Chapter 42

Circulation & Gas Exchange

Functions of the Circulatory System

• Transport oxygen to cells• Transport nutrients from the

digestive system to body cells• Transport hormones to body cells• Transport waste from body cells to

excretory organs• Distribute body heat

Gastrovascular Cavity of Aurelia

Open Circulatory System

Closed Circulatory System

AtriumVentricle

Circulatory Systems in Fish, Amphibian, & Mammal

Ectotherms Endotherm

• P = atrial depolarization ~ 0.1 sec atria contracts• QRS = ventricular depolarization ventricles contract

(lub), contraction stimulated by Ca++ uptake• T = ventricular repolarization ventricles relax (dub)

Electrocardiogram (ECG)

Artery Vein

Valve

Tunica intima

Tunica media

Tunica externa

Artery

vein

Arteries

• Carry blood away from the heart.• Thick-walled to withstand

hydrostatic pressure of the blood during ventricular systole.

• Blood pressure pushes blood through arteries.

Veins

• Carry blood to the heart.• Thinner-walled than arteries.• Possess one-way valves that prevent

backwards flow of blood.• Blood flow due to body movements, not

from blood pressure.

One-Way Valves in Veins

Capillaries

capillary vesselcapillary vessel

venulevenule capillariescapillaries

arteriolearteriole

arteriole

venule

lymphatic capillaries

blood capillaries

lymphatic vessel

Lymph Lymph TransportTransport

• lacks pump for circulation• relies on activity of skeletal muscles and

pulsation of nearby arteries for movement of fluid

• 3L of lymph enters blood stream every 24 hrs• proteins easily enter lymphatic system• uptake of large particles such as cell debris,

pathogens, and cancer cells• lymph nodes where it is cleansed of debris

and examined by cells of the immune system (WBC)

Formation of Lymph

interstitial fluid

blood capillary

lymphatic capillary

tissue cell

Sphygnomamometer

Measuring Blood Pressure

brachial

carotid

Superficial Pulse Points- arteries, not veins

radial femoral

•Temporal artery•Facial artery•Common carotid artery•Brachial artery•Radial artery•Femoral artery•Popliteal artery•Posterior tibial artery•Dorsal pedis artery

60 beats/minute

popliteal

facial

temporal

Posterior tibial Dorsal pedis

White blood cells

Platelets

Red blood cells

Artery

• Deliver O2• Remove metabolic wastes• Maintain temperature, pH, and fluid volume• Protection from blood loss- platelets• Prevent infection- antibodies and WBC• Transport hormones

Plasma-55%

Formed elements-45%

Buffy coat-<1%

90% Water8% Solutes:• Proteins

Albumin (60 %)Alpha and Beta GlobulinsGamma Globulinsfibrinogens

• Gas• Electrolytes

• Organic NutrientsCarbohydratesAmino AcidsLipidsVitamins

• Hormones• Metabolic waste

CO2Urea

• Leukocytes• Platelets

• Erythrocytes (red blood cells)• Leukocytes (white blood cells)• Platelets

Erythrocytes

Erythrocyte7.5m in dia    Anucleate- so can't reproduce; however, repro

in red bone marrow   Hematopoiesis- production of RBC   Function- transport respiratory gases   Hemoglobin- quaternary structure, 2 chains

and 2 chains   Lack mitochondria. Why?   1 RBC contains 250 million hemoglobin

molecules   Men- 5 million cells/mm3

   Women- 4.5 million cells/mm3

   Life span 100-120 days and then destroyed in spleen (RBC graveyard)

Types of Leukocytes

GranulocytesNeutrophils- 40-70%Eosinophils- 1-4%Basophils- <1%

AgranulocytesMonocytes- 4-8%

Lymphocytes- 20-45%

Never let monkeys eat bananas

4,000-11,000 cells/mm 3

Leukocyte Squeezing Through Capillary WallDiapodisis

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 filament

organization

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

Countercurrent exchange system

Fig. 42-23

Air sacs

Tracheae

Externalopening

Bodycell

AirsacTracheole

Tracheoles Mitochondria Muscle fiber

2.5 µmBody wall

Trachea

Air

Tracheal Systems

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

Fig. 42-25

Lung

Diaphragm

Airinhaled

Rib cageexpands asrib musclescontract

Rib cage getssmaller asrib musclesrelax

Airexhaled

EXHALATIONDiaphragm relaxes

(moves up)

INHALATIONDiaphragm contracts

(moves down)

Fig. 42-26

Anteriorair sacs

Posteriorair sacs Lungs

Air

Lungs

Air

1 mm

Trachea

Air tubes(parabronchi)in lung

EXHALATIONAir sacs empty; lungs fill

INHALATIONAir sacs fill

Fig. 42-27

Breathingcontrolcenters

Cerebrospinalfluid

Pons

Medullaoblongata

Carotidarteries

Aorta

DiaphragmRib muscles

Uptake of Oxygen by Hemoglobin in the Lungs

O2 binds to hemoglobin to form oxyhemoglobin

High Concentration of O2 in Blood Plasma

High pH of the Blood Plasma

Unloading of Oxygen from Hemoglobin in the Tissues

Low Concentration of O2 in Blood Plasma Lower pH of the Blood Plasma

When O2 is releaseddeoxyhemoglobin

Carbon Dioxide Chemistry in the Blood

COCO22 + H + H22O O H H22COCO3 3 HCOHCO33-- + H + H++

carbonic carbonic acidacid

bicarbonatebicarbonateionion

enzyme = carbonic anhydraseenzyme = carbonic anhydrase

Transport of Carbon Dioxide from the Tissues to the Lungs

• 60-70% as bicarbonate dissolved in the plasma (slow reaction)• 7-10% dissolved in the plasma as CO2

• 20-30% bound to hemoglobin as HbCO2 CO2 + hemoglobin HbCO2

Haldane Effect- the amt of CO2 transported in the blood is markedly affected by the degree of oxygenation of the blood

The lower the P02 and hemoglobin saturation w/O2, the more CO2 that can be carried by the blood

7. Deep-diving air-breathers stockpile oxygen and deplete it slowly

Deep Diving Breath-holding • Adaptations to pressure

- Collapse of lung cavity (ribs)- Collapse of lungs

7. Deep-diving air-breathers stockpile oxygen and deplete it slowly

Adaptations to oxygen conservation

• Oxygen stores 2-3 x more than humans– Humans: 36% of our total O2 in lungs and 51% in our

blood.– Weddell seal holds 5% of its O2 in its small lungs and

stockpiles 70% in the blood.

• Skeletal muscles and blood as primary storage site (myoglobin)

• Weddell seal to store about 25% of its O2 in muscle, 13% in humans

Deep-diving air-breathers stockpile oxygen and deplete it slowly

Adaptations to oxygen conservation • Reduce heart rate when diving (120 beats/min to 6

b/min)• seals and sea lions store oxygenated blood in their

extra-large spleen (which can be 45% of their body weight)

• Maintain blood flow to brain, heart

Average Dive Times

• Sperm whale: 90 minutes to 2 hrs• Northern elephant seal: 20 to 35 minutes• Harbor seal: 3 to 7 minutes• Walrus: 10 minutes• Bottlenose dolphin: 8 minutes• Killer whale: 10 minutes• Amazon river dolphin: 2 minutes • Loggerhead turtle: 20 minutes