Cardiovascular

• Blood also move via

  1. Elastic recoil of arteries
  2. squeezing of vessels during body movement
  3. Peristaltic contractions of smooth muscles moves
• The vertebrate heart has 3 types of muscle fibres (myocardial cells):

  1. located in sinoatrial node (autorhythmic, slow e.c)
  2. in ventricular wall (large, fast e.c)
  3. other parts of the heart
• contraction of each cell associated with action potential
• where is pacemaker situated in heart?

  sinoatrial node (right atrium)
• how many substances regulate heartbeat?

  3 (acetylcholine, adenosine, epinephrine)
• Acetylcholine slows heartbeat (increase K+ conductance, reduce Ca+ conductance)
• what do epinephrine do?

  accelerates pacemaker potential, increasing heart rate
• The Na+/K+ pump contributes to the resting potential in cardiac muscle cells by pumping K+ in, and pump 3Na+ out and 2K+ in cells
• how does the heart deal with increased demand during exercise?

  increase heart rate and increase stroke volume
• In open circulatory systems, pressure are low, and blood is pumped by the heart empties into a space called the hemoceol
• In closed circulatory systems, blood passes via capillaries from the arterial to the venous circulation. Pressures are high.
• Disadvantages of completely divided lung is cardiac output must be the same to avoid shifts in blood volume
• Explain the cardiovascular system of water breathing fishes?

  Oxygenated blood goes into gills into the dorsal aorta, transported to the tissues, then into the heart (atrium then ventricle) and then to the ventral aorta.
• Differences between water-breathing fish and lung-breathing fish?

  water-breathing has 4 chambers, undivided heart and gill circulation has higher pressure than systemic circulation.

  lung-breathing fish has 2 chambers, partial divided heart. When breathing in water, blood shunted into dorsal aorta. When breathing in air, blood shunted to lung.
• In amphibians, O2 uptake is by lungs and skin
• Amphibians heart is not divided
• flow rate is proportional to pressure and radius
• flow rate is inversely proportional to length and fluid
• where does right to left shunt occurs in?

  mammalian fetus and bird egg
• Lymph System return excess fluid
• when injured, histamine is released causing vasodilation