Cardiovascular Physiology Flashcards
What are two ways that cardiovascular fluid can travel?
Diffusion and bulk flow through vessels/ chambers with one way valves
What is a disadvantage of diffusion?
It is slow over long distances
What kind of organism uses diffusion?
Bacteria
What kind of valves do we have in the cardiovascular system?
One-way valves
What are three ways that circulatory systems move fluid? Which on uses skeletal muscle?
Contractile Chamber
External Pump*
Peristaltic Contraction
*Uses skeletal muscle
What are the two types of circulatory systems?
OPEN CIRCULATORY SYSTEM
CLOSED CIRCULATORY SYSTEM
For an open circulatory system... What pumps the fluid? What is the fluid called? Are there cells in the fluid? What are the vessels called?
- Heart
- Hemolymph
- No cells (no red blood cells)
- Sinuses, together are Hemocoel
For an open circulatory system…
What pumps the fluid?
What is the fluid called?
Are there cells in the fluid?
- Heart
- Blood
- Yes, red blood cells
What is one advantage for an open circulatory system? How about for closed?
Open- Allows oxygen diffusion directly to tissues
Closed- Can get oxygen to tissues RAPIDLY and SELECTIVELY
What is the fluid in blood called?
Plasma
What do both open and closed fluids have?
Proteins
What is unique to closed fluid?
Cells (red blood cells)
Name another system that may be part of a closed circulatory system? What is its function?
The LYMPHATIC SYSTEM, collects the fluid that leaks out of capillaries (LYMPH) and returns it to the circulatory system
Name five organisms with no circulatory system…
Hydra Planaria Nematoad Starfish Sponge
Name four organisms with open circulatory systems
Leech
Insects (Ants, bees)
Mollusks
Crustacians (lobster, crab)
Name one class of animals with closed circulatory systems? What is another animal that has a closed circulatory system? How about another?
Vertebrates
the Squid
the Earthworm
How does fluid move if no circulatory system?
Bulk flow
What is the difference between diffusion and bulk flow?
Diffusion is movement down a concentration gradient, bulk flow is a movement because of pressure!
What are leeches/worms called? Do leeches/different types of worms have different types of circulatory systems?
Annelids
Yes! some open, some closed
Describe the difference between an open and closed circulatory system
Open system doesn’t have vessels returning fluid to the heart, while closed system is a closed loop of vessels
What are the holes in the wall of the heart that allow the heart of an open circulatory system to fill with blood?
Ostia
What are the two phases of blood movement? Describe them in an open circulatory system
- Systole and Diastole
- Systole: ostia close, heart contracts, blood pumped out
- Diastole: ostia open, heart relaxes, blood drawn into heart
What kind of circulatory system does the frog have?
Closed circulatory system
How many chambers does the frog heart have?
3
What kind of circulation does the frog have? What does this mean?
Pulmocutaneous circulation: means that blood flows to both skin and lungs to get oxygen
Describe the path of blood through the frog circulatory system…
Blood is pumped out of single ventricle, goes to tissues via SYSTEMIC ARTERY or to skin and lungs via PULMOCUTANEOUS ARTERY, which splits to the CUTANOUS ARTERY (skin) and PUMLOMARY ARTERY (lungs). Returns to right atrium from tissues via SINUS VENOSUS, or to left atrium via PULMONARY VEIN.
What does the frog do to adapt to changing conditions?
Regulates the amount of blood that is sent to the lungs vs. skin
What is it called when the blood goes from heart, to lungs and skin, then back to heart, then to tissues? Name two animals
DOUBLE-CIRCUIT CLOSED SYSTEM
Frog and rat
What is it called if the blood goes from the heart, to the gills/lungs, to the tissues, then back to the heart? Name two animals
SINGLE-CIRCUIT CLOSED SYSTEM
Lizard and fish
What kind of circulatory system do mammals have?
Double-circuit closed circulatory system
What is heart size proportional to?
Body mass
How do heart rates vary with body size?
Inversely proportional
What is the avg human heart beat? How about a very fit human?
Average: 72
Fit: 40
What happens to a snake heart when it eats a big meal? What does this mean?
It HYPERTROPHIES, meaning it gets BIGGER
Name the four chambers of a shark/bony fish heart
1) sinus venosus
2) atrium
3) ventricle
4) arteriosus
What is the name for heart muscle? What are the two types? What is the difference between the two types?
- Myocardium (spongy and compact)
- Spongy myocardium allows blood to mix with heart tissues, so muscle gets oxygen, while compact myocardium doesn’t allow for mixing, so heart needs a special artery to provide it with blood.
Name the three layers of the heart wall in a human…
Endocardium, myocardium, pericardium
What artery carries blood to and through the heart? What layer does it flow through?
CORONARY ARTERY, flows through the myocardium
What does the pericardium hold? What is its function?
The pericardial fluid in the pericardial cavity, protects the heart if it is pumped
Name the layers of a frog heart wall
Endocardium, spongy myocardium, compact myocardiu, pericardium
Does a frog have a coronary artery? Comment
yes it does, but it is more of a sinus, doesn’t provide as much blood like in humans, rather frog gets blood from spongy myocardium
Describe the path of blood through the human heart!
Blood enters the RIGHT ATRIUM from the SUPERIOR VENA CAVA (collects blood from upper body) and INFERIOR VENA CAVA (collects blood from lower body). It passes through the RIGHT AV (Tricuspid Valve), and into the RIGHT VENTRICLE. It is pumped through the PULMONARY SEMI-LUNAR VALVE and carried to the lungs via the RIGHT AND LEFT PULMONARY ARTERIES. It is carried back to the heart by the RIGHT AND LEFT PULMONARY VEINS into the LEFT ATRIUM. It enters the LEFT VENTRICLE via the LEFT AV VALVE (bicuspid valve), and is pumped out the AORTIC SEMI-LUNAR VALVE into the AORTA.
How many pouches do SEMI LUNAR VALVES have? Describe how they work
- 3 pouches
- They work b/c they are like flaps, so they can get blown open one way, but catch blood and squeeze shut if it tries to flow back the other way
What does AV Valve stand for?
Atrioventricular Valve
What anchors the AV value to the wall? How does the AV valve work?
CHORDAE TENDINEAE
- Works like a parachute, only catching air one way
What is the cause of heart murmers? Name two specifics
Defective valves! Can either be too narrow when open, or can be leaky when closed
What provides the baby with oxygen?
Oxygenated blood from placenta via umbilical cord
What’s interesting about fetal lungs?
They receive oxygenated blood from mother
What happens to the umbilical veins and arteries?
They turn into ligaments
Name two modifications that alter blood flow in the fetal heart. What do they connect? What is their purpose?
DUCTUS ARTERIOSIS- connects pulmonary artery to aorta
FORAMEN OVALE- connects right and left atria
Both shunt blood away from the lungs
What happens to the modifications when the baby is born?
They both close!
What are the two phases of the cardiac cycle? Describe them
Systole: contraction of the atria and ventricles
Diastole: relaxation of the atria and ventricles
How long does systole and diastole take?
systole: 0.3 sec
dialstole: 0.5 sec
What can we say about the contraction of the atria vs the ventricles?
The atria contract first and relax first
What is the combination of systole and diastole called?
The Cardiac Cycle
What are the two phases of diastole? What does each involve?
1) Isovolumetric ventricular relaxation: All valves closed, atria and vntricle relaxed.
2) Ventricular filling: AV valve opens, allows ventricle to fill, atria contracts slightly to pump more blood into ventricle
* Note: this happens to both atria and ventricles simulatneously
What are the two phases of systole? What does each involve?
1) Isovolumetric Ventricular contraction: Ventricles contract, AV Valve closes
2) Ventricular ejection: Ventricles contract, Semilunar valve opens, blood flows out
What is the driving force behind blood flow?
Pressure differences
What does EDV stand for? What is it?
End Diastolic Volume: Volume in ventricle at end of diastole
What does ESV stand for? What is it?
End systolic volume, volume in ventricle at end of systole
Define stroke volume (words and equation)
SV= EDV - ESV
Volume ejected per beat from each ventricle!
Define cardial output (two equations)
Cardiac Output= SV* heart rate
Cardiac Output= Mean arterial pressure (MAP) / Total peripheral resistance (TPR)
What is stroke volume compared to EDV?
stroke volume= 60% of EDV, so only 60% of full ventricle is pumped out
Name and define the three determinants of stroke volume
1) Preload: how much blood can we cram into the ventricle (stretching)
2) Contractility: the strength of contraction
3) Afterload: the pressure that must be overcome to pump blood out (pressure in the aorta)
What is the main determinant of preload? What affects this?
EDV!
Affected by how stretchy the heart walls are
Name two determinants of EDV
1) venous return: the more blood that flows into the atrium, the more we fill the ventricle
2) duration of ventricular diasole: the longer the relaxation, the more filling can occur
What happens when more blood fills the ventricle? What is the names for this phenomenon?
- The ventricle contraction is stronger!
- Called the Frank-Starling Mechanism
What is an important result of the Frank-Starling Mechanism?
It equalizes the output of the left and right side of the heart!
What does the strength of contraction affect?
The STROKE VOLUME
What do we call the substances that affect the strength of contractility?
Inotropic Agents
What two things do inotropic agents affect? Do they increase or decrease
1) Strength of contraction
2) Heart rate
INCREASE
Name three inotropic agents
1) Epinephrine
2) Calcium channel blockers
3) Digoxing
What plant does Digoxin come from?
the Foxglove plant
Sympathetic activity leads to…
Greater stroke volume!
What is the normal level of heart activity called?
Basal level
What is the pressure that must be overcome to open the semilunar valves?
Systemic Resistance
Name two things that increase afterload
- Hypertension
- Atherosclerosis
Which side of the heart has greater pressures?
The LEFT side
Name the four parts of the hear in order of greatest pressure generated
Left ventricle, right ventricle, left atrium, right atrium
What does a high afterload cause? (two things)
- Dilated cardiomyopathy (stretching and enlarging or heart chambers)
- Congestive heart failure
Discuss the conduction system in the heart
The Sinoatrial Node (SA Node), depolarizes, causing the atrium to contract. The atroventricular (AV) node recieves the signal from the AV node. It delays, then sends the signal through the Bundle of His and the Purkinje Fibers, causing the ventricles to contract. These cells never rest, they are always depolarizing or repolarizing. The SA node is always driving the AV node.
What do we call the SA and AV nodes? What do they do?
Pacemaker Cells. Fire spontaneouly and rhythmically
What are the Purkinje fibers and what do they do?
Specialized cardiac cells, conduct impulses rapidly
Discuss the flow of ions during the depolarizing and repolarizing phase…
Pacemaker causes an influx of Na and and outflux of K. Once the action potential starts, Ca pours in. As the action potential winds down, Ca pours out and K pours in.
Name three types of Pacemaker cells with impulses/min, location and function
- SA node: Fast Pacemaker (100/min), right atrium, begins heart activity
- AV node: Medium Pacemaker (40-60/min), atrial septum, transmits SA node signal to Bundle of His
- Bundle of His: Slow Pacemaker (20/min) Connects atria and ventricles, spreads signal
The bundle of his is the _____ connection between the atria and ventricles
Only
How does the electrical signal spread between heart cells? All cardiac cells are _________
Gap Junctions!
Electrically coupled
What two types of stimulation affect heart rate? What do they do? How do they achieve this (what do they alter)?
Parasympathetic -> beats slower
Sympathetic -> beats faster
They cause FASTER or SLOWER DEPOLARIZATION
Describe the stimulation of the heart pathway
The CARDIOVASCULAR CONTROL CENTER (in the MEDULLA) stimulates the SYMPATHETIC NEURONS, which causes the release of NOREPINEPHRINE (from sympathetic nervous system) and EPINEPHRINE from the ADRENAL MEDULLA. This attaches to the BETA RECEPTORS of the PACEMAKER CELLS, leading to an activation of CAMP by ADENALINE CYCLASE, leading to an activation of PKA, leading to the opening of FUNNY (Na) CHANNELS and Ca CHANNELS, leading to a depolarization and an increase in heart rate.
Describe the paraympathetic inhibition of heart rate pathway
The CARDIOVASCULAR CONTROL CENTER (in the MEDULLA) stimulates the PARASYMPATHETIC NEURONS, which release ACETYLCHOLINE, which binds to the MUSCARINIC RECEPTORS on the PACEMAKER CELLS, this causes a HYPERPOLARIZATION (K out, Ca in), which makes it harder to depolarize the heart and DECREASES HEART RATE.
What nerve causes parasympathetic stimulation?
the Vagus Nerve
The cardiac action potential is longer/shorter than skeletal muscle, because of a _________ created by
longer
calcium plateau, slow Ca channels
What is the purpose of the long duration of cardiac action potential?
Allows for development of contraction
How do we “look at heart beats”? What does it measure?
We use an EKG / ECG. It measures the electrical currents of the heart at the surface of the body.
Name the parts of an EKG. What does each represent.
p-wave: atrial depolarization
QRS complex: ventricular depolarization
t-wave: ventricular repolarization
Name and describe one issue that can be seen on an EKG
Atrioventricular (AV) block: Lack of coordination between P wave and QRS complex
