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 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 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 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

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

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

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

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

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

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 42.17 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

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

Platelet releases chemicals that make nearby platelets sticky Fig. 42-18-4 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 42.18 Blood clotting Prothrombin Thrombin Fibrinogen Fibrin 5 µm

(b) Partly clogged artery Fig. 42-20 Connective tissue Smooth muscle Endothelium Plaque Figure 42.20 Atherosclerosis (a) Normal artery 50 µm (b) Partly clogged artery 250 µm

Smooth Connective muscle tissue Endothelium (a) Normal artery 50 µm Fig. 42-20a Connective tissue Smooth muscle Endothelium Figure 42.20 Atherosclerosis (a) Normal artery 50 µm

(b) Partly clogged artery 250 µm Fig. 42-20b Plaque Figure 42.20 Atherosclerosis (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

Parapodium (functions as gill) Fig. 42-21a Figure 42.21 Diversity in the structure of gills, external body surfaces that function in gas exchange Parapodium (functions as gill) (a) Marine worm

Gills (b) Crayfish Fig. 42-21b Figure 42.21 Diversity in the structure of gills, external body surfaces that function in gas exchange Gills (b) Crayfish

Coelom Gills Tube foot (c) Sea star Fig. 42-21c Figure 42.21 Diversity in the structure of gills, external body surfaces that function in gas exchange Gills Tube foot (c) Sea star

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 42.22 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

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

Branch of pulmonary vein (oxygen-rich blood) Branch of pulmonary Fig. 42-24 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 42.24 The mammalian respiratory system Bronchus Bronchiole Diaphragm Heart SEM Colorized SEM 50 µm 50 µm