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. Ch. 42 Circulation and Gas Exchange
Slide 2
42.1 Circulatory Systems Link Exchange Surfaces with Cells
Throughout the Body Every cell in your body needs resources (O 2
and Glucose) and needs to get rid of wastes (CO 2 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 Radial canals 5 cm (a) The moon
jelly Aurelia, a cnidarian (b) The planarian Dugesia, a flatworm
Gastrovascular cavity Mouth Pharynx 2 mm
Slide 3
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 hearts ventricle (lower
chambers) in arteries, back to hearts atria (upper chambers) in
veins, and exchanges materials with cells in capillaries. EX:
annelids, cephalopods, and all vertebrates (a) An open circulatory
system Heart Hemolymph in sinuses surrounding organs Pores Tubular
heart Dorsal vessel (main heart) Auxiliary hearts Small branch
vessels in each organ Ventral vessels Blood Interstitial fluid
Heart (b) A closed circulatory system
Slide 4
Single Circulation Bony fish, rays and sharks 2 chambers (1
atrium, 1 ventricle) Blood flows through the heard only once. A V
artery gills body vein (a) Single circulation Artery Heart: Atrium
(A) Ventricle (V) Vein Gill capillaries Body capillaries Key
Oxygen-rich blood Oxygen-poor blood
Slide 5
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
AmphibiansReptiles (Except Birds) Pulmocutaneous circuit Pulmonary
circuit Lung and skin capillaries Atrium (A) Atrium (A) LeftRight
Ventricle (V) Systemic capillaries Systemic circuit Systemic
capillaries Incomplete septum Incomplete septum Left systemic aorta
LeftRight systemic aorta A A VV Lung capillaries Lung capillaries
Pulmonary circuit AA V V Left Right Systemic capillaries Key
Oxygen-rich blood Oxygen-poor blood Mammals and Birds
Slide 6
42.2 Coordinated Cycles of Heart Contraction Drive Double
Circulation in Mammals Pulmonary artery Right atrium Semilunar
valve Atrioventricular valve Right ventricle Left ventricle
Atrioventricular valve Semilunar valve Left atrium Pulmonary artery
Aorta Superior vena cava Pulmonary artery Capillaries of right lung
Pulmonary vein Aorta Inferior vena cava Right ventricle Capillaries
of abdominal organs and hind limbs Right atrium Aorta Left
ventricle Left atrium Pulmonary vein Pulmonary artery Capillaries
of left lung Capillaries of head and forelimbs
Slide 7
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 dont fully close, causing blood to backflow. Atrial and
ventricular diastole Atrial systole and ventricular diastole
Ventricular systole and atrial diastole 0.1 sec 0.4 sec 0.3 sec 2 1
3
Slide 8
Maintaining the Hearts 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. SA node (pacemaker) AV node Bundle branches Heart
apex Purkinje fibers ECG 1234 P Q R S T
Slide 9
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).
Slide 10
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:
120/70 120 70 Sounds stop Sounds audible in stethoscope 120 Artery
closed 1 2 3
Slide 11
Capillary Function Capillaries are the sight of exchange with
the interstitial fluid. Some molecules move via endo- and
exocytosis. Some molecules (O 2 and CO 2 ) 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 Blood pressure Osmotic
pressure Arterial end of capillary Direction of blood flow Venous
end of capillary Body cell
Slide 12
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.
Slide 13
42.4 Blood Components Function in Exchange, Transport, and
Defense Blood Composition Plasma 55% ConstituentMajor functions
Water Ions (blood electrolytes) Sodium Potassium Calcium Magnesium
Chloride Bicarbonate Solvent for carrying other substances Osmotic
balance, pH buffering, and regulation of membrane permeability
Plasma proteins Osmotic balance, pH buffering Albumin Fibrinogen
Immunoglobulins (antibodies) Clotting Defense Substances
transported by blood Nutrients Waste products Respiratory gases
Hormones Separated blood elements Basophils Neutrophils Monocytes
Lymphocytes Eosinophils Platelets Erythrocytes (red blood cells) 56
million 250,000400,000Blood clotting Transport of O 2 and some CO 2
Defense and immunity Functions Number per L (mm 3 ) of blood Cell
type Cellular elements 45% Leukocytes (white blood
cells)5,00010,000
Slide 14
Blood Clotting Mechanism Coagulationsolid 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
Hemophiliaresults when a mutation causes a change in any one of the
proteins involved in the cascade
Slide 15
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 Smooth muscle
Endothelium Plaque Smooth muscle cell T lymphocyte Extra- cellular
matrix Foam cell Macrophage Plaque rupture LDL Cholesterol Fibrous
cap 12 4 3
Slide 16
42.5 Gas Exchange Occurs Across Specialized Respiratory
Surfaces Air is less dense, viscous, and has a higher concentration
of O 2. These animals do not need to be very efficient breathers
Water is more dense, viscous, and has a lower concentration of O 2.
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
Slide 17
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. Gill arch
O 2 -poor blood O 2 -rich blood Blood vessels Gill arch Operculum
Water flow Water flow Blood flow Countercurrent exchange P O (mm
Hg) in water 2 150 P O (mm Hg) in blood 2 120906030 140110805020
Net diffu- sion of O 2 Lamella Gill filaments
Slide 18
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. Tracheoles Mitochondria Muscle fiber 2.5 m
Tracheae Air sacs External opening Trachea Air sac Tracheole Body
cell Air
Slide 19
Lungs Localized organ which needs the circulatory system to go
to cells for gas exchange. Air flows: Nose/mouth Pharynx Larynx
(vocal cords) Epiglottis closes esopohogous Trachea (windpipe) 2
bronchi (1 to each lung) Bronchioles (cilia/mucous trap dirt)
Alveoli (gas exchange) Leukocytes patrol and keep clean Smoking can
overwhelm Pharynx Larynx (Esophagus) Trachea Right lung Bronchus
Bronchiole Diaphragm (Heart) Capillaries Left lung Dense capillary
bed enveloping alveoli (SEM) 50 m Alveoli Branch of pulmonary
artery (oxygen-poor blood) Branch of pulmonary vein (oxygen-rich
blood) Terminal bronchiole Nasal cavity
Slide 20
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 doesnt mix with old air. Anterior air sacs Posterior air
sacs Lungs 1 mm Airflow Air tubes (parabronchi) in lung Anterior
air sacs Lungs Second inhalation First inhalation Posterior air
sacs 3 2 4 1 4 3 1 2 Second exhalation First exhalation
Slide 21
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. Rib cage expands.
Air inhaled. Air exhaled. Rib cage gets smaller. 12 Lung
Diaphragm
Slide 22
Control of Breathing Involuntary action controlled by the
medulla oblongata. Uses pH as an indicator of CO 2 concentrations
of the surrounding tissues. CO 2 reaction with H 2 O of CS fluid
creating carbonic acid. This dissociates into a bicarbonate ion and
H +. Homeostasis: Blood pH of about 7.4 CO 2 level decreases.
Stimulus: Rising level of CO 2 in tissues lowers blood pH.
Response: Rib muscles and diaphragm increase rate and depth of
ventilation. Carotid arteries Aorta Sensor/control center:
Cerebrospinal fluid Medulla oblongata
Slide 23
42.7 Adaptations for Gas Exchange Include Pigments that Bind
and Transport Gases O 2 transport proteins bound to a metal; called
pigments because they have distinctive colors. Hemoglobin 4
polypeptide chains each with a heme group attached to iron. Can
carry up to 4 O 2 When 1 subunit binds to O 2 the others change
shape to become more susceptible to O 2. When pH drops, it releases
more O 2 (Bohr shift). Iron Heme Hemoglobin (b) pH and hemoglobin
dissociation P O (mm Hg) 2 020406080100 0 20 40 60 80 100
Hemoglobin retains less O 2 at lower pH (higher CO 2 concentration)
pH 7.2 pH 7.4 O 2 saturation of hemoglobin (%)
Slide 24
Carbon Dioxide Transport CO 2 is not directly transported in
blood. It dissociated into bicarbonate and H+ H+ attaches to
hemoglobin Bicarbinate travels in plasma In lungs, it recombines to
for CO 2 again. Body tissue Capillary wall Interstitial fluid
Plasma within capillary CO 2 transport from tissues CO 2 produced
CO 2 H2OH2O H 2 CO 3 Hb Red blood cell Carbonic acid Hemoglobin
(Hb) picks up CO 2 and H +. H+H+ HCO 3 Bicarbonate HCO 3 To lungs
CO 2 transport to lungs HCO 3 H 2 CO 3 H2OH2O CO 2 H+H+ Hb
Hemoglobin releases CO 2 and H +. CO 2 Alveolar space in lung
Slide 25
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.
Slide 26
Putting the Two Together Exhaled air Inhaled air Pulmonary
arteries Systemic veins Systemic arteries Pulmonary veins Alveolar
capillaries Alveolar spaces Alveolar epithelial cells Heart
Systemic capillaries CO 2 O2O2 Body tissue (a) The path of
respiratory gases in the circulatory system CO 2 O2O2 8 1 2 3 7 64
5