Chapter 21 Circulation Flashcards
Open Circulatory System
Fluid is called hemolymph or interstitial fluid. hemolymph is pumped into body cavities known as sinuses.
Arthropods have
- Jointed appendages
- Segmentation (head, throax, abdomen)
- Hard chitinous exoskeletons
- Bilateral symmetry
- Complete digestive tracts
Open circulatory system
Arthropods examples
Insects, lobsters, crayfish, spiders, and scorpions.
Exoskeletons that are hard and do not expand. Periodically they molt. Enzymes partially dissolve the old exoskeleton.
Open circulatory system.
Mollusks
Oysters, clams, octopuses and squids. Most secrete hard CaCO3 shell.
Open circulatory system.
Closed circulatory system
Blood is confined in continuously connect walls of heart and vasculature. Annelids and all vertebrates have close systems.
Arteries
Usually high in O2, blood is under high pressure. Carries blood away from the heart.
Resistance is highest in the
Arterioles than in any part of the systemic circulation. Resistance is vital to blood flow regulation.Large diameters offer very little resistance to flow.
Capillaries
Smallest blood vessels; single layer of squamous epithelium. Thin walls allow for O2 and nutrient exchange. Speed of blood is slowest. Largest cross sectional area in any part of the circulatory system. Capillaries converge to the venule.
Veins
High in CO2, thinner walls, less smooth muscle and less elasticity than arteries.
Carries blood to the heart. Many veins have valves to prevent backward blood flow. Blood pressure is lowest here.
More fluid leaves the capillaries than returns to them
Any excess is collected and returned to the venous circulation by the lymphatic system.
of Heart chambers for organisms
Mammals (man) and birds: 4 chambered heart
Reptiles: 3 chambered heart (crocs and alligators have 4)
Amphibians: 3 chambered heart
Fish: 2 chambered heart
Heart terms basic
Atria: Upper Chamber
Ventricle: Lower chamber
Superior Vena cava: Brings blood low in O2 to the right atria from the upper body
Tricuspid Valve: Between right atria and right ventricle
Mitral Valve: Between left atria and left ventricle
Semilunar Valves (Pulmonary valve and Aortic)
Aortic valve separates left ventricle and aorta (largest artery). Keep blood from flowing backward.
Pulmonary valve separates right ventricle from pulmonary artery.
Lup Dup
Heart sounds due to closing of the valves.
Lub: 1st sound; AV valve closes (tricuspid and mitral).
Dub: 2nd sound, Semilunar valves close (aortic and pumonary).
Papillary Muscles
Muscles in the ventricles that help stabilize heart valves.
Chordae tendineae
Fibrous strings attached to the cusps on the ventricular side, originating from the papillary muscles.
Systolic pressure
Arterial blood pressure when ventricles contract (120mmHg)
Diastolic pressure
Arterial blood pressure when ventricles relax (80mmHg)
Cardiac Muscle
Usually mononucleated, striated, loads of mitochondria
Intercalated discs
Transverse bands that separate adjacent ends in cardiac muscle fibers; low resistance so impulses can move rapidly.
SA Node, Pacemaker
Found in the RA, generates electrical impulses analogous to nerve cells.
Heart’s Electrical System
SA node, AV node, His purkinje system
- SA Nodes sends out an impulse; both atria contract
- SA -> AV node - slight delay at the AV node to allow time for atrial systole before ventricles contract. Once the impulses reach the His bundle and purkinje fibers the ventricles contract.
Heart Electrical Path
SA node - > AV anode - > Bundle of His and Purkinje Fibers
