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Flashcards

the heart

Lydia McCarrick physiology univeristy English 45 cards

What is the structure of the heart?

Cards in this deck (45)

  1. 1the circulatory system in invertebrates- pump/circulatory system isn't needed, the internal cavity or intestine exposes the body cells to materials essential for metabolism (no need for heart as material diffuse into correct tissues)
  2. 2what was the evolutionary stimulus for haemoglobin/circulatory development?limited solubility of 02 in water, development of aerobes in aquatic environments
  3. 3where did open systems with a heart develop and in what organisms are they present?- developed in sedentary organisms e.g. molluscs, also present in arthropods
  4. 4What is the definition of an open system?no tubes directing blood flow around the body
  5. 5in what organism did a closed circulation first appear?appeared early on amongst annelids (worms)
  6. 6WHat does the two circuits of the heart allow for?1) low pressure system to the lungs
    2) high pressure system to remainder of body
  7. 7What are the 5 critical features in evolution of the heart?1) development of single central pumps
    2) unidirectional flow
    3) one way valves at base of arteries for high pressure
    4) high resistance exchange beds for efficient gas exchange
    5) the separation of a high pressure side from a low pressure reservoir by capillary beds
  8. 8Why do we need a heart?1) it is primary organ
    2) in a large multicellular animal the other organs can't function without a contestant blood supply
    3) therefore in an embryo it is the first organ to develop
  9. 9What is the location/ structure of the heart?1) upper parts of thorax between the sternum and the vertebrae
    2) conical structure 12 cm L, 8 cm diameter, and 250-300g
    3) 4 chambers, 4 valves and 4 vessels
  10. 10What is the structure of the heart?What is the structure of the heart?
  11. 11What is the pericardial sac?skin sack that surrounds the heart to protect it
  12. 12What valves make up the atrioventricular valves? what aids their function? What is their role?-the tricuspid and bicuspid valves
    -the heartstrings
    -prevents back flow from the ventricular arteries
  13. 13Why are there no valves on the atrial vessels? what is the operating system of these valves?- it is important that blood can continue to flow into atria without obstruction
    - they are one way valves i.e. only allow flow in one direction ( When pressure is greater behind valve it opens, greater in front then closes )
  14. 14Where is fibrous ring present and what is it's function? All valves occur in the same plane TRUE/FALSEatrio-ventricular valves are fitted with a fibrous ring, electrically insulates the atria from the ventricles
    TRUE
  15. 15what type of muscle is cardiac muscle and what is it formed from? How is each cell connected?1) striated (striped muscle)
    2) formed from v. small short muscle cell (myocytes) 0.1mm long
    3) each myocyte is connected at gap junctions called intercalated discs
  16. 16What is the role of intercalated disks?-physical/electrical junctions
    -allow for rapid transmission of electrical signals
  17. 17what is the role of the heart of and what are the two phases of it's action?-it is a dual synchronous pump variable in both rate/capacity
    - diastole and systole
  18. 18What occurs during 1) systole 2) diastole1) contraction
    2) expansion
  19. 19What is the average heart at rest?1) 5 lmin-1 @ 70 ml per beat
  20. 20What are the two main functions of the heart? How is this achieved?1) pumps fluid to lungs (pulmonary circulation)
    2) pumps fluid to rest of body (systemic circulation)
    -achieves this by two synchronised events
    atrial/ventricular contraction
  21. 21what are the sequence of actions in a heart beat?1) upper/lower chambers fill, the pulmonary and aortic (semi lunar valves close)
    2) upper chambers contract and primes the lower chamber
    3) the lower chamber contracts, the AV closes, blood ejects through the semi-lunar valves which then close.
  22. 22How is a heart beat generated?-no nerves within heart but specialised electrical cells i.e. SAN
    - heart generates beats that are under ANS control
    - muscle cells not intrinsically active but instead there is an internal pacemaker system made up of modified muscle cells that generate action potentials spontaneously
  23. 23how does electrical wave travel through atrial walls?Via gap junctions between cells
  24. 24What cells conducts impulse to ventricular walls from atria?the bundles of HIS
  25. 25What is the delay of transmission of signal from the atria to the ventricles essential for?the 160 ms delay is essential for atrial emptying prior to ventricular contraction
  26. 26What is the process of electrical stimulation of the heart?1) stimulus initiated by SAN
    2) conduction via atrial msucle and internodal tracts (1ms-1)
    3) conduction via AVN
    4) dispersal via bundle of HIS left, right bundles and purkinje fibres to ventricular mass
  27. 27LOCATION OF 1) SAN 2)AVN 3) bundle of HIS1) in left atrium
    2) at top of inter ventricular septum above ventricles
    3) interventricular spetum
  28. 28what are the two type of cells in the heart?1) pacemaker
    2) contractile
  29. 29What is the changes in ions that affect membrane potential of the heart?What is the changes in ions that affect membrane potential of the heart?
  30. 30What is the process by which ion concentrations are changed to depolarise and polarise the membrane (looking at membrane pot diagram)1) increase pumping of ca2+ and decrease na+ leads to slow depolarisation of the membrane
    2) reaches threshold value and peak
    3) after peak K+ is pumped out
    4) membrane is polarised again
  31. 31What cells are electrical changes in the heart transferred from and to? What actions of the contracting muscle cells lead to them having a prolonged contraction and absence of tenatus?1) from pacemaker cells to contractile cells
    2) fast inward sodium currents and important plateau response due to ca2+ entry
  32. 32Excitation contraction coupling1) current spreads through gap junctions into contractile cell
    2) action potentials travel along plasma membrane and tubules
    3) ca2+ channels open in plasma membrane and tubules
    4) ca2+ induces ca2+ release in sarcoplasmic reticulum
    5) Ca2+ binds to troponin exposing myosin binding sites
    6) crossbridge cycle begins (muscle fibre contracts)
    7) Ca2+ is actively transported back into SR/ECF
    8) Tropomysoin blocks myosin binding sites (muscle fibre relaxes)
  33. 33What is the equation for cardiac output?cardiac output= heart rate x stroke vol
  34. 34what two mechanisms are involved in the variation of output?1) change in pump rate
    2) change in quantity of blood pumped at each stroke
  35. 35What two things control cardiac output?1) muscle itself
    2) ANS
  36. 36Heart is myogenic T/f? What does starling's law of the heart state? For what two reasons is this law important?1) TRUE
    2) energy released during contraction depends on the initial fibre length
    3) -to match output of both pumps
    -to match output with input
    -
  37. 37What does the ANS control about the heart?1) heart rate/ contractile force
  38. 38What causes the SAN to spontaneously generate action potentials?1) balance/type of ion channels in the cell membrane
  39. 39What happens to heart rate during rest? Via what receptors does acetylcholine act to reduce heart rate?1)'parasympathetic tone' decreases rate of SAN to 70 bpm,
    2) muscarinic receptor to increase outward current of K+ maintaining -ve below threshold value
  40. 40How is HR stimulated during exercise? What neurotransmitters ar einvolved and what receptors?-activity in parasympathetic increase elevating HR/contractile force
    - caetcholamines/noradreneline act via beta adrenorecpetors to enhance rate of depolarisation allowing MORE Ca2+ in/by increase background inflow of sodium
  41. 41Control of autonomic inervation of the heart?1) MOTOR CORTEX- higher brain areas i.e. central command acts on
    2) VENTROLATERAL MEDULLA (cardiovascular centre)
  42. 42What are the inputs to the ventrolateral medulla?1) arterial barorefelexes- aortic/carotid arterial mechano receptors
    2) cardiopulmonary reflexes- cardiac mechano receptors
    3) exercise presser reflex
    - recepts in skeletal muscle
  43. 43what parts of the heart are these nerves connected to ? 1) parasympathetic 2) sympathetic1) nerve endings conentrate in atria incl SA/AV nodes
    2) supply SAN/AVN and muscle of atria and ventricles
  44. 44What is the typical ecg images? what does each of these sections relate to? 1) P 2) QRS complex 3) st segment 4) T wave 5) TP interval at what points are systole and diastole occurring?1)p - atrial depolarisation
    2) QRS complex- ventricular depolarisation (atria polarising simultaneously)
    3) ST segment- time during which ventricles are emptying and contracting
    4) T wave- ventricular depolarisation
    5) TP interval- time during which ventricles are emptying and relaxing
    -D=r-t
    -S=tR    What is the typical ecg images? what does each of these sections relate to? 1) P 2) QRS complex 3) st segment 4) T wave 5) TP interval at...
  45. 45when does isovolumetric contraction/ relaxation and dicrotic notch occur?1) whilst the ventricle pressure is increasing/decreasing while it contracts
    2) when the aortic pressure increases then decreases slightly and then increases again

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univeristy physiology Flashcards on the heart , created by Lydia McCarrick on 20/05/2015.
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Lydia McCarrick
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