Download Ch. 42 Circulatory and Respiratory Systems

Ch. 42 Circulation and Gas Exchange
LO 2.25 The student can construct explanations based on scientific evidence that
homeostatic mechanisms reflect continuity due to common ancestry and/or divergence
due to adaptation in different environments.
LO 2.27 The student is able to connect differences in the environment with the
evolution of homeostatic mechanisms.
LO 4.8 The student is able to evaluate scientific questions concerning organisms that
exhibit complex properties due to the interaction of their constituent parts.
LO 4.9 The student is able to predict the effects of a change in a component(s) of a
biological system on the functionality of an organism(s).
LO 4.10 The student is able to refine representations and models to illustrate
biocomplexity due to interactions of the constituent parts.
42.1 Circulatory Systems Link Exchange
Surfaces with Cells Throughout the Body
 Every cell in your body needs resources (O2 and Glucose) and
needs to get rid of wastes (CO2 and Ammonia).
 All cells need to be in contact with the environment.
 Gastrovascular cavities containing nutrients and wastes bath all the
cells of the organism.
Circular
canal
Mouth
Gastrovascular
cavity
Mouth
Pharynx
Radial canals
5 cm
(a) The moon jelly Aurelia, a cnidarian
2 mm
(b) The planarian Dugesia, a flatworm
 Circulatory system – fluid, interconnecting vessels, and a muscular pump
(heart)
 Open – circulatory fluid (hemolymph) bathes the organs.
Fluid is released around organs when the heart contracts, and floods back into vessels
with valves when the heart relaxes.
 EX: arthropods and molluscs
 Closed – circulatory fluid (blood) stays confined to vessels.
 Blood travel out of heart’s ventricle (lower chambers) in arteries, back to heart’s
atria (upper chambers) in veins, and exchanges materials with cells in capillaries.
 EX: annelids, cephalopods, and all vertebrates

(a) An open circulatory system
(b) A closed circulatory system
Heart
Heart
Interstitial fluid
Hemolymph in sinuses
surrounding organs
Pores
Blood
Small branch
vessels in
each organ
Dorsal
vessel
(main heart)
Tubular heart
Auxiliary
hearts
Ventral vessels
Single Circulation
 Bony fish, rays and sharks
(a) Single circulation
 2 chambers (1 atrium, 1 ventricle)
 Blood flows through the heard only
once.
 A V  artery  gills  body
 vein
Gill
capillaries
Artery
Heart:
Atrium (A)
Ventricle (V)
Vein
Body
capillaries
Key
Oxygen-rich blood
Oxygen-poor blood
Double Circulation
 Amphibians, reptiles, mammals and birds.
 Blood goes to the heart twice, through 2 circulations.
 Pulmonary circuit – blood travels from (right) heart to gas exchange tissue
 Systemic circuit – blood travel from (left) heart to the body cells
Amphibians
Pulmonary circuit
Pulmocutaneous circuit
Lung
and skin
capillaries
Atrium
(A)
Atrium
(A)
Right
Mammals and Birds
Reptiles (Except Birds)
Left
Pulmonary circuit
Lung
capillaries
Lung
capillaries
Right
systemic
aorta
Left
systemic
aorta
A
A
V
V
Right
Incomplete
septum
Left
A
A
V
V
Left
Right
Ventricle (V)
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
Systemic
capillaries
Systemic
capillaries
Systemic
capillaries
Systemic circuit
Systemic circuit
42.2 Coordinated Cycles of Heart Contraction
Drive Double Circulation in Mammals
Superior vena cava
Aorta
Pulmonary artery
Pulmonary
artery
Left
atrium
Right
atrium
Semilunar
valve
Semilunar
valve
Atrioventricular
valve
Atrioventricular
valve
Right
Left
ventricle ventricle
Capillaries of
head and forelimbs
Pulmonary
artery
Capillaries
of right lung
Pulmonary
vein
Right atrium
Right ventricle
Pulmonary
artery
Aorta
Capillaries
of left lung
Pulmonary vein
Left atrium
Left ventricle
Aorta
Inferior
vena cava
Capillaries of
abdominal organs
and hind limbs
The Mammalian Heart
 Contraction phase heart is called




systole.
The relaxation phase is called
diastole.
Average cardiac output is 5L/min
at a heart rate of 72 beats/min.
The “lub-dub” sound is the sound
of blood recoiling against closed
atrioventricular valves and
semilunar valves (respectively).
A heart murmur occurs when
the valves don’t fully close,
causing blood to backflow.
2 Atrial systole and ventricular
diastole
1 Atrial and
ventricular diastole
0.1
sec
0.4
sec
0.3 sec
3 Ventricular systole and atrial
diastole
Maintaining the Heart’s Rhythmic Beat
 Sinoatrial (SA) node in the right atrium coordinates the
contraction of the other heart cells (pacemaker).
 This impulse can be seen on an electrocardiogram (ECG)
 Atrioventricular (AV) node delays the impulse to the
ventricles then sends it to have both contract at the same time.
 Controlled by sympathetic (quickens) and parasympathetic
(slows) nervous system.
1
2
SA node
(pacemaker)
ECG
AV
node
3
4
Bundle
branches
Heart
apex
Purkinje
fibers R
T
P
Q
S
Blood Pressure
 A beating heart generates high blood pressure, causing blood to flow
from the heart to the arteries.
 Ventricular contraction causes systolic pressure.
 Elastic connective tissues expand and recoil to maintain blood pressure away
from the heart once the ventricle relaxes (diastolic pressure).
 Vasoconstriction
 Increases blood pressure due to artery walls constricting
 Caused by physical or emotional stress resulting in nervous and hormonal response to
release endothelin to smooth muscle.
 Vasodilation
 Decreases blood pressure due to artery walls opening up (dilating)
 Caused by environmental or physical cues to release nitric oxide (NO).
Blood Pressure and Gravity
 Measured at same height as heart.
 Standing decreases blood pressure to the brain because it is further
from the heart and working harder against gravity.
 Apply to long necked organisms (giraffes) – need valves to slow blood
flow when the neck is bend over to take a drink.
Blood pressure reading: 120/70
1
3
2
120
120
70
Artery
closed
Sounds
audible in
stethoscope
Sounds
stop
Capillary Function
 Capillaries are the sight of exchange with the interstitial fluid.
 Some molecules move via endo- and exocytosis.
 Some molecules (O2 and CO2) can diffuse across the endothelium.
 Blood pressure tends to drive fluid out of the capillaries.
 Proteins dispersed in the blood tend to drive fluid into the
capillaries (osmotic pressure)
 Blood pressure is typically greater than osmotic pressure, particularly
close to the arteriole.
INTERSTITIAL
FLUID
Net fluid movement out
Body cell
Blood
pressure
Osmotic
pressure
Arterial end
of capillary
Direction of blood flow
Venous end
of capillary
Fluid Return by the Lymphatic System
 The lymphatic system is a network of vessels and nodes that returns fluids,
proteins and cells to the circulatory system.
 Lymph is the fluid lost by the capillaries.
 Vessels work similarly to veins (valves and muscle contractions)
 Lymph nodes filter lymph and house cells that attach pathogens (immune system).
 Found in the neck, armpits, and groin.
 Honeycomb of white blood cells that quickly divide when the body is infected.
 This causes them to swell and is why they are checked by doctors.
42.4 Blood Components Function in Exchange,
Transport, and Defense
Blood Composition
Cellular elements 45%
Plasma 55%
Constituent
Water
Solvent for
carrying other
substances
Ions (blood
electrolytes)
Osmotic balance,
pH buffering,
and regulation
of membrane
permeability
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Plasma proteins
Albumin
Fibrinogen
Number per L
(mm3) of blood
Leukocytes (white blood cells)
5,000–10,000
Separated
blood
elements
Basophils
Osmotic balance,
pH buffering
Clotting
Substances transported by blood
Functions
Defense and
immunity
Lymphocytes
Eosinophils
Neutrophils
Immunoglobulins Defense
(antibodies)
Nutrients
Waste products
Respiratory gases
Hormones
Cell type
Major functions
Monocytes
Platelets
Erythrocytes (red blood cells)
250,000–400,000 Blood
clotting
5–6 million
Transport
of O2 and
some CO2
Blood Clotting Mechanism
 Coagulation—solid clot forms
from liquid blood
 A cascade of complex reactions
converts inactive fibrinogen to
fibrin, forming a clot
 A blood clot formed within a
blood vessel is called a
thrombus and can block blood
flow
 Hemophilia—results when a
mutation causes a change in any
one of the proteins involved in
the cascade
Cardiovascular Disease
 Atherosclerosis
 Hardening of arteries by accumulating of fatty deposits due to high levels of
low-density lipoprotein (LPL)
 Heart Attacks
 Damage or death of cardiac muscle tissue resulting from blockage of one or more
coronary arteries.
 Strokes
 Death of nervous tissue in the brain from ruptured or blocked arteries in the head.
Lumen of artery
Endothelium
Smooth
1
muscle
LDL
Foam cell
Macrophage
Plaque rupture
Plaque
2
Extracellular
matrix
4
3
Fibrous cap
Cholesterol
T lymphocyte
Smooth
muscle
cell
42.5 Gas Exchange Occurs Across
Specialized Respiratory Surfaces
 Air is less dense, viscous, and has a higher concentration of O2.
 These animals do not need to be very efficient breathers
 Water is more dense, viscous, and has a lower concentration of O2.
 These animals expend a lot of energy for gas exchange.
Respiratory Surfaces
 Moist
 Large surface area and thin
 Sponges, cnidarians, and flatworms have body cells in direct contact
with environment (diffusion).
 Earthworms and some amphibians use their skin.
 Fish use gills
 Insects use trachea
 Other vertebrates use lungs
Gills in Aquatic Animals
 Outfoldings of the body surface that are suspended in the water.
 Water must move across gills for gas exchange (ventilation)




Paddle-like appendages that drive a current of water over the gills
Cilia move water over gills
Taking in and ejecting water over gills
Swimming and opening of mouth for water to pass through the pharynx, over the
gills, and out of the body.
 Countercurrent exchange for diffusion of gases and heat.
O2-poor blood
Gill
arch
O2-rich blood
Lamella
Blood
vessels
Gill arch
Water
flow
Operculum
Water flow
Blood flow
Countercurrent exchange
PO (mm Hg) in water
2
Gill filaments
150 120 90 60 30
Net diffusion of O2
140 110 80 50 20
PO (mm Hg)
2
in blood
Tracheal Systems in Insects
 Air tubes that run throughout the body.
 Tracheae open to the outside which branch into smaller tubes
which come close to every cell.
 Gas is exchanged by diffusion across the epithelium.
Mitochondria
Muscle fiber
2.5 m
Tracheoles
Tracheae
Air sacs
Body
cell
Air
sac
Tracheole
Trachea
External opening
Air
Lungs
 Localized organ which needs the circulatory system to go to cells for gas exchange.
 Air flows:
 Nose/mouth
Branch of
pulmonary vein
(oxygen-rich
blood)
 Pharynx
 Larynx (vocal cords)
Terminal
bronchiole
 Epiglottis closes esopohogous
Nasal
cavity
 Trachea (windpipe)
Pharynx
 2 bronchi (1 to each lung)
Larynx
Left
lung
Alveoli
(Esophagus)
 Bronchioles (cilia/mucous trap dirt) Trachea
 Alveoli (gas exchange)
 Leukocytes patrol and keep clean
 Smoking can overwhelm
Branch of
pulmonary artery
(oxygen-poor
blood)
50 m
Right lung
Capillaries
Bronchus
Bronchiole
Diaphragm
(Heart)
Dense capillary bed
enveloping alveoli (SEM)
42.6 Breathing Ventilates the Lungs
How an Amphibian Breathes
 Positive pressure breathing
forces (pushes) air down
the trachea.
 The lungs elastically recoil,
forcing air out (exhale)
How a Bird Breathes
 Air moves in 1 direction
across gas exchange
surface.
 Fresh air doesn’t mix with
“old” air.
Anterior
air sacs
Posterior
air sacs
Lungs
Airflow
Air tubes
(parabronchi)
in lung
1 mm
Posterior
air sacs
Lungs
3
2
Anterior
air sacs
4
1
1 First inhalation
3 Second inhalation
2 First exhalation
4 Second exhalation
How a Mammal Breathes
 Negative pressure breathing pulls air into lungs.
 The rib muscles and diaphragm contract, creating a negative pressure
in the thoracic cavity. This causes air to rush into the lung (high to low
pressure).
 When they relax, air is pushes out.
 Tidal volume is the average volume of air inhaled whereas vital
capacity is the maximum volume. Residual volume is air that is left
in the lungs after exhalation.
1
Rib cage
expands.
2
Air
inhaled.
Rib cage gets
smaller.
Lung
Diaphragm
Air
exhaled.
Control of Breathing
Homeostasis:
Blood pH of about 7.4
 Involuntary action controlled by
the medulla oblongata.
 Uses pH as an indicator of CO2
concentrations of the surrounding
tissues .
CO2 level
decreases.
Response:
Rib muscles
and diaphragm
increase rate
and depth of
ventilation.
Stimulus:
Rising level of
CO2 in tissues
lowers blood pH.
Carotid
arteries
 CO2 reaction with H2O of CS fluid
creating carbonic acid. This
dissociates into a bicarbonate ion
and H+.
Sensor/control center:
Cerebrospinal fluid
Medulla
oblongata
Aorta
42.7 Adaptations for Gas Exchange Include
Pigments that Bind and Transport Gases
 O2 transport proteins bound to a metal; called pigments because they
have distinctive colors.
 Hemoglobin
Iron
Heme
Hemoglobin
 4 polypeptide chains each with a heme group attached to iron.
 Can carry up to 4 O2
susceptible to O2.
 When pH drops, it releases more O2 (Bohr shift).
O2 saturation of hemoglobin (%)
 When 1 subunit binds to O2 the others change shape to become more
100
pH 7.4
80
Hemoglobin
retains less
O2 at lower pH
(higher CO2
concentration)
60
40
20
0
pH 7.2
0
20
40
60
80 100
PO2 (mm Hg)
(b) pH and hemoglobin dissociation
Body tissue
CO2 produced
CO2 transport
from tissues
Interstitial
CO2
fluid
Carbon Dioxide Transport
Plasma
within capillary CO2
H2O
 CO2 is not directly transported in blood.
 It dissociated into bicarbonate and H+
Red
blood
cell
Capillary
wall
CO2
H2CO3
Hb
Carbonic
acid
HCO3 
Bicarbonate
 H+ attaches to hemoglobin
HCO3
 Bicarbinate travels in plasma
HCO3
 In lungs, it recombines to for CO2 again.
HCO3 
H2CO3
Hemoglobin (Hb)
picks up
CO2 and H+.
H+
To lungs
CO2 transport
to lungs
H+
Hb
Hemoglobin
releases
CO2 and H+.
H2O
CO2
CO2
CO2
CO2
Alveolar space in lung
Respiratory Adaptations of Diving Mammals
 Apneatic mammals
 Stores more O2 in blood or attached to myoglobin proteins in
muscles for later use.
 “Turn off ” unnecessary organs and shunt blood away from them.
Putting the Two Together
1 Inhaled air
8 Exhaled air
Alveolar
epithelial
cells
2 Alveolar
spaces
CO2
O2
Alveolar
capillaries
7 Pulmonary
arteries
3 Pulmonary
veins
6 Systemic
veins
4 Systemic
arteries
Heart
CO2
O2
Systemic
capillaries
5 Body tissue
(a) The path of respiratory gases in the circulatory
system