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Stage 1 Physiology > Flashcard set 2 > Flashcards

Flashcard set 2

1
Q

How do we get cardiac muscle to contract?

A

Rise in cystolic calcium which comes from the SR calcium stores = actin / myosin interaction

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2
Q

Pathway of electrical conduction in the heart

A
  1. SA node
  2. AV node
  3. Bundle of His
  4. R/L bundle branches
  5. Purkinje fibres
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3
Q

What is the role of ‘trigger’ calcium in cardiac muscle contraction?

A

calcium enters the heart cell from calcium channels = activates ryanodine receptor to release enough calcium from the SR to initiate contraction

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4
Q

What does each wave/complex in the electrocardiogram represent?

A

P wave = atrial depolarisation
QRS complex = ventricular depolarisation
T wave = ventricular repolarisation

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5
Q

What do the heart sounds represent?

A 
Lubb = AV valve closing
Dupp = SL valve closing
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6
Q

What are the 4 phases of the ventricular cycle?

A
  1. ventricular filling
  2. isovolumetric ventricular contraction
  3. ventricular ejection
  4. isovolumetric ventricular relaxation
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7
Q

Change in pressure and vol. during cardiac cycle?

A
  1. Late diastole = chambers are relaxed and ventricles are filled passively
  2. Atrial systole = atrial contraction
  3. Isovolumetric ventricular contraction = AV valve close, not enough pressure to open SL valve = EDV
  4. Ventricular ejection = ventricular pressure increases = SL valve open and blood ejected
  5. Isovolumetric ventricular relaxed = pressure decreases, SL valve close = ESV
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8
Q

What is the relationship between MABP, CO and TPR?

A

MABP = CO x TPR

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9
Q

Sympathetic and Parasympathetic autonomic control of the heart

A
  1. Sympathetic nerves release NA which bind to beta1 adrenergic receptors = increases heart rate and contractility
  2. Parasympathetic nerves release Ach which binds to muscarinic receptors = negative effect on heart rate
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10
Q

Intrinsic and extrinsic regulation of stroke volume

A

Intrinsic:

  • Starling’s law
  • heart will pump whatever volume of blood it receives

Extrinsic:

  • increase in sympathetic activity
  • enhances contractility
  • enhances stroke volume
  • positive iontropic effect
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11
Q

What are the vasodilators and vasoconstrictors of hormonal control?

A

Vasodilators:

  • Histamine
  • Kinins
  • Nitric oxide
  • Adrenaline (beta2)

Vasoconstrictor:

  • Angiotensin II
  • Vasopressin (ADH)
  • Adrenaline (alpha1)
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12
Q

Explain baroreceptor reflex

A

sensory detectors feed information into control centre about the changes in blood pressure. Control centre regulates input of information to determine what changes need to be made

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13
Q

Location of baroreceptors and what are baroreceptors

A

Carotid sinus and aortic arch

baroreceptors = are stretch receptors which respond to stretch in the arteries due to change in blood pressure

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14
Q

Mechanisms involved in control of renal blood flow

A
  1. increase resistance of afferent arteriole = reduce blood flow to glomerulus
  2. increase resistance of afferent arteriole = increase blood flow in glomerulus
  3. decrease resistance of afferent = increase blood to glomerulus
  4. decrease efferent resistance = increase blood out glomerulus
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15
Q

Formation of concentrated urine

A
  • Anti-duretic hormone = collecting duct is more permeable to H2O
  • Countercurrent systems maintain osmotic gradient in medullary interstitum
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16
Q

What are countercurrent systems?

A
  • 2 flows moving opposite each other
  • passive transfer of molecules

a countercurrent maintains osmotic gradient for reabsorption of H2O by preventing reduction of osmolarity

17
Q

Acidosis and alkalosis in the kidneys

A

acidosis:
- alpha intercalated cells in collecting duct excrete H+ and reabsorb HCO3-

alkalosis:
- beta intercalated cells in collecting duct excrete HCO3- and reabsorb H+

18
Q

How is ADH released?

A
  • produced in hypothalamus
  • stored in vesicles in posterior pituitary gland
  • changes in osmolarity are sensed by osmoreceptors in the hypothalamus which cause the release of ADH
  • increased osmolarity = increased ADH*
19
Q

Mechanics of ventilation

A

Inhalation:

  • diaphragm moves down
  • external intercostal muscles raise rib cage upwards

Exhalation:

  • diaphragm moves up
  • intercostal muscles move down
20
Q

Factors influencing respiratory/ pulmonary ventilation

A
  1. Airway resistance = anything that prevents airflow
  2. alveolar surface tension = gas water boundary
  3. lung compliance = lungs and chest wall stretch
21
Q

How does sodium nitroprusside treat angina due to ischaemic heart disease?

A

produces nitric oxide within the body to cause vasodilation which increases coronary blood flow

22
Q

What is the immediate physiological response to exercise and what causes it?

A

increase in ventilation caused by feedforward reflex receptors in muscle

23
Q

What percentages of Na+ are reabsorbed in the nephron?

A

66% in proximal convoluted tubule
25% in ascending limb
5% in distal convoluted tubule
3% collecting duct

24
Q

What is reabsorbed in the proximal convoluted tubule?

A

66% Na+, K+ and H2O
50% urea, urate
80% HCO3-
100% glucose

25
Q

How do macala densa cells sense change in glomerular filtration rate?

A

detect the resulting changes in Na+ and Cl-

26
Q

What is the location of the pneumotaxic and apneustic centre?

A

pneumotaxic= upper part of pons -> inhibits inspiration

apneustic = dorsally in pons -> promotes inspiration

27
Q

What are the roles of the dorsal and ventral respiratory groups?

A

Dorsal:

  • controls inspiratory drive
  • output via phernic nerve

Ventral:

  • controls expiratory drive
  • inactive during quiet breathing

Stage 1 Physiology (5 decks)

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