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Human Physiology > Week 6 > Flashcards

Week 6 Flashcards

1
Q

what is cardiac output

A

Cardiac output = volume of blood pumped out the heart every minute
= Heart rate x stroke volume

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2
Q

What causes an increase in heart rate

A

• Sympathetic nervous system supply SA and AV node (cardiac nerves)
• Causes membrane to depolarise which shortens AV node delay
• Norepinephrine released
• Heart rate increases and myocyte action potential decreases
**circulating epinephrine in the blood can increase heart rate

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3
Q

What causes a decrease in heart rate?

A

• Parasympathetic nervous endings (vagus nerve)
• Stimulates SA node and causes membranes to hyper polarise (slowing down SA release)
• Secrete ach neurotransmitter
• Heart rate slow

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4
Q

how is stroke volume regulated

A

• The force by which the muscle cells contract, and
• The arterial pressure against which they have to eject the blood

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5
Q

how is the force of contraction regulated?

A

• The length-tension properties of cardiac muscle cells, and
• The effects of hormonal influence on the contractility of cardiac muscle

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6
Q

what is the relationship between end diastolic volume and stroke volume

A
  • End diastolic volume is increased by increased venous return (frank stirling law)
  • This leads to increase stroke volume as the cardiac muscle stretch and contract with more force
  • Sympathetic nervous activity (norepinephrine and circulating epinephrine increase the contraction force)
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7
Q

what is the summary of all the heart mechanisms

A
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8
Q

what is the summary of all the heart mechanisms

A
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9
Q

what is blood pressure?

A

Blood pressure (systolic 120mmHg and diastolic 80mmHg)
- Driving force for blood flow in the cardiovascular system and maintains a pressure gradient between veins and arteries
- Pulsatile in arteries and continuous in the veins

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10
Q

What is mean arterial pressure

A

93mmHg= calculated from systolic and diastolic blood pressure (not average)

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11
Q

what factors affect blood pressure?

A

Age- arteries becomes stiffer and loose elasticity
Higher in the foot and lower in the head- to hydrostatic pressure
Women have lower blood pressure then men
Dynamic exercise by is maintained and in weight bearing exercises it increases

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12
Q

what is the mean arterial blood pressure total equation?

A
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13
Q

what is the SA node

A
  • located in right atrium
  • Initiates cardiac contraction in the absence of external control (nerves/hormones)
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14
Q

what is pacemaker potential

A

• SA node initiatives action potential
• There is an unstable membrane potential Continuously drifting towards the threshold

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15
Q

what does SA node firing rate depend on

A
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16
Q

how does sympathetic stimulation affect as node firing rate

A
  • increases slope of the drift
  • increase permeability of the na+ current
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17
Q

how does parasympathetic stimulation affect rate of SA node

A
  • leads to a decrease in the slope of the drift
  • decrease inwards current
  • hyper-polarisation of the membrane
  • increased k+ permeability
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18
Q

What is the order of events of cardiac muscle conduction?

A
  1. SA stimulates contraction and causes atria contraction
  2. AV node holds firing so atria finishes contracting
  3. AV node and bundle of his are the only pathway that electrical stimulus travels from atria to ventricles
  4. The electrical stimulus travels down inter ventricular septum via two bundle branches
  5. Ventricles contract by lurking fibres and stimulus spread upwards depolarising muscle fibres
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19
Q

when do the following occur
- atrial excitation
- ventricular excitation
- ventricular relaxation

A
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20
Q

Describe the electro cardiogram

A
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21
Q

What are the four heart valves

A

1st on the right- tricuspid valve
• Opens when right atrial pressure is greater pressure than right ventricle pressure
2nd on the right- pulmonary valve
• Open when right ventricle pressure is greater pressure than pulmonary artery pressure
1st on the left- bicuspid (mitral valve)
• Opens when left atrium is greater pressure than left ventricle
2nd on the left- aortic valve
• Opens when left ventricle is greater pressure than aortic valve

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22
Q

what is isometric ventricular contraction

A

when pressure becomes equal

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23
Q

what is isovolunetric ventricular relaxation

A

diastole

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24
Q

Describe the pressure volume curve

A
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25
Q

what is smooth muscle

A

• Form layers and line hollow organs
• Controlled by automatic nervous system
• Connected eclectically and mechanically
• Smooth muscle takes the longest to contract (then cardiac then skeletal is the quickest)

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26
Q

what are the properties of smooth muscle

A
  • No sarcomere: actin and myosin form a cross cross lattice
  • Actin filaments connect to dense bodies
  • Smooth muscle cells connect by dense bands
  • They join electrically by gap junctions (no neuromuscular junctions)
  • There is no all or none law and instead the contraction is graded
27
Q

what are the two ways an action potential occurs in smooth muscle

A
  1. Slow waves- constant state of readiness as the waves are between excitatory stimuli and inhibitory stimuli
  2. Pacemaker potential- similar to SA nose and relies on rhythmic activity
28
Q

what is the role of calcium in smooth muscle?

A
29
Q

how does smooth muscle and skeletal muscle differ ?

A
30
Q

how does the force of contraction in smooth muscle vary?

A
  • less myosin and more actin
  • the force of contraction varies over a large range of lengths due to filaments sliding past each other further
31
Q

what is design of the respiratory system

A

• Interlink between environment and body tissues for diffusion
• Communicates with cardiovascular system
• Muscular pump- required for air movement= formed by lungs inhaling and exhaling
• Hydration- effective diffusion requires moist surrounding within a closed space

32
Q

what are the functions of the respiratory system?

A
  • Gas exchange between environment and blood
  • Vocalisation
  • Control of acidity
  • Filter inhaled air
33
Q

what does the lungs divide into

A

The lungs- divided into compartment called lobes, the right lungs has three lobes and the left lung has two lobes. Lungs fill the entire thoracic cavity

34
Q

what is the pleural sac and what does it do?

A

The pleural sac- double walled enclosure filled with pleural fluid
- Reduces friction
- fixes lung to thoracic wall

35
Q

Label the thoracic cavity parts

A
36
Q

what are the muscles and bones for in the thoracic cavity?

A

• The bones (rib cage and spine) offer rigid protection to sensitive organs (heart and lungs).
• The muscles (diaphragm, intercostals, abdominals) support the rib cage and turn the chest into a pump that drives air flow

37
Q

how does the airways split

A

Upper respiratory tract & lower respiratory tract
* bronchial tree undergoes 23 divisions

38
Q

what are the functions of the airways

A

• Warming up of inspired air.
• Humidification of dry inspired air.
• Filtration of inhaled foreign materials

39
Q

describe the parts of the nasal cavity

A

The nasal cavity- predominant way to breathe
• Contains Turbinates- increase surface area
• Lots of blood supply- warm up and humidify air
• Small hairs and mucus- trap inhaled particles

40
Q

Label the airways surfaces

A
41
Q

what is the alveoli

A
  • A single layer of alveolar epithelial cells
  • A thin barrier= enough out surface area for gas exchange
  • Alveoli layer and capillary endothelial layer are the only two layers between blood and air
42
Q

what is the relationships between pressure and volume in the lungs

A
43
Q

what are the airflow properties

A
44
Q

what is viscosity?

A

Viscosity= how easily the air flows through the airways (affects the resistance)
-it is affected by humidity and air concentration (altitude)

45
Q

What is the equation linking resistance to viscosity?

A
46
Q

What are the factors affecting airway radius?

A

Bronchidilation- airways become bigger (c02 and epinephrine)
Bronchoconstriction- airways become smaller (parasympathetic stimulation)

47
Q

Is inhalation passive or active

A

Passive

48
Q

Describe inspiration at rest and during exercise

A

Inhalation- contraction of diaphragm and external intercostal muscle.
Inhalation in exercise- further contraction and additional contraction of the sternocleidomastoid and scalenes elevate sternum

49
Q

Describe expiration at rest and during exercise

A

Expiration- relaxation of contracted muscles
Exhalation in exercise- internal intercostal muscles and abdominal muscles contract and pull ribs in and down and forces diaphragm higher

50
Q

What is intrapleural pressure

A
51
Q

What is intrapleural pressure

A
52
Q

what is atmosphere pressure set as?

A

0 and everything is based off that

53
Q

what is
P atm
P all
P ip
P tp

A
54
Q

What are the basic principles of inspiration and expiration?

A
55
Q

what is surfactant?

A
  • Stabilises alveoli and increases lung compliance
  • Stops the smaller alveoli collapsing into the bigger alveoli
    +contains proteins which disrupts water molecule and reduces surface tension on alveolar walls. This tension reduction the alveoli spaces are less likely to collapse and the lung inflates easier
56
Q

What is the spirometer trace?
what is tidal volume?
what is reserve volume?
what is vital capacity?
what is functional residual value?
what is residual volume?

A
57
Q

what is respiratory dead space?

A

Respiratory dead space= the air breathed that doesn’t contribute to gas exchange

58
Q

What is anatomical dead space?

A

Anatomical dead space= the part of the air space where gas exchange doesn’t occur (150ml)

59
Q

What is alveolar dead space?

A

Alveolar dead space= where gas exchange takes place but doesn’t connect properly with blood

60
Q

Why does signing occur?

A

Sighing= there is an imbalance at the top of the lung and causes alveoli to collapse so sighing opens up alveoli and resets lung

61
Q

how does air movement in ventilation lead to stale air

A
62
Q

how does air movement in ventilation lead to stale air

A
63
Q

what is minute ventilation

A

Minute Ventilation= tidal volume x breathing frequency (6l at rest and can be 150l during exercise)

64
Q

What is hyperpnoea and what is hyperventilation?

A

Human Physiology (7 decks)

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