Chapter 42: Circulation and Gas Exchange Flashcards
Animals with gastrovascular cavities do not require
an organ system for transporting nutrients and gases within the body because each cell is in close contact with a source of nutrients and oxygen
Small molecules can move between cells andtheir surroundings by
Diffusion
Diffusion is only efficient…
over small distances because the time it takes to diffuse is proportional to the square of the distance
Open circulatory system
circulatory fluid is not contained in vessels during its entire trip through the body, but instead drains into the body cavity; circulatory fluid directly bathes the cells and and the blood is not kept in blood vessels
Closed circulatory system
circulatory fluid is contained within vessels during its entire trip (a circuit) through the body and never leaves the network of blood vessels; interstitial fluid bathes cells
Single circulation
blood travels from the heart to the gas exchange structures, and then directly to the rest of the body without being pumped a second time by the heart
Double circulation
blood travels from the heart to the gas exchange structures, but then returns to the heart to be pumped a second time before traveling to the rest of the body (4 chambered heart)
Pulmonary circuit
the arteries and veins that circulate blood through the gas exchange organs (heart and lungs)
Systemic circuit
the arteries and veins that circulate blood through all parts of the body other than the gas exchange structures
2 atria and 1 ventricle, no septum found in….
Amphibians
2 atria and 1 ventricle partially divided by an incomplete septum found in….
Reptiles excluding birds
2 atria and 2 ventricles with complete septum found in…
Mammals and birds
pulmonary circuit pathway
right ventricle to respiratory surface (oxygen gained, CO2 lost) and back to left atrium
(RV > lungs > LA)
systemic circuit pathway
takes oxygenated blood from the left ventricle of the heart to the tissues, removes carbon dioxide from the tissues, then returns deoxygenated blood to the right atrium
(LV > organ tissues > RA)
What week of fetal development does heart start beating?
Third
The vertebrate cardiovascular system works in tandem with the….
Respiratory system
Blood
the tissue that transports oxygen, carbon dioxide, hormones, wastes, and nutrients to the body
Atrium
a chamber of the heart that receives blood arriving from the rest of the body
Ventricle
a chamber of the heart that pumps blood out of the heart; receive blood from large veins and direct it into the ventricles
Artery
large blood vessels that carry blood away from the heart toward capillaries
Capillaries
small blood vessels with very thin walls where exchange between blood and interstitial fluid occurs
Veins
blood vessels that return blood from the capillaries back to the heart
Left ventricle
Pushes blood throughout body
Right ventricle
Pushes blood to nearby lung (less muscular)
septum
thick wall dividing two sides of the heart
As the ventricles contract…
the atria relax
Left side of heart
receives oxygenated blood from lungs; pumps blood to the rest of body (far distance).
Right side of heart
receives deoxygenated blood from body; pumps blood to lungs (short distance).
diastole
relaxation (filling phase)
systole
contraction (pumping phase)
Cardiac cycle (3 steps)
- Entire heart in diastole
- Atria systole & ventricle diastole
- Ventricle systole & atria diastole
atrioventricular valves
separate the atria from the ventricles (atrial blood enters ventricles through here)
aorta
blood pumped throughout body via this
Valves within the heart prevent
backflow of blood
chordae tendinae
heart strings; hold valves in place
sound caused by blood pressure against the atrioventricular valves
lub
semilunar valves closing makes this sound
dub
semilunar valves
The valves between the ventricles and the major arteries leaving the heart