2. Lecture 11 Outline (Ch. 42) I. Circulatory Systems II. Human Heart
III. Blood & Vessels
Cardiovascular disorders
V. Methods – bulk flow vs. diffusion
VII. Gas exchange and partial pressures
Breathing mechanisms
Preparation for next lecture

3. Circulation carries energy, dissolved gasses, wastes
Circulation Overview
Circulation carries energy, dissolved gasses, wastes
Connects individual cells in distant parts of body
Requirements
Blood – fluid for transport
Blood vessels – channels for transport
Heart – pump for circulation

4. Circulatory systems are open or closed
Circulation Overview
Circulatory systems are open or closed
Open- bathes organs in a hemocoel
Closed- direct vessel connections to organs
Heart
Hemolymph in sinuses
surrounding organs
Interstitial
fluid
Small branch vessels
In each organ
Blood
Dorsal vessel
(main heart)
Auxiliary hearts
Ventral vessels
(b) A closed circulatory system
(a) An open circulatory system
Tubular heart
Pores

5. Vertebrates have a closed circulatory system
Circulation Overview
Vertebrates have a closed circulatory system
More efficient
Blood is 5 – 10% of body volume
Flow is more rapid, pressure is higher
Multifunctional
Transport dissolved gasses
Distribute nutrients & hormones
Transport waste
Thermoregulation
Circulate immunodefenses
Arteries – away from heart,
Veins – toward heart

6. Bony fishes, rays, sharks
The Vertebrate Heart
Artery
Heart:
Atrium (A)
Ventricle (V)
Vein
Gill
capillaries
Body
Key
Oxygen-rich blood
Oxygen-poor blood
Set of muscular chambers
Atria collect blood
Ventricles send blood through body
The heart has evolved
Ventricle  gill capillaries: gas exchange
Blood collects - body capillaries  gas exchange
Blood returns to heart, swimming helps
Single circulation
Bony fishes, rays, sharks

7. Amphibians, reptiles, mammals
The Vertebrate Heart
Systemic circuit
Systemic
capillaries
Right
Left A V
Lung
Pulmonary circuit
Key
Oxygen-rich blood
Oxygen-poor blood
2 atria empty into 2 ventricles
Complete septum (this varies) – right side receives oxygen poor blood from body – sends to lungs
Endotherms need to deliver 10X as much dissolved gasses and nutrients/waste as same size ectotherms!
Double circulation – pulmonary circuit and systemic circuit
Amphibians, reptiles, mammals

8. 4-chambered heart: A closer look
Pulmonary artery
Right
atrium
Semilunar
valve
Atrioventricular
ventricle
Left
Pulmonary
artery
Aorta
2 pumps
Right: deoxygenated blood
Left: oxygenated blood

9. Heart Right atrium receives deO2 blood from veins Superior vena cava
Inferior vena cava
Right ventricle pumps deO2 blood to lungs through pulmonary arteries
Pumps into right ventricle

10. Heart
Oxygenated blood returns to left atrium from lungs via pulmonary veins
Oxygenated blood pumped to body through aorta
Pumps into left ventricle

11. Heart Keeping blood moving Heart valves maintain one-way flow
Atrioventricular valves
Between atria & ventricles
Semilunar valves
Between ventricles & arteries

12. Heart The Cardiac Cycle Atrial systole and ventricular diastole
0.1
sec 2
The Cardiac Cycle
Atrial and
ventricular diastole
0.4
sec 1
Ventricular systole and atrial
diastole
0.3 sec 3

13. The Cardiac Cycle & Blood Pressure
Heart
The Cardiac Cycle & Blood Pressure
Normal blood pressure ~120/70
Systolic
Ventricular contractions (higher pressure)
Diastolic
Period between contractions (lower pressure)
sphygmomanometer
“Lub-dup” sounds heard with stethoscope
Lub – blood against closed AV valves
Dup – blood against closed semilunar valves

14. Cardiac muscle contracts
Heart
Cardiac muscle contracts
Cells linked by intercalated discs
Prevents strong contractions from tearing muscle
Allows rapid spread of electrical signal for simultaneous regional contraction
Present only in the heart

15. Heart Keeping blood moving
Pacemaker cells initiate and coordinate contractions
Sinoatrial (SA) node
Primary pacemaker
Stimulates atrial contractions
Atrioventricular (AV) node
Delayed impulse received from SA node
Ventricular contraction after atrial contractions have filled them with blood (delay ~0.1 sec)

16. Blood Plasma Blood Primarily water Dissolved proteins and electrolytes
Plasma fluid
Cells
Red blood cells – transport
White blood cells – defense
Platelets – clotting

17. Red blood cells: Erythrocytes
Most abundant blood cells (over 99%)
Transport O2 and CO2
Iron-based hemoglobin protein binds to O2 and transports from areas of high concentration to low concentration

18. Erythrocytes are short-lived
Blood
Erythrocytes are short-lived
Formed in bone marrow
Lack nuclei (cannot divide or make proteins)
Dead cells are removed by liver and spleen
Iron is recycled, although some is excreted
Number of erythrocytes maintained by negative feedback

19. White blood cells: leukocytes
Less than 1% of blood cells
Disease defense
Consume foreign
particles
(macrophages)
Produce antibodies
(lymphocytes)

20. Blood Platelets Cellular fragments aid blood clotting
Ruptured cells and platelets work together to produce substances that plug damaged vessels
Scabs are platelets embedded in web of fibrin proteins

21. Blood is carried in vessels21

22. Artery
Vein
SEM
100 µm
Endothelium
Smooth
muscle
Connective
tissue
Capillary
Basal lamina
Valve
Arteriole
Venule
Red blood cell
15 µm LM

23. Blood Vessels Arteries Arteries Arterioles Capillaries Heart
Carry blood away from heart
Thick-walled:
Smooth muscle/elastic fibers
Withstand high pressure
Venules
Veins

24. Blood Vessels Arteries Arterioles Arterioles Capillaries Heart
Control distribution of blood flow
Smooth muscle expands / contracts
Under hormone / NS control
Venules
Veins

25. Blood Vessels Arterioles
Contract walls: redirects blood to heart and muscles when needed (stress, exercise, cold)
Relax walls: brings more blood to skin capillaries to dissipate excess heat
Precapillary sphincters control blood flow to capillaries

26. Blood Vessels Arteries Arterioles Capillaries Capillaries Heart
Nutrients/waste exchanged with cells:
Vessel wall one-cell thick
Blood flow very slow
Materials exit/enter via diffusion
Venules
Veins

27. Blood Vessels Arteries Arterioles Capillaries Heart Venules & Veins
Carry blood towards the heart
Thin-walled; large diameter
One-way to prevent backflow
Venules
Veins

28. Blood Vessels
Skeletal Muscle Pump:
Vein Valve:

29. Blood Vessels
Varicose veins occur if the vein valves become inefficient

30. Blood Vessels Cardiovascular Disorders:
Leading cause of death in the United States
1) Hypertension = High blood pressure
 Resistance in vessels =  work for heart
2) Atherosclerosis = Deposits (plaques) collect in vessels
Connective
tissue
Smooth
muscle
Endothelium
Plaque
(a) Normal artery
(b) Partly clogged artery
50 µm
250 µm

31. Thought Question:
If you are an athlete who trains at high elevations, what happens if you compete at a lower elevation?
At high altitudes, the lower air pressure makes it more difficult for oxygen to enter our vascular systems. 
Hypoxia usually begins with the inability to do normal physical activities, such as climbing a short flight of stairs without fatigue.  Other early symptoms of "high altitude sickness" include a lack of appetite, distorted vision, and difficulty with memorizing and thinking clearly.
More red blood cells and capillaries are produced to carry more oxygen.  The lungs increase in size to facilitate the osmosis of oxygen and carbon dioxide.  There is also an increase in the vascular network of muscles which enhances the transfer of gases.
On returning to sea level after successful acclimatization to high altitude, the body usually has more red blood cells and greater lung expansion capability than needed.  Since this provides athletes in endurance sports with a competitive advantage, the U.S. maintains an Olympic training center in the mountains of Colorado.  Several other nations also train their athletes at high altitude for this reason.  However, the physiological changes that result in increased fitness are short term at low altitude.  In a matter of weeks, the body returns to a normal fitness level. 

32. Living things process energy
Overview
Living things process energy
They need oxygen for this - Why?

33. Respiratory systems enable gas exchange
Gas Exchange Systems
Respiratory systems enable gas exchange
Bulk flow
Movement in bulk
Air/water to respiratory surface
Blood through vessels
Diffusion
Individual molecules move down concentration gradients
Gas exchange across respiratory surface
Gas exchange in tissues

34. Gas Exchange Systems Gills Aquatic gas exchange
Elaborately folded ( surface area)
Contain capillary beds
Gill size inversely related to [O2]
Large gills = low [O2]

35. Gas Exchange Systems Fish Efficiency
Dissolved O2 is < 1% of water (21% of air)
Countercurrent exchange increases efficiency

36. Reptiles & Mammals use lungs exclusively
Gas Exchange Systems
Reptiles & Mammals use lungs exclusively
Lack permeable skin
Lungs are more efficient
Especially birds!

37. Mammals Human Respiration Air enters through nose and mouth to pharynx
Larynx
(Esophagus)
Trachea
Right lung
Bronchus
Bronchiole
Diaphragm
(Heart)
Left
lung
Nasal
cavity
Air enters through nose and mouth to pharynx
Travels through larynx (voice box)
Epiglottis directs travel
Larynx contains vocal cords, which allow vocalization- exhaled air vibrates the cords, and produces sound. Stretching the cords can change pitch 37

38. Human Respiration On to the lungs Air is warmed & cleaned
Dust & bacteria trapped by mucus
Swept up and out by cilia
Trachea 
Bronchi 
Bronchioles
 Alveoli
Capillaries
Alveoli
Branch of
pulmonary artery
pulmonary vein
Terminal
bronchiole
provide enormous surface area
Surfactant keeps surface moist
Association with capillaries
Diffusion of gasses

39. Human Respiration Gas exchange is driven by differences in pressures
Exhaled air
Inhaled air
Pulmonary
arteries
Systemic
veins
Alveolar
capillaries
spaces
epithelial
cells
Heart
CO2 O2
Body tissue 8 1 2 3 7 6 4 5
Gas exchange is driven by differences in pressures
Blood from body with low O2, has a partial oxygen pressure (PO2) of ~40 mm Hg
By contrast, the PO2 in the alveoli is about 100 mm Hg
Blood leaving lungs, thus, normally contains a PO2 of ~100 mm

40. Transport of gasses CO2 Transport CO2 binds hemoglobin loosely
Dissolved in plasma
Combines with H20 to form bicarbonate (HCO3-)
More CO2 = lower pH
The Bohr Effect:
Hemoglobin binds more tightly to O2 when pH is increased and loosely when pH is decreased

41. Transport of gasses O2 Transport Binds to hemoglobin
Removes O2 from plasma solution
Increases concentration gradient; favors diffusion from air via alveoli
CO binds more tightly to hemoglobin than O2
Prevents O2 transport

42. Breathing Mechanisms Inhalation:
Rib muscles contract to expand rib cage
Diaphragm contracts (down) expands the volume of thorax and lungs
Rib cage
expands.
Air
inhaled.
exhaled.
Rib cage gets
smaller. 1 2
Lung
Diaphragm
Some air always remains in the lungs to fill alveoli and breathing tubes and prevent collapse
Thoracic cavity expands, produces negative pressure which draws air into the lungs 42

43. Breathing is involuntary
Breathing Mechanisms
Homeostasis:
Blood pH of about 7.4
CO2 level
decreases.
Stimulus:
Rising level of
CO2 in tissues
lowers blood pH.
Response:
Rib muscles
and diaphragm
increase rate
and depth of
ventilation.
Carotid
arteries
Aorta
Sensor/control center:
Cerebrospinal fluid
Medulla
oblongata
Breathing is involuntary
Controlled by respiratory center of the brain
Adjusts breath rate & volume based on sensory input
Maintain a constant concentration of CO2

44. Things To Do After Lecture 11…
Reading and Preparation:
Re-read today’s lecture, highlight all vocabulary you do not understand, and look up terms.
Ch. 42 Self-Quiz: #2, 3, 4, 6, 7 (correct answers in back of book)
Read chapter 42, focus on material covered in lecture (terms, concepts, and figures!)
Skim next lecture.
“HOMEWORK” (NOT COLLECTED – but things to think about for studying):
Compare and contrast veins and arteries in terms of structure and function.
Diagram the path blood takes from the body, to the heart and lungs, back to the body.
Explain in detail how oxygen is carried in the bloodstream and exchanged in the lungs and at cells, from drawing a breath to bulk flow in blood to diffusion at cells. What do cells use this oxygen for?
Explain homeostatic control of breathing.