery Low pressure at capillaries allows for exchange of gases and nutrients.
Exercise causes an increase in BP- why?
Systolic pressure rises, therefore your left ventricle is pumping faster because your body is in demand for faster oxygen exchange in order to keep performing at the level that it is currently at.
Describe redistribution of blood flow during exercise (What else requires O2?)
The skeletal muscle at rest = ~15-20% of Q max exercise= ~80-85% of Q Rest (5000ml): Heart- 4% 200ml Skin- 6% 300ml Exercise (25000ml): Heart- 4% (1000ml) Skin- 2% (600ml) Brain 4% (900ml)
Outline the basic structure and function of the entire cardiovascular system
There are 2 different Circuits 1. Pulmonary Circuit 2. Systemic Circuit 1. DEOXY BLOOD/ VENOUS BLOOD Right atrium Right ventricle Pulmonary Arteries Capillary Beds of lungs (Arterial Blood) Pulmonary Veins Left Atrium Left Ventricle The pulmonary circuit is primarily made up of venous blood and is exchanged for arterial blood at the capillary beds of lungs, it delivers deoxygenated blood from the right atrium to the right ventricle up to the the pulmonary arterires exchanges at the capillary beds of the lungs, oxygenated blood is then delivered through the pulmonary veins and into the left atrium and left ventricle. 2. OXY BLOOD/ARTERIAL BLOOD Arterial Blood from the lungs Left Atrium Left Ventricle Aorta and branches Capillary beds of all body tissues (Venous Blood) Superior and Inferior Vena Cava Right Atrium Right Ventricle The Systemic Circuit primarily plays a role in exchanging oxygenated blood (arterial blood) in the capillary beds of the body for deoxygenated blood (venous blood)
Why does EDV increase with training?
There is an increase in blood plasma volume Increases filling and therefore force of contraction by Frank-Starling mechanism
Describe the Cardiac Wall Thickness.
Thick! The thicker it is, the greater the force produced
main function of the heart valves? When do they know to open and close?
To pump blood in one direction through the heart. They prevent backflow They open and close in response to pressure changes
Fick equation
VO2 = Q x a-vO2 difference Measure of oxygen consumption at WHOLE BODY LEVEL - Increasing either "Q" or "a-vO2 diff" OR both = increase VO2 for the body Q--> increases blood flow to working tissues a-vO2 diff--> increase in O2 delivery to working tussue
What happens during a) Atrial Diastole b) Atrial Systole c) Ventricle Systole d) Ventricle Diastole
a) Atrial Diastole- the heart is relaxed, and the atria is filling up with blood coming from the superior and inferior vena cava b) Atrial Systole- atria is contracted, av valve open, blood flows to ventricles c) Ventricular Systole- ventricle contracted, atroventricular valves close, and semi lunar valves open, blood goes to arteries d) Ventricular Diastole- all heart muscles are relaxed, all heart valves closed, blood returns to atria
Describe vessel radius control: a) Extrinsic Control b) Intrinsic Control
a) Of Vascoconstriction and Vasodilation is based on sympathetic neural stimulation -> Norepinephrine: Vasoconstriction or peripheral blood vessels --> Epinephrine: Vasoconstriction & Vasodilation -Vasodilation to skeletal muscles -Vasoconstriction to inactive tissue(intestines, liver, kidneys) b) vasoconstriction and vasodilation changes within skeletal muscle during exercise stimulates smooth muscle chemoreceptors located in the precapillary sphincters- increases vasodilation >Autoregulation: -stimulation of smooth muscle chemoreceptors in precapillary sphincters increase vasodilation and vasoconstriction -->INFLUENCED BY O2, CO2, H+, Lactate, etc -Vasodilation balanced with sympathetic stimulation to ensure blood flow to heart and brain
How is a-vO2 difference related to oxygen consumption
a-vO2 diff increases as oxygen consumption increases
Arteries are _____ pressure, veins are _______ pressure
arteries= High veins= Low
Factors affecting redistribution of blood: Paralell Circuitry
blood flows to all organs without the need to pass through another tissue or organ first
blood flow is equal to
change in pressure/resistance to flow
What is Intrinsic control of the heart?
control of rate of heartbeat by the SA and AV nodes
capacitance increases with
endurance training
What affects cardiac output?
heart rate and stroke volume
Name the discharging chambers of the heart
make up most of the volume of heart thicker walls because the atria push blood through at higher pressures 1. Right ventricle pumps deoxy blood to pulmonary circuit 2. Left ventricle pumps oxy blood into aorta (largest artery in body) (systemic circuit/peripheral circuit)
What is a electrocardiogram?
measures movement of ions (electrical impulses) during muscle contraction and relaxation -electrical activity happens at same time with contraction and relaxation of heart chambers
Factors affecting redistribution of blood Precapillary Sphincters
muscular rings at entrance of capillary bed, will increase or decrease diameter or vessel react to local changes by constricting or relaxing therefore controls blood flow to tissues
Rate of flow is proportional to
pressure differences between 2 ends of a blood vessel OR 2 chambers within cardiovascular system
Capacitance increases, decreases and no change seen with
resistance training alone