1. Circulation and Gas Exchange

2. The Respiratory System
What is its function? Why is it necessary?
GETS oxygen for the body
Needed for cellular respiration
GETS RID of carbon dioxide
Produced during cellular respiration
Characteristics/Requirements of ALL Gas Exchange Mechanisms:
MOIST membranes
High surface area-to-volume ratio
An animal’s respiratory surfaces must be large enough to provide oxygen and expel carbon dioxide for the entire body

3. Respiration in Non-Mammals
Small animals (earthworms, etc.) exchange gases by diffusion across its general body surface
Gills are outfoldings of the body surface specialized for gas exchange for aquatic organisms
Blood flowing through the capillaries picks up oxygen from the water

4. Countercurrent Exchange- blood & water flow in opposite directions

5. Countercurrent Exchange (Aquatic Animals)
Countercurrent exchange allows for the efficient transfer of oxygen to the blood
As blood flows through the capillary, it becomes more and more loaded with oxygen
Steep concentration gradient allows for efficient uptake of oxygen

6. Tracheae The respiratory system used by insects
Tracheae are air tubes that branch throughout the insect body
The finest branches of the tracheae extend to the surface of nearly every cell, where gas is exchanged by diffusion

7. Lungs Lungs are found in terrestrial vertebrates
Reptiles, birds, mammals, amphibians
Lungs of mammals have a large enough surface area to carry out gas exchange for the entire body
How do the gases get from the lungs throughout the rest of the body, though??
The circulatory system transports the gases throughout the body after they’re exchanged in the lungs

8. Human Respiratory System

9. Human Respiratory System
Air enters the lungs by a system of branching ducts
Nostrils
Pharynx
Larynx
Trachea (w/ cilia)
2 bronchi
Bronchioles
Alveoli

10. Alveoli Alveoli are clusters of air sacs at the end of bronchioles
Alveoli have thin epithelium, which serve as the respiratory surface
Oxygen diffuses from the alveoli into the web of capillaries around each alveolus
The capillaries then transfer the oxygen throughout the body, via the circulatory system
ALVEOLI/CAPILLARY DIAGRAM

11. Why is the circulatory system necessary?
TRANSPORTATION!
Diffusion is not fast enough to transport chemicals throughout an animal’s body
The circulatory system transports fluid throughout the body
This solves the problem of diffusion by ensuring that no substance had to diffuse far to enter or leave a cell

12. Open vs. Closed Circulatory Systems
In open circulatory systems, hemolymph bathes the internal organs directly
Insects, arthropods, mollusks
In closed circulatory systems, blood is confined to vessels
Blood exchanges materials with the ISF bathing the cells
Earthworms, squids, octopuses, vertebrates

13. Open vs. Closed Circulatory Systems

14. Adaptations of the Vertebrate Circulatory System
Fish - Heart with 2 chambers (one atrium, one ventricle)
Amphibians (frogs)- 3-chambered heart (two atria, one ventricle)
Reptiles – (3-chambered with partial septum)
Birds/Mammals-4-chambered heart (two atria, two ventricles)

15. REPTILES (EXCEPT BIRDS) Pulmocutaneous circuit
FISHES
AMPHIBIANS
REPTILES (EXCEPT BIRDS)
MAMMALS AND BIRDS
Systemic capillaries
Lung capillaries
Lung and skin capillaries
Gill capillaries
Right
Left
Systemic circuit
Pulmocutaneous circuit
Pulmonary circuit
Systemic circulation
Vein
Atrium (A)
Heart: ventricle (V)
Artery
Gill circulation A V
Systemic aorta
Right systemic aorta
Figure 42.4
Vertebrate circulatory systems

16. Double Pump
Right side pumps to the lungs and back to left atrium (PULMONARY CIRCUIT)
Left side pumps to the entire body and returns blood to right atrium (SYSTEMIC CIRCUIT)
Oxygenated & deoxygenated blood never mix!

17. The mammalian cardiovascular system
Pulmonary
vein
Right atrium
Right ventricle
Posterior
vena cava
Capillaries of
abdominal organs
and hind limbs
Aorta
Left ventricle
Left atrium
artery
Capillaries
of left lung
head and
forelimbs
Anterior
of right lung
Figure 42.5 1 10 11 5 4 6 2 9 3 7 8

18. The Heart About the size of a clenched fist
Made up of mostly cardiac muscle tissue: striated with branches; involuntary
Atria have thin walls, ventricles have thicker walls
Why??
Ventricles must pump blood through the pulmonary & systemic circuits. (LONG DISTANCE)

19. The Heart: Structure and Function
AV Valves:
Located between each atrium and ventricle
Keep blood from flowing back into the atria
Semilunar Valves:
Located at the exits of the heart (at the bottom of each ventricle)
Prevent blood from flowing back into the ventricles

20. The Human Heart

21. Blood Vessels Arteries are thicker than veins…why??
Arteries carry blood away from the heart to organs throughout the body
Arteries are thicker than veins…why??
Thick layer of smooth muscle (nonstriated; involuntary)+ elastic tissue
Veins return blood to the heart
Categorized by direction of flow, NOT whether or not they contain oxygen
Thinner layer of smooth muscle; VALVES to prevent back flow of blood; not very elastic
Capillaries are microscopic vessels with very thin, porous walls

22. Figure 42.9 Artery Vein Basement membrane 100 µm Valve Endothelium
Arteriole
Venule
Connective tissue
Smooth muscle
Endothelium
Valve
Basement membrane
Capillary

23. Venous Transport In the thinner-walled veins
Blood flows back to the heart mainly as a result of muscle action
Figure 42.10
Direction of blood flow in vein (toward heart)
Valve (open)
Skeletal muscle
Valve (closed)

24. Capillary Exchange
The capillary wall is a single layer of flattened cells
The transfer of substances occurs between the capillaries and the interstitial fluid (which bathes the cells)
This occurs by bulk flow, the movement of fluid due to pressure
Water, sugars, salts, oxygen, and urea pass through the capillary walls

25. Capillary Exchange

26. Velocity, B. Pressure, & Area
Figure 42.11
5,000 4,000
3,000
2,000
1,000
Aorta
Arteries
Arterioles
Capillaries
Venules
Veins
Venae cavae
Pressure (mm Hg)
Velocity (cm/sec)
Area (cm2)
Systolic pressure
Diastolic pressure
50 40 30 20 10 80 60 40
The velocity of blood flow varies in the circulatory system
And is slowest in the capillary beds as a result of the high resistance and large total cross-sectional area

27. Blood Pressure Systolic pressure Diastolic pressure
Is the pressure in the arteries during ventricular systole
Is the highest pressure in the arteries
Diastolic pressure
Is the pressure in the arteries during diastole
Is lower than systolic pressure
Measured with sphygmomanometer
Normal pressure = 120/80 mm Hg

28. Control of the Heart
Cardiac muscles contract (systole) and relax (diastole) in a rhythmic cycle
The sinoatrial node (SA node), also known as the pacemaker, maintains the heart’s pumping rhythm by setting the rate at which all cardiac muscles contract

29. Control of the Heart

30. Cardiac Cycle Atria Ventricles EKG Systole Diastole P wave
Diastole Systole QRSwave
Diastole Diastole T wave

31. The cardiac cycle Figure 42.7 2 Atrial systole; ventricular diastole
Semilunar valves closed
AV valves open
AV valves closed
Semilunar valves open
Atrial and ventricular diastole 1
Atrial systole; ventricular diastole 2
Ventricular systole; atrial diastole 3
0.1 sec
0.3 sec
0.4 sec

32. The Structure of Blood
Blood is made up of plasma, red blood cells, white blood cells, and platelets
Plasma, which makes up about 55% of blood volume, is mostly water
Plasma also contains antibodies
Plasma also contains fibrinogens, proteins that act as clotting factors
Fibrinogen (inactive) is a protein in blood that is converted into fibrin (active), when needed
Thrombin is the enzyme that activates the fibrinogen. K & Ca are important minerals for clotting reaction to occur.
Hemophilia is an inherited disorder, characterized by excessive bleeding from minor cuts and bruises
People with hemophilia can die from minor cuts

33. The Structure of Blood Red Blood Cells (Erythrocytes)
The human body contains 25 trillion red blood cells
Major function is to transport oxygen
Contains hemoglobin, an iron-containing protein that carries oxygen
Red blood cells are produced in the bone marrow

34. Hemoglobin Carries Oxygen
Like all respiratory pigments
Hemoglobin must reversibly bind O2, loading O2 in the lungs and unloading it in other parts of the body
Heme group
Iron atom
O2 loaded
in lungs
O2 unloaded
In tissues
Polypeptide chain O2
Figure 42.28

35. Carbon Dioxide Transport
Small amount binds to hemoglobin to form carboxyhemoglobin.
MOST is transported as bicarbonate ion:
CO2 + H2O H2CO3H+ + HCO3-
Serves as a buffer to control pH of blood.
pH = 7.4

36. The Structure of Blood White blood cells (leukocytes)
Major function is to fight infection
5 major types
Monocytes, neutrophils, basophils, eosinophils, lymphocytes
White blood cells spend most of their time patrolling through the ISF and the lymphatic system, where most of the battles against pathogens are waged

37. The Structure of Blood Platelets (Thrombocytes)
Platelets are fragments of cells
Platelets enter the blood and function in the process of blood clotting

38. Blood: An Overview

39. Cardiovascular Disease
Cardiovascular disease (diseases of the heart and blood vessels) cause more than half of all deaths in the US
Heart attack:
Death of cardiac muscle tissue as a result of blockage of a coronary artery
Stroke:
Death of nervous tissue in the brain, resulting from blockage of arteries in the head

40. Artherosclerosis
Plaque (cholesterol and triglycerides/fats) deposit in blood vessels
Can lead to stroke or heart attack.