1. Circulation and Gas Exchange
Chapter 42
Circulation and Gas Exchange

2. Diffusion alone is not enough!
I. Circulation
Diffusion alone is not enough!

3. A. Invertebrates Gastrovascular Cavity - jelly fish and planarians
- bring into g.v.c. and diffuses in
Open Circulatory System
- blood (hemolymph) bathes organs directly through sinuses
Closed Circulatory System
- blood kept in vessels and stays separate from interstitial fluid
- heart pumps the blood

5. All have a closed circulatory system
B. Vertebrates
All have a closed circulatory system

6. 1. Components Heart – one or two atria and one or two ventricles
Arteries – carry blood away from the heart and lead to arterioles
- 3 layers / connective tissue, smooth muscle, and endothelium
- thick middle and outer layers
- blood flows fastest through the arteries

8. 1. Components Veins – carry blood to the heart and lead to venules
- same three layers / thinner middle layer
- one way check valves
Capillaries – connect arterioles and venules
- 2 thin layers
- allow diffusion to occur

10. 2. Types of Circulatory Schemes
Fish
- one atrium and one ventricle
- gill circulation / from ventricle to gills and capillaries
- systemic circulation / from gills to body and back to atrium

12. 2. Types of Circulatory Schemes
Amphibians (some reptiles)
- 2 atria, one ventricle
- pulmocutaneous circulation / from ventricle to lungs and skin, back to left atrium
- systemic circulation / from ventricle to body, back to right atrium
- double pump system

14. 2. Types of Circulatory Schemes
Mammals / Birds / Crocs
- 2 atria and ventricles
- double pump / right side only unoxygenated, left oxygenated
- pulmonary and systemic circuit

16. 3. Human Heart
4 valves
- 2 arterioventricular / tricuspid (R), mitral (L) / “Lub”
- 2 semilunar / pulmonary (R), aortic (L) / “Dub”
- Ventricles thicker than atria
- Know the pathway! Let’s review it!

19. 3. Human Heart Cardiac Cycle - one complete pumping and filling
- contraction is systole / relax is diastole
Heart Beat Rhythm
- sinoatrial (SA) node (pacemaker) are cells in the wall of the right atrium that sends rhythmic signal to atrioventricular (AV) node between the right atrium and ventricle which contracts the ventricles .1 seconds later
- ECG picks that up

21. 4. Blood Flow and Pressure
- blood flows slower through capillaries because they spread out over a large area
- precapillary sphincters and muscle move blood through the capillaries
- muscles push blood back up the veins
Pressure
- systolic pressure – higher from contraction of ventricles (120)
- diastolic pressure – lower from relaxing (80)

24. 5. Lymphatic System
Fluid is lost through capillary clefts and is regained by lymphatic system
Lymph drains into the circulatory system near the vena cava and right atrium

25. 6. Blood Specialized only in closed circulatory system organisms
Plasma – water and proteins (antibodies, fibrinogens)
RBC / Eurythrocytes – oxygen transport, biconcave, no nuclei or mitochondria, hemoglobin
WBC / Leukocytes – fight infection

26. 6. Blood Platelets – fragments for clotting
- fibrinogen → fibrin / clotting factors
Differentiation of Blood Cells
- develop from pluripotent cells
- What is erythropoietin?

27. 7. Cardiovascular Diseases
Heart attack
Stroke
Atherosclerosis (plaque)
Arteriosclerosis (hardens)
Hypertension

28. II. Gas Exchange - Respiratory Medium – source of oxygen
- Respiratory Surface – part where gases are exchanged
- Gills, tracheae, lungs are the most common respiratory organs

29. A. Gills Outfoldings of the body Ventilation – “waft” water over gill
Countercurrent Exchange

32. B. Tracheal Systems Used in air More oxygen in air
Air requires less ventilation
Lose oxygen through evaporation
Series of tubes open to outside
Body movements act as lungs

34. C. Lungs
Work with circulatory system to move oxygen and carbon dioxide around

35. 1. Mammal Lungs
Nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli
Alveoli
- site where gas exchange occurs
- covered in surfactants which lower surface tension in the alveoli
Breathing – ventilating lungs
- negative pressure breathing / How does it work?
- always retain a residual volume of air
- birds have multiple air sacs
- medulla controls breathing by “watching” the pH / carbonic acid lowers the pH

37. 2. Transporting Gases
Respiratory Pigments – hemoglobin (Fe) / hemocyanin (Cu)
CO2 Transport – 7% plasma, 23% hemoglobin, 70% bicarbonate (dissociates into H+ and bicarbonate ion)

39. World’s Ugliest Dog