1. Circulation
Chapters 32 and 33

2. Circulation and Circulatory Systems
heart
atria: receive blood
ventricles: pump blood
veins
vessels that transport blood back to heart
all veins carry deoxygenated blood (CO2-rich) , except those leaving the lungs
connective tissue  thin layer of smooth muscle  elastin  epithelial tissue
contain one-way valves  prevent backflow
venules
smallest veins in body  leave capillaries  join larger veins
arteries
vessels that transport blood away from heart
all arteries carry oxygenated blood (O2-rich) , except those bringing blood to lungs
connective tissue  thick layer of smooth muscle  elastin  epithelial tissue
arterioles
smallest arteries in body  merge into capillaries
capillaries
smallest blood vessels in body
thin layer of epithelial tissue
gas and nutrient exchange
capillary beds

3. blockages can be a problem in all vessels especially arteries
Fig. 32.3
Arteries, capillaries, and veins

4. Page 605 Coronary arteries and plaque

5. Some Animals Lack a Circulatory System
utilize diffusion, osmosis, or cell-to-cell transport
Invertebrate Circulatory Systems
open circulatory systems
blood enters and then leaves the vessels
after leaving, blood fills hemocoels (“blood cavities”)
saturates body tissues in blood  muscular contractions  blood returns to heart
closed circulatory systems
more efficient
blood remains in vessels
blood flows much more rapidly

6. Fig. 32.2 Open vs. closed circulatory systems

7. Vertebrate Circulatory Systems
all vertebrates have closed systems
blood
a connective tissue; 0.9% saline
formed elements (cell types) – 45%
erythrocytes (rbc’s)
transport O2 t0 body (hemoglobin)
concave shape and no nucleus
spleen
removes old rbc’s and stores wbc’s
leukocytes (wbc’s)
many different types  function in the immune system
thrombocytes (platelets)
cellular fragments that play a major role in blood clotting
all derive from hemocytoblasts in red bone marrow
plasma (a watery substance) – 55%
92% H2O, 7% proteins, 1% other solids, gases, wastes
plasma proteins
albumins, globulins, fibrinogen, prothrombin, etc.
salts, fats, glucose, amino acids, hormones, vitamins, ions, etc.
gases: extra O2, CO2
nitrogenous wastes: urea, uric acid
Fig Formed elements

8. Fig. 32.13 Composition of blood

9. blood clotting 7-10 steps; about 15 substances involved
some substances prevent accidental clotting
three major reactions
platelets form a “plug” at wound site  release thromboplastin
thromboplastin and Ca+ ions convert prothrombin to thrombin
thrombin converts fibrinogen to fibrin fibers  seal wound
the damaged cells, collagen, and other substances also help seal wound
Fig Blood clotting

10. fish
two-chambered heart
1 atrium, 1 ventricle
gas exchange across gill capillaries
amphibians and most reptiles
three-chambered heart
2 atria, 1 ventricle
systemic vs. pulmonary circuit
pulmonary: blood flow to and from lungs
systemic: blood flow to and from rest of body
the two are not completely separate
deoxygenated vs. oxygenated blood
some mixing occurs in the single ventricle
birds, crocodilians, mammals, humans
four-chambered heart
2 atria, 2 ventricles
systemic and pulmonary circuits completely separate
normally no mixing of deoxygenated and oxygenated blood

11. Fig. 32.5 Comparison of circulatory systems in vertebrates

12. Human Circulatory System
path of blood flow through body
deoxy. blood in body capillaries  body venules  body veins 
superior/inferior vena cavas  right atrium  right AV valve  right
ventricle  pulmonary semilunar valve  pulmonary artery  lung
arterioles  lung capillaries (gas exchange; blood now oxy.)  lung
venules  pulmonary veins  left atrium  left AV valve  left ventricle
 aortic semilunar valve  aorta  body arteries  body arterioles 
body capillary beds (gas & nutrient exch.; blood now deoxy.)  REPEAT
blood makes a complete circuit with every beat

13. Fig. 32.6 External view of the heart

14. Fig. 32.7 Internal view of the heart
Fig Heart valves

15. Fig Path of blood

16. control of heart contractions
unique nature of heart (cardiac) muscle
branching of muscle fibers
extrinsic control
external control outside of heart
nervous system and hormones (esp., epinephrine)
speeds up or slows down heart rate
intrinsic control
control within heart itself
sinoatrial (SA) and atrioventricular (AV) nodes
specialized regions of cells that can generate and carry electrical impulses
ventricular septum and Purkinje fibers
SA node creates impulse  walls of atria  atria contract  signal travels
to AV node  signal routed down ventricular septum in two paths 
Purkinje fibers  walls of ventricles  ventricles contract
SA node initiates heartbeat; AV signals ventricles to contract

17. Fig. 32.9 Contraction system of the heart

18. the working heart
heart beat and activity
1st sound: right and left AV valves closing
2nd sound: aortic and pulmonary semilunar valves closing
all valves prevent backflow of blood
can be monitored with an EKG (electrocardiogram)
systole vs. diastole
stroke volume vs. cardiac volume
heart rate (pulse) – average = 72 beats/minute
blood pressure
sphygmomanometer
systolic vs. diastolic pressure (mm Hg)
normal measurements (120/80)
arterioles
vasoconstriction  muscle walls thicken  increases blood pressure
vasodilation  muscle walls thin  decreases blood pressure
all gas and nutrient exchange takes place across capillaries
blood pressure lowest in veins (venous blood)
movement assisted by valves and smooth/skeletal muscle contraction

19. Fig. 32.12 Cross section of a valve in a vein

20. human circulatory circuits
circuit: a major pathway of blood flow and return
pulmonary
systemic
hepatic portal
nutrients absorbed by small intestine  travel in hepatic portal vein to liver  liver
monitors blood content and stores extra nutrients  blood enters general circulation
renal
cardiac
coronary arteries and veins
numerous ones in head and brain

21. Lymphatic System
series of small vessels that parallel circulatory system
transports lymph instead of blood
colorless, interstitial fluid that is derived from tissues
may be in tissue cells or between tissue layers
may be blood plasma that seeps into tissues
fluid moves in same fashion as venous blood  merges with circ. system
four essential functions
maintain fluid and ion balances in body
transports certain fatty acids
part of the immune system and cooperates with it
route by which interstitial fluids can return to the circ. system
structures
lymph capillaries  larger lymph vessels
lymph nodes
mass of lymphoid tissue located along the course of a lymph vessel
highly involved with immune system
lymph organs
other organs strongly associated with lymph
spleen, bone marrow, tonsils, thymus gland, etc.

22. Fig Lymphatic system

23. Fig. 33.2 Some lymphoid organs