V. Heart and Circulation/Transport 			

	A. Internal transport is necessary in larger organisms

		1. Diffusion and active transport 
		
			a. can deliver O2, H2O, nutrients, and remove wastes

			b. only a short distance
			
				i. a few cell layers

				ii. ok for single cell organisms
				    and very small multicellular
	
		2. Larger distances and higher metabolic rates
		
			a. require specialized adaptations for transport
				using
				i.  capillary action  
				and
				ii. hydrodynamic peristaltic propulsion
	
	B. Separated Transport O2:CO2:H2O:nutrients:wastes

		1. Plants and Insects separate gas exchange
		
			a. stomata and tracheae: local diffusion
			
		2. Plants also separate H2O and nutrient delivery
		
			a. Transpiration - H2O
			
				i. H2O from soil ð leaf ð atmosphere
				
				ii. Xylem
				
					(1) tracheids conduct water upward
					
						(a) vertically cylindrical cells
						
						(b) open or perforated on the ends
					
					(2) form a continuous H2O stream from roots 
					    to leaves
					
						(a) upward along H2O potential gradient  
						
						(b) H2O diffuses to vascular bundle
						    in the center of the root & xylem
							
						(c) soil & roots have highest H2O potential
						
						(d) leaves have the lowest
						    due to evaporation
						
						(e) evaporation at stomata pulls H2O
						    from xylem
						
							(i) by cohesion
							    of H2O molecules
							
							(ii) pull creates tension
							    (negative pressure)
							
						(f) evaporation + cohesion + tension ð
						    ð H2O pressure gradient
				
				iii. 2° xylem = wood 
				
					(1) supports plant
					
					(2) stores waste
			
			b. Translocation - nutrients
			
				i. sugars and organic molecules
				
				ii. Phloem conducting cells = sieve-tube members
				
				iii. movement by bulk flow
				
					(1) sugar/solute moved into sieve-tube
					
						(a) active transport
						
							(i) uses ATP (energy)
					
					(2) H2O follows solutes
					
						(a) along [gradient] = low H2O potential
					
					(3) excess H2O ð positive pressure
					
					(4) pressure gradient moves solution 
					
						(a) toward areas not rich in sugars
						    and organic molecules
						
						(b) and storage areas
	
	C. Fused Transport systems
			
		1. Circulatory Systems move gases, nutients and waste
		
			a. plus hormones, immune cells and antibodies
			
			b. in an aqueous medium (blood)
			
		2. Open Circulatory Systems
		
			a. Blood directly bathes internal tissues
			
				i. delivering nutrients and absorbing wastes
				
				ii. blood flows in spaces (sinuses)
				
					(1) hemolymph
				
				iii. moves sluggishly from anterior to posterior
				
			b. insects, crustaceans
				
				i. do not rely on blood for O2 transport or CO2 removal
					
					(1) tracheal system
			
			c.  Heart contraction forces blood into the head region
			
				i. reduced circulatory system 
				
					(1) primarily consisting of a longitudinal tube 
					
						(a) contractile and functions as a heart

   					(2) dorsal tube runs longitudinally
					    through thorax and abdomen

  				ii. Open ended: Posterior valved openings (ostia)  

					(1) directional flow


		3. Closed: unidirectional circuit of vessels
		
			a. one-way blood movement facilitates transport
			
				i. modulated by one-way valves
			
			b. vasculature includes muscular wrapping 
			
				i. muscular tube can produce peristaltic contractions
				
					(1) Ý blood pressure
					
						(a) pressure ð movement
					
		4. folded muscular vaculature ð heart
		
			a. regular directional contractions
			
			b. reliably Ý pressure ð blood movement


	D. the Heart of Vertebrate Circulation

		1. Blood enters R atrium
		
			a. low O2
			
				i. high CO2
			
			b. sinoatrial (SA) node = pacemaker
			
				i. autogenic = myogenic = spontaneously fire
				
				ii. fastest depolarization cycle ð pacing
				
				iii. rapidly travels across the atria
				
			c. atrioventricular (AV) node: 2nd myogenic group
			
				i. delay at AV insures that the atrial contraction is complete
				
     
		2. Blood through tricuspid valve to R ventricle
		
			a. contraction signal accelerates down bundle of His
			
				i. ð Purkinje fibers ð myocardial walls ð contraction
			
			b. blood out through semi-lunar valves out of the heart
			
			c. via pulmonary artery to lungs for oxygenation
			
				i. or to gills
			
			d. hemoglobin = four protein chains: each with a Fe++ heme group
				
				i. binding 4 molecules of O2
				
				ii. binding the first O2 is the most difficult
			
		3. Return by pulmonary veins to L atrium
		
			a. now Blood contains O2-hemoglobin-red blood cells, H20, ions,  
			   proteins, clotting proteins & platelets, antibodies and white blood 
			   cells, hormones, buffering for pH, heat 
		
		4. final contraction L ventricle
		
			a. Ventricles contract simultaneously (as a unit) 
			
			b. separation of ventricles mammals > reptiles > amphibians
		
		5. Blood passes out via dorsal aorta
		
			a. aortic semilunar valves
		
		6. Arteries: carry blood away from the heart
		
			a. muscular
			
				i. heart beat + muscular resistance - Blood Pressure
				
				ii. L ventriclular contraction ð systolic pressure
				
				iii. ventricular relaxation (diastole) elastic arterial recoil ð
				     ð diastolic pressure  left over pressure
  					    
 				iv. systolic/diastolic pressure 
							
			b. delivers blood to tissues

			
  		7. *Capillaries* - deliver O2, H2O, nutrients, hormones
		
			a. thin walled
			
				i. only place plasma may diffuse
			
			b. connect arteries and veins
			
				i. plasma + wastes diffuse back into capillaries
				
					(1) a little plasma left over
					
						(a) edema

  		8. veins - back to the heart
		
			a. very little muscle
			
				i. number + flexibility - BP
			
			b. to heart via superior + inferior vena cava
			
		9. Lymphatic vessels - also back to the heart
		
			a. left over plasma collected by lymph capillary

 			b. ends one cell thickopen to lymph pressure
			
			c. internal one-way valves
			
			d. lymph nodes contain phagocytic cells