Circulation and Gas Exchange Flashcards
Chapter 42
what are the major brain regions?
forebrain, midbrain, hindbrain
exchanges with the environment occur at what level?
cellular
in unicellular organism where do exchanges occur?
directly with the environment
what’s an example specialized exchange system in animals?
gills
what type of gills do segmented worms have
flaplike gills; extending from each segment of the body
what type of gills do some invertebrate have?
simple shape; distributed over most of the body
when are gills restricted to a local body region?
in clams, crayfish
how is the effectiveness of gas exchange increased in gills of some fishes
by ventilation and countercurrent flow of blood and water
what is diffusion proportional to?
the square of the distance (efficient over small distances)
in most animals exchange materials with the environment via what system?
fluid-filled circulatory system
what three things does a circulatory system have?
- circulatory fluid (blood)
- set of
interconnecting vessels (veins) - muscular pump (heart)
open circulatory system
insects, other arthropods, and most molluscs,
blood bathes the organs directly
in an open circulatory system, there is no
distinction between?
blood and interstitial fluid
closed circulatory system?
blood is
confined to vessels and is distinct from the
interstitial fluid
what type of system is more efficient at transport?
closed systems
what have closed circulatory systems?
annelids, cephalopods, and vertebrates
cardiovascular system?
vertebrates closed circulatory system
three main types of blood vessels?
arteries,
veins, and capillaries
blood flows how many ways in the three vessels?
one way
arteries
branch into arterioles and carry blood
away from the heart to capillaries
capillary beds
sites of chemical exchange between the blood
and interstitial fluid
venules
converge into veins and return blood
from capillaries to the heart
how are arteries and veins distinguished?
direction of blood flow
vertebrates contain how many chmabers?
2+
blood enters through an _____ and is pumped
out through a _____
atrium, ventricle
what type of heart do bony fish, rays, and sharks have?
two-chmabered
single circulation
blood leaving he heart passes through two capillary beds before returning
what organisms have double circulation?
amphibian, reptiles, and mammals
how is oxygen-poor and oxygen-rich blood are pumped?
separately from the right and left sides of the heart
pulmonary circuit
in reptiles and mammals, oxygen-poor blood flows
through the pulmonary circuit to pick up oxygen
through the lungs
pulmocutaneous circuit
in amphibians, oxygen-poor blood flows through a
pulmocutaneous circuit to pick up oxygen
through the lungs and skin
systemic circuit
oxygen-rich blood delivers oxygen throughm
cardiac cycle
heart contracts and relaxes in a rhythmic
cycle
systole
contraction, or pumping, phase
diastole
relaxation, or filling, phase
heart rate
also called the pulse, is the
number of beats per minute
stroke volume
amount of blood
pumped in a single contraction
cardiac output
the volume of blood pumped into the systemic circulation per minute and depends on both the heart rate and stroke volume
how many valves prevent backflow of blood?
four
atrioventricular (AV) valves
separate each atrium and ventricle
semilunar valves
control blood flow to the aorta and the pulmonary artery
what causes the sound of a heartbeat?
the recoil of blood against the AV valves (lub) then against the semilunar (dup) valves
heart murmur
backflow of blood through a defective valve
self-excitable cardiac muscles
contract without any signal from the nervous
system
sinoatrial (SA) node
pacemaker sets the rate and timing at which cardiac muscle cells contract
electrocardiogram (ECG or EKG)
impulses that travel during the cardiac cycle can
be recorded
atrioventricular (AV) node
AV node impulses are delayed and then trigger
Purkinje fibers that make the ventricles contract
what two divisions regulate the nervous system
sympathetic and parasympathetic
sympathetic division
speeds up the pacemaker
parasympathetic
slows down the pacemaker
what also regulates the pacemaker?
hormones and temperature
central lumen
blood vessel’s cavity
endothelium
epithelial layer that lines blood vessel (smooth and minimizes resistance)
capillaries
delicate blood vessels that exist throughout your body, have thin walls
where is the velocity of blood flow slowest
capillary beds, for exchange of materials
bloodpressure
pressure that blood exeets against the wall of a vessel
bloods flows from what areas to what other areas?
high pressure areas to low pressure areas
systolic pressure
the pressure in the arteries during ventricular systole; highest pressure in the arteries
diastolic pressure
pressure in arteries during diastole; lower than systolic pressure
vasoconstriction
contraction of smooth muscle in arteriole walls; increases blood pressure
vasodilation
relaxation of smooth muscles in the arterioles, causing BP to fall
major inducer of vasodilation
nitric oxide
blood pressure for healthy 20 year old at rest
1200 mm Hg systole
60 mm Hg diastole
what cuases fainting
inadequate blood flow to the head
what animals require higher systolic presure
those with long necks, to pump blood against greater distance against gravity
what prevents backflow in blood
one-way valves
blood flows through how many capillaries at a time?
5-10%
what two mechanisms regfulate distribution of blood in capillary beds
- contraction of smooth muscle layer in the wall of arteriole
- precapillary spinchters
precapillary sphincters
control flow of blood between arterioles and venules
difference between blood pressure and osmotic pressure?
hydrostatic pressure ensures blood circulation, whereas osmotic pressure helps exchange the necessary fluids in the body
what’s too large to pass through the endothelium?
most blood proteins and blood cells
lymphatic system
returns fluid that leaks out from capillary beds
lymph
fluid reenters circulation directly at the venous end of the capillary bed and indirectly thourhg the lymphatic system
plasma
liquid matrix which suspends cells
cellular elements occupy how much of volume of blood
45%
blood plasma is what percent water?
90% water
what are the functions of plasma proteins
lipid transport, immunity, blood clotting
leukocytes
function in defense by phagocytizing bacteria and debris or by producing antibodies
where are leukocytes
inside and outside circulatory system
platelets
fragments of cells, function in blood clotting
coagulation
formation of solid clot from liquid blood
thrombus
blood clot formed from within vessel
erhtrocytes
red blood cells, most numerous
hemoglobin
iron-containing protein that transports O2
what do birds and reptiles have that mammals lack
nuclei mitochondria
what does gas exchange supply and dispose of
supply O2 for cellular respiration, disposes of CO2
partial pressure
pressure exerted by a particular gas in mixture of gases
what surface is required for diffusion
large, moist
lungs
infolding of the body surface
air inhaled through nostrils…
warmed,
humidified, and sampled for odors
where does air pass through
pharynx, larynx, trachea, bronchi, and bronchioles
where does gas exchange occur?
alveoli
what creates sound?
exhaled air passing over the vocal chords
alveoli
air sacs at tips of bronchioles
carbon dioxide diffusion journey?
diffuses from capillaries across the epithelium and into air space
what lacks cilia and is susceptible to contamination?
alveoli
surfactants
secretions which coat the surface of the alveoli
breathing
process which ventilates the lungs
negative pressure breathing
mammals ventilation system, pulling air to the lungs
tidal volume
volume of air inhaled with each breath
breathing control centers
medulla oblongata, pons
medulla
regulates the rate and depth of
breathing in response to pH changes in the
cerebrospinal fluid
what monitors O2 and CO2 concentrations in the blood?
sensors in aorta and carotid
blood arriving in lungs
low partialP O2, hisgh partialP CO2
partialP in capillaries
partialP favors diffusion of O2 into interstitial fluids and CO2 into the blood
how many oxygen molecules can a single hemoglobin carry?
four, one for each iron-containing heme group
in addition to O2, hemoglobin also transports…?
CO2
CO2 from respiring cells diffuse where?
into the blood
and is transported either in blood plasma, bound
to hemoglobin, or as bicarbonate ions (HCO3–)
