Cardiovascular System Flashcards
What does the cardiovascular include?
The heart and a system of vessels that distributes blood to the tissues of the body and to the lungs for exchange of gases
What is the term to describe the heart and lung combination portion of the cardiovascular system?
Pulmonary circulation
What are arteries?
Vessels that carry blood away from the heart and are highly oxygenated
What are veins?
Vessels that carry blood to the heart and are low in oxygenation
What is the term for circulation to everywhere in the body except the lungs?
Systemic circulation
How do pulmonary and systemic circulation relate?
Pulmonary circulation is functionally and anatomically separate from systemic circulation
In terms of pumps, how can the heart be visualized, and what does each of the pumps do?
The heart can be thought of as two pumps in one organ
One pump is low in pressure and directs blood returning from the body to the lungs
The other pump is high in pressure and distributes blood to the systemic circulation
What is the heart’s overall shape?
A cone-shaped, hollow, muscular structure
What is the base of the heart?
The dorsally-oriented part that is attached to thoracic structures via large arteries, veins, and the pericardial sac
What is the apex of the heart?
The ventrally-oriented part that is free within the pericardial sac
How is the heart angled?
So the left and right sides are somewhat cranial and caudal to each other
What is the pericardium?
A serous membrane that partially surrounds the heart and allows for movement with little friction
What is the pericardial space?
A closed cavity formed by the pericardium that contains a small amount of fluid which allows for frictionless beating of the heart
What are the two layers of the pericardium?
Visceral pericardium (epicardium) and the parietal pericardium
What is the visceral pericardium?
The inner layer of the pericardium that is adherent to the outer parts of the heart
What is the parietal pericardium?
The outer layer of the pericardium that is consistent with the visceral pericardium at the base (top) of the heart
What is the fibrous pericardium?
A superficial fibrous layer that reinforces the parietal pericardium
What makes up the pericardial sac?
The parietal pericardium, the fibrous pericardium, and the mediastinal pleura
What is the pericardial sac?
A thin and tough tissue surrounding the heart
What are the three layers of the heart wall?
The epicardium, the endocardium, and the myocardium
What is the epicardium?
A thin, outer, serous covering of the heart
What is the endocardium?
A thin, inner endothelial covering of the heart
What are endothelial cells?
A single cell layer that lines all blood vessels and regulates exchanges between the bloodstream and surrounding tissues
What is the myocardium?
A think muscular layer of the heart
What is the epicardium the same as?
It’s the same thing as the visceral layer of pericardium
What is the endocardium?
A layer of simple squamous endothelial cells
Where can endocardium be found?
Lining the chambers of the heart, covering heart valves, and being continuous with the lining of blood vessels
What is the myocardium made of?
Cardiac muscle
What are the left and right divisions of the heart associated with?
Right- low-pressure and pulmonary circulation
Left- high-pressure and systemic circulation
What are the two chambers located in each side of the heart?
Atrium and ventricle
What does the atrium do?
Receives blood via a large vein and contracts to fill itself
What does the ventrical do?
Pumps blood from the heart through a large artery
What type of animals have 4 chambered hearts and what type differs?
Mammalians have 4 chambered hearts, this can differ with avians
What is an auricle?
An appendage within the thin-walled chambers of the atrium
Where is the myocardium thickest?
a. atrium or ventricle
b. left or right
a. ventricle
b. left
Why is the left ventricle’s myocardium thicker than the right ventricle’s?
Because blood is ejected at a higher pressure from the left ventricle than it is from the right ventricle
Which ventricle entirely forms the apex?
The left ventricle, which is more muscular. The right ventricle doesn’t quite reach the apex
What is the ventricular septum?
Myocardium between the two ventricle chambers
There is also a version for the atriums
What is the atrioventricular (A-V) valve?
A one-way operating valve that is between the atrium and the ventricle on each side
What is the bicuspid valve?
It’s another name for the left A-V valve since it has 2 flaps/cusps in humans
What is the mitral valve?
A synonym for the A-V valve
What is the tricuspid valve?
Another name for the right A-V valve since it has 3 flaps/cusps in humans
Where are the flaps of the valves connected?
The inner wall of the ventricle where the atrium and ventricle meet
What is the semilunar valve?
A valve in the ventricle that ensures blood only flows from the ventricle into the artery and not vice versa
What way is the semilunar valve situated?
With the convex side of the three flaps facing toward the ventricle
What is the aortic valve?
A valve at the junction of the left ventricle and the aorta
What is the pulmonary valve?
A valve at the junction of the right ventricle and the pulmonary trunk
What does blood returning to the heart from systemic circulation enter through and what part of the heart does it go to?
It enters through the cranial and caudal vena cava and goes into the right atrium before it moves through the right A-V valve into the right ventricle
What is the conus arteriosus?
The origin of the pulmonary trunk, which it is split away from by the pulmonary valve
What does the pulmonary trunk divide into?
The left and right pulmonary arteries
What do the pulmonary arteries do?
Carry deoxygenated blood to each of the lungs
What do pulmonary veins do?
Carry blood back to the lungs into the left atrium
After blood is pumped from the left atrium to the left ventricle, where is it pumped next?
Past the aortic valve and into the aorta
What does the aorta do?
It branches and carries oxygenated blood to all the parts of the body
What do the septum and myocardium look like when the atrium contracts?
They’re in a relaxed state
What do the septum and myocardium look like when the ventricle contracts?
They contract with them and are no longer relaxed
How are arteries structured?
They begin as large vessels and divide into smaller and smaller branches to carry blood to the body
What is an arteriole?
The smallest artery, which is continuous with capillaries, which are the smallest blood vessels
What are venules?
The structures formed when capillaries begin to come together
What are veins?
Large blood vessels formed from venules coming together that carry blood to the heart
What are the largest veins and where do they lead?
The cranial and caudal venae cava that lead to the atrium
What tissue layers both arteries and veins?
Smooth muscle
Why are capillaries important?
They have a high level of diffusion and are located close to tissues, so oxygen is taken from the blood at the capillaries and distributed to the tissues
Where is the most oxygen rich blood area?
Aorta
How do arteries and veins typically interact with each other?
They’re usually paired and run similar courses
What do capillaries allow to move through them?
Since their walls are so thin, it’s not just oxygen that can get through. Fluid, nutrients, and gases can get through and enter tissues as well
Some of the fluid that exited through the capillaries does not return to the blood vessels. Where does it go?
It is taken up by thin walled lymphatic vessels
How are lymphatic vessels similar to veins?
They have many valves that only permit flow in one direction- toward the heart
What are lymph nodes?
Ducts throughout the body that store the fluid that exits through the capillaries and is carried in the lymphatic vessels
What is lymph?
The fluid in the lymphatic vessels that is transported to larger and larger lymphatic vessels until it is emptied into the cranial vena cava
What are the tracheal trunks?
Two large lymph vessels that drain the head and the neck and usually end in jugular veins
What is the thoracic duct(s)?
A duct that takes up lymph from the caudal part of the body and runs through the thoracic cavity adjacent to the aorta and empties lymph into the cranial vena cava
How is blood delivered to the pulmonary system?
By contraction of the right ventricle
Which arteries lead to which lung?
The right pulmonary artery goes to the right lung and the left pulmonary artery goes to the left lung
What does each pulmonary artery subdivide into?
Lobar arteries
Where do the lobar arteries lead to?
Individual lobes of the lungs
What do lobar arteries divide into?
Arterioles
After blood exits the capillaries in the lungs, what happens?
It is reoxygenated and sent back into the capillaries where it goes back to the pulmonary veins and is taken back to the left atrium of the heart
How does the color of the blood change when it is receiving gases from the lungs?
It goes from a blue/maroon indicative of deoxygenated blood to bright red indicative of oxygenated blood
What does systemic circulation refer to?
The movement of oxygenated blood to all areas of the body and the return of deoxygenated blood to the heart
What are coronary arteries?
Two large vessels coming from the aorta that supply blood to the myocardium (heart muscle) itself
What are common carotid arteries?
The arteries that supply structures of the face, head, and neck with blood and run cranially while embedded in a connective tissue sheath
What are subclavian arteries?
An artery that branches and supplies the caudal part of the neck, the thoracic wall, and the dorsal part of the shoulder with blood
How do subclavian arteries interact with each other?
They run the same course on each side of the body and branch very similarly
What is an internal iliac artery?
A branching artery that supplies the hip, pelvis, and genitals with blood
How does the abdominal aorta relate to the internal iliac arteries?
It terminates at the lumbosacral junction of the vertebral column and splits into the two internal iliac arteries
What is the median sacral artery?
A midline continuation of the abdominal aorta at the midline between the two internal iliac arteries
What are the external iliac arteries?
Arteries cranial to the internal iliac arteries that supply the caudoventral parts of the abdominal wall and parts of the reproductive system`
How do veins relate to arteries?
They usually accompany arteries of the same name
They’re larger than their artery counterparts and are often duplicated
What is venipuncture?
Inserting a needle into a superficial vein that is visible in the subcutaneous layer
Where do almost all systemic veins drain?
Cranial or caudal vena cava
What does the cranial vena cava drain?
Head, neck, thoracic limbs, part of the thorax
What types of veins are tributaries to the cranial vena cava?
Jugular veins, subclavian veins, and vertebral veins
What do internal and external jugular veins drain?
Internal drain the brain
External drain the face and head
Where do the subclavian veins receive their blood from?
From the areas that are supplied by the subclavian artery and its branches
What is an azygous vein?
An unpaired vein that is adjacent to the vertebral column and networks with veins in the vertebral system
Where do azygous veins drain?
Depends on species, but oftentimes not the cranial or caudal vena cava
Where and how is the caudal vena cava formed?
In the abdomen by joining paired internal and external iliac veins
Joining the internal and external iliac veins brings blood from what?
The gluteal and perineal regions and the pelvic limbs
What are the three types of veins the caudal vena cava receives from body wall structures?
Lumbar veins, testicular or ovarian veins, and renal veins
What is the caval foramen?
The area of the diaphragm that the caudal vena cava passes through
What type of veins does the caudal vena cava receive directly from the liver
Short hepatic veins
What must all components of the cardiovascular system do to maintain proper blood flow through the body?
Function together
What is another word for hydrostatic pressure?
Mean blood pressure
What does hydrostatic pressure measure?
The force generated by contraction of the heart that pushes blood through the vessels
What is systole?
When the blood leaves the heart during contraction/the squeezing of blood to the rest of the body
What allows the aorta to accept the high volume of blood being pumped through it?
High amounts of elastic tissue within it
What is diastole?
When the heart fills with blood in a resting state to prepare to contract again
How is mean blood pressure calculated?
It’s the average of systolic and diastolic blood pressure, with the first number being systole and the second being diastole
In terms of pressure, how does blood flow?
From a point of high mean pressure to a point of low mean pressure
What area of the heart has the highest pressure?
Left ventricle and the aorta
Rank the types of blood vessels in order from highest pressure to lowest pressure.
arteries -> capillaries -> veins
How is blood flow regulated to be a one-way process?
With valves
Why is it necessary for blood pressure to be created during systole?
To overcome vascular resistance in the blood vessels
What are the three factors that affect resistance to flow in a blood vessel?
Radius (resistance decreases with increase in radius), length (resistance increases with length), and viscosity (resistance increases with viscosity increase)
Changes in radius have biggest effect
What is the cardiac cycle?
A complete cycle, called a heartbeat, of cardiac contraction (pressure increase) and cardiac relaxation (pressure decrease)
List the steps of the cardiac cycle in order
Deoxygenated blood enters the right atrium through superior vena cava
Right atrium contracts, pumping blood into the right ventricle through the tricuspid valve
Tricuspid valve closes
Right ventricle contracts, opening the pulmonary valve and pumping blood into the pulmonary artery
The pulmonary valve closes and blood travels to the lungs
Right atrium relaxes to accept blood
Oxygenated blood enters the right atrium through the pulmonary veins
Left atrium contracts, pumping blood into the left ventricle through the mitral valve
Mitral valve closes
Left ventricle contracts, opening the aortic valve and pumping blood into the aorta
Aortic valve closes and blood travels to the body
When do A-V valves open and when do they close?
They open when atrial pressure is larger than ventricular pressure and close when ventricular pressure is larger than atrial pressure
What is the function of the SA node?
It’s the pacemaker of the heart because it develops action potential that is sent around the heart to stimulate action potential in all the muscle cells in the heart to make it contract
What are the A-V node and the bundle of His and what do they do?
They are specialized conducting cells that allow the ventricles to fill with blood
What is cardiac output?
The volume of blood pumped out of a ventricle into its vessel per unit time
What determines cardiac output?
Heart rate and stroke volume
How is heart rate controlled?
By the autonomic nervous system
What are the two factors that change stroke volume?
Ventricular filling and cardiac contractility
What is cardiac preload?
The force on the heart muscle before contraction and is measured by the amount cardiac muscle stretches before it contracts
What is cardiac afterload?
The force applied to the ventricle during contraction
What affects ventricular filling?
Filling pressure (blood pressure in the veins and atria that push blood into the ventricle), filling time, and ventricular compliance (how easily the ventricle relaxes)
What does filling pressure depend on?
Constriction of muscles in the vein and blood volume
What is a change in cardiac contractility?
When the contraction force generated by individual myocardial cells is changed and is not related to the length it is stretched before contracting
What are the agents that change cardiac contractility?
Inotropes
What are two examples of a positive inotrope (something that increases cardiac contractility)?
Norepinephrine and epinephrine
What is the innermost layer of the blood vessel walls?
A single layer of endothelium
What type of blood vessels have basically only endothelium cells?
Capillaries
What type of junction joins the capillary cells and what does it do?
Tight junctions that form a barrier that doesn’t allow non-lipid soluble materials to cross
What are the three layers of the walls that make up all veins and arteries?
Tunica interna, tunica media, and the tunica externa
What are the three layers of the tunica interna?
The single layer of endothelium, a subendothelium layer of connective tissue, and an elastic membrane
What is the tunica media made of?
Smooth muscle
What type of vein has the thickest tunica media?
Arteries
What is the tunica externa made of and what is its function?
Connective tissue that protects the vessel
What is the purpose of arterioles?
To work as on-off valves to regulate the rate of blood flow from the arteries to the capillaries
What type of vein innervates the smooth muscle wall in arterioles?
Sympathetic vasoconstrictor nerves
What regulate the degree of constriction of ateriolar smooth muscle?
Vasoactive agents
What is the word for locally produced vasoactive agents and what do they typically do?
Paracrine and usually increase blood flow
What is the process that regulates blood flow with locally produced mechanisms called?
Autoregulation
What determines the rate of capillary exchange?
Rate of blood flow into the capillaries
What state do tissues need to be in to increase the number of capillaries being used at a time?
They need to be in an unresting state. In resting tissues, blood only flows through a small number of capillaries at a time
What is edema?
A high amount of fluid collected in the interstitial space
What force keeps fluid in capillaries?
Osmotic force/pressure generated by the plasma proteins
What does vein compliance allow?
Large changes in blood volume with little change in blood pressure
How compliant (ability to change volume and pressure) are arteries?
Relatively noncompliant
What two things determine arterial blood pressure?
Cardiac output and total peripheral vascular resistance
What contributes to the majority of vascular resistance and in turn is one of the main regulators of arterial pressure and blood flow?
Arterioles
What is directly related to arterial blood pressure?
Blood volume
What organ is the primary regulator of blood volume?
Kidney
What are the 3 ways to control blood pressure and blood volume?
Neural reflexes, humoral agents, and paracrine agents
What is an example of a neural reflex and what do they do?
Arterial baroreceptor reflex, which is primarily responsible for the short-term or immediate regulation of arterial blood pressure
What do humoral agents do and how do they do it?
They control blood pressure through vasodilation (increasing vessel volume and decreasing pressure), vasoconstriction (decreasing vessel volume and increasing pressure), and alteration of blood volume
How do paracrine glands affect blood pressure?
By manipulating the release of nitric oxide or endothelin peptide from the endothelial lining of the blood vessels
Does high or low blood pressure decrease the flow of blood?
High blood pressure
