Circulation Flashcards
What do unicellular organisms use to exchange material with their environment directly
diffusion
when is diffusion efficient
small distances
How do protosomes exchange material with their environment
through diffusion, they live in aquatic environments with thin body walls
what do gastrovascular cavities do
minimize diffusion distances for digestion and circulation
what are the three components of a CS
circulatory fluid, interconnecting vessels, muscular pump
what are the two types of CS
open and closed
what does a CS do?
connects fluid that surrounds cells with organs that exchange gases, nutrients, wastes
What are open Cs
no distinction between blood and IF (hemolymph)
What organisms have open systems
insects, arthropods, molluscs
what are some characteristics in an open CS
internal fluid is circulated through body cavity, pressure rapidly dissipates (requires a faster heart rate or accessory hearts)
what is a closed Cs
blood is confined to vessels and is distinct from IF
where do substances move between in a closed CS
blood —> IF, IF —> cells
what is a key characteristic of closed CS
more efficient at transport (maintain pressure gradients)
What are arteries
carry blood away from the heart to capillaries
what are veins
return blood from capillaries to heart
what are capillary beds and their function
networks of capillaries, sites of chemical exchange between blood and IF
What animals use single circulation, how many heart chambers do they have?
fish, rays, sharks, two or more chambers
Single circulation pathway
Atrium, Ventricle, Gill capillary beds, Body capillary beds
what is a disadvantage of single circulatio
low pressure, no fresh perfusion to the heart
How many chambers do amphibian hearts have
3, 2 atria and 1 ventricle
what is the pathway of double circulation in amphibians
the ventricle pumps blood into a forked artery that goes into the pulmonary and systemic circuit
what can amphibians do to their bloodflow
can shut off the blood flow to lungs when underwater
how many heart chambers do mammals and birds have
four (2 atria, 2 ventricles)
What is the function of the systemic circuit
carries oxygen rich blood from heart to the rest of the body
what is the pulmonary circuit
where blood travels between heart and lungs
why do mammals and birds require more oxygen
because they are endotherms (regulate body temp) and therefore have higher metabolic rates
what is cardiac output
the volume of blood pumped into systemic circuit per minute
what does cardiac output depend on
heart rate and stroke volume (amount of blood pumped in a single contraction)
do larger or smaller animals have a faster heart rate, why?
smaller, mass-specific metabolic rates
pulmonary artery function
brings de-oxygenated blood from right ventricle to lungs
pulmonary veins function
return oxygenated blood to left atrium from lungs
aorta function
distribute oxygenated blood through the body from the left ventricle
superior and inferior vena cava function
bring de-oxygenated blood back to the right atrium
atria structure and function
thin walls, collect chambers for blood returning to the heart
ventricles structure and function
thick walls (contract more forcefully), eject blood to distal sites
What is the heart wall made of?
Muscle (myocardium) encapsulated between inner lining (endocardium) and a fibrous protective sheath (pericardium)
What is the function of the AV valves and where are they located?
control blood flow within the heart, between the atria and ventricles
SL valve function
control cardiac output via the aortic and pulmonary arteries
what causes a heart murmer
backflow of blood through a defective valve
what is the systole phase
contraction or pumping
what is the diastole phase
filling or relaxation
what is the first step of the cardiac cycle
heart = relaxed, atria fill with blood, valves closed, AV valves pushed open and ventricles begin to fill
what is the second step of the cardiac cycle
atria contract and fully fill ventricles once they fill 80% of the way
what is the third stage of the cardiac cycle
ventricles begin to contract, force AV valves closed, as contraction builds SL valves open
how is the cardiac cycle coordinated?
muscle cells are autorhythmic
what is the SA nodes function
sets the rate and timing at which cardiac muscle cells contract
impulse pathway from the SA node
SA —> AV (impulses delayed) —> purkinje fibers (ventricles contract)
what regulated the pacemaker
NS: para and sympathetic
how does each division of the NS impact the pacemaker
Sympathetic = speeds up (adrenaline)
Para = slows down (acetylcholine)
what also regulates the pacemaker
hormones and temperature
what do barorecptors do and where are they located
in the heart muscle, aorta and carotid arteries (supply blood to brain), provide blood pressure information to the medulla
vein structure, how does blood flow
thin walls, flows to heart via gravity and muscle action
arteries structure
thick walls, accommodate high blood pressure of blood pumped from the heart
what are three components of arteries and veins
endothelium, smooth muscle, connective tissue
what is the endothelium made of and its function
the epithelial layer that lines blood vessels, minimizes resistance
what is a vessels cavity called
the central lumen
how is backflow prevented in veins
one-way valves
how is blood moved through veins
smooth, skeletal muscle contraction and the expansion of the vena cava with inhalation
components of capillaries
thin walls, endothelium, basal lamina to facilitate exchange
systolic pressure
pressure in arteries during ventricle systole, high pressure
diastolic pressure
pressure in arteries during diastole
what is the pulse
rhythmic bulging of artery walls with each heartbeat
what dissipates pressure in capillaries and arterioles
resistance to blood flow in the narrow diameter
where is blood flow slowest and why
capillary beds, high resistance due to large surface area, slow exchange of materials
where does exchange between blood and IF take place in capillaries
endothelial walls
what drives out fluid from the capillaries
difference between blood and osmotic pressures
what is the function of the lymphatic system
returns fluid that leaks out from the capillary beds
what are lymph nodes functions
filter lymph and have role in defense
what regulates the distribution of blood in capillary beds
constriction/dilation of arterioles and pre-capillary sphincters between arterioles and venules
how does vasoconstriction and vasodilation affect blood pressure
constriction increases, dilation decreases
what are inducers of vasodilation/constricton (one each)
dilation = nitric oxide, constriction = peptide endothelin
what is plasma made of
water, inorganic salts (electrolytes0 and proteins
what is the functions of proteins in blood (4)
influence blood pH, help maintain osmotic balance between blood and IF, lipid transport and clotting
what are suspended in plasma
erthrocytes, leukocytes, platelets
where do blood cells develop from
stem cells in red marrow of bones
what does EPO do
stimulate erythrocyte production when O2 delivery is low, can treat anemia
what are the two main types of stem cells
lymphoid and myeloid
what do erythrocytes contain, what is their structure
packed with hemoglobin, lack nuclei and mitochondria
what is the function of leukocytes
defense either through phagocytizing bacteria and debris or by mounting immune responses against foreign substances
what are platelets
fragments of bone marrow cells
platelet function
blood clotting
how are platelets activated
exposed collagen fibers or by thrombin, once activated change shape and form plug and release clotting factors
what is coagulation
formation of a solid clot from blood, fibrin mesh
what is a blood clot in a blood vessel called, why is it dangerous
a thrombus, can block blood flow
