Review set 6 Flashcards
Atria
receiving chambers (pump blood into ventricles at the SAME time)
Ventricles
pumping chambers (highly muscular, left ventricle = thickest walls) - pump blood OUT of heart into arteries at the SAME time
Coronary arteries
supply oxygen and glucose to heart muscle (aerobic respiration) for pumping action – if a coronary artery is blocked, a heart attack may occur
Flow of blood into, through, and out of the heart
- Vena cava delivers deoxygenated from body to right atrium
- Blood passes through right atrioventricular (AV) valve into right ventricle, which pumps it through the right semilunar valve into the pulmonary arteries which take it to the lungs to be oxygenated (pulmonary circulation)
- Oxygenated blood returns to the left atrium of the heart through the pulmonary veins
- Blood passes through left AV valve into left ventricle, which pumps it through left semilunar valve into the aorta which takes it to the body (systemic circulation)
Note: Heart valves (and valves in veins) maintain one-way blood flow!
a. Atrial contraction builds atrial pressure and opens AV valves (blood flows into ventricles)
b. Ventricle contraction closes AV valves and opens semilunar valves (blood flows into arteries – as
arterial pressure increases, semilunar valves close)
Diagram the heart and check it from ms. manns slides
how do you feel?
Myogenic
signal for cardiac contraction arises in heart muscle itself
SA (sinoatrial) node works/process/ PACE MAKING
- SA (sinoatrial) node (pacemaker – specialized collection of nerves) in right atrium generates impulse, stimulating atria to contract (top to bottom)
- Impulse reaches junction between atria and ventricles and activates AV (atrioventricular) node
- AV node waits ~0.1 sec then sends signals causing ventricles to contract (from the bottom – apex of heart – up, so that blood is pushed up and out of ventricles to arteries)
*This sequence of events ensures delay
between atrial and ventricular contraction
(maximizing blood flow
The RATE at which this sequence of events happens is your
RESTING( myogenic) heart rate
SA node is controlled by the
Medulla, Adrenal gland (on top of kidney) can also speed up heart rate by releasing adrenaline into bloodstream
IF CO2 levels rise what does the medulla do?
medulla sends signal to SA node through cardiac nerve to cause SA node to fire more frequently (increase heart rate)
As CO2 levels decrease what does the medulla do
medulla sends signal to SA node through vagus nerve to cause SA node to fire less frequently (decreasing heart rate/ returning to normal/ resting)
The Cardiac Cycle is
the series of events that take place in the heart over the course of ONE HEARTBEAT
Cardiac Cycle
Involves Systole (contraction – higher blood pressure reading) and Diastole (relaxation - lower blood pressure reading)
a. Blood flows freely from atria to ventricles (diastole) until ventricles almost full (~70%). This occurs due to slightly higher pressure in the atria than in ventricles
b. SA node fires, causing atria to contract (atrial systole), which causes higher pressure in atria in order to fill ventricles to maximum capacity (both atria contract at same time)
Note: atria have relatively thin walls, so the pressure produced by atrial systole is not very high, but because most of the volume of blood has already passively moved into each ventricle, atrial systole does not need to generate much pressure.
c. AV node is activated, “waits” for 0.1 sec, then sends signals to cause ventricles to contract (ventricular systole) - from bottom to top
d. Increased ventricular pressure causes AV valves to close (between atria and ventricles) causing first heart sound (“lub”) - the closing of these valves prevents backflow of any blood to the atrium.
e. High ventricular pressure overcomes the high pressures in arteries, causing semilunar valves to open and blood flows away from heart.
f. Pressure increases in the pulmonary arteries and aorta and decreases in the ventricles, which causes the semilunar valves to close, causing the second heart sound = “dub”)
g. Blood flows freely into the atria (atrial diastole)
h. Pressure in ventricles drops below pressure in atria (ventricular diastole), allowing AV valves to reopen and cardiac cycle starts again
Arteries, Pressure, Diameter and Vessel Wall thickness, Vessel Wall Features, Additional features
Pressure: High
Diameter and vessel wall thickness: Narrow Lumen surrounded by a thick wall (3 layers)
Vessel wall features: 3 layers; middle layer of wall is thick layer of smooth muscle/elastic fibers to maintain pressure between heart beats- high elasticity allows for elastic recoil to help push blood.
Additional features: Outer layer of wall contains collagen to prevent artery from rupturing under high pressure (no valves)
Capillaries, Pressure, Diameter and Vessel Wall thickness, Vessel Wall Features, Additional features
Pressure: Low
Diameter and Vessel Wall thickness: Narrow diameter with walls only one cell thick (decrease diffusion distance/ increase rate)
Vessel Wall Features: Some Contain pores/ fenestrations
Additional features: Involved in material and gas exchange between blood and tissues, so narrow to increase SA/V ratio for diffusion
Veins, Pressure, Diameter and Vessel Wall thickness, Vessel Wall Features, Additional features
Pressure: Low
Diameter and Vessel Wall thickness: Wide lumen (low pressure decrease resistance and increase blood flow) surrounded by a thin wall
Vessel Wall Features: 3 layers; thin walls because blood not traveling in pulses less muscle than arteries easier to compress and misshape
Additional features: Contain valves to prevent pooling of blood and maintain one way blood flow
What is blood composed of?
is a TISSUE, composed of plasma (fluid ~55%), erythrocytes (RBC’s ~45%), leucocytes (WBC’s = phagocytes – nonspecific immunity, and lymphocytes – specific immunity) and platelets (less than 1% for WBC’s + platelets)
What does blood transport?
nutrients (glucose, lipoproteins), oxygen, carbon dioxide, hormones, antibodies, urea and heat.
Atherosclerosis
build-up of plaque deposits (fats, cholesterol, cell debris etc.) in arteries
Atherosclerosis can cause partial or complete occlusions; plaque deposits are so substantial that vessel can no longer
supply even a minimally healthy amount of blood to the tissue.
Plaque deposits cause increased blood pressure (narrower lumen) in arteries, which causes chronic inflammation (swelling) and damages endothelial wall
Chronic inflammation leads to lipid, cell debris, calcium and cholesterol accumulation (rough/ hardened walls)
Fatty deposits (atheromas) develop in the arteries, narrowing the lumen (stenosis) and reducing elasticity of the arterial wall (more prone to rupture b/c cannot stretch as well under pressure)
If plaques break off of original deposits, they damage artery walls and cause clots to form (called a thrombosis)
If a thrombosis develops in a coronary artery what occurs?
coronary thrombosis) it can reduce blood flow/ oxygen and lead to a heart attack (an acute myocardial infarction)
risk factors for coronary heart disease
eggsoda
Exercise(lack of) Genetics Gender (male lower estrogen) Smoking Obesity Diet Age
Respiration
transport of oxygen to cells producing energy;
Respirations 3 processes
- Ventilation: Exchange of air between lungs and atmosphere (through breathing)
- Gas exchange: Exchange of oxygen and carbon dioxide in alveoli (lungs) and in bloodstream (by diffusion)
- Cell Respiration: Release of ATP from organic molecules (enhanced by oxygen – aerobic respiration)
Ventilation
Exchange of air between lungs and atmosphere (through breathing)
Gas exchange
Exchange of oxygen and carbon dioxide in alveoli (lungs) and in bloodstream (by diffusion)
