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Circulation and Respiration
Chapter 22
The Circulatory System
• Works with other organ systems
• Maintains volume, solute concentration and
temperature of interstitial fluid
• Interstitial fluid and blood are body’s internal
environment
Blood Circulation
• Blood flows through blood vessels
• Heart generates force to keep
blood moving
• Closed system
– Blood is confined to vessels and heart
• Open system
– Blood mingles with fluid in tissues
Open and Closed Systems
aorta
heart
Fig. 22-1a, p.361
Open and Closed Systems
pump
spaces or
cavities
in body
tissues
Fig. 22-1b, p.361
Open and Closed Systems
dorsal blood vessel
two of five
hearts
ventral blood
vessels
gut cavity
Fig. 22-1c, p.361
Open and Closed Systems
pump
large-diameter
blood vessels
(rapid flow)
large-diameter
blood vessels
(rapid flow)
small-diameter blood vessels
(leisurely flow in diffusion zone)
Fig. 22-1d, p.361
Blood Flow and Gas Exchange
• Rate of blood flow varies with diameter of
blood vessels
• Slowest flow in smallest vessels, the
capillaries
• Gases are exchanged between blood and
interstitial fluid across capillary walls
Vertebrate Circulatory Systems
• Fish
– Two-chambered heart, one circuit
• Amphibians
– Three-chambered heart, two partially
separate circuits
• Birds and mammals
– Four-chambered heart, two entirely separate
circuits
Vertebrate Circulatory Systems
capillary beds of gills
heart
rest of body
a In fishes, a two-chambered heart (atrium, ventricle) pumps blood in one circuit.
Blood picks up oxygen in gills, delivers it to rest of body. Oxygen-poor blood flows
back to heart.
Fig. 22-2a, p.362
Vertebrate Circulatory Systems
lungs
right
atrium
left
atrium
heart
rest of body
b In amphibians, a heart pumps blood through two partially separate circuits. Blood
flows to lungs, picks up oxygen, returns to heart. But it
mixes with oxygen-poor blood still in the heart, flows to rest of body, returns to
heart.
Fig. 22-2b, p.362
Vertebrate Circulatory Systems
lungs
right
atrium
left
atrium
right ventricle
left ventricle
rest of body
c In birds and mammals, the heart is fully partitioned into two halves. Blood circulates in
two circuits: from the heart’s right half to lungs and back, then from the heart’s left half
to oxygen-requiring tissues and back.
Fig. 22-2c, p.362
Double Circuits
• In birds and mammals
• Right half of heart
– Pulmonary circuit
– Heart to lungs and return
• Left half of heart
– Systemic circuit
– Heart to body tissues and return
Functions of Blood
• Transports oxygen and nutrients to cells
• Carries carbon dioxide and wastes away from
cells
• Helps stabilize internal pH
• Carries infection-fighting cells
• Helps equalize temperature
Components of Blood
• Plasma
– Water
– Proteins
– Dissolved materials
• Cells
– Red blood cells
– White blood cells
– Platelets
Components of Blood
Components
Relative Amounts
Plasma Portion (50%–60% of total volume):
91%–92% of
1. Water
plasma volume
2. Plasma proteins (albumin, globulins,
7%–8%
fibrinogen, etc.
3. Ions, sugars, lipids, amino acids,
hormones, vitamins, dissolved gases
1%–2%
Cellular Portion (40%–50% of total volume):
1. Red blood cells
2. White blood cells:
Neutrophils
Lymphocytes
Monocytes (macrophages)
Eosinophils
Basophils
3. Platelets
4,800,000–5,400,000
per microliter
3,000–6,750
1,000–2,700
150–720
100–360
25–90
250,000–300,000
Fig. 22-3b, p.363
Blood Cell Development
• Stem cells in bone marrow produce blood cells
and platelets
• Body continually replaces blood cells
Blood Cell
Development
white blood cell
red blood cell
platelets
Fig. 22-3a, p.363
Erythrocytes (Red Cells)
• Most numerous cells in blood
• Transport oxygen and carbon dioxide
• Colored red by oxygen-binding pigment
(hemoglobin)
• Have no nucleus when mature
Leukocytes (White Cells)
• Function in housekeeping and defense
• Cell types
Basophils
Dendritic cells
Eosinophils
B cells
Neutrophils
T cells
Macrophages
Platelets
• Membrane-bound cell fragments
• Derived from megakaryocytes, which arise
from stem cells
• Release substances that initiate
blood clotting
Human Heart Is a
Double Pump
• Partition separates heart into left
and right sides
• Each pumps blood through a
different circuit
Pulmonary Circuit
right pulmonary artery
Heart to lungs
Oxygenates
blood
capillary
bed of
right
lung
left pulmonary artery
capillary bed
of left lung
pulmonary
trunk
(to systemic circuit)
(from
systemic
circuit)
pulmonary
veins
heart
lungs
Systemic
Circuit
capillary beds of head
and upper extremities
(to pulmonary
circuit)
(from
pulmonary
circuit)
Starts at aorta
Carries
oxygenated blood
to body tissues
aorta
heart
capillary beds of other
organs in thoracic cavity
capillary bed of liver
capillary beds of intestines
capillary beds of other abdominal
organs and lower extremities
Major Vessels
carotid arteries
jugular veins
ascending aorta
superior vena cava
pulmonary veins
hepatic portal vein
renal vein
inferior vena cava
iliac veins
femoral vein
pulmonary arteries
coronary arteries
brachial artery
renal artery
abdominal aorta
iliac arteries
femoral artery
Four Chambers
• Each side has two
chambers
– Upper atrium
– Lower ventricle
• Valves between atria
and ventricles
Major Vessels
arch of aorta
superior vena cava
Heart Anatomy
right semilunar valve
trunk of
pulmonary
arteries
left semilunar valve
left pulmonary
veins
left atrium
right pulmonary veins
right atrium
left AV valve
right AV valve
right ventricle
left ventricle
endothelium and
connective tissue
inferior vena cava
inner layer of
pericardium
septum
myocardium
heart’s apex
Cardiac Cycle
Diastole
(mid to late).
Ventricles fill,
atria contract.
Diastole
(early). Both
chambers
relax.
Ventricular
systole (atria are
still in diastole).
Ventricles eject.
Conduction and Contraction
• SA node in right atrium
is pacemaker
• Electrical signals cause
contraction of atria
• Signal flows to AV node
and down septum to
ventricles
SA node
Blood Vessels
• Arteries: carry blood
away from heart
• Arterioles: diameter is
adjusted to regulate
blood flow
• Capillaries: diffusion
occurs across thin walls
Blood Pressure
• Highest in arteries, lowest in veins
• Usually measured in the brachial artery
• Systolic pressure is peak pressure
– Ventricular contraction
• Diastolic pressure is the lowest pressure
– Ventricular relaxation
Measuring Blood Pressure
Resistance
• Adjusted at arterioles
• Vasodilation
– Increases vessel diameter
– Lowers blood pressure
• Vasoconstriction
– Decreases vessel diameter
– Increases blood pressure
100%
lungs
heart’s right half
liver
digestive tract
kidneys
skeletal muscle
brain
skin
Distribution
heart’s left half
6%
21%
20%
15%
13%
9%
5%
bone
cardiac muscle
all other regions
3%
8%
Fig. 22-10, p.367
Capillary Beds
• Diffusion zone; site of exchange between
blood and interstitial fluid
• Capillary wall is one cell thick
• Flow is slow; allows gases to diffuse across
membranes of blood cells and across
endothelium
Bulk Flow in Capillary Bed
blood to
venule
blood
from
arteriole
outward-directed
bulk flow
inward-directed
osmotic movement
cells of
tissue
Net Bulk Flow
• Normally, ultrafiltration only slightly exceeds
reabsorption
• Fluid enters interstitial fluid and returned to
blood via the lymphatic system
• High blood pressure causes excessive
ultrafiltration and results in edema
The Venous System
• Blood flows from capillaries to venules to veins
• Veins are large-diameter vessels with some
smooth muscle in wall
Vein Function
• Valves in veins prevent blood from flowing
backward
Vein Function
blood flow to heart
valve
closed
valve
open
valve
closed
venous valve
valve
closed
Fig. 22-13, p.369
Hemostasis
• Processes that stop blood loss and repair
vessels
– Blood vessel spasm
– Platelet plug formation
– Blood coagulation
– Clotting
Clotting Mechanism
• Prothrombin is converted to
thrombin
• Fibrinogen is converted to fibrin
• Fibrin forms net that entangles
cells and platelets
Hypertension
•
•
•
•
•
Blood pressure above 140/90
Tends to be genetic
May also be influenced by diet
Contributes to atherosclerosis
“Silent killer”, few outward signs
Atherosclerosis
• Arteries thicken, lose
elasticity
• Fill up with cholesterol
and lipids
• High LDL
increases risk
wall of artery, crosssection
unobstructed lumen
of
normal artery
Fig. 22-15a, p.370
atherosclerotic plaque
blood clot sticking
to plaque
narrowed
lumen
Fig. 22-15b, p.370
Coronary Artery Disease
• Atherosclerosis in arteries of heart
• Causes heart attacks
Coronary Artery
Disease
coronary
artery
aorta
coronary artery blockage
location of a shunt made of a section
taken from one of the patient’s other
blood vessels
Fig. 22-16, p.371
Risk Factors
Smoking
Genetics
High cholesterol High blood pressure
Obesity
Diabetes
Age
Gender
Respiration
• Respiration
– Physiological process by which oxygen moves into
an animal’s internal environment and carbon
dioxide moves out
• Aerobic respiration
– Cellular process, produces ATP
– Oxygen is used
– Carbon dioxide is produced
Respiratory System
• Works with the circulatory system to deliver
oxygen and remove carbon dioxide
• Also helps regulate acid-base balance
Pressure Gradients
• Concentration gradients for gases
• Gases diffuse down their pressure gradients
• Gases enter and leave the body by diffusing
down pressure gradients across respiratory
membranes
Factors In Gas Exchange
• Surface-to-volume ratio
– Small, flat animals
• Ventilation
– Adaptations enhance exchange rate
• Respiratory pigments
– Hemoglobin and myoglobin
Surface-to-Volume Ratio
• As animal size increases, surface-to-volume
ratio decreases
• Small, flat animals can use the body surface
as their respiratory surface
• Larger animals have special structures to
increase respiratory surface, such as gills or
lungs
Respiratory Surfaces
• In flat animals
CO2
O2
Fish Gills
• Usually internal
• Water is drawn in
through mouth and
passed over gills
water
flows in
through
mouth
FISH GILL
water flows
over gills,
then out
FISH GILL
water
flows into
mouth
a
mouth
closed
mouth
open
water flows
over gills,
then out.
lid
open
lid
closed
b
c
respiratory
surface
gill arch
gill
filament
direction
of water
flow
d
e
oxygenated
blood back
toward body
direction of
blood flow
oxygen-poor
blood from deep
in body
Fig. 22-18, p.372
Countercurrent Flow
• Blood flows in the
opposite direction of
water flow over the
filaments
• Enhances movement of
oxygen from water to
blood
respiratory surface
direction of
water flow
oxygenated blood
back toward body
direction of
blood flow
oxygen-poor blood
from deep in body
Vertebrate Lungs
• Originated in some
fishes as outpouching
from gut wall
• Allow gas exchange in
air and in oxygenpoor aquatic habitats
salamander
reptile
Avian Respiration
• Lungs are inelastic
and connect to a
series of air sacs
• Air is drawn
continually
though each lung
air
sacs
air
sacs
lungs
air
sacs
Mammals
Mammal
Human; adapted
to dry habitats
Fig. 22-20c, p.373
Human Respiratory System
pharynx (throat)
epiglottis
larynx (voice box)
trachea (windpipe)
pleural membrane
Bronchiole
Alveoli
intercostal muscle
diaphragm
NASAL CAVITY
ORAL CAVITY
(MOUTH)
PHARYNX (THROAT)
EPIGLOTTIS
LARYNX (VOICE BOX)
PLEURAL
MEMBRANE
INTERCOSTAL MUSCLES
TRACHEA (WINDPIPE)
LUNG (ONE OF A PAIR)
BRONCHIAL TREE
DIAPHRAGM
Fig. 22-21a, p.374
bronchiole
alveolar sac
(sectioned)
alveolar duct
alveoli
Fig. 22-21b, p.374
alveolar sac
pulmonary
capillary
Fig. 22-21c, p.374
Speech Production
• Vocal cords stretch
across laryngeal
opening; opening
between them is
glottis
• Position of cords is
varied to create
different sounds
vocal cords
glottis (closed)
epiglottis
tongue’s base
Fig. 22-22a, p.375
Breathing
• Moves air into and out of lungs
• Occurs in a cyclic pattern called the
respiratory cycle
• One respiratory cycle consists of
inhalation and exhalation
Inhalation
• Diaphragm flattens
• External intercostal
muscles contract
• Volume of thoracic cavity
increases
• Lungs expand
• Air flows down pressure
gradient into lungs
Normal (Passive) Exhalation
• Muscles of inhalation
relax
• Thoracic cavity
recoils
• Lung volume
decreases
• Air flows down
pressure gradient
and out of lungs
INWARD BULK
FLOW OF AIR
b Inhalation. The
diaphragm contracts,
moves down.
External intercostal
muscles contract and
lift rib cage upward
and outward. The
lung volume expands.
OUTWARD
BULK FLOW OF
AIR
c Exhalation.
Diaphragm,
external intercostal
muscles return to
resting positions.
Rib cage moves
down. Lungs recoil
passively.
Fig. 22-23, p.376
Active Exhalation
• Abdominal and internal intercostal muscles contract
• Contraction decreases thoracic cavity volume more
than passive exhalation
• Greater volume of air flows out to equalize
intrapulmonary pressure with atmospheric pressure
Cutaway View of Alveolus
red blood cell
air space
inside
alveolus
(see next slide)
pore for airflow
between alveoli
Respiratory Membrane
• Area between an
alveolus and a
pulmonary capillary
• Oxygen and carbon
dioxide diffuse
across easily
alveolar
epithelium
capillary
endothelium
fused
basement
membranes
of both
epithelial
tissues
Oxygen Transport
• Most oxygen is bound to heme groups in
hemoglobin in red blood cells
• Hemoglobin has higher affinity for oxygen
when it is at high partial pressure (in
pulmonary capillaries)
• Lower affinity for oxygen in tissues, where
partial pressure is low
Bicarbonate Formation
CO2 + H2O
H2CO3
carbonic acid
•
Most carbon dioxide is transported as bicarbonate
•
Some binds to hemoglobin
•
Small amount dissolves in plasma
HCO3– + H+
bicarbonate
DRY
INHAILED AIR
Partial Pressure
Gradients
160
0.03
pulmonary
arteries
40
MOIST
EXHAILED AIR
45
120
alveolar sacs
104 40
pulmonary
veins
100 40
start of
systematic
veins
40
27
start of
systemic
capillaries
45
100
cells of body tissue
less than 40
more than 45
40
Control of Breathing
• Nervous system controls rhythm and
magnitude of breathing
• Breathing is adjusted as a result of changes in
– Carbon dioxide levels
– Oxygen levels
– Blood acidity