1. AP Biology Presentation Chapter 42
Circulation and Gas Exchange
By: Joe D’Ambrosia

2. 42.1 Circulatory Systems Reflect Phylogeny
Invertebrate Circulation
Hydras & other cnidarians
Have gastrovascular cavities,
Serves both digestion and distribution of substances
Open and Closed Circulatory Systems
Overcome the limitations of diffusion
3 basic components –
blood
blood vessels
heart
Open system bathes organs directly in blood
Closed system blood confined to vessels separate from interstitial fluid

3. 42.1 Circulatory Systems Reflect Phylogeny
Survey of Vertebrate Circulation
Vertebrates
Closed circulatory systems
Called cardiovascular systems
Fishes
Gill circulation
Systemic circulation
Amphibians
Pulmocutaneous circuit
Systemic circuit
Reptiles (minus birds)
Pulmonary & systemic circuit
Ventricle divided by a septum
Mammals & Birds
Heart divided into right and left chambers

4. Vertebrate Circulatory Systems
Fish Circulation
Amphibian
Circulation
Reptile Circulation
Mammal
Circulation
Diagrams of
Vertebrate Circulatory Systems

5. 42.2 Double Circulation in Mammals depend on the heart
Mammalian Circulation: the pathway
Right ventricle pumps blood to lungs
Blood picks up O2 and rids CO2, the O2 blood goes to left atrium
Left ventricle pumps blood to body tissues through systemic circuits
Blood leaves left ventricle via aorta to supply blood to heart, head arms, abdomen and legs
O2 poor blood leaves upper body through anterior vein posterior vein drains blood from lower body
Both veins dump blood in right atrium

6. 42.2 cont.. The Mammalian Heart Cardiac Cycle – complete sequence
Systole – contraction phase
Diastole – relaxation phase
Atrioventricular valve (AV)
Between atrium and ventricle
Keeps blood from flowing back into the atria
Semilunar valves
Located at heart exits;
where aorta leaves left ventricle and pulmonary artery leaves right ventricle

7. 42.2 cont.. HEART DIAGRAM Maintaining Heart’s Rhythmic Beat
Sinoatrial (SA) node (aka pacemaker)
sets rate and timing of cardiac muscles
SA impulses ensure the atria empty completely before the ventricles contract
Impulses produce electrical currents
Conducted through bodily fluids
Recorded as electrocardiogram
SA node sets the tempo for the entire heart
Influenced by nerves hormones & body temperature
HEART
DIAGRAM

8. 42.3 Physical Principles Govern Blood Circulation
Blood Vessel Structure & Function
Circulatory system consists of network of blood vessels
Outside layer of vessels are elastic
Middle layer contains smooth muscle & elastic fibers
Endothelium lines all blood vessels to minimize resistance of blood flow
Blood Flow Velocity
Blood travels like fluid through a pipe
following the law of continuity
Blood flow is faster in arteries than capillaries – why?
blood travels through one artery faster than an entire cross-section of capillaries

9. 42.3 Physical Principles Govern Blood Circulation
Blood Pressure
Force
Hydrostatic pressure drives fluids thru pipes
Pushes fluid from high to low pressure areas
Blood pressure is greater in arteries than veins
Ventricular systole
Heart contracts
Blood pressure is highest in the arteries
Peripheral resistance
Walls of arteries snap back during diastole
Heart contracts before pressure of arteries is relieved

10. 42.3 Physical Principles Govern Blood Circulation
Capillary Function
5-10% of body’s capillaries have blood flowing through them at one time
Each tissue has many capillaries so blood is supplied at all times
Two mechanisms to regulate capillary bed blood distribution
Contraction of the smooth muscle layer decreases blood flow to capillary bed
Precapillary sphincters control the flow of blood between arterioles and venules

11. Fluid Return by Lymphatic System
Lymphatic system – system that returns lost fluid and proteins to the blood
Fluid inside the lymphatic system is called lymph (composition same as interstitial fluid)
Lymph nodes along lymph vessel and filter the lymph and attack viruses & bacteria
Lymphatic system helps defend against infection & maintains volume & protein concentration of blood

12. 42.4 Blood is Connective Tissue with Cells Suspended in Plasma
Blood Composition and Function
Plasma – cells suspended in a liquid matrix
About 90% water, rest are solutes
Blood electrolytes maintain osmotic balance
Plasma proteins –
buffers for pH changes,
maintain osmotic balance,
contribute to bloods thickness
Also contains nutrients, metabolic wastes, respiratory gases, and hormones

13. 42.4 Blood is Connective Tissue with Cells Suspended in Plasma
Cellular Elements
Red blood cells transport O2
White blood cells defense
Platelets involved in clotting process
Red blood cells = most numerous
Hemoglobin – iron-containing protein transports O2
5 major white blood cells:
Monocytes
Neutrophils
Basophils
Eosinophils
Lymphocytes
Platelets = fragments of large cells in bone marrow & contribute to process of blood clotting

14. 42.4 Blood is Connective Tissue with Cells Suspended in Plasma
Stem Cells and Replacement of Cellular Elements
Stem cells
Located in red marrow of bones
Develop red and white blood cells and platelets
Erythropoietin
Hormone from the kidney that simulates the production of erythrocytes if tissues not receiving enough O2
Blood Clotting
Fibrinogen = sealant in its inactive form
Fibrin
Assembles into threads that help form the clot
Active form
Platelets release factors that transforms fibrinogen to fibrin

15. 42.4 Blood is Connective Tissue with Cells Suspended in Plasma
Cardiovascular Disease
Disorders of the heart and blood vessels
develop genetically or non-genetically
Bad cholesterol
(low-density lipoproteins)
can clog the arteries,
Good cholesterol
(high-density lipoproteins)
Help reduce bad cholesterol
Heart attack
Death of cardiac muscle tissue due to blockage of arteries
Stroke
Death of nervous tissue in the brain from blockage of arteries in the head

16. 42.5 Gas Exchange across Respiratory Surfaces
Uptake of O2 from environment
Discharge of CO2 to environment
Respiratory medium
The source of O2
Air for land animals
Water for aquatic animals
Respiratory surface
Part of an animals body where gases are exchanged with the surrounding environment

17. 42.5 Gas Exchange across Respiratory Surfaces
Gills in Aquatic Animals
Outfoldings of the body surface
that are suspended in the water
Ventilation increases the flow of the respiratory medium over the respiratory surface
Tracheal Systems in Insects
Made up of air tubes that branch throughout the body
The tracheae open outside and fine branches exchange gas to nearly every cell
Lungs
Restricted to one location, connected to body by circulatory system
Size & complexity are correlated with animal’s metabolic rate

18. 42.6 Breathing Ventilates the Lungs
Alternate inhalation and exhalation of air
How an Amphibian breathes
Ventilate lungs by using positive pressure breathing
How a Mammal breathes
Ventilate lungs by using negative pressure breathing
How a Bird breathes
Birds have both lungs & air sacs
Birds have Para bronchi instead of alveoli, allows air to flow in one direction and renews it
Control of Breathing in Humans
Breathing control centers located in brain, the medulla oblongata and the pons
Aided by the pons, the medulla sets basic breathing rhythm

19. 42.7 Respiratory Pigments Bind/Transport Gases
The Role of Partial Pressure Gradients
Gases diffuse down pressure gradients in the lungs & other organs
Gas always diffuses from high partial pressure region to lower on
Respiratory Pigments
Respiratory pigments –
certain proteins that circulate in the blood
bind to O2
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