Transcript Chap 23 — CV System, Part 1

Chapter 23
Circulation
PowerPoint Lectures for
Campbell Biology: Concepts & Connections, Seventh Edition
Reece, Taylor, Simon, and Dickey
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Lecture by Edward J. Zalisko
23.1 - 23.5 INTRO TO
CIRCULATORY
SYSTEMS
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Function of CV System
 Circulatory systems facilitate exchange with all body
tissues
 All cells must
– receive nutrients,
– exchange gases, and
– remove wastes.
 Diffusion alone is inadequate for large and complex bodies.
 Circulatory systems assists diffusion by moving materials
between surfaces of the body and Internal tissues.
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Simple Gastrovascular Cavity is Found in
Cnidarians and Flatworms
 Gastrovascular cavity
serves both in
digestion and
distribution of
substances
throughout body
 This is adequate for
these organisms as
they are only two
layers of cells thick all cells can exchange
materials directly with
water.
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Cnidarians = jellyfish and hydra
Notice only one opening in/out!
polyp
medusa
Flatworms - We’re so flat because we exchange
materials directly with environment.
Only ONE entrance/exit! YIKES!!
Gastrovascular
cavity
Nerve cords
Mouth/Anus
Eyecups
Nervous
tissue clusters
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Bilateral symmetry
Small organisms have
sufficient SA:volume ratio that
they do not require a
specialized circulatory
system.
Diffusion
Mouth
Gastrovascular
cavity
Diffusion
Diffusion
Single cell
Two cell layers
Large, more complex organisms require a true
circulatory system
 True circulatory system consists of:
– circulatory fluid (blood),
– muscular pump (heart), and
– set of tubes (blood vessels) to carry the fluid.
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EXTERNAL ENVIRONMENT
CO2
O2
Food
Mouth
ANIMAL
Respiratory
system
Digestive
system
Interstitial
fluid
Heart
Nutrients
Circulatory
system
Body
cells
Urinary
system
Intestine
Anus
Unabsorbed
matter (feces)
Metabolic waste
products (urine)
But large,
complex
organisms
require true CV
system to
maintain
sufficient
SA:volume ratio
2 Types of Circulatory Systems
 Open circulatory systems are found in arthropods
and many molluscs and consist of
– a heart,
– open-ended vessels, and
– blood that directly bathes the cells and functions as the
interstitial fluid.
Pores
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Tubular
heart
Two Types of Circulatory Systems
 Closed circulatory systems are found in
vertebrates, earthworms, squids, and octopuses and
consist of
– a heart and
– vessels that confine blood, keeping it distinct from
interstitial fluid.
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Three Types of Blood Vessels Found in CV
Systems
1. Arteries carry
blood away
from the heart.
2. Veins return
blood to the
heart.
Capillary
beds
Artery
(O2-rich blood)
Arteriole
3. Capillaries
convey blood
between
arteries and
veins.
Venule
Vein
Gill
capillaries
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Atrium
Artery
(O2-poor blood)
Ventricle
Heart
Vertebrate cardiovascular systems reflect
evolution
 Closed circulatory systems may exhibit:
 In single circulation blood moves
– from gill capillaries,
– to systemic (body) capillaries, and
– back to the heart.
– Blood pressure drops significantly as blood flows thru gill capillaries
– Single circuit would never provide enough pressure to push blood
thru the lungs and rest of body in a terrestrial (land) animal.
– Characteristic of fish.
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Figure 23.2A
Gill
capillaries
Heart:
Ventricle
Atrium
Body
capillaries
Double circulation
 double circulation consists of a separate
– pulmonary circuit (heart to lungs and back to heart)
– systemic circuit (heart to body tissue and back to heart)
– Found in land animals - amphibians, reptiles, birds, mammals
– Allows for a second ‘push’ of blood returning from lungs to
provide enough pressure for blood to travel without
organism’s body.
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Figure 23.2B
Lung and
skin capillaries
Pulmocutaneous
circuit
Atrium
Atrium
Ventricle
Left
Right
Systemic
circuit
Systemic
capillaries
Four Chambered hearts are essential for
organism with high metabolic rates (energy
demands)
 Four-chambered hearts
– are found in crocodilians, birds, and mammals and
– consist of
– two atria and
– two ventricles.
–
Birds, mammals and crocodiles are warm-blooded (endotherms) and thus
require much greater rates of cellular respiration (thus more O2) to meet
energy demands
– Prevents oxygen-rich and oxygen-poor blood from mixing and keeps
pulmonary and systemic circuits completely separate
– oxygen-rich and
– oxygen-poor blood.
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Figure 23.2C
Lung
capillaries
Pulmonary
circuit
Atrium
Atrium
Ventricle
Ventricle
Right
Left
Systemic
circuit
Systemic
capillaries
THE HUMAN
CARDIOVASCULAR
SYSTEM AND HEART
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Blood flow through the human CV circuits
 Blood flow through the double circulatory system of
humans
– drains from the superior vena cava (from the head and
arms) or inferior vena cava (from the lower trunk and
legs) into the right atrium,
– moves out to the lungs via the pulmonary artery,
– returns to the left atrium through the pulmonary vein,
and
– leaves the heart through the aorta.
Animation: Path of Blood Flow in Mammals
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Figure 23.3A
8
Capillaries of
head, chest and
arms
Superior
vena cava
Pulmonary artery
Pulmonary artery
Aorta
9
Capillaries of
right lung
2
7
Capillaries
of left lung
2
3
3
5
4
10
4
Pulmonary vein
6
1
Right atrium
9
Pulmonary vein
Left atrium
Left ventricle
Right ventricle
Aorta
Inferior vena cava
8
Capillaries of
abdominal region
and legs
D1 _Pulmonary Artery (to lung)
H ___Aorta________
A1 _superior vena cava_
D2 _Pulmonary Artery
(to lung)
B _right atrium__
F left atrium
E2 Pulmonary Vein
(from lung)
E1 Pulmonary Vein
(from lung)
Note: Atria accept
blood to heart;
ventricles pump
blood out therefore have
much more
muscular walls.
Note: arteries take
blood AWAY from
heart
Veins take blood to
heart
A2 _inferior vena cava_
C _right ventricles
G _left ventricle
The Cardiac Cycle
 The repeated contraction and relaxation of pumping
blood is called the cardiac cycle. The cycle consists
of two main phases.
1. During diastole, heart relaxes and all chambers fill with
blood
2. During systole, heart contracts and blood flows
– from atria into ventricles
– Then from ventricles into arteries
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Figure 23.4_s1
Diastole
1 The heart
is relaxed.
The semilunar
valves are
closed.
All chambers
fill with blood
0.4 sec
The AV
valves are
open.
Figure 23.4_s2
Systole
Diastole
1 The heart
is relaxed.
The semilunar
valves are
closed.
2 The atria
contract.
Pushes blood into
ventricles
0.1 sec
0.4 sec
The AV
valves are
open.
Figure 23.4_s3
Systole
Diastole
1 The heart
is relaxed.
The semilunar
valves are
closed.
2 The atria
contract.
0.1 sec
3 The ventricles
contract.
0.4 sec
0.3 sec
The AV
valves are
open.
The AV valves
are closed.
Ventricles pump
Blood out thru
arteries
23.4 The heart contracts and relaxes rhythmically
 Cardiac output is the amount of blood pumped per
minute from the ventricles.
 Cardiac output = Heart rate x volume of blood pumped
with each contraction
 Heart rate = is the number of heart beats per
minute.
 Heart rate and cardiac output vary with physiological
conditions
 Athletes have high CO even with low heart rates due to
increased blood volume acquired from training
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23.5 The SA node sets the tempo of the heartbeat
 The SA (sinoatrial) node
– generates electrical signals in atria
and
– sets the rate of heart contractions.
– Called the pacemaker of the heart
– SA Node receives nervous signal
info from central nervous system
and relays these changes in heart
rate to rest of heart to coordinate
cardiac cycle and heart rate.
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1 Signals from the
SA node spread
through the atria.
SA node
(pacemaker)
Right
atrium
ECG