1. Chapter 42: Circulation and Gas Exchange
Ms. Klinkhachorn
April 29, 2011
AP Biology

2. The need for a circulatory system
Need to exchange gases, nutrients, and wastes
BUT Diffusion is slow and only occurs over small distances
How do we get around this?

3. Two Solutions in Nature
Organisms with body shapes and sizes that keep almost all of their cells in contact with the environment
Can have a gastrovascular cavity that help a dual-function (digestion and distribution)

4. Two Solutions in Nature
Organism has a circulatory system
More complex species
Circulatory systems have 3 parts:
Blood (circulatory fluid)
Vessels (tubes that move the fluid)
Heart (structure that pumps the fluid)

5. Main Blood Vessel Types
Arteries
Carry blood away from the heart
Capillaries
Microscopic vessels (one cell layer thick)
Sites of diffusion
Veins
Carry blood back to the heart

6. Parts of the Heart
Atria (atrium) are heart chambers that receive blood from veins
Ventricles take blood from the atria and then pump the blood back out

7. Circulatory Systems Can Vary
Vary based on the organism
Mammals and birds have hearts with 4 chambers
Reptiles and amphibians have 3
Fish have 2
In mammals, left side of the heart deals with oxygen-rich blood while right side deals with oxygen-poor blood

8. Fig. 42-5
Amphibians
Reptiles (Except Birds)
Mammals and Birds
Lung and skin capillaries
Lung capillaries
Lung capillaries
Right
systemic
aorta
Pulmocutaneous
circuit
Pulmonary
circuit
Pulmonary
circuit
Atrium (A)
Atrium (A) A A A A
Ventricle (V) V V
Left
systemic
aorta V V
Right
Left
Right
Left
Right
Left
Systemic
circuit
Systemic
circuit
Systemic capillaries
Systemic capillaries
Systemic capillaries

9. Superior vena cava Capillaries of head and forelimbs 7 Pulmonary
Fig. 42-6
Superior
vena cava
Capillaries of
head and
forelimbs 7
Pulmonary
artery
Pulmonary
artery
Capillaries
of right lung
Aorta 9
Capillaries
of left lung 3 2 3 4 11
Pulmonary
vein
Pulmonary
vein 5 1
Right atrium 10
Left atrium
Right ventricle
Left ventricle
Inferior
vena cava
Aorta
Capillaries of
abdominal organs
and hind limbs 8

10. Steps of Circulation in Mammals
Blood is pumped from right ventricle to the lungs via the pulmonary artery
Blood picks up oxygen in capillary beds of lungs and releases carbon dioxide
Blood returns to the left atrium via the pulmonary vein and move into the left ventricle
Blood moves through the aorta and ultimately to other places in the body

11. Steps of Circulation in Mammals
Blood travels through body and, in capillary beds, releases oxygen and picks up carbon dioxide
Blood returns back to the right atrium of the heart via the vena cava
Blood flows into the right ventricle and the cycle restarts

12. Pulmonary artery Aorta Pulmonary artery Right atrium Left atrium
Fig. 42-7
Pulmonary artery
Aorta
Pulmonary
artery
Right
atrium
Left
atrium
Semilunar
valve
Semilunar
valve
Figure 42.7 The mammalian heart: a closer look
Atrioventricular
valve
Atrioventricular
valve
Right
ventricle
Left
ventricle

13. Cardiac Cycle
Cycle of contraction and relaxation = cardiac cycle (time from one beat to the next)
Systole: contraction (pumping) phase
Diastole: relaxation (filling) phase
Heart rate = beats per minute
SA node is the pacemaker of the heart
This controls the heart contractions

14. Blood Pressure
Typical blood pressure for a 20 year old at rest is 120/70
First number is the systolic pressure
Second number is the diastolic pressure

15. Blood Components Suspended in blood plasma are two types of cells:
Red blood cells (erythrocytes) transport oxygen via hemoglobin
White blood cells (leukocytes) function as defense in the immune system
Platelets are fragments of cells that are involved in clotting

16. Figure 42.17 The composition of mammalian blood
Plasma 55%
Constituent
Major functions
Cellular elements 45%
Cell type
Number
per µL (mm3) of blood
Functions
Water
Solvent for
carrying other
substances
Erythrocytes
(red blood cells)
5–6 million
Transport oxygen
and help transport
carbon dioxide
Ions (blood electrolytes)
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Osmotic balance,
pH buffering, and
regulation of
membrane
permeability
Separated
blood
elements
Leukocytes
(white blood cells)
5,000–10,000
Defense and
immunity
Plasma proteins
Albumin
Osmotic balance
pH buffering
Lymphocyte
Basophil
Fibrinogen
Figure The composition of mammalian blood
For the Discovery Video Blood, go to Animation and Video Files.
For the Cell Biology Video Leukocyte Adhesion and Rolling, go to Animation and Video Files.
Clotting
Immunoglobulins
(antibodies)
Defense
Eosinophil
Neutrophil
Monocyte
Substances transported by blood
Nutrients (such as glucose, fatty acids, vitamins)
Waste products of metabolism
Respiratory gases (O2 and CO2)
Hormones
Platelets
250,000–
400,000
Blood clotting

17. RBC Structure and Function
Disc shaped
Maximize surface area for oxygen to bind to hemoglobin
Lack nuclei
Gives more space
Lack mitochondria
Oxygen held isn’t used

18. Platelet releases chemicals that make nearby platelets sticky
Fig
Red blood cell
Collagen fibers
Platelet
plug
Fibrin clot
Platelet releases chemicals
that make nearby platelets sticky
Clotting factors from:
Platelets
Damaged cells
Plasma (factors include calcium, vitamin K)
Figure Blood clotting
Prothrombin
Thrombin
Fibrinogen
Fibrin
5 µm

19. (b) Partly clogged artery
Fig
Connective
tissue
Smooth
muscle
Endothelium
Plaque
Figure Atherosclerosis
(a) Normal artery
50 µm
(b) Partly clogged artery
250 µm

20. Smooth Connective muscle tissue Endothelium (a) Normal artery 50 µm
Fig a
Connective
tissue
Smooth
muscle
Endothelium
Figure Atherosclerosis
(a) Normal artery
50 µm

21. (b) Partly clogged artery 250 µm
Fig b
Plaque
Figure Atherosclerosis
(b) Partly clogged artery
250 µm

22. Countercurrent Exchange
Gills in fish
Water flow through, opposite the direction of blood flow
Picks up oxygen from the water

23. Parapodium (functions as gill)
Fig a
Figure Diversity in the structure of gills, external body surfaces that function in gas exchange
Parapodium (functions as gill)
(a) Marine worm

24. Gills (b) Crayfish Fig. 42-21b
Figure Diversity in the structure of gills, external body surfaces that function in gas exchange
Gills
(b) Crayfish

25. Coelom Gills Tube foot (c) Sea star Fig. 42-21c
Figure Diversity in the structure of gills, external body surfaces that function in gas exchange
Gills
Tube foot
(c) Sea star

26. Figure 42.22 The structure and function of fish gills
Fluid flow
through
gill filament
Oxygen-poor blood
Anatomy of gills
Oxygen-rich blood
Gill
arch
Lamella
Gill
arch
Gill filament
organization
Blood
vessels
Water
flow
Operculum
Water flow
between
lamellae
Blood flow through
capillaries in lamella
Figure The structure and function of fish gills
Countercurrent exchange
PO2 (mm Hg) in water
150
120 90 60 30
Gill filaments
Net diffu-
sion of O2
from water
to blood
140
110 80 50 20
PO2 (mm Hg) in blood

27. Flow of Oxygen Into your mouth or nose Past the voice box (larynx)
Into the trachea (windpipe)
Into one of the two bronchi
Into a branch called a bronchiole
Into an alveoli

29. Branch of pulmonary vein (oxygen-rich blood) Branch of pulmonary
Fig
Branch of
pulmonary
vein
(oxygen-rich
blood)
Branch of
pulmonary
artery
(oxygen-poor
blood)
Terminal
bronchiole
Nasal
cavity
Pharynx
Larynx
Alveoli
(Esophagus)
Left
lung
Trachea
Right lung
Figure The mammalian respiratory system
Bronchus
Bronchiole
Diaphragm
Heart
SEM
Colorized
SEM
50 µm
50 µm