Transcript AP Biology Human Body Systems

AP Biology Human Body Systems
Lab 10: Physiology of the
Circulatory System
Lab 10: Physiology of the Circulatory
System
• Circulatory System—Made of
the Heart, Blood Vessels and
Blood
• Large organisms require a
transport system to distribute
nutrients and oxygen and to
remove wastes and CO2 from
cells.
Two Kinds of Circulatory Systems
• Open Circulatory System—
pumps blood into an internal
cavity called a hemocoel (or
cavities called sinuses.
• The hemocoel bathes tissues
with oxygen- and nutrientcarrying fluid (hemolymph).
• The hemolymph returns to the
heart through holes called
ostia.
• Insects and most mollusks
• Closed Circulatory System—
the oxygen- and nutrientcarrying fluid (blood) is
confined to vessels
• Annelids, certain mollusks and
vertebrates
Circulatory System in Vertebrates
• Heart—a 4-chambered organ
whose function is to circulate
blood by rhythmic
contractions
• The heart pumps oxygenated
blood from the left ventricle
out to the aorta.
Blood Vessels
• Arteries
• Vessels moving away from the
heart
• Branch into smaller vessels,
the arterioles, and then into
capillaries
• Veins
• Vessels moving toward the
heart
• Coming from capillaries, then
into larger vessels called
venules, then into veins
arteries
veins
artery
venules
arterioles
arterioles
capillaries
venules
veins
Arteries:
Built
for
their
job
•
▫ blood flows away from heart
▫ thicker walls
 provide strength
for high pressure
pumping of blood
▫ elastic & stretchable
Blood flows
toward heart
Veins: Built for their job
▫ blood returns back to heart
▫ thinner-walled
Open valve
 blood travels back to heart
at low speed & pressure
 why low pressure?
 far from heart
 blood flows because muscles
contract when we move
Closed valve
 squeeze blood through veins
▫ valves in large veins
 in larger veins one-way valves
allow blood to flow only toward heart
Structure-function relationship
• Capillaries
▫ very thin walls
▫ allows diffusion of
materials across capillary
waste
body cell
CO2
 O2, CO2, H2O,
food, waste
O2
food
Cardiac Cycle
• The cardiac or heart cycle refers to
the rhythmic contraction and
relaxation of heart muscles.
• http://highered.mcgrawhill.com/sites/0072495855/student
_view0/chapter22/animation__the
_cardiac_cycle__quiz_2_.html
• http://www.youtube.com/watch?v=
rguztY8aqpk
Blood Pressure
• Blood moving through the
blood vessels exerts pressure
against the vessel walls.
• This blood pressure is highest
in the aorta.
• It decreases as the blood
moves through the arterioles,
capillaries, venules, and veins.
Pulse
• With each contraction of the
heart, you can feel the
expansion and recoil of the
elastic arteries where they pass
near the surface of the skin.
• This is the pulse. When you
take your pulse, you measure
heart rate—the number of
times the heart contracts per
minute.
Blood Pressure—a measure of the pressure of the
blood against the wall of the blood vessel
• Two components of Blood
Pressure:
• Systolic Pressure—the pressure in
the arteries during the ventricular
contraction phase of the heart
cycle. The pressure in the vessel is
the highest at this time.
• Diastolic Pressure—the pressure in
the arteries when the ventricles are
relaxed. The pressure is at its
lowest point, but it doesn’t drop to
zero.
Measuring Blood Pressure Procedure
• http://www.phschool.com/sci
ence/biology_place/labbench/
lab10/measpr1.html
Lab 10 Procedure
• Measurement 1: Baseline—
take BP after the student has
been lying down for 5-10
minutes.
• Measurement 2: Take BP right
after standing up. The
expected change is that the BP
will increase in an effort to
overcome the force of gravity
that makes the movement of
blood through the circulatory
system more difficult.
• Measurement 3: Now the
pulse rate is taken after
standing for a few minutes.
This will provide a baseline to
compare the effects of physical
challenges on an individual’s
pulse.
• Measurement 4: The pulse rate
is taken after lying down for 510 minutes. The expected
change here is that the pulse
rate will decline when lying
down just as BP does; the force
of gravity is reduced and thus
less effort is required to move
blood through the system.
Lab 10 Procedures, Continued
• Measurement 5: The pulse rate
is taken after standing up
again. As with BP, the
expected change is that the
pulse rate will increase on
standing up, owing to gravity.
• Measurement 6: The subject
performs some type of exercise
and then immediately
measures his or her heart rate.
The subject then measures his
or her pulse every 30 seconds
after the completion of the
exercise, until the pulse has
returned to the original level
from measurement 2.
• The point of the repeated pulse
readings in measurement 6 is
to determine the “physical
fitness” of an individual. The
quicker an individual’s heart
rate and BP return to normal,
the more “fit” that individual
is.
• Following that same logic, it
takes longer for people who
are in better shape to reach
their maximum heart rate
because their hearts are
“trained” to pump out more
volume per beat.
Lab 10, Part 2: Ectothermic
Cardiovascular Physiology
• An ectothermic animal is one
whose basic metabolic rate
increases in response to
increases in temperature.
• Examples of ectothermic
animals are: all animals except
birds and mammals.
• In contrast, endothermic
animals such as birds and
mammals have body
temperatures that are
relatively unaffected by
external temperatures.
Cellular Respiration and Metabolic
Rate in Pea Plants
• In the Cellular Respiration
Lab, you experimented with
peas and saw how the rate of
oxygen consumption during
cellular respiration varied with
temperature.
• In that lab, you experimented
with peas to see how the rate
of oxygen consumption during
cellular respiration increased
with temperature.
Cellular Respiration and Metabolic
Activity in Animals
• In animals, an increase in
cellular respiration triggers
homeostatic mechanisms that
increase both breathing and
heart rate, resulting in more
oxygen being available to cells.
• In the second part of this lab,
you will study the relationship
between temperature and
metabolic activity in an
ectothermic animal.
Daphnia magna
Thermoregulation
• Thermoregulation is is the
maintenance of internal
temperatures within a range
that allows cells to function.
• It may involve both
physiological and behavioral
adaptations.
• For example, humans
thermoregulate by sweating
and shivering, dogs by
panting, and snakes by
basking on sunny rocks.
Because ectotherms' temperature
remains close to that of their
environment, they face special
challenges in thermoregulation.
Ectotherms exhibit a variety of
behaviors that allow them to gain
or lose heat.
Measuring Temperature and
Metabolic Rate
• The rate of metabolism in
ectothermic animals increases as
the environmental temperature
increases.
• This rise occurs because the
reactants in the cell have greater
thermal energy, and many
cellular enzymes are more active
as temperature increases.
What is the relationship between
• This effect is noticeable in a
metabolic rate and a 10°C increase in
range from approximately 5°C to temperature?
35°C; at temperatures much
higher than this, enzymes
become denatured.
Lab 10, Part 2 Procedure
• In this experiment, water fleas
(Daphnia), are used to
measure the effect of
temperature changes on
ectothermic animals.
• This experiment requires the
establishment of a baseline
heart rate for the animal
• After this, the temperature
should be raised in 5-degree
increments and the heart rate
recorded every 5 degrees.
• What would the expected
result be?
http://www.youtube.com/watch
?v=HhOUwlOdxkA
Because metabolic rate increases
with increasing temperature,
ectotherms do not become active
until their body has absorbed heat
and warmed up. This accounts for
the sluggish early morning
behavior of ectotherms such as
snakes.
Q10
• The relationship between
temperature and metabolic
rate is often measured as Q10.
If the metabolic rate doubles
with a 10°C increase in
temperature, then Q10 = 2.
• http://www.phschool.com/sci
ence/biology_place/labbench/
lab10/design2.html