Respiration and Circulation are coupled processes in most animals
The systems function together to exchange gases with the environment and transport them to the tissues
I. Types of Respiratory Exchange “Organs”:
A. The Body Surface –
1. Requires no respiratory system
2. Animal must be small or thin
3. Must have low oxygen /energy requirements
4. Diffusion alone accounts for gas exchange
Oxygen
Carbon Dioxide
Animals who use their body surface for respiratory exchange include
Sponges Jellyfish Flatworms (previous slide) Sea stars
B. Gills –
1. Evaginations from the body surface
2. Used by aquatic animals
Gill arch
(In mouth to oral cavity over gills and out slit)
Muscles in oral cavity serve as pump for one-way water flow, due to density of water
Animals who use gills for respiratory exchange include
Marine worms Clams and mussels Lobsters and shrimp Vertebrate fishes
(previous slide)
C. “Lungs”
Used by terrestrial animals Invaginations from the body surface to
decrease water loss Two major types –
True lungs – used by snails and slugs, vertebrates from amphibians to mammals
Tracheal system of insects
a. True lungs – localized exchange surface where oxygen is loaded into the bloodstream
Trachea with cartilaginous rings
bronchuslungBronchial tree
alveolus
oxygen Carbon dioxide
b. Trachea = system of air filled tubes that branches throughout body
Tracheole delivers oxygen to individual cells
Note unique uncoupling between respiratory and circulatory systems
D. All Respiratory Systems have the Following Things in Common –
Large surface area to maximize gas exchange
Thin exchange surfaces to maximize the rate of gas exchange
D. All Respiratory Systems have the Following Things in Common –continued Gills and true lungs are also –
Ventilated = use muscle pumps to keep oxygen rich medium in contact with the exchange surface
Perfused = use muscle pumps to move blood through the vessels at the exchange surface to keep oxygen depleted blood in contact with the exchange surface
Together these processes ensure a large concentration gradient for oxygen diffusion
II. Circulation:
A. Components-
1. The cardiovascular system = heart + blood vessels
Function = Circulates the blood to and from the tissues
Superiorvena cava
Pulmonaryartery
Capillariesof right lung
8
9
2
3
Aorta
4 510
16
Pulmonaryvein
9Right atrium
Inferiorvena cava
Right ventricle
4
8
3
Pulmonaryartery
Capillariesof left lung
Aorta
Pulmonaryvein
Left atrium
Left ventricle
27
Capillaries ofhead, chest, andarms
Capillaries ofabdominal regionand legs
Right atrium To lung
From lung
Semilunarvalve
Atrioventricular(AV) valve
Left atrium
To lung
From lung
Semilunarvalve
Atrioventricular(AV) valve
Rightventricle
Leftventricle
2. The lymphatic system = lymph vessels + lymph nodes
Functions –
-immune defense
- returns some fluid from the tissues
B. Functions of the Circulatory System1. Transport – oxygen, carbon dioxide,
nutrients, wastes and hormones in blood
2. Blood clotting – to seal breaks in vessels, uses platelets and clotting proteins
3. Protection – internal defense using the white blood cells and the lymphatic system
C. Types of Circulatory Systems
1. None –a. Only used by small animals and/or those
with low rates of oxygen use
b. Circulation occurs due to simple diffusion through the body tissues
Examples of Animals That Lack a Circulatory System
sponges (not shown) jellyfish flatworms sea stars
2.
3.
(Pump)Few vessels
(Tissue sinuses)Few vessels
Blood leaves vessels, loses pressure, thus low flow, low oxygen demand system
large vessels (arteries, arterioles)
Capillaries in tissues for exchange
(pump)
large vessels (veins)
Blood stays in vessels, thus high pressure, high flow system for high oxygen demand
Examples of Animals with an Open Circulatory System clams Crayfish, shrimp,
lobsters (not shown) insects as exception
to low oxygen use rule (remember the tracheal system)
D. The Vertebrate Circulatory System -1. Blood consists of–
a. Plasma = fluid with dissolved substances (examples – nutrients, hormones and most carbon dioxide)
b. Cells and cell fragments –1) White blood cells – defense
2) Red blood cells – oxygen transport
3) Platelets – blood clotting
2. Vertebrate hearts and circulatory patterns -Note that the evolution of the four-
chambered heart of the mammals and birds allows blood to be returned to the heart after exchanging gases at the lungs and to be pumped a second time before traveling to the tissues, needed for high oxygen demand associated with high body temperatures
Mammals and
aorta
Vena cava
Atrium = receiving chamber
Ventricle = pump
Two-chambered heart with blood pumped once; lower pressure, lower flow system
And thus blood is pumped twice for a higher pressure, higher flow system
arteries
(Pressure declines)
CO2
O2
O2CO2
Pulmonary artery
Pulmonary vein
aorta
Vena cava
Left atriumRight ventricle
Right atrium
CO2
O2
CO2
O2
Copyright © 2009 Pearson Education, Inc.
23.4 The heart contracts and relaxes rhythmically
During diastole, blood flows– From veins– Into heart chambers
During systole, blood flows– From atria– Into ventricles
Semilunarvalvesclosed1 Heart is
relaxed.
AV valvesare open.
Diastole
0.4 sec
2 Atriacontract.
Systole0.1 sec
Semilunarvalvesclosed1 Heart is
relaxed.
AV valvesare open.
Diastole
0.4 sec
2 Atriacontract.
Systole0.1 sec
Semilunarvalvesare open.
3 Ventriclescontract.
AV valvesclosed
0.3 sec
3. Generation of the heart beat – note that all cardiac cells are autorhythmic and contract on their own
Pacemaker (fastest rate of contraction) =
Electrical signals = action potentials pass due to intercalated discs
(Holds signal before passing to ventricles, connective tissue between atria and ventricles prevents immediate passage of signal