Lecture Notes: Circulation and Gas Exchange in Mammals Flashcards
anatomy of circulatory system of mammals
- fully divided ventricle, four-chambered heart
- double circulation, pulmonary and systemic circuit
- same in birds and crocodiles
advantages of closed circulatory systems
- gas exchange maximized
- full seperation of oxygen rich and poor blood
- arterial and venous circuits work at different pressures
- arterial blood receives the highest oxygen content
- ability to maintain higher blood pressure to sustain energetically expensive tissues
right atrium
- receives deoxygenated blood from the superior and inferior vena cava
- pumps blood to right ventricle past the tricuspid valve
right ventricle
- send blood to the pulmonary circuit via pulmonary trunk (carries deoxygenated blood)
- back flow is prevented by pulmonary semilunar valve
left atrium
- receives blood from the pulmonary veins (carry oxygenated blood)
- sends oxygenated blood to the left ventricle past the bicuspid valve
left ventricle
- sends oxygenated blood to the systemic circuit via aortic arch
- aortic semilunar valve prevents the back flow
layers of the wall of the heart
endocardium- connective + epithelial (protection)
myocardium- cardiac muscle (contraction)
pericardium
- protection and support
- fibrous layer (outer), then serous layer ( parietal and visceral)
parietal
fused to fibrous layer
visceral
aka epicardium adheres to the hearts surface
pericardial cavity
between the parietal and visceral
pericardial fluid reduces friction
coronary arteries
openings below the aortic semilunar valve
blood supply to the heart
coronary arteries
coronary veins..coronary sinus..right atrium
control of heartbeat
- cardiac muscle fibers are joined by intercalated disks
- sinoatrial (SA) node
- atrioventricular (AV) node
intercalated disks
- gap junctions that spread action potentials
- desmosomes that reinforce the connections between fibers
Sinoatrial (SA) node
- acts as a pacemaker, maintains self rhythm
- near where superior vena cava enters the right atrium
Atrioventricular (AV) node
- transmits the action potential from the atria to ventricles via bundle of His.
- bundle branches left and right to purkinje fibers
- impulses are delayed…atria contract first; empty before ventricles contract
arteries
- composed of collagen, provides support for high blood pressure
- elastic fibers store energy from blood pressure
- recoil during diastole
- smoother blood flow
- smooth muscle vasodilation and vasoconstriction control direction and pressure of blood
veins- how does blood travel against gravity?
- veins in between muscles, muscles squeeze
2. one-way valves, preventing backflow
capillaries
- connect arterioles to venules
- small diameter, RBC pass in single line
- walls (single layer of endothelial cells) are permeable to water, lipid-soluable and small molecules
- some with intercellular clefts
- some fenestrated
- some very selective, some not
arteriole side of capillary
-blood pressure > osmotic pressure
fluid exits
venule side of capillary
-blood pressure < osmotic pressure
fluid enters
lymphatic tissue
loss of fluid at capillaries returned to blood by the lymphatic system
- diffusion of fluid into lymph capillaries
- formation of lymph
- drainage of lymph into circulation from thoracic duct at left brachiocephalic vein
regulation of blood flow
- pre capillary sphincters (smooth muscle) control flow from arterioles to capillary beds
- low [oxygen], high [carbon dioxide] or [metabolic products] causes smooth muscle to relax
blood
- connective tissue
- plasma (extracellular matrix)
- cellular elements (hematocrit: fracked cell volume)
erythrocytes
- transport respiratory gases through hemoglobin
- anucleated and biconcave, increases area
- flexible
- production in bone marrow controlled by erythroprotein
- stored and recycled in the spleen
erythroprotein
released in kidney in response to hypoxia (low oxygen levels)
leukocytes
- immune response
- can move out of capillaries and into extracellular fluid—amoeboid
platelets
- a-nucleated cytoplasmic bodies with cytoskeletal elements, enzymes and some organelles
- promote blood clotting and formation of platelet plug
