Animal Circulation Ch 42 Lecture Objectives 1 Why

Animal Circulation Ch. 42 Lecture Objectives 1. Why Circulation? 2. Circulatory Systems 3. Mammalian Circulation Lectures by Erin Barley Kathleen Fitzpatrick

Why Circulation? 1. Every organism must exchange materials with its environment - cells exchange materials with the environment via a fluid-filled circulatory system 2. Exchanges ultimately occur at the cellular level by crossing the plasma membrane * Except unicellular and very thin organisms exchange occurs directly with the environment……………….

Gastrovascular Cavities - distribution of substances throughout the body Circular canal Mouth Gastrovascular cavity Mouth Pharynx Radial canals 5 cm (a) The moon jelly Aurelia, a cnidarian 2 mm (b) The planarian Dugesia, a flatworm Figure 42. 2

Circulatory Systems 1. Connects fluid surrounding cells w/ the organs that exchange gases, absorb nutrients, & dispose of wastes Minimizes diffusion distance in animals with many cell layers 2. Open or closed and vary in the number of circuits in the body

(a) An open circulatory system (b) A closed circulatory system Heart Interstitial fluid Hemolymph in sinuses surrounding organs Pores Blood Small branch vessels in each organ Dorsal Auxiliary vessel hearts (main heart) Tubular heart Ventral vessels Figure 42. 3

Muscle fiber 2. 5 m Tracheoles Mitochondria Tracheae Air sacs Body cell Air sac Tracheole Trachea External opening Air Figure 42. 23

Coelom Gills Parapodium (functions as gill) (a) Marine worm Gills Tube foot (b) Crayfish (c) Sea star Figure 42. 21

O 2 -poor blood Gill arch O 2 -rich blood Lamella Blood vessels Gill arch Water flow Operculum Water flow Blood flow Countercurrent exchange PO 2 (mm Hg) in water Gill filaments 150 120 90 60 30 Net diffusion of O 2 140 110 80 50 20 PO 2 (mm Hg) in blood Figure 42. 22

Branch of pulmonary vein (oxygen-rich blood) Terminal bronchiole Branch of pulmonary artery (oxygen-poor blood) Nasal cavity Pharynx Left lung Larynx (Esophagus) Alveoli 50 m Trachea Right lung Capillaries Bronchus Bronchiole Diaphragm (Heart) Dense capillary bed enveloping alveoli (SEM) Figure 42. 24

Organization of Vertebrate Circulatory Systems 1. Humans and other vertebrates have a closed circulatory system called the cardiovascular system 2. Consists of three parts Vessels Circulating fluid Pump

Vein LM Artery Red blood cells 100 m Valve Basal lamina Endothelium Smooth muscle Connective tissue Endothelium Capillary Smooth muscle Connective tissue Artery Vein Capillary 15 m Red blood cell Venule LM Arteriole Figure 42. 9

INTERSTITIAL FLUID Net fluid movement out Body cell Blood pressure Osmotic pressure Arterial end of capillary Direction of blood flow Venous end of capillary Figure 42. 14

Mammalian blood 1. Contributes to exchange, transport, and defense 2. Specialized connective tissue 3. Composed of Plasma – liquid matrix 55% Cellular elements – cells or cellular components 45%

Cellular elements 45% Plasma 55% Constituent Water Solvent for carrying other substances Ions (blood electrolytes) Sodium Potassium Calcium Magnesium Chloride Bicarbonate Osmotic balance, p. H buffering, and regulation of membrane permeability Plasma proteins Albumin Fibrinogen Number per L (mm 3) of blood Cell type Major functions Leukocytes (white blood cells) Separated blood elements 5, 000– 10, 000 Functions Defense and immunity Lymphocytes Basophils Eosinophils Osmotic balance, p. H buffering Neutrophils Monocytes Platelets 250, 000– 400, 000 Clotting Immunoglobulins Defense (antibodies) Substances transported by blood Erythrocytes (red blood cells) 5– 6 million Blood clotting Transport of O 2 and some CO 2 Nutrients Waste products Respiratory gases Hormones Figure 42. 16

Fibrin clot Red blood cell 5 m Figure 42. 18

The Mammalian heart 1. Has 4 chambers: Atria Upper R & L Ventricles Lower chambers R & L * Members of class Aves also have a 4 chambered heart

Aorta Pulmonary artery Right atrium Left atrium Semilunar valve Atrioventricular valve Right ventricle Left ventricle Figure 42. 6

Superior vena cava Capillaries of head and forelimbs Pulmonary artery Capillaries of right lung Pulmonary vein Right atrium Right ventricle Inferior vena cava Pulmonary artery Aorta Capillaries of left lung Pulmonary vein Left atrium Left ventricle Aorta Capillaries of abdominal organs and hind limbs Fig 42. 5

1 SA node (pacemaker) 2 AV node 3 Bundle branches 4 Heart apex Purkinje fibers ECG Figure 42. 8

* Double Circulation 1. Oxygen-poor and oxygen-rich blood are pumped separately from the right and left sides of the heart - Seen in amphibians, reptiles, and mammals

Amphibians Pulmocutaneous circuit Pulmonary circuit Lung and skin capillaries Atrium (A) Right Pulmonary circuit Lung capillaries Right systemic aorta A V Right Left Mammals and Birds Reptiles (Except Birds) A V Left systemic aorta Incomplete septum A V Right A V Left Ventricle (V) Systemic circuit Systemic capillaries Systemic circuit Key Oxygen-rich blood Oxygen-poor blood Figure 42. 4

Single Circulation 1. Blood leaves the heart before passing through two capillary beds - Bony fishes, rays, and sharks have single circulation with a two-chambered heart

(a) Single circulation (b) Double circulation Pulmonary circuit Gill capillaries Lung capillaries Artery Heart: A Atrium (A) V Right Ventricle (V) A V Left Vein Systemic capillaries Body capillaries Systemic circuit Key Oxygen-rich blood Oxygen-poor blood Figure 42. 4

Direction of blood flow in vein (toward heart) Valve (open) Skeletal muscle Valve (closed) Figure 42. 12