[bio] Animal Transport

Topics  Transport systems  functionally connect the organs of exchange with the body cells

 Most invertebrates have a

gastrovascular cavity or a circulatory system for internal support  Vertebrate phylogeny  reflected in adaptations of the cardiovascular system

Topics  Double circulation in mammals

depends on the anatomy and pumping cycle of the heart  Structural differences of arteries, veins and capillaries correlate with their different functions  Physical laws governing the movement of fluids through pipes affect blood flow and pressure

Topics  Transfer of substances between the

blood and the interstitial fluid across the thin walls of capillaries  Components of blood  Cardiovascular diseases are the leading cause of death in the United States and other developed nations

Invertebrates circulatory system  Gastrovascular cavity

 Presence of 2-cell thick body wall  Serves for digestion and circulation  Both layers are bathed by fluid  Inner layer- only exposed to food

Invertebrates circulatory system

 Planarians and other flatworms  Also have gastrovascular system  Body shape ensures the efficient

transfer of food

Open vs Closed Circulatory System  Gastrovascular cavity

 Not suitable for animals with many cell

layers

 Open vs closed  Overcomes the limits of diffusion  Three basic components

 Circulatory fluid (blood)  Tubes (blood vessels)  Pumping organ (heart) Blood pressure- motive force for fluid movement

Open circulatory system  No distinction between blood and

interstitial fluid  hemolymph

 Sinuses- interconnected spaces that

surround organs  Heart contraction

 Pumps hemolymph

 Heart relaxation  Draws hemolymph through ostia

Closed Circulatory System  Blood

 Confined to vessels  Blood is distinct from interstitial fluid

 Movement of materials  Larger vessels to smaller vessels  Exchange of materials is through

diffusion

Vertebrate Phylogeny is reflected in adaptations of the cardiovascular system • Cardiovascular system- presence of heart and vessels • Atrium- receives blood • Ventricle- pumps blood • Vessels • Arteries • Veins • Capillaries

Vertebrate Phylogeny Is Reflected in Adaptations of the Cardiovascular System  Venules  Arterioles

 Capillary beds  High metabolic rate- complex

cardiovascular system  Low metabolic rate- less complex

Fish heart  Two main chambers  Gill circulation  Systemic circulation

Frogs and Other Amphibians

 Three-chambered heart  Presence of forked artery  Pulmocutaneous circulation  Systemic circulation

 Double circulation restores blood pressure

 Mixing of blood  Reptiles  Presence of ridge in the ventricle

Mammals, birds and crocodilians  Four-chambered heart  Left side- oxygen-rich

 Right side- oxygen poor  No mixing of blood 

Double Circulation in Mammals Depends on the Anatomy and Pumping Cycle of the Heart

The Human Heart  Cardiac cycle- complete pumping

and filling  Systole- contraction  Diastole- relaxation  Cardiac output- vol of pumped blood into systemic circuit per min  Heart rate- no of beats per min  Stroke volume- amount of blood pumped

per contraction

The Valves  Atrioventricular (AV) valve  Close due to ventricular pressure

 Semilunar valves  Aorta  Pulmonary artery  Open due to ventricular pressure  Heart murmur- hissing sound  Pulse- rhythmic stretching of arteries

The Valves  Lub dup sound  Lub- recoil of blood against closed AV

valves  Dup- recoil of blood against semilunar valves

Maintaining the Heart’s Rhythmic Beat  Heartbeat- maintained by specialized

heart cell  Sinoatrial (SA) node- sets rhythmic beat  Also called the pacemaker  Found in the wall of right atrium,

superior vena cava

 Atrioventricular (AV) node- relay

point  Found bet right atrium and right

Heart rate  Electrocardiogram (EKG or ECG)  Record of impulse produced in the heart

Heart beat  P wave  Atrial contraction

 QRS complex  Ventricular

contraction

 T wave  Ventricular

recovery phase

Structural Differences of Blood Vessels Correlate with Their Different Functions

 Capillaries- lack two outer layers  Arteries- thicker outer layers than

veins  Veins- presence of valves

Movement of Fluid Through Pipes  Law of Continuity

Blood Pressure  Blood Pressure- highest in arteries

during ventricular systole  Hydrostatic Pressure  Peripheral Resistance  Impedance caused by arterioles

 Blood pressure is influenced by

different factors  Nerves- slows, speed up  Hormones  Body temperature  Exercise  Gravity- large animals

Transfer of Substances through Capillaries  Two mechanisms that control blood

flow  Contraction of smooth muscle  Constricts the arteriole that decrease blood flow  Dilation increases blood flow  Precapillary sphincters

 Control blood flow

Capillary exchange  Takes place in the endothelial wall  Maybe carried though bulk transport

(endocytosis and exocytosis)  Diffusion (O2 and CO2)  Diffusion or bulk flow through

intercellular clefts

Blood  Plasma  Cellular component  RBC  hemoglobin  WBC  Platelets