The Transport System: Topic 6.2 and D.4 Flashcards
Label the structures of the human heart (and know the function of each).
Superior (top) and inferior (bottom) vena cava, right atrium, right ventricle, pulmonary artery, pulmonary vein, left atrium, left ventricle, aorta
Atrio-ventricular valves between atria and ventricles
Semilunar valves between ventricles and pulmonary artery/aorta
Right/left for the person whose heart it is (so looking at a diagram right and left will be switched from you!)
FUNCTIONS:
Valves (Semilunar and AV): Prevent backflow/ maintain a one-way flow of blood
Atria: receive blood from the body (veins) and pump it into the ventricles
Ventricles: receive blood from the atria and pump it out of the heart into arteries (because they are the “pumping chambers” of the heart, the ventricles have thicker muscular walls to generate higher pressures than atria!
Superior/Inferior Vena Cava: brings deoxygenated blood from the body to the right atrium
Pulmonary Artery: brings deoxygenated blood from the right ventricle to the lungs
Pulmonary Vein: brings oxygenated blood from the lungs to the left atrium
Aorta: brings (oxygenated) blood from the left ventricle to the rest of the body
Outline the flow of blood to, through, and from the heart (including pulmonary and systemic circulation, and the benefits of the double circulation).
- Vena cavae (veins - superior and inferior) deliver deoxygenated blood from the body to the right atrium
- The right atrium pumps deoxygenated blood through the right atrioventricular valve = AV valve (tricuspid valve) into the right ventricle
- The right ventricle pumps deoxygenated blood out of the heart through the right semilunar valve (pulmonary valve) into the pulmonary arteries (right and left), which carry it to the lungs (to exchange CO2 for O2)
- Oxygenated blood from the lungs returns to the heart through the pulmonary veins (right and left) and is delivered to the left atrium
- The left atrium pumps oxygenated blood through the left AV valve (bicuspid/ mitral valve) into the left ventricle
- The left ventricle pumps oxygenated blood out of the heart through the left semilunar valve (aortic valve)into the aorta, which carries it to the body
Note: Blood flow from the heart (right side) to the lungs (through the pulmonary arteries) is called your pulmonary circulation (deoxygenated blood pumped to lungs to release CO2 and pick up O2), and blood flow from the heart (left side) to your body (through the aorta) is called your systemic circulation (oxygenated blood to all cells in body).
This double circulation is beneficial because it ensures that we are giving our tissues and muscles blood full of oxygen, instead of a mixture of oxygenated and deoxygenated blood.
Describe the myogenic, autonomic (medulla), and endocrine (adrenal gland) control of the heartbeat.
MYOGENIC: signal for cardiac contraction arises in the heart itself (cardiac muscle can contract and relax on its own without any control by the nervous system!)
- SA (SINOATRIAL) NODE (aka: the pacemaker – specialized collection of muscle cells/ nerves) in upper right atrium, starts the heartbeat by generating an impulse (action potential), which travels through the thin walls of the atria, stimulating atria to contract (top to bottom)
- Impulse reaches AV (atrioventricular) node (in lower wall of right atrium/ septum between atria
- AV node “waits”/ delays for approximately 0.1 sec, then sends signals (action potentials) down septum of ventricles (Bundle of His) to apex, through conducting fibers (Purkinje fibers). Impulse spreads to cardiac muscles through gap junctions in intercalated discs and this causes ventricles to contract (from the bottom – apex of heart – up, so that blood is pushed up and out of ventricles to arteries)
During periods of increased body activity (exercise etc.), heart rate needs to increase above resting/ myogenic rate (as cells need more oxygen for cellular respiration, and there is more CO2 that accumulates in the bloodstream = ↓ pH, and the body needs to get rid of it)
MEDULLA OBLONGATA monitors/chemically detects CO2 levels/ pH in the blood
* sends a signal through the CARDIAC NERVE to release noradrenaline/ norepinephrine, which causes SA node to fire more frequently – speeds up heart rate/ rate of contraction
* sends a signal through the VAGUS NERVE to release acetylcholine, which causes SA node to fire less frequently – slows down heart rate/ rate of contraction, returning heart to resting/myogenic rate
The ADRENAL GLANDS (part of the endocrine system - on top of kidneys) can also speed up heart rate/ force of contraction by releasing the hormone adrenaline (epinephrine) into the bloodstream (stress, excitement, “fight or flight”)
Describe the role/ functions of valves in the human heart.
Prevent backflow/ maintain a one-way flow of blood
- AV valves prevent backflow from
ventricles to atria - Semilunar valves prevent backflow from
arteries to ventricles
Cause pressure changes in the heart chambers and control the timing of blood flow in the cardiac cycle (as they open and close)
- Open valves allow blood to flow
- Closed valves allow chambers of the heart to fill with blood
- Closed valves allow pressure to rise rapidly in chambers of heart
- Closed AV valves allow pressure to rise in atria, and AV valves open when atrial pressure is greater than ventricular pressure
- Closed semilunar valves allow ventricular pressure to rise, and AV valves close when ventricular pressure is greater than atrial pressure, and then semilunar valves open when ventricular pressure is higher than arterial pressure (as ventricles contract)
Explain the events of the cardiac cycle (including systole and diastole of the atria and ventricles, the roles of the SA and AV nodes/ bundle of His/ purkinje fibers, the reasons for a delay between atrial and ventricular contractions, and the heart sounds).
Cardiac cycle: the series of events that take place in the heart over the duration of one heartbeat/ the series of events from the beginning of one heartbeat to the next.
Note that the “heart sounds” are produced when VALVES close!
When there is contraction in any chamber of the heart, the contraction is called SYSTOLE (higher blood pressure reading), and when any chamber of the heart is at rest/ chambers filling with blood (not contracting) this is called DIASTOLE (lower blood pressure reading)
- Blood flows freely from (BOTH) atria to ventricles (diastole) until ventricles almost full (~70%). This occurs due to slightly higher pressure in the atria than in ventricle
- SA node fires, causing BOTH atria to contract (atrial systole) = 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, and because most of the volume of blood has already passively moved into each ventricle, atrial systole does not need to generate much pressure.
- AV node is activated, “waits” for 0.1 sec, then sends signals to Bundle of His, which sends signals to Purkinje fibers that cause BOTH ventricles to contract (ventricular systole) - from bottom to top
- 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 atria
- A very large increase in ventricular pressure (ventricles have very thick walls to generate high enough pressure to overcome the high pressures in the arteries that take blood away from the heart) causes semilunar valves to open and blood flows away from heart (aorta and pulmonary arteries). Pressure increases in the pulmonary arteries and aorta and decreases in the ventricles, which causes semilunar valves to close, causing the second heart sound = “dub”
- All valves are closed and blood flows freely into both atria again (atrial diastole)
- Pressure in ventricles drops below pressure in atria (ventricular diastole), AV valves reopen and cardiac cycle starts again (entire heart in diastole)
Identify (on a graph) and outline pressure and volume changes and sounds in the left atrium, left ventricle, and aorta during systole and diastole.
Look at The Transport System: The Heart notes (slides 15-16) - https://docs.google.com/presentation/d/1zHpYr-ZhxgMsBOeyu50neIu0tGjb0Ob6X1ahIpLss40/edit#slide=id.gf08b72e9ee_0_5
From top to bottom lines are:
Aortic pressure: top line that meets curve and goes with it but starts and ends higher
Atrial pressure: line along the bottom of the curve
Ventricular pressure: the main curve that starts alongside atrial pressure but goes way up
Ventricular volume: under all of those
Semilunar valves open when aortic pressure jumps and close when it returns to starting line
AV valves close when ventricular pressure jumps and open when it returns to starting line
Explain how the structure of cardiac muscle cells is adapted to their function.
- Heart (cardiac) muscle tissue is composed of cardiac muscle cells, which can contract/ transmit electrical signals without stimulation from nervous system (myogenic)
- Cardiac muscle cells are highly branched/ Y-shaped to increase surface area of contact/ connection between cells, and they are interconnected by structures called intercalated discs (regions between plasma membranes of adjacent cells)
FUNCTIONS
- Highly branched/ Y-shaped to ***increase surface area of contact/connection between cells
- Intercalated discs contain structures called gap junctions which are ion channels that allow the cytoplasm to flow freely/ be shared between cells, which ***allows electrical signals/ impulses to be rapidly transmitted between cells)
- Cardiac muscle cells contain more mitochondria than skeletal muscle cells and lots of glycogen granules (rich supply of glucose) ***for aerobic respiration/ ATP (continuous, lifelong contraction!)
Identify and diagram the P, QRS, and T waves in an ECG trace and explain what happens in the heart during each.
Look at The Transport System: The Heart notes (slide 17) - https://docs.google.com/presentation/d/1zHpYr-ZhxgMsBOeyu50neIu0tGjb0Ob6X1ahIpLss40/edit#slide=id.g160935011c4_0_0
BASICALLY… P is atrial contraction, QRS is contraction of ventricles, and T is relaxation of ventricles
———
P wave (little bump at beginning): The atria is electrically excited/depolarized, leading to the contraction of both atria.
QRS complex (big spike): The ventricles are depolarized, initiating the ventricular contraction. The contraction starts shortly after Q and marks the beginning of the systole.
T wave (little bump at end): The ventricles return from their excited to their normal state (repolarization). The end of the T-wave marks the end of systole.
Calculate heart rate using an ECG trace (use the R-R interval to determine the time it takes for ONE heart beat (usually in seconds) and then convert seconds to minutes using the conversion 60 seconds = 1 minute, as heart rate is measured in beats per minute).
Look at notes and worksheets!
Outline the factors that can affect heart rate.
- Age
- Fitness and activity levels
- Being a smoker
- Having cardiovascular disease, high cholesterol or diabetes
- Air temperature
- Body position (standing up or lying down, for example)
- Emotions
- Body size
Explain the use of a defibrillator and artificial pacemaker.
DEFIBRILLATOR: medical device (with paddles or electrodes) placed on a person’s chest (or on cardiac muscle) that delivers an electrical shock(s) to depolarize the heart muscle so SA node can re-establish a normal rhythm
* Note that many defibrillators will determine if fibrillation is actually happening before they send electrical shock
* Used in life-threatening cardiac conditions such as arrhythmias, or atrial or ventricular fibrillation (if heart pumps irregularly, blood not being pumped effectively to tissues that need it - including heart itself)
ARTIFICIAL PACEMAKER: medical device that contains a
battery and pulse generator and delivers electrical stimuli
to heart to regulate heartbeat. Connects to heart via
cables/ wires and detects if heart’s natural rhythm is
incorrect. If so, it sends electrical impulses to heart to
generate a regular/ constant rhythm/ coordinate contraction
of atria and ventricles.
* Used when heartbeat is too slow/ too fast/ irregular, SA node is defective or malfunctioning, or pathway that carries impulses from SA node is impaired.
Explain how the structure of arteries, veins, and capillaries are adapted to their function.
ARTERIES:
* Narrow lumen (to maintain high pressures) surrounded by a thick wall (3 layers – to prevent rupturing/ withstand high pressure)
* 3 layers; Middle layer of wall (tunica media) is thick layer of smooth muscle/ elastic fibers to maintain pressure between heart beats (can stretch/ contract to pump blood) - high elasticity allows for elastic recoil to help push blood
* Outer layer of wall (tunica adventitia) contains collagen to prevent artery from rupturing under high pressure (NO valves)
CAPILLARIES:
* Narrow diameter (low pressures) with walls only ONE CELL THICK (decrease diffusion distance/ increase diffusion rate for exchange of materials and gases between blood and tissues)
* Some contain pores/ fenestrations (to aid in exchange of materials)
* Involved in material and gas exchange between blood and tissues, so NARROW to increase SA/V ratio for diffusion (NO valves)
VEINS:
* Wide lumen (low pressures, decrease resistance, and increase blood flow) surrounded by a thin wall (3 layers – thin to allow skeletal muscle to squeeze blood through)
* 3 layers; THIN walls because blood NOT traveling in pulses (like in arteries); less muscle/ thinner elastic layer than arteries; easier to compress/ misshape
* Contain valves (to prevent pooling of blood in extremities and maintain one-way blood flow/ no backflow - valves open when skeletal muscles
contract, pushing blood through)
Identify vessels as arteries, veins, or capillaries in diagrams or micrographs based on the structure of their walls.
Look at notes and worksheets! - https://docs.google.com/presentation/d/1MgRmTnEnzXerKB7UsuU7xXaKC0u0WjVI6uRC5gPAwGs/edit#slide=id.p5
ARTERIES:
* Thick outer and inner layers, endothelium, and narrow central lumen
VEINS:
* Thick outer and thin inner layers, endothelium, and wide central lumen
* Floppy/misshapen because they don’t have collagen/same thickness of walls as arteries
CAPILLARIES:
* Endothelial layer and lumen
* Significantly smaller structure
List the components of blood and what is transported by the blood.
COMPONENTS:
- Plasma (liquid/ fluid component of the blood – water based) ~55%
- Erythrocytes (red blood cells – transport O2) ~45%
- Leukocytes (white blood cells)
- Phagocytes (nonspecific immunity)
- Lymphocytes (specific immunity)
- Platelets (involved in blood clotting)
- Note: Leukocytes and platelets make up less than 1% of the blood
TRANSPORTS: (nacho-uh)
* Nutrients (glucose, lipoproteins etc.)
* Antibodies
* Carbon dioxide
* Hormones
* Oxygen
* Urea
* Heat
Explain how materials are exchanged between the capillaries and tissues (and know which SPECIFIC materials would go INTO cells/ tissues from the blood and which SPECIFIC materials would come OUT of cells/ tissues and go into the blood)
Capillaries have permeable walls that allow exchange of materials between cells in the tissue and the blood in the capillary
Capillaries exchange materials (glucose, hormones, water, nitrogenous wastes)/ gases between the blood and body cells/ tissues (lower pressures and thin walls to facilitate diffusion) - DIFFUSION between capillaries and tissues (in capillary BEDS - a network of capillaries that serve one artery/ vein)
Capillaries bring nutrients and oxygen to cells and take carbon dioxide and wastes from cells
