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.