Card Set Information
Lecture 3: Circulation & Gas Exchange
the pressure exerted by a articular gas in a mixture of gases
Describe Tracheal System
consists of tiny branching tubes that penetrate the body
Respiratory and circulatory systems are separate
Instead of taking oxygen in and transporting it to cells that need it, they have a series of tubes/canals that brings the air to the cell
Gas diffusion increases with _____ and decreases with ______
increases with surface area
decreases with distance
Gills have large ____ and small _____
large area, small distance
Requirements of gills
circulate water to exchange gases
In water the solubility of gases
is lower than it is in air
Why is countercurrent exchange used in fishes/underwater?
to maximize efficiency of extracting oxygen
flow in same direction
as they most left-right, start to equilibrate
but only 50% of ink/gas is extracted
flows in opposite directions
100% of ink/gas is extracted this way
much more efficient
an infolding of the body surface
Circulatory system of birds
they never stop breathing
unidirectional flow of air
: clean and dirty air do not mix
How does a mammal breathe?
inhale air, rib cage expands
exhale air, rib cage gets smaller
What kind of breathing do mammals have?
discontinuous breathing (unlike birds)
Open circulatory system
circulatory fluid bathes all the cells, taken up by heart and pumped throughout body
Closed circulatory system
fluid never leaves the body, travels from one organ to the next
What is the advantage of a closed circulatory system over an open one?
this system has pressure, which allows heart to be able to overcome gravity
pumps to head and forces blood to come back from feet
Single Circulation vs. Double circulation
single— blood only passes through heart once
double— two pumps, blood goes out of heart, goes up to lungs, comes back, pressurized by heart again, and travels at high pressure throughout the rest of the body
Amphibians are special because they have (advantage)
3 chambered heart instead of 2
advantageous because it allows them to divert blood where need when they are underwater
Purpose of valves in the heart?
help keep the blood where it should be
due to amount of pressure generated, don’t want blood to travel backwards anywhere you don’t want it
How does the heart work?
by contracting/squeezing itself
Cardiac output (and what it depends on)
volume of blood pumped into the system circulation per minute
Depends on both heart rate and stroke volume
number of bets per minute, aka pulse
amount of blood pumped into a single contraction
If stroke volume is lower than usual and you need same amount of cardiac output, what happens?
heart rate is increased
Pacemaker is regulated by?
sympathetic (speeds up) and parasympathetic (slows down) divisions
3 types of blood vessels
Structural difference between arteries and veins
arteries have a lot of muscle surrounding them, whereas veins do not have that much muscle around them
What are capillaries?
smallest blood vessels that connect arterioles and venules
How are arteries and veins different?
Arteries carry blood away from heart, veins bring blood back to heart
Area vs. Speed vs. Pressure in Capillaries
Huge surface area
Speed is very slow - same amount of blood is being distributed into many capillaries, needs to be slow to equilibrate
Pressure decreases gradually as area decreases
at lower pH, hemoglobin ________
releases more oxygen
What happens when hemoglobin picks up CO2
reacts with water, acidifies the blood
(the more CO2, the more acidic the blood becomes)
What is the Bohr shift?
when CO2 produced during cellular respiration lowers blood pH and decreases affinity of hemoglobin for O2
so hemoglobin retains less O2 at lower pH
Why/how do fetus’ steal oxygen from their mothers?
Because fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin does
How does the body measure how much CO2 is in our body?
by looking at the pH
Describe process of acclimatization when there is low oxygen present?
Low oxygen, high CO2, pH drops
pH sensors in blood/fluids detect that
trigger a response (breathe more deeply to bring in more O2 and release more CO2 until pH returns to normal)
What does the hemoglobin dissociation curve show?
how much oxygen hemoglobin can carry at a particular partial pressure concentration
The partial pressure of oxygen is maximal in ____ and minimal in ______
lungs, tissues at rest