BIOL 273 - Unit 4.1 + 4.2 Flashcards
What are the materials transported between the environment to tissues
nutrients/ water/ gases (O2)
What are the materials transported between tissues of body
wastes/nutrients/ hormones
What are the materials transported from tissues to external environment
metabolic wastes, gases (CO2), heat
What is the pericardium
a tough membranous sac surrounding the heart
- made of two layers with a small amount of fluid between them that acts as lubricant
What are coronary arteries
- Nourish the heart muscle
- Heart ha a high oxygen demand - depends on adequate blood flow
- lack of blood supply to heart - leads to a heart attack
Left atrium
receives blood from the pulmonary vein - sends to the left ventricle
Left venctricle
receives blood from left atrium - sends to body via aorta
Right atrium
receives blood from venae cavae - sends to the right ventricle
Right ventricle
receives blood from right atrium - sends to lungs
Valves
ensure flow is unidirectional
(doesn’t exist at entrance to the atria’s since atrial contraction is already weak relative to ventricular contraction)
Atrioventricular valves ; what are its other names and where is it found
tricuspid and bicuspid (mitral)
- attached on ventricular side to collagenous cords
What prevents valves from being pushed back into atrium
chordae tendineae
Semilunar valves
aortic and pulmonary
- inside aorta and pulmonary arteries - prevents backflow into ventricles
- do not need cords to brace them because of their shape
What are the two divisions of blood flow
- pulmonary circuit
- systemic circuit
Describe the main idea of the pulmonary circuit
blood vessels in the lungs and those that connect the lungs to the heart
Describe the path of the pulmonary circuit
- blood flows from right atrium to right ventricle - pumped to pulmonary arteries to the lungs
- lungs have many capillaries to increase O2 transfer
- Oxygenated blood has low pressure - need to return to heart via pulmonary veins to left atrium
Describe the main idea of systemic circuit
encompasses the rest of the blood vessels in the body
Describe the path of the systemic circuit
- blood flows from left atrium to left ventricle (pumped to aorta that branches into smaller arteries and then to capillary networks throughout the body)
- oxygen diffuses from the blood into the tissues in the capillary beds - then flow to small venules and then larger veins
- oxygen poor blood has low pressure - need to return to hear via superior/inferior vena cava to the right atrium
How is the heart muscle different from other muscles
- heart does not need input from the nervous system
What are the specialized heart cells called and what is its function and location
cells called autorhythmic cells that excite heart without nervous system
- forms a conducting system in heart that spontaneously generates AP’s
- found in SINOATRIAL NODE (right atrium near superior vena cava)
Describe the membrane of pacemaker cells
unstable membrane potential
- slow drift (from -60 mV) of depolarization until it reaches threshold (pacemaker potential) to rapidly depolarize+repolarize
What are the special channels of pacemaker cell membranes and what is it permeable to
“funny” channels
- permeable to K+ and Na+
What is the cause of slow depolarization of the membrane of pacemaker cells
sodium influx greater than potassium efflux
(net influx of positive charge)
What is the cause of the membrane continued depolarization in pacemaker cells
funny channels close; caclium channels open
- leads to threshold reached
- leads to rapid influx of calcium from calcium channels (steep polarization)
What is the cause of the end of depolarization in pacemaker cells
calcium channels close and potassium channels open slowly ; efflux of potassium causes repolarization
What is a major difference between action potentials and pacemaker potentials in the pacemaker cells
- sodium and calcium ions influx for pacemaker potential
- only calcium influx for action potential
How does heart rate go up
Norepinephrine released via post ganglionic sympathetic neuron onto the cells of the SA node
- epinephrine for reinforcement
- bind to beta adrenergic receptor
What happens when norepinephrine and epinephrine are bindind to beta adrenergic receptor
involved use of G proteins - release of cAMP
- membrane depolrizes due to second messenger passway
- makes it easier for cell to hit threshold (heart rate goes up)
How is heart race reduced
Acetylcholine released from parasympathetic neurons
- target cells have muscarinic receptors
- more potassium released,
- pacemaker starts at a more negative value therefore it takes longer to reach threshold potential
Describe the events of conduction in heart muscle contraction
- AP fired from SA node - spreads to adjacent cells
- Rapid spread through cells of internodal pathway
- signal passed through AV node ONLY at AV junction (connective tissue acts as insulator prevents electrical signals from atrium to ventricle)
- therefore AV node ONLY pathway for action potential - Signal is carried to bottom of heart through bundle of His
- His divides into left and right branches (Purkinje fibres)