chapter 42: circulation and gas exchange
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Chapter 42: Circulation and Gas Exchange. Ms. Klinkhachorn April 29, 2011 AP Biology. 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?. Two Solutions in Nature. - PowerPoint PPT PresentationTRANSCRIPT
Chapter 42: Circulation and Gas Exchange
Ms. KlinkhachornApril 29, 2011
AP Biology
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?
Two Solutions in Nature
1. 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)
Two Solutions in Nature
2. 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)
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
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
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
Fig. 42-5
Amphibians
Lung and skin capillaries
Pulmocutaneouscircuit
Atrium (A)
Ventricle (V)
Atrium (A)
Systemiccircuit
Right Left
Systemic capillaries
Reptiles (Except Birds)
Lung capillaries
Pulmonarycircuit
Rightsystemicaorta
Right LeftLeftsystemicaorta
Systemic capillaries
A A
VV
Systemic capillaries
Pulmonarycircuit
Systemiccircuit
Right Left
A A
VV
Lung capillaries
Mammals and Birds
Fig. 42-6
Superiorvena cava
Pulmonaryartery
Capillariesof right lung
3
7
3
8
9
24
11
51
10
Aorta
Pulmonaryvein
Right atrium
Right ventricle
Inferiorvena cava
Capillaries ofabdominal organsand hind limbs
Pulmonaryvein
Left atrium
Left ventricle
Aorta
Capillariesof left lung
Pulmonaryartery
Capillaries ofhead andforelimbs
Steps of Circulation in Mammals
1. Blood is pumped from right ventricle to the lungs via the pulmonary artery
2. Blood picks up oxygen in capillary beds of lungs and releases carbon dioxide
3. Blood returns to the left atrium via the pulmonary vein and move into the left ventricle
4. Blood moves through the aorta and ultimately to other places in the body
Steps of Circulation in Mammals
5. Blood travels through body and, in capillary beds, releases oxygen and picks up carbon dioxide
6. Blood returns back to the right atrium of the heart via the vena cava
7. Blood flows into the right ventricle and the cycle restarts
Fig. 42-7
Pulmonary artery
Rightatrium
Semilunarvalve
Atrioventricularvalve
Rightventricle
Leftventricle
Atrioventricularvalve
Leftatrium
Semilunarvalve
Pulmonaryartery
Aorta
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
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
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
Fig. 42-17
Plasma 55%
Constituent Major functions
Water Solvent forcarrying othersubstances
Ions (blood electrolytes)
Osmotic balance,pH buffering, andregulation ofmembranepermeability
SodiumPotassiumCalciumMagnesiumChlorideBicarbonate
Osmotic balancepH buffering
Clotting
Defense
Plasma proteins
Albumin
Fibrinogen
Immunoglobulins(antibodies)
Substances transported by blood
Nutrients (such as glucose, fatty acids, vitamins)Waste products of metabolismRespiratory gases (O2 and CO2)Hormones
Separatedbloodelements
Cellular elements 45%
Cell type FunctionsNumberper µL (mm3) of blood
Erythrocytes(red blood cells)
5–6 million Transport oxygenand help transportcarbon dioxide
Leukocytes(white blood cells)
5,000–10,000 Defense andimmunity
Basophil
Neutrophil
Eosinophil
Lymphocyte
Monocyte
Platelets Blood clotting250,000–400,000
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
Collagen fibersPlateletplug
Platelet releases chemicalsthat make nearby platelets sticky
Clotting factors from:PlateletsDamaged cellsPlasma (factors include calcium, vitamin K)
Prothrombin Thrombin
Fibrinogen Fibrin5 µm
Fibrin clot
Red blood cell
Fig. 42-18-4
Fig. 42-20
Connectivetissue
Smoothmuscle Endothelium Plaque
(a) Normal artery (b) Partly clogged artery50 µm 250 µm
Fig. 42-20a
Connectivetissue
Smoothmuscle Endothelium
(a) Normal artery 50 µm
Fig. 42-20b
Plaque
(b) Partly clogged artery 250 µm
Countercurrent Exchange
• Gills in fish– Water flow through, opposite the direction of
blood flow– Picks up oxygen from the water
Fig. 42-21a
Parapodium (functions as gill)
(a) Marine worm
Fig. 42-21b
Gills
(b) Crayfish
Fig. 42-21c
(c) Sea star
Tube foot
Coelom
Gills
Fig. 42-22
Anatomy of gills
Gillarch
Waterflow Operculum
Gillarch
Gill filamentorganization
Bloodvessels
Oxygen-poor blood
Oxygen-rich blood
Fluid flowthrough
gill filament
Lamella
Blood flow throughcapillaries in lamella
Water flowbetweenlamellae
Countercurrent exchange
PO2 (mm Hg) in water
PO2 (mm Hg) in blood
Net diffu-sion of O2
from waterto blood
150 120 90 60 30
110 80 20Gill filaments
50140
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
Fig. 42-24
Pharynx
Larynx
(Esophagus)
Trachea
Right lung
Bronchus
Bronchiole
DiaphragmHeart SEM
Leftlung
Nasalcavity
Terminalbronchiole
Branch ofpulmonaryvein(oxygen-richblood)
Branch ofpulmonaryartery(oxygen-poorblood)
Alveoli
ColorizedSEM50 µm 50 µm