Tom Petty & The Heartbreakers Flashcards
In what organisms are open circulatory systems found?
Open circulatory systems are found in arthropods and most mollusks
The closed vascular system contains:
arteries, capillaries, venules
Arteries
carry blood away from the heart and branch into arterioles that feed the capillary beds
Capillaries
the site of exchange between blood and tissue fluid
Venules
drain the capillary beds and form veins, which deliver blood back to the heart
Fish circulatory system
Atrium—receives blood from the body
Ventricle—receives pumped blood from the atrium and sends it to the gills
Blood from the gills collects in the aorta and is distributed throughout the body
Where does the right atrium receive blood from?
The right atrium receives deoxygenated blood from the body from the superior and inferior vena cava
Super and inferior vena cava
Superior vena cava—blood from upper body
Inferior vena cava—blood from lower body
After the right atrium receives blood from the vena cava, where is it sent to?
The pulmonary artery pumps blood from the heart to the lungs,
After blood is oxygenated in the lungs, where is it sent to?
oxygenated blood returns to the left atrium of the heart through the pulmonary veins
In the mammalian heart: the right ventricle pumps blood through the ______ circuit, the left ventricle pumps blood through the ______ circuit
In the mammalian heart: the right ventricle pumps blood through the “pulmonary” circuit, the left ventricle pumps blood through the “systemic” circuit
Why are valves needed in hearts?
Valves prevent backflow of blood
What is the atrioventricular (AV) valve?
Atrioventricular (AV) valves lie between the atria and ventricles and prevent backflow when ventricles contract
How do the pulmonary valve and aortic valve work together?
The pulmonary valve and aortic valve lie between the ventricles and the major arteries and prevent backflow when ventricles relax.
They are either both open or closed.
Two phases of the cardiac cycle
Systole, when ventricles contract;
&
Diastole, when ventricles relax
In the cardiac cycle both sides of the heart contract at the same time—first the two atria contract, then the two ventricles
How is heart muscle contraction coordinated?
Cells are in electrical contact with each other through gap junctions—spread of action potentials stimulates contraction in unison
What are pacemaker cells?
Some cells in the heart are pacemaker cells and can initiate action potentials without input from the nervous system
What are the primary pacemaker cells called?
The primary pacemaker cells are the sinoatrial node.
Function of the sinoatrial node
An action potential is generated in the sinoatrial node.
The action potential spreads through gap junctions in the atria and they contract together, but it does not spread to the ventricles
The action potential in the atria stimulates what node?
The action potential in the atria stimulates the atrioventricular node.
the atrioventricular node.
The node consists of non-contracting cells that send action potentials to the ventricles via the bundle of His. Located inside right atriunm
projection of the bundle of His
The bundle divides into right and left bundle branches that run to the tips of the ventricles.
Why do heart muscles have longer contraction than skeletal muscles?
Much longer contractions (~300msec) compared to skeletal muscles.
Why?
To allow enough time for emptying and re-filling.
How are action potentials in heart tissue different from neurons and other muscle cells?
Action potentials slow to rise, have broader plateau, slower to return to resting potential (which is unstable), compared to other muscle cells and neurons
Why are capillaries adaptive for gas exchange?
Capillaries contribute an enormous surface area
What is the difference in blood pressure between arteries and capillaries?
Blood pressure and flow through large arteries are high, and are lower through the capillaries.
Why is pressure reduced in smaller vessels?
Pressure is reduced in smaller vessels because arterioles and capillaries are highly branched, presenting a large surface area.
How do capillaries exchange molecules?
Capillary walls are a single layer of endothelial cells and have tiny holes called fenestrations.
Capillary beds are permeable to water, ions, and small molecules, but not to large proteins.
How can the lining of arteries be damaged?
The lining of arteries can be damaged by high blood pressure, smoking, poor diet, or microorganisms
What occurs in blood vessel disease?
In atherosclerosis, connective tissue and calcium deposits make the artery wall less elastic (wall is “hardened”), which can precipitate
a heart attack when the coronary arteries are involved.
What is a thrombus?
A thrombus (blood clot) may form if platelets stick to the plaque;
Embolus
A blood clot becomes an embolus if it breaks loose and moves in the bloodstream.
Circulatory system in crawfish
A pump (heart) moves hemolymph through vessels to fluid-filled spaces in viscera.
Fluid returns to the heart through openings with valves—ostia.
In closed circulatory systems, what is the relationship between blood and interstitial fluid?
In a closed circulatory system blood is kept separate from the interstitial fluid
Advantages of closed circulatory systems:
1) Faster transport through vessels than through interstitial space
2) Blood can be directed to specific tissues by varying resistance (vasoconstriction
or vasodilation)
3) Specialized cells and molecules (nutrients, hormones) can travel in the vessels and be offloaded where needed
4) High pressure system facilitates efficient waste collection and excretion
(e. g. in vertebrate kidney)
