Transcript Figure 42.5 The mammalian heart: a closer look

Internal transport in the Cnidarian
Aurelia
Open and Closed Circulatory Systems
The Mammalian Heart: A Closer Look
Generalized Circulatory Schemes
of Vertebrates
The Mammalian Cardiovascular System: An
Overview
The Heart
• Cardiac muscle
• Atria have thin walls
• Ventricles have thick and
powerful walls
• Systole = ventricular contraction
blood is pumped
• Diastole = ventricular filling
The Cardiac Cycle
•One complete
sequence of pumping
and filling
•Lub dub = heart sounds opening and
closing of the valves
–Lub = blood recoiling against the AV
valves
–Dub = blood recoiling against SL
valves
•Heart murmur = valve defect
The Control of Heart Rhythm
The Structure of Blood Vessels
Blood Pressure
• The force that blood exerts against
vessel walls
• BP is greater in arteries than veins
• Pulse is measure of BP
• Exact BP is measured as
systolic/diastolic pressures
• Constricted blood vessels have
higher BP than dilated vessels
• In veins heart has little effect on BP
Measurement of Blood Pressure
The Interrelationship of Blood Flow Velocity,
Cross-Sectional Area of Blood Vessels, and
Blood Pressure
Blood Flow in Capillary Beds
The thoroughfare
channels remain
open whether or
not the sphincter
muscles are
contracted or
relaxed
The Movement of Fluid Between
Capillaries and the Interstitial Fluid
fluid moves out of capillary
fluid moves into capillary
Lymphatic System
• Lymphatic system returns lost
fluid to circulatory system
(about 4L per day or 15% of the
fluid)
• Lymph nodes filter the lymph
and help fight infection
Differentiation of Blood Cells
5-6 million/mm3
Atherosclerosis: Normal Artery and
Artery With Plaque
• A cascade of complex reactions
converts prothrombin to thrombin and
then fibrinogen to fibrin, forming a clot
1
The clotting process begins
when the endothelium of a
vessel is damaged, exposing
connective tissue in the
vessel wall to blood. Platelets
adhere to collagen fibers in
the connective tissue and
release a substance that
makes nearby platelets sticky.
2
The platelets
form a
plug that
provides
emergency
protection
against blood
loss.
This seal is reinforced by a clot of fibrin when
3
vessel damage is severe. Fibrin is formed via a
multistep process: Clotting factors released from
the clumped platelets or damaged cells mix with
clotting factors in the plasma, forming an
activation cascade that converts a plasma protein
called prothrombin to its active form, thrombin.
Thrombin itself is an enzyme that catalyzes the
final step of the clotting process, the conversion o
fibrinogen to fibrin. The threads of fibrin become
interwoven into a patch (see colorized SEM).
Collagen fibers
Platelet
plug
Platelet releases chemicals
that make nearby platelets sticky
Fibrin clot
Clotting factors from:
Platelets
Damaged cells
Plasma (factors include calcium, vitamin K)
Prothrombin
Figure 42.17
Thrombin
Fibrinogen
Fibrin
5 µm
Red blood cell
Blood Clot
In which type of blood vessel
is the blood pressure the highest?
What type of blood vessel provides
the heart muscle with oxygen?
Name two factors which are
under your control that affect your
heart and cardiovascular
health.
What do you think is an
“ideal” blood pressure?
When is the blood blue?
After leaving the right
ventricle blood flows to . .
The heart is enclosed in a
protective sac of muscle called
the ______________.
The “pacemaker” of the heart
is. . ..
Of what three substances
are the walls of arteries,
capillaries, and veins
composed?
Oxygen and carbon dioxide are
exchanged in the lungs in vessels
called _____________.
During inhalation air passes from
the mouth through the pharynx
and into the __________.