Summary of the topic circulation from Campbell Biology a Global Approach, 11th edition. This summary includes notes of accompanying MasteringBiology assignments, lectures and any lectures.
Summary of the topic of circulation from Campbell Biology a Global Approach, 11th edition. This summary inclu...
Samenvatting Hoofdstuk 12 van Biology a Global Approach 11th edition
Samenvatting Hoofdstuk 8 van Biology a Global Approach 11th edition
Samenvatting Hoofdstuk 7 van Biology a Global Apprach 11th edition
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Circulatie (BOOK)
43.1
In animals with a gastrovascular cavity such as jellies, hydras and other cnidarians, fluid
bathes both the inner and outer tissue layers, facilitating exchange.
A circulatory system basically has three compartments:
- Circulatory fluid
- Set of interconnecting vessels
- Muscular pump heart
Circulatory systems can be:
- Open
o Circulatory fluid (=hemolymph) is also the interstitial fluid
o Lower energy
- Closed
o Circulatory fluid (=blood) is distinct from the interstitial fluid
o Annelids, cephalopods, vertebrates
o Practical for regulating distribution of blood
Three types of blood vessels:
- Arteries
o Carry blood from heart to organs
- Arterioles
o Branched arteries in organs
- Capillaries
o Microscopic vessels with thin porous walls
o A network is called capillary beds and they infiltrate tissues
o At the end, they converge to venules which converges to veins, which carry
blood back to the heart
!! Arteries and veins are also distinguished by the direction in which they carry blood !!
The only exceptions are portal veins which transport between pairs of capillary beds.
The heart chamber that receives blood is called the atrium, the other chamber is called
ventricles.
There are different kinds of circulation:
- Single circulation is circulation in which blood travels through the body and returns
to its starting point in a single circuit.
o Two chambers atrium and ventricle
o In sharks, rays and bony fish
o When they swim, muscle contraction and relaxation help accelerate the
relatively sluggish pace of circulation
, - Double circulation is a circulation with two circuits of blood flow
o In amphibians, reptiles and mammals
o Pumps for two circuits are combined in one organ heart
o Right side pumps O2-poor blood to capillary beds of gas exchange tissues
in most vertebrates this is called the pulmonary circuit (pulmo = lung), in
most amphibians it is called the pulmocutaneous circuit because it takes
place in both the lungs and skin.
o Left side (systemic circuit) pumps oxygen rich blood to tissues, the oxygen
poor blood returns to the heart.
43.2
Systole is the contraction phase of the cardiac cycle, and diastole the relaxation phase.
Atrial and ventricular diastole atrial systole and ventricular diastole ventricular systole
and atrial diastole
The volume of blood each ventricle pumps per minute is called the cardiac output and it
depends on the heart rate and the stroke volume.
Atrioventricular (AV) valve lies between each atrium and ventricle, semilunar valves are
located at the two exits for the heart.
The sinoatrial (SA) node or pacemaker is a cluster of cells that coordinate the contractions in
the heart. Impulses from the SA first rapidly spread through the walls of the atria and after
that they reach the atrioventricular (AV) node, a group of cells which form a relay point.
Then they are conducted to the heart apex and conducted through bundle branches and
Purkinje fibers.
An increase of 1 degrees Celsius raises the heart rate by about 10 beats per minute.
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