chapter 49: circulatory systems
reptiles have a
-3-chamber heart, partially divided ventricle, 2 aortas -Pump blood to lungs & body when active —When inactive & not breathing, bypass pulmonary circuit
amphibians have a
-3-chamber heart; ventricle pumps blood to lungs & body —1 atrium gets oxygenated blood from lungs, 2nd atrium gets blood from body
crocodiles have a
-4 separate heart chambers, 2 aortas —Aortas are connected & blood flow to either circuit can be altered
fish have a
-4-chamber heart -Unidirectional blood flow —Gills to body to heart
mammals & birds have a
-4-chamber heart, separate pulmonary & systemic circuits —Systemic circuit gets blood with higher O2 content: maximizes gas exchange —Circuits can operate at different pressures
lung fish have a
-Partially divided atrium in heart -Lung picks up O2 —Separate pulmonary circuit
humans have
2 atria & 2 ventricles
Which situation is most likely to facilitate a parasympathetic response and cause heart rate and arterial pressure to decrease?
A relaxing massage
Evolutionary trend
As circulatory systems become more complex, blood that flows to gills or lungs—pulmonary circuit—is increasingly separated from blood that flows to rest of body—systemic circuit
closed circulatory systems
Blood kept separate from interstitial fluid; pumped by one or more hearts
Which feature does not characterize the circulatory system of water-breathing fishes?
Blood leaving the gills returning to the heart for additional pumping before entering the systemic circuit
Cardiac cycle
Both sides contract at the same time—first the atria, then the ventricles
Which of the following is not an advantage of closed circulatory systems?
Extracellular fluid is the same as the fluid in the circulatory system.
closed system advantages
Faster transport, Blood can be directed to specific tissues by varying blood vessel diameter, Specialized carriers take hormones & nutrients to specific sites
open circulatory system flows?
Fluid leaves vessels, filters through tissues, returns to heart through one-way valves
Which of the following is not transported in a closed circulatory system?
Hemolymph
Which statement about circulatory systems is false?
Hemolymph remains in the vessels of open circulatory systems.
In what way is a closed circulatory system more efficient than an open circulatory system?
In a closed circulatory system, blood vessels can control the delivery of O2 to specific tissues by controlling vessel diameter.
Which statement about open circulatory systems is false?
In arthropods, blood is pumped out of openings in the heart called ostia.
Which statement about respiratory adaptations is true?
In fish, water flows unidirectionally into the mouth, over the gills, and out from under the opercular flaps.
Which of these features do(es) not characterize animals without a circulatory system?
Large body size and very active
blood flow of a human heart
Right ventricle pumps blood through pulmonary circuit —Left ventricle pumps blood through systemic circuit
AP is generated in sinoatrial node which
Spreads through atria but not spread ventricles
Which of the following does not characterize open circulatory systems?
They are present in small aquatic vertebrates.
Cardiac cells are in electrical contact with each other through gap junctions
action potentials can spread rapidly
open circulatory systems inlcude:
arthropods & mollusks
AP in atria stimulates
atrioventricular node
Platelets initiate
blood clotting in response to exposed collagen in damaged blood vessels
Conducts APs to ventricles via
bundle of His, & then Purkinje fibers
(Small diameter) × (very large number) = the reason that ___________ have the greatest total cross-sectional area of all the blood vessel types.
capillaries
In vertebrates, exchange of substances between the blood and the interstitial fluid occurs in the
capillaries
The diameter of a capillary is about the same as that of a(n)
capillary
Breathing provides the body with the oxygen required to support the energy metabolism of all cells and also eliminates _______, one of the waste products of cell metabolism.
carbon dioxide
arteries
carry blood away from heart, branch into arterioles, feed into capillary beds
Neuronal & hormonal mechanisms
control vessel resistance by influencing smooth muscle cells in arteries & arterioles
Autonomic nervous system
controls heart rate by influencing rate at which resting potentials of pacemaker cells drift upward
Gas exchange in animals always involves
diffusion between internal body fluids and the outside medium.
venules
drain capillary beds, form veins, deliver blood back to heart
na+ enters more
easily then K+
mature ________ are flexible discs packed with hemoglobin
erythrocytes
A paleontologist finds a fragment of a fossilized vertebrate that indicates that the adult animal had a four-chambered heart arranged in a single circuit. The animal could have been a(n)
fish
By being aquatic, _______ are in a double bind, because their demand for oxygen increases as the temperature of their water environment increases, but the oxygen content of water declines with increasing water temperatures.
fish
6 types of vertebrate circulatory systems
fish, lungfish, amphibians, reptiles, crocodiles, mammals & birds
closed circulatory system
fluid contained in continuous system of vessels (human)
extracellular fluid
fluid in the circulatory system plus fluid around cells
open circulatory system
fluid leaves circulatory system & moves between cells
Blood pressure is _______ than osmotic pressure at the arterial end of a capillary bed, which is where the process of _______ occurs.
greater; filtration
Large artery walls
have collagen and elastin fibers; stretched during systole; have elastic recoil
hemolymph
heart moves extracellular fluid through vessels
pacemaker cells
initiate action potentials without nervous system input
In animals with a closed circulatory system, the liquid around the body cells is called
interstitial fluid.
Blood
is connective tissue of cells in extracellular fluid matrix, the blood plasma
Blood pressure
is higher at arterial end of capillary bed; fluid leaves capillary
Hematocrit
is the percent of blood that is red blood cells; normally 42-46%
Lymph nodes
make lymphocytes: remove foreign materials by phagocytosis
Norepinephrine from sympathetic nerves
makes resting potential rise more rapidly, & APs closer together
Acetylcholine from parasympathetic nerves
makes resting potential rise more slowly, & APs farther apart.
circulatory system consist of:
muscular pump, fluid, seriesof conduits
Circulatory system depends
on blood & blood vessels
Oxygen can be exchanged more easily in air than in water in part because
oxygen diffuses more slowly in water than in air.
Bone marrow stem cells make megakaryocytes that break off cell fragments called
platelets
one way valves
prevent backflow of blood
heart function depends on
properties of cardiac muscles
pulmonary veins
return oxygenated blood to left atrium
Lymphatic system
returns interstitial fluid to the blood
Capillary wall is a
single layer of endothelial cells, permeable to water, ions, & small molecules
primary pacemaker is
sinoatrial node
Right atrium get deoxygenated blood from body through two large veins
superior vena cava & inferior vena cava
In an open circulatory system,
there is no distinction between hemolymph and extracellular fluid.
capillaries
tiny, thin-walled vessels; site of exchange between blood & interstitial fluid
circulatory system
transports materials around the body; heart distributes extracellular fluid through body, transporting nutrients, respiratory gases, wastes
Atrioventricular
valves between atria & ventricles prevent backflow when ventricles contract
Blood is at its lowest pressure in the
veins
pressure drops at
venous end: fluid returns
closed circulatory systems include:
vertebrates & annelids
A platelet is activated to initiate clotting
when it encounters collagen fibers.
systole
when ventricles contract
diastole
when ventricles relax
The carcass of a newly discovered deep-diving species of whale washes up on shore, and biologists scramble to study the adaptations that allow this species to circulate blood when it is under pressure at depth. A cross section of its flipper shows what seem to be a vein and an artery running parallel. The artery would be the structure
with more muscle tissue and elastin in the wall.