Circulation Flashcards
Gastrovascular cavities
Digestion and distribution of substances throughout the body
Simple animals such as cnidarians
Circulatory system components
Circulatory fluid (blood) Tubes (blood vessels) Muscular pump (heart)
Open circulatory system
Insects, arthropods, most molluscs
Blood bathes organs directly
Valves keep hemolymph going in right direction
Advantage: all cells are directly exposed to hemolymph
Hemolymph
Exchange fluid in open circulatory system
Closed circulatory system
Blood is confined to vessels and is distinct from interstitial fluid
More efficient at transporting circulatory fluids to tissues and cells
Advantage: concentrate blood in specific areas- move particles more efficiently
Interstitial fluid
Completes exchange between blood and cells
Cardiovascular system
Vertebrate closed circulatory system
Blood vessels and 2-4 chambered heart
Arteries
Carry blood to capillaries away from heart
Veins
Return blood from capillaries to heart
Capillaries
Most direct contact with cells
Exchange of substances between blood and interstitial fluid
Double circulation
2 trips to heart before going to rest of body
Pulmonary circuit and systemic circuit (rest of body)
Ventricle
Pumps blood out of heart
Atrium
Pumps blood into heart
Fish circulatory system
2 chambered heart: 1 ventricle and 1 atrium
Single circulation
Ventricle -> artery -> gill capillaries -> systemic capillaries -> vein -> atrium
Amphibian circulatory system
3 chambered heart: 2 atria and 1 ventricle
Double circulation
Pulmocutaneous: breathe through skin
Ventricle pumps blood into forked artery- splits ventricle’s output into pulmocutaneous circuit (oxygen-poor blood) and systemic circuit (oxygen-rich blood)
Reptile circulatory system
Double circulation
Turtles, snakes, and lizards: 3 chambered heart
Extra vessel from ventricle: bypass lungs, allowing animal to swim for prolonged periods of time
Mammalian and avian circulatory system
Ventricle is completely divided into separate right and left chambers
Left side of heart pumps and receives only oxygen-rich blood
Right side of heart pumps and receives only oxygen-poor blood
4-chambered heart and endothermic lifestyle
Increased oxygen input- needed for oxidative phosphorylation (O2 is final electron receptor in electron chain)
Mammalian circulatory pathway
Right ventricle -> pulmonary artery -> lung capillaries (diffusion of oxygen) -> pulmonary vein -> left atrium -> left ventricle -> aorta -> systemic capillaries -> vena cava -> right atrium
Atrioventricular valves
Separate atria from ventricles
Semilunar valves
Separate ventricles from arteries
Systole
Pumping or contraction phase of cardiac cycle
Diastole
Relaxation or filling phase of cardiac cycle
Cardiac cycle
- Atrial and ventricular diastole: AV valves open, semilunar valves closed
- Atrial systole and ventricular diastole
- Atrial diastole and ventricular systole: AV valves closed, semilunar valves open
Self-excitable
Some cardiac muscle cells
Contract without any signal from the nervous system
Sinoatrial (SA) node
Pacemaker: sets rate and timing for cardiac muscle cell contraction
Influenced by nerves, hormones, body temperature, and exercise
Heartbeat
- SA node generates wave of signals to contract
- Signals are delayed at AV node
- Signals pass to heart apex and then Purkinje fibers
- Ventricles contract
Heart sounds
AV valve recoil: “lub”
Semilunar valve recoil: “dub”
Electrocardiogram (EKG)
Displays electric impulses that travel through the cardiac cycle
Blood vessels
Infrastructure of circulatory system
Cavity: central lumen
Valve in veinous lumen: prevent backflow
3 layers (inside to outside): Epithelium (endothelium), smooth muscle, connective tissue
Skeletal muscle
Aids in veinous blood flow
Velocity of blood flow
Varies in the circulatory system
Slowest in capillaries: high resistance and large cross-sectional area to allow diffusion
Blood pressure
Hydrostatic pressure that blood exerts against the wall of a vessel
Systolic pressure
Pressure in arteries during ventricular systole
Highest pressure in arteries
Diastolic pressure
Pressure in arteries during diastole
Lower than systolic pressure
Measuring blood pressure
Cuff puts pressure against an artery (almost cutting off blood flow): measure systolic
Slowly release pressure: measure diastolic
Distribution of blood in capillary beds
Contraction of smooth muscle layer in wall of arteriole (small branch of artery) constricts vessel
Precapillary sphincters control the flow of blood between arterioles and venules: open- blood flow into capillaries, closed- blood flow only between arterioles and venules
Atherosclerosis
Buildup of cholesterol within arteries
Hypertension
High blood pressure
Promotes atherosclerosis and increases risk of heart attack or stroke
Heart attack
Death of cardiac muscle resulting from blockage of one or more coronary arteries
Stroke
Death of nervous tissue in the brain
Usually results from rupture or blockage of arteries in head
