Chapter 20 Lecture 3 Flashcards
What are required for directional circulation?
Pump Valves Muscle location/structure Timing of contractions Tubes in a circuit
Valves:
one-way entrance and exit
A-V valves open and:
allow blood to flow from atria into ventricles when ventricular pressure is lower than atrial pressure
A-V valves close and:
prevent backflow of blood into atria
SL valves open
Semilunar - with ventricular contraction
allow blood to flow into pulmonary trunk and aorta
SL valves close
with ventricular relaxation
prevents blood from returning to ventricles, blood fills valve cusps, tightly closing the SL valves
Pre-load
- Ventricles relax, drawing blood into atria
2. Atria then contract, sending blood into ventricles
After Load:
- Ventricles contract, blood enters ascending aorta and pulmonary arteries
Stenosis -
valve narrowing (restricts blood flow)
Insufficiency –
valve does not close completely (“murmur”; congenital, scar tissue or autoimmune damage from disease)
Prolapse –
valve cusp escapes backwards into previous chamber (blood backflow)
Septal defect –
opening between chambers, usually between ventricles (allows mixing of oxygenated and deoxygenated blood)
3 Circuit:
Pulmonary, Systematic, Coronary
Pulmonary Circuit:
right ventricle –> deoxygenated blood to/from lungs –> 1. left atrium
- right side of heart pumps deoxygenated blood to lungs
- right ventricle pumps blood to pulmonary trunk
- pulmonary trunk branches into pulmonary arteries
- pulmonary arteries carry blood to lungs for exchange of gases
- oxygenated blood returns to heart in pulmonary veins
Systematic Circuit:
left ventricle –> oxygenated to/from body –> right atrium
- pumps oxygenated blood into aorta
- aorta branches into many arteries that travel to organs
- arteries branch into many arterioles in tissue
- arterioles branch into thin-walled capillaries for exchange of gases and nutrients
- begins its return in venules
- venules merge into veins and return to right atrium
Coronary Circuit:
left ventricle –> ascending aorta –> myocardium –> coronary sinus –> right atrium
1.Thick myocardium needs separate, dedicated cardiac circulation
2. Two arteries branch immediately off ascending aorta:
left coronary artery:
right coronary artery:
3. Largely parallel veins
Blood flow
blue = deoxygenated red = oxygenated
Coronary Circulation is:
blood supply to the heart
- Heart as a very active muscle needs lots of O2
- When the heart relaxes high pressure of blood in aorta pushes blood into coronary vessels
- Many anastomoses (branches come back together in short distances)
Coronary arteries:
Branches off aorta above aortic semilunar valve
Left coronary artery:
circumflex branch
-supplies left atrium and left ventricle
anterior interventricular art.
-supplies both ventricles
Right coronary artery:
marginal branch
-supplies right ventricle
posterior interventricular art.
-supplies both ventricles
Coronary Veins:
Collects wastes from cardiac muscle
Drains into a large sinus on posterior surface of heart called the coronary sinus
Coronary sinus empties into right atrium
Principal tributaries of coronary sinus
Great cardiac vein
Middle cardiac vein
Small cardiac vein
Anterior cardiac veins
Cardiac Muscle Histology
Branching, intercalated discs with gap junctions, involuntary, striated, single central nucleus per cell
Structured much like skeletal:
striated with overlapping actin and myosin filaments
Interconnected by many gap junctions =
pass deplorization from cell-to-cell.
Able to produce»_space; ATP:
more mitochondria
