Circulation and Blood Vessels Flashcards
What is pulmonary circulation?
blood flow between the heart and lungs
What is systemic circulation?
blood flow from the heart to the rest of the body
What is cardiac/coronary circulation?
blood flow within the heart
Describe the process of blood flowing around the body.
- The process begins with the contraction of the right ventricle which pumps blood to the lungs via the pulmonary arteries.
- Blood flows through the capillery beds in the lungs, where CO2 and O2 are exchanged.
- The oxygen-rich blood then returns to the heart via the pulmonary veins to the left atrium of the heart.
- The oxygen rich blood then flows into the left ventricle, which pumps the blood out to the body tissues through the systemic circuit.
- The blood exits the heart through the aorta which moves blood to arteries throughout the body.
- The arteries branch out and become arterioles, which then lead to capillary beds. O2 and CO2 are exchanged.
- the capillaries rejoin to form venules and then veins.
- The oxygen poor blood is them channeled into the superior vena cava.
- The inferior vena cava drains the blood from the trunk and hindlimbs, which empty into the right atrium, which then flows into the right ventricle restarting the cycle.
What’s the function of the artery and arteriole?
to transport blood away from the heart
What are some examples of arteries and arterioles?
the aorta
pulmoary artery
What’s the function of the veins and venules?
to transport the blood towards the heart
What are some examples of veins and venules?
the vena cava and pulmonary vein
What is the function of a capillary?
the material exchange between blood and body
What materials are exchanged through the capillaries?
- gases (oxygen and carbon dioxide)
- nutrients
- waste
How thick are the walls of capillaries? Why?
They have walls made up of one thin layer of cells which allow for rapid diffusion of materials from blood to surrounding tissue
What control the flow of the blood into capillaries?
the sphincter muscles where arterioles branch into capillaries
Are there muscles in the capillaries?
No. No smoothe muscles in the capillaries to control the diameter and therefore the blood flow
What happens if blood is not required in an area?
sphincters will constrict
What are the three layers in the arteries and veins?
- outermost layer
- middle layer
- innermost layer
What’s in the outermost layer of the arteries and veins?
connective tissue
What’s in the middle layer of the arteries and veins?
alternating circular bands of elastic fibres and smooth muscle. It provides elasticity to vessles
What’s in the innermost layer of the arteries and veins?
epithelial cells that reduce friction and blood courses through vessels
How thick is the innermost layer of the arteries and veins?
a single cell thick
What characteristic do the elastic fibers near the heart have?
more elastic fibers
What do the arteries further from the heart have more of?
more smooth muscle
What does the structure of the arteries ensure?
continuous blood flow even when the heart is relaxed
What’s in the middle layer of the artery? What do they do?
a thick middle elastic layer. It provides resistance to withstand high pressure
What does the muscle tissue in an artery do?
helps maintain pressure by having contractile ability, which is the ability to expand and contract to keep blood moving
What is a pulse?
a rhythmic expansion and contraction of an artery as blood moves through it
What qualities must an artery have to feel a pulse?
- be large
- close to the skin surface
- against a bone or other firm structure
What arteries are commonly used to detect a pulse?
radial, brochial or carotid arteries
What are the characteristics of veins?
- thinner walls
- less elastic and muscle tissue
- larger circumference
- lacks elasticity but has greater capacity (veins hold twice as much blood as arteries)
- blood pressure is low
- blood flow is slower
What contribute to returning the blood to the heart around veins?
surrounding skeletal muscles
When do valves open in veins?
when surrounding muscles contract allowing blood to return to the heart?
When do valves in the veins close?
when muscles relax so that blood cannot flow backwards.
What are varicose veins?
deformed valves
What are endotherms?
organisms that maintain an internal body temperature
What are the physiological responses to cold in endotherms?
- shivering
- vasoconstriction
What’s the physiological response to heat in endotherms?
- sweating
- vasodilation
What is vasoconstriction?
muscles contract walls of blood vessels in exterminites, which leads to narrowed blood vessels and reduced blood flow, the blood is redirected to the torso
What is vasodilation?
blood vessels in extermities dilated, which leads to increased blood flow at skin surface, excess heat is released into the environment.
