Download Circulatory system

The circulatory system
Chapter 23
• Internal transport
• Compare the mammalian system to that of a
fish.
• Function and location of organs.
• Trace blood flow through the body.
• Study the heart beat and cardiac cycle.
• Diseases.
Announcements
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• Next weeks lab is on Circulation
The Circulatory System
Overview
• The circulatory system transports gases, nutrients,
and wastes
• Different body designs demand a heart for
pumping blood to the tissues because gravity
opposes blood circulation
• Muscles contract around the blood vessels and
work together with valves to pump blood to the
heart
• Skin and connective tissue keep blood vessels
from enlarging
Capillaries and diffusion
Fig 23.5
Capillaries and diffusion
Fig 23.1B
The circulation reaches all cells
• Diffusion is insufficient for moving
substances over large distances
• Capillaries are the smallest vessels, and
reach all cells
• RBC’s exchange materials with the
interstitial fluid.
• O2 and nutrients diffuse to the tissues and
wastes and CO2 diffuse to the blood
• Homeostasis is maintained in the blood by
the liver and kidney
Types of internal transport
Fig 23.2
Types of Internal transport
• Gastrovascular cavity
– Digestion and respiration occur in the same
cavity
– Intricately branched system that allows water to
bathe the entire system, fluid moved by flagella
– Not good in animals with thick multiple layers
of cells
Types of internal transport
Fig 23.2
What other system is here but not shown?
Types of Internal transport
• Open circulatory system
– Found in Arthropoda and Mollusca
– Blood pumped by hearts through open ended
vessels - no interstitial fluid
– Fluid is called hemolymph
– Contracts -heart pumps blood out of the sinuses
– Relaxes - heart draws hemolymph into the
circulatory system
Closed Circulatory System
Fig 23.2
Types of Internal transport
• Closed circulatory system
– Blood is confined to vessels, keeping it separate
from the interstitial fluid
– Arteries carry blood away from the heart, veins
carry blood to the heart
– Fish Gills- gill capillaries- two chambered
heart- atrium - ventricle
Evolution of cardiovascular systems
Fish vs mammal
• Fish have a single circuit of blood flow,
with the heart receiving and pumping
oxygen poor blood flow
• Mammals have two circuits, a four
chambered heart, two atria and two
ventricles
– Pulmonary right side - blood to lungs
– Systemic - left side to the body
• Double system - rapid delivery of oxygen to
support high activity
A trip through the cardiovascular
system
A trip through the cardiovascular
system
• Heart is size of fist- composed of cardiac muscle cells are electrically connected by intercalated
disks
• Atria are thin walled and receive blood, ventricles
are thick walled and pump blood.
• AV valves separate the atria and ventricles,
Semilunar valves separate the heart and the
circulation (pulmonary and systemic)
• Valves maintain flow in one direction
• Learn the flow!
Structure and function of blood vessels
Structure and function of blood vessels
• Capillaries - supply cells, thin walled, single layer
of epithelial cells and a basement membrane.
Promotes diffusion of material to and from the
interstitial fluid.
• Arteries - pressure vessels that are thick walled,
contain smooth muscle and connective tissue
• Arteioles- small vessels that control flow by
changing diameter
• Veins -capacitance vessels- hold much blood more elastic than arteries, contain valves to
prevent backflow of blood
Cardiac cycle
Cardiac Cycle
• The heart passively fills with blood, then actively
contracts pumping out blood
• Diastole- blood fills the heart while it is relaxed,
all the valves are open
• Systole- atria contact and force blood to ventricles,
ventricles contract next forcing the AV valves
closed and semilunar valves open - blood is
pumped to the body
• Lubb = closing of AV valve, Dubb=closing of
semilunar valve
• Cardiac output - amount of blood leaving heart
each beat, 75 ml per beat
Pacemaker
Pacemaker and heartbeat
• SA node or pacemaker maintains the heartrate in
the wall of the right atrium
• Generates electrical signals that travel to the atria,
then to the ventricles
• The AV node delays the signal allowing the
ventricles to fill before they contract
• The heart is regulated autonomically just like the
lungs
• A slight decrease in blood pH increased heartrate
Heart Attack
Heart Attack
•Death of cardiac cells resulting from lack of
blood delivered to the heart
•Coronary artery blockage
•Dietary influences narrow arteries, blood clots
block the arteries
•Angina
•Corrective surgery
•Coronary bypass
•Balloon angioplasty
Blood pressure and flow in arteries
Pressure declines
Velocity declines
Flow reduced from
Friction
area increased
Garden hose analogy
Blood pressure and flow in arteries
• Blood pressure - force that blood exerts against
the walls of blood vessels
• Pulse - stretching of arteries causes by pressure of
blood from the heart during systole
• Caused by pumping of heart against the resistance
of the smaller blood vessels, greatest in aorta then
decreases with distance form the heart
• Blood flow (velocity) decreases with distance
from the heart lowest in the capillaries. This
allows for maximum diffusion
Blood flow in veins
Blood flow in veins
• Pressure in the veins is near zero
• How does it return to the heart?
– Skeletal muscle pumps the veins
– Valves allow the blood to flow only to the heart
– Breathing also helps by enlarging the veins
around the heart
Measuring blood pressure
Measuring blood pressure
• Blood pressure varies throughout the body
• 120/70 - 120 @ systole and 70 during diastole
• Sphygomomanometer
– Cuff cuts off pressure, systole pushes blood through when the
pressure is reduced
– Diastole - when turbulent sounds are no longer heard
• Hypertension - a consistent BP of 140/90 or higher
– Pumping against greater resistance wears out the heart
– athlerosclerosis
Figure 23.12 Atherosclerosis: normal artery and artery with plaque
Smooth muscle controls the
distribution of blood
Smooth muscle controls the
distribution of blood
Smooth muscle controls the
distribution of blood
• Blood flow is constant to the heart and brain, but
varies in other tissues
• Constriction of the arterioles reduces flow to the
capillaries, it is controlled by nerves and hormones
• Precapillary sphincters control blood flow into
capillary beds
• Meals- capillary beds in the digestive tract receive
more blood after eating
Capillary transfer of substances
Capillary transfer of substances
Transfer of substances
• Movement across the membrane occurs by
diffusion, endocytosis, osmosis
• Capillaries are the only vessels small
enough
• Water, sugar, salt,and O2, leak through
small cracks between epithelial cells
• Blood pressure tends to actively force fluid
out of capillaries
• Osmosis tends to cause fluids to move in
• Arteries = hi pressure, veins = low pressure
Structure and function of blood
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Blood consists of cells suspended in plasma
Avg blood volume = 4-6 liters
45% cells, 55% plasma
Ions/salts maintain osmotic balance and pH
Proteins help in blood clotting and
immunity
Figure 23.14-23.15 Blood smear
Red and white blood cells
• RBC’s -erythrocytes, formed in bone
marrow
• Biconcave disk to increases surface area
• 250 million molecules of hemoglobin each
• RBC’s carry gases
• Production of RBC’s controlled by O2
levels and erythropoetin and neg. feedback
• Anemia, low iron
Red and white blood cells
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WBC’s help defend the body
Leukocytes, help defend the body
Basophils- fight infection by releasing chemicals
Phagocytes- move into body tissue and eat
bacteria and foreign proteins (neutrophils and
monocytes)
• Eosinophil -phagocytic and eat protozoans
• Lymphocytes -specific defense
Blood clotting
Figure 23.16 Blood clot
Blood clotting
• Blood contains self sealing material, activated
after injury
• Involves platelets, fibrinogin, and clotting factors
• Tissue damage exposes connective tissue to blood
• Pin pricks - platelets adhere and attract other
platelets
• Serious cuts - fibrin clot forms, thrombrin,
fibrinogin form fibrin which traps white blood
cells
• Hemophilia/ Thrombus
Stem cells
Stem Cells
• RBC’s, WBC’s and platelets all arise from stem
cells in the bone marrow
• Leukemia
– Overproduction of WBC’s (cancer)
– Interferes with gas exchange and clotting