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year 1 > Systems Physiology > Flashcards

Systems Physiology Flashcards

1
Q

In controlling blood flow, what controls the resistance?

A

Arteriolar radius

Resistance is proportional to 1/r^4

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2
Q

What local effect occurs with changes to arteriolar radius?

A

Regulates blood flow it tissues

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3
Q

What central effect occurs following changes in arteriolar radius?

A

Affects blood pressure because the change in total peripheral resistance affects central blood volume

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4
Q

What are the intrinsic factors that control vascular smooth muscle?

A
  • temperature
  • transmural pressure
  • local metabolites, endothelium derived factors and autocoids
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5
Q

What is a precapillary sphincter?

A

A band of smooth muscle at the arteriolar end of the capillary

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6
Q

what is the hypodermis?

A

the third layer of the skin - underneath the dermis and consist of loose CT - adipose cells

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7
Q

what are the layers of epidermis?

A

(from top)

1) stratum corneum
2) stratum lucidum
3) stratum granulosum
4) stratum spinosum
5) stratum basale

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8
Q

which epidermal layer is not found in thin skin?

A

stratum lucidum

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9
Q

which cell type is the most abundant in the epidermis?

A

keratinocytes

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10
Q

which cell type are the most abundant in the dermis?

A

fibroblasts

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11
Q

what are the two layers of the dermis?

A

papillary layer

reticular layer

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12
Q

describe the cells in the stratum spinosum

A

many desmosomes = spiky appreance
express keratin
active protein synthesis

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13
Q

how can you characterise the cells in the stratum granulosum

A

large granules of keratohyalin

cell death occurs in outermost aspect

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14
Q

which type of connective tissue is found in dermal papillary layer?

A

type III collagen

elastin

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15
Q

what type of CT is found in reticular layer of the dermis?

A

dense irregular CT

type I collagen and elastin

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16
Q

what are the three phases of hair growth?

A

anagen (active)
catagen (regressive)
telogen (resting)

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17
Q

what is a pilosebaceous unit ?

A

hair follicle and sebaceous gland

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18
Q

which gland is found opening into the hair follicle?

A

appocrine gland

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19
Q

what are the three gland types found in the skin? describe their release of content

A

holocrine - release content by complete cell lysis
appocrine - content released in vesicles
eccrine - content released by exocytosis

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20
Q

what is the difference between vellus and terminal type of hair?

A

vellus: body hair
terminal: scalp, secondary sexual hair

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21
Q

in the structure of the hair follicle, here do the hair follicle stem cells lie?

A

the bulge

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22
Q

what is pseudostratified epithelia?

A

all cells lie at the basal lamina however not all reach the surface and nuclei are at different levels giving the appearance of many layers

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23
Q

what is transitional epithelium and where is it found?

A

epithelia that have two forms; stratified squamous when stretched and stratified cuboidal at rest. they are specialised to withstand toxic environment found int he urinary tract

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24
Q

what are the five types of epithelial junctions?

A 
tight
adherens 
desmosomes
hemisdesmosomes
gap
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25
Q

what are mucous membranes composed of?

A

epithelium, basement membrane, lamina propria, smooth muscle

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26
Q

what are the 5 types of connective tissues?

A 
fibrocollagenous
adipose
cartilage
bone
blood
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27
Q

what is ground substance composed of?

A

glycoaminoglycans (GAGs)

proteoglycans

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28
Q

which collagen type is found in basement membranes?

A

type IV

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29
Q

what are the types of fibrocollagenous connective tissue?

A

LOOSE:

  • areolar
  • adipose
  • reticular

DENSE:

  • regular
  • irregular
  • elastic
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30
Q

where is dense irregular CT found?

A

dermis - reticular layer

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31
Q

where is dense regular CT found?

A

tendons, ligaments

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32
Q

what is the difference between white and brown adipose tissue?

A

WHITE:

  • unilocular
  • adults
  • energy store, shock absorber, insulator

BROWN:

  • multilocular
  • newborns
  • rich in mitochondria
  • heat source
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33
Q

what are the three types of cartilage?

A

hyalin - type II collagen
elastic - type II collagen + elastic fibres
fibrocartilage - type II and type I collagen

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34
Q

three cells types in bones?

A

osteoclasts - resorb
osteoblasts - form
ostecytes - maintain

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35
Q

what are the types of glycoproteins found in ECM?

A

laminin and fibrolectin: cell adhesion
fibrillin : elastic fibre formation
osteocalcin: mineralisation

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36
Q

what is the precursor for elastin?

A

tropoelastin

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37
Q

which cells produce cartilage?

A

chondroblasts

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38
Q

where are chondrocytes found?

A

lacunae

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39
Q

where is fibrocartilage found ?

A

intervertebral disks

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40
Q

what is ‘osteoid’?

A

the ground substance of bone - type I collagen

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41
Q

what are the types of bone?

A

spongy/trabecular/cancellous bone - spaces filled with bone marrow
lamellar bone - has layers/lamellae
compact bone - organised into osteons

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42
Q

what is periosteum?

A

dense vascular CT surrounding bone except at surface of joints

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43
Q

what is the perichondrium?

A

the fibrous tissue surrounding cartilage but not of developing joints
consists of two layers: inner chondrogenic
outer fibrous

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44
Q

where do the calcium ions come from in smooth muscle contraction?

A

extracellular calcium

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45
Q

what are the two types of bone growth?

A

ENDOCHONDRAL

  • long bone
  • requires hyalin cartilage for model

INTRAMEMBRANOUS

  • flat bone formation
  • formed within fibrous membrane
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46
Q

briefly list the steps of endochondral bone formation

A

1) fetal hyalin cartilage develops with perichondrium around it
2) invasion of capillaries at diaphysis, perichondrium becomes peristeal collar as osteoblasts are carried to the site (by the blood). the cartilage begins to deteriorate at the diaphysis and trabecular bone forms

3) primary ossification centre forms.
epiphyseal capillaries invade the epiphysis

4) secondary ossification centre forms at epiphysis and medullary cavity forms at diaphysis
5) osteoblasts replace all of cartilage to bone except at articular cartilage and epiphyseal growth plate
6) epiphyseal growth plate too ossifies and forms epiphyseal lines

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47
Q

briefly describe intramembranous ossification

A

1) mesenchymal cells cluster at sites in fibrous connective tissue
2) mesenchymal cells differentiate into osteoblasts, which secrete bone matrix called osteoid - formation of ossification centre
3) osteoid matrix begins to calcify, trapped osteoblasts become osteoclasts
4) with further osteoblast activity, trabeculae form which fuse together forming spongy bone

woven bone remodelled into lamellar bone

5) vascularisation of surrounding mesenchymal cells cause them to condense and form the periosteum
6) layer of compact bone covers the spongy bone

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48
Q

what protein do calcium ions bind to in smooth muscle contraction?

A

calmodulin

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49
Q

what are the blood supplies of:

a) periosteum
b) outer compact bone
c) inner compact bone, trabecular bone and bone marrow of diaphysis
d) epiphyseal trabecular bone

A

a) periosteal arteries
b) Haversian and Volkmann’s canals
c) i nutrient artery
d) epiphyseal arteries

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50
Q

what happens to smooth muscles in asthma?

A

hypertrophy and hyperplasia of smooth muscles

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51
Q

what controls smooth muscle contractions?

A

autonomic stimulation,
hormones,
local physiological conditions

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52
Q

what is found at the junction of A and I bands in sarcomeres?

A

T tubules

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53
Q

what controls skeletal muscle contraction?

A

alpha motor neurones

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54
Q

what does calcium bind to during contraction of skeletal muscle?

A

troponin

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55
Q

which muscle type has no stem cells?

A

cardiac

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56
Q

what is a sarcomere?

A

a unit of a myofibril from one Z-line to the next

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57
Q

what type of junctions are predominantly found at intercalated discs in cardiac muscle?

A

longitudinal component: gap

transverse component: desmosomal junctions

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58
Q

which muscle type does not have an extracellular source of Calcium ions for contraction?

A

skeletal muscle - from sarcoplasmic reticulum

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59
Q

how is force of contraction regulated in skeletal muscles?

A

recruitment of motor units and frequency of action potentials

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60
Q

describe skeletal muscle contraction

A

1) action potential depolarises the sarcolemma
2) depolarisation reaches T tubules
3) depolarisation of T tubules causes release of calcium ions from sarcoplasmic reticulum
4) calcium ions bind to troponin
5) troponin changes shape, dislocating the tropomyosin from the actin filament, revealing myosin-head-binding-site
6) myosin hydrolyses an attached ATP molecule (low energy conformation) into ADP and Pi (high energy conformation) which causes the myosin head form a cross-bridge with the actin filament.
7) the myosin head bends and pulls the actin filament towards the M line - power stroke
8) the ADP and Pi molecules diffuse away and a new ATP molecule attaches
9) this causes the cross-bridge to break and go back to its low energy state again
10) the process is repeated as the ATP is hydrolysed again until either calcium ions are taken back up or no more ATP.

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61
Q

which component is NOT found in smooth muscle but is found in skeletal and cardiac muscles?

a) actin
b) myosin
c) troponin
d) tropomyosin

A

c) troponin (instead calcium ions bind to calmodulin)

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62
Q

what is leiomyoma?

A

benign neoplasms of smooth muscle

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63
Q

what are the zones of epiphyseal growth plate?

A

1) resting chondrocyte reserve
2) proliferating chondrocytes
3) mature chondrocytes
4) calcified chondrocytes - dying

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64
Q

what is the difference between woven and lamellar bone?

A

woven:
- production of osteoid is rapid
- disorganised collagen
- mechanically weak

lamellar:

  • secondary bone created by remodelling of woven bone
  • regular parallel alignment of collagen fibres
  • mechanically strong
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65
Q

what is appositional growth and interstitial growth

A

appositional growth:

  • growth in diameter
  • at periosteal surface

interstitial growth:

  • growth in length
  • via epiphyseal growth plate
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66
Q

factors affecting remodelling of bone?

A
  • change in mechanical stresses
  • fracture
  • hormones eg parathyroid hormone, calcitonin
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67
Q

what are the boundaries of the superior thoracic cavity?

A

body of thoracic vertebra 1
medial margin of rib 1
manubrium

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68
Q

what is the inferior thoracic cavity closed by?

A

diaphragm + structures passing through/posteriorly to it

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69
Q

at which point is the mediastinum divided horizontally into superior and anterior mediastinum?

A

horizontal line through sternal angle between T4 and T5

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70
Q

how are the lungs attached to the mediastinum?

A

via the root

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71
Q

what are the divisions of the mediastinum?

A

superior

inferior -> post, middle, ant

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72
Q

what is the name given to the lining covering the thorax and enveloping the lungs?

A

pleura

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73
Q

describe the two types of pleura

A

visceral pleura - attached to lungs

parietal pleura - attached to thorax

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74
Q

what are the boundaries of the thoracic wall?

A

anteriorly: sternum
posteriorly: thoracic vertebra + intervertbral discs
laterally: ribs and intercostal muscles

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75
Q

what are the main anatomical features of the sternum?

A

manubrium
sternal angle
body of sternum
xiphoid process

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76
Q

where do the intercostal nerves and blood vessels lie?

A

costal groove between the inner two intercostal muscles

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77
Q

which ribs are called “floating ribs”

A

ribs 11 and 12

they do not articulate with anything anteriorly

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78
Q

what are the structures within the hilum of the lungs?

A 
1 pulmonary artery
2 pulmonary veins
bronchus branch
bronchial vessels
nerves
lymphatics
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79
Q

what does the articulating facet of the tubercle on a rib articulate with?

A

the articulating facet on the transverse process of its corresponding verterbrae

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80
Q

which nerve innervates the diaphragm?

A

phrenic nerve

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81
Q

which muscles are involved in quiet breathing?

A

inspiration: diaphragm + external intercostal muscles
expiration: passive, recoil of elastic fibres in lungs

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82
Q

which nerve innervates the innermost and internal intercostal muscles?

A

segmental nerve

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83
Q

which muscles are the most important during forced expiration?

A

abdominal muscles

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84
Q

what is intrapleural pressure?

A

the pressure in the intrapleural fluid between the visceral and parietal pleura

usually negative with respect to the atmosphere

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85
Q

how is the intrapleural pressure affected during:

a) quiet inspiration
b) quiet expiration
c) forced expiration

A

a) intrapleural space becomes more negative
b) intrapleural pressure becomes less negative(returns to normal)
c) intrapleural pressure becomes positive

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86
Q

what is lung compliance dependent on?

A

surfactant

elastic fibres + collagen in tissue

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87
Q

what is lung compliance affected by?

A

disease:

  • emphysema : increase in compliance
  • fibrosis/inflammation : decrease in compliance
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88
Q

what factors affect ventilation of lungs ?

A
  • lung compliance
  • airway resistance (increase resistance = decrease airflow)
  • alveolar surface tension (fluid in alveolar create tension wanting to close them - surfactant reduces this tension)
89
Q

what is lung compliance?

A

change in pressure

90
Q

what is airway resistance?

A

resistance to the flow of gas within the airways of the lungs

91
Q

what are the two types of airflow

A 
turbulent = chaotic 
laminar = streamlined
92
Q

what is airway resistance effected by?

A

obstructive pulmonary diseases

  • inflammation or smooth muscle contraction (asthma)
  • increased secretions blocking airways (bronchitis)
  • collapse of airways (eg emphysema
93
Q

what does Poiseuille’s law suggest about airway resistance?

A

the wider the tube, larger the radius, the lower the resistance to airflow

94
Q

what are the sites of airway resistance during breathing?

A

UPPER HALF:

  • nose
  • vocal folds of larynx
  • mouth

LOWER HALF:

  • ” poiseuille’s law”
  • branches become smaller = resistance increases = decreased airflow)
95
Q

describe the mechanism for quiet inspiration

A

1) external intercostal muscles and diaphragm contract
2) diaphragm flattens decreasing pressure in thorax
3) rib cage moves up and outwards = pulling parietal pleura
4) intrapleural pressure becomes more negative
5) visceral pleura is pulled out = pulling lung tissue out
6) pressure within lungs decreases
7) air drawn into lungs

96
Q

which organ in the body receives the entire cardiac output?

A

lungs

97
Q

what are the four functions of the pulmonary circuit?

A
  • gas exchange
  • nutrient supply for lung tissue
  • ACE : formation of angiotensin II = vasoconstriction = increase in BP
  • blood reservoir : can increase cardiac output without relying on venous return
98
Q

list the properties of pulmonary blood vessels

A
  • walls: thin and elastic (allows quicker diffusion and stretching)
  • high density of capillary network in alveoli
  • small difference between arteriole and venous pressure therefore small change in venous pressure causes a large change to the driving pressure
  • maintain low BP : dilation ( increase in diameter= decrease in resistance)
    recruitment of capillaries ( decrease resistance )
99
Q

is bronchial circulation part of systemic or pulmonary?

A

systemic

high BP
contains cartilage

100
Q

what is “ massive pulmonary embolism” ?

A

clot in pulmonary circulation stopping 50% of blood flow

right ventricle unable to withstand high pressure and so cannot sustain blood flow

arterial hypoxia (low oxygen in arterial blood)

reduced filling of left ventricle = circulation fails

101
Q

what is the ideal relationship between perfusion and ventilation in the lungs?

A

ventilation and perfusion closely matched:

ratio - 0.8:1.0

102
Q

what affects blood flow distribution in the systemic and pulmonary circulation?

A

SYSTEMIC:
> controlled by smooth muscle contraction/relaxation - arteriolar radius affects resistance = blood flow

PULMONARY:
> gravity: - perfusion : four times as much at base than apex
- ventilation : twice as high at base than apex

> alveolar gas pressure: if blood pressure is lower than alveolar gas pressure, then capillaries may compress (only occurs during artificial ventilation)

> nervous control: - sympathetic : release of NA binds to alpha 1 receptors = vasoconstriction
- parasympathetic : Ach release, binds to M3 receptors = release of NO = vasodilation

> hypoxic pulmonary vasoconstriction: arterioles constrict in areas receiving less oxygen
= blood diverted away from under-ventilated areas
= maintains ventilation/perfusion ratio

103
Q

define tidal volume

A

the volume of air inspired/expired at rest

0.5L/breath

104
Q

define vital capacity

A

the total amount of air that is moved from full inspiration to full expiration

105
Q

define inspiratory reserve volume

A

maximum volume of air that can be inspired above tidal volume

106
Q

define expiratory reserve volume

A

maximum volume of air expelled below tidal volume

107
Q

define functional residual capacity

A

air that remains in the lungs after a normal expiration

108
Q

define residual volume

A

amount of air remaining in lungs after a full exhalation

109
Q

what are lung volumes determined by?

A
  • size
  • elasticity of chest and lungs
  • strength of respiratory muscles
110
Q

what are the three pressures that are involved in pulmonary ventilation?

A
  • atmospheric
  • intra-alveolar
  • intrapleural
111
Q

what is anatomical dead space?

A 
space that does not take part in gas exchange:
mouth
trachea
pharynx
bronchus
terminal bronchi
112
Q

what is physiological dead space?

A

anatomical dead space (existing) + alveolar dead space (develops)

113
Q

what is the respiratory quotient?

A

RQ = CO2 being eliminated/ O2 being consumed

(tells you about the fuel being metabolised)

  1. 0 = carbohydrates
  2. 8 = fats
  3. 7 = proteins
114
Q

how can diet and exercise affect the respiratory quotient?

A

diet: increase CO2 due to carbon from glucose
exercise: increases RQ (due to increased lactic acid)

115
Q

what do central chemoreceptors in the medulla oblongata respond to?

A

pH of cerebral spinal fluid

116
Q

why does an acute rise in blood Pco2 result in a greater Pco2 change in the cerebrospinal fluid?

A

in the CFS , there are only bicarbonate ions to act as buffers, no proteins or haemoglobin

117
Q

where are the peripheral chemoreceptors located?

A

aortic arch

common carotid arteries

118
Q

what are the two types of cells found in the carotid body?

A

glomus - detect Po2

         - associated with sensory neurones
         - contain neurotransmitter

sustentacular - wrap around glomus cells and nerve cells

119
Q

describe the action of the glomus cell in a carotid body

A

cell senses low Po2

K+ ion channels close

depolarisation

Ca2+ ion channels open = calcium floods in

vesicle fuse = neurotransmitter released and binds to sensory neurones (glossopharyngeal) inducing action potential

120
Q

what is the difference between the peripheral chemoreceptors in the aortic bodies and carotid bodies

A

CAROTID:

  • sensitive to Po2,Pco2 and pH
  • associated with sensory glossopharyngeal nerve

AORTIC:

  • sensitive to Po2 and Pco2 but NOT pH
  • associated with sensory vagus nerve
121
Q

what is meant by “hypoxic drive”? in terms of breathing

A

if CO2 is not removed from the blood, the chemoreceptors become unresponsive to Pco2 and so the Po2 becomes the principle respiratory stimulus

122
Q

what is the ‘Hering-Breur Reflex’?

A

a protective mechanism

pulmonary stretch receptors located in the visceral pleura, bronchial walls and bronchi

during inhalation, lungs expand = triggering slowly adapting stretch receptors

signals sent via vagus nerve to the DRG to stop inspiration (shorten inspiration time)

helps conserve energy and in infants prevents over expansion of lungs

123
Q

explain how central chemoreceptors indirectly respond to change in arterial Pco2

A

BBB is impermeable to H+ but allows CO2 to pass through

the CO2 combines with water, in Cerebrospinal fluid, eventually forming H+ and HCO3- ions

the more CO2 diffusing into the CSF, the greater the [H+]

124
Q

what does the dorsal respiratory group in the medulla oblongata receive sensory input from?

A

peripheral mechanoreceptors, chemoreceptors, proprioreceptors

and from apneutic centres

125
Q

what does the ventral respiratory group in the medulla oblongata send impulses to? and when is it active?

A

active during exercise or stress

  • inspiratory muscles : diaphragm, external intercostal
  • accessory inspiratory muscles: pharyngeal and laryngeal muscles
  • expiratory muscles: abdominal muscles and internal intercostal muscles
126
Q

define asthma

A

chronic inflammatory disease of airways
episodic, reversible bronchospasms
due to exaggerated bronchoconstrictor response to various stimuli

127
Q

which antibody is produced in asthma?

A

IgE

128
Q

list the structural changes to the airways caused by asthma

A
  • hyperplasia and hypertrophy of smooth muscle
  • hyperplasia of mucous glands
  • increased mucous secretions
  • thickening of basement membrane

sub-epithelial fibrosis

blood vessels dilate and proliferate

129
Q

what are the effects of sympathetic stimulation to the lungs? which receptor mediates this?

A

Beta 2 receptors - Gs coupled

cause bronchodilation

increased secretions

increased mucocilairy clearance

decreased mast cell release

less vascular leakage

130
Q

what are the parasympathetic effects on the lungs?

A

bronchoconstriction

increased mucus secretions

increased ion transport

131
Q

name the inflammatory cells involved in asthma

A

macrophages

T-lymphocytes

basophils

132
Q

what are the effects of histamine

A

stimulation of parasympathetic nervous system

bronchoconstriction

chemotaxis (late phase)

oedema formation

narrowing of lumen = decreased airflow

133
Q

what is the difference between the early and late phase of asthma?

A

EARLY PHASE: allergen stimulus
> mast cells, macrophages release mediators

> cytokines = attract more inflammorty cells

> spasmogens eg histamine = bronchoconstriction

LATE PHASE:
>infiltration and activation of inflammatory cells

> bronchoconstriction
vasodilation
oedema
bronchial hyper-responsiveness (eosinophils)

134
Q

what is the lifespan of RBC?

A

120 days

135
Q

which cells break down RBC?

A

Kupffer cells : macrophages

136
Q

what is the normal male and female haemocrit?

A

males: 40-54%
females: 37-47%

137
Q

what is the normal blood cell count for males and females?

A

males: 4.5 - 6.3 million
females: 4.0- 5.5 million

138
Q

what is the normal haemoglobin amount in males and females?

A

males: 14-18 g/dl
females: 12-16 g/dl

139
Q

how many molecules of oxygen can each haemoglobin molecule carry?

A

4

140
Q

what non-protein group is found in haemoglobin?

A

iron

141
Q

what is methaemoglobin?

A

the iron is in the oxidised form Fe3+ - cannot bind to oxygen

142
Q

when is haemoglobin in the R (relaxed) and T (tense ) states?

A

tense state: deoxyhaemoglobin

relaxed state: oxyhaemoglobin

143
Q

why does CO and NO displace oxygen from haemoglobin?

A

CO and NO have a higher affinity for Fe2+ than oxygen

144
Q

what is co-operativity of haemoglobin?

A

co-operativity means the binding of one protein subunit to a substrate causing a change in the other subunits affinity for their substrates

haemoglobin shows positive co-operativity

once the first oxygen binds to one of the four haem groups, the molecules goes from T state to R state, and the other subunits express a higher affinity for oxygen

145
Q

define allosterism

A

a change in the activity and conformation of a protein due to a substrate binding to an allosteric site (not the active site)

146
Q

what is the Bohr effect?

A

H+ ions affect the oxygen binding to haemoglobin

H+ ions bind to the haemoglobin (protein side) and form haemoglobininc acid (remember haemoglobin acts as a buffer)
this causes a change in structure
reducing the oxygen carrying capacity

↑ H+ = more oxygen being displaced

147
Q

what factors affect the haemoglobin binding to oxygen?

A
  • ACIDITY (↑ H+ = more oxygen being displaced )
  • PARTIAL PRESSURE OF CO2 (Bohr effect)
  • TEMPERATURE -causes more O2 to be displaced
  • 2:3-BISPHOSPHOGLYCERATE (increases O2 displacement)
  • FETAL HB (fetal haemoglobin has a higher affinity for oxygen that adult Hb therefore it causes displacement of O2 > right shift to the saturation curve)
  • myoglobin also has a higher affinity for oxygen that haemoglobin
148
Q

what is myglobin and its role?

A

found in muscle cells, it shuttles oxygen from the cell membranes to the mitochondria

it has a higher affinity for oxygen that haemoglobin

shows no co-operativity

149
Q

what is 2,3-bisphosphoglycerate and its role?

A

found in RBCs

negative effector = shifts the oxygen saturation curve of haemoglobin to the right

causes MORE oxygen to be displaced

binds to deoxyhaemoglobin

150
Q

how does hypoxia affect 2,3-bisphosphpglycerate levels in RBC?

A

increases levels so more oxygen is displaced and supplied to tissues

151
Q

define the term: oxygen carrying capacity

A

the amount of oxygen carried by 1 litre of blood in equilibrium with room air

152
Q

define: oxygen content

A

the amount of oxygen carried by 1 litre of blood at any given partial pressure of O2 (Po2)

153
Q

define : oxygen/haemoglobin saturation

A

the percentage of oxygen carrying capacity at any given Po2

154
Q

how does partial pressure affect gas diffusion?

A

the greater the difference in partial pressures, the greater the rate of diffusion

155
Q

why is there more carbon dioxide dissolved in plasma than oxygen?

A

because carbon dioxide is more soluble

156
Q

what is the difference between external and internal respiration?

A

internal: body tissues
oxygen and carbon dioxide exchange between body tissues and blood vessels

external: in LUNGs only
- diffusion of gases between atmosphere (alveoli) and lung capillaries

157
Q

how is carbon dioxide transported in the body?

A
  • bicarbonate ions (70%)
  • bind to haemoglobin = carboaminohaemoglbin (23%)
  • dissolved directly in plasma (7%)
158
Q

what does rate of gaseous exchange depend on in the luncgs?

A
  • partial pressure difference
  • surface area
  • diffusion distance
  • solubility of each gas
159
Q

what is the haldane effect?

A
  • the ability of deoxygenated blood to carry more carbon dioxide than oxygenated blood

> Hb carries more carbon dioxide than HbO

> Hb buffers more H+ than HbO
↓ H+ = more CO2 converted to HCO3-

160
Q

what is the chloride shift?

A

Cl- ions exit or move into RBC to maintain electric balance during movement of H+ ions

161
Q

what is this
“the amount of oxygen carried by 1 litre of blood at any given partial pressure of O2 (Po2)”

a) oxygen carrying capacity
b) oxygen content
c) oxygen saturation

A

b) oxygen content

162
Q

what does the pericardium consist of?

A

fibrous pericardium (outermost layer)

serous pericardium > parietal + visceral (attached to heart)

163
Q

what are the functions of the pericardium?

A
  • maintain position of heart
  • prevent over expansion
  • shock absorber + reducing friction
  • limits motion
164
Q

what is the coronary sulcus?

A

separates the atria from the ventricles on the external surface - contains the trunk of the nutrient vessels

165
Q

what is the interventricular sulcus?

A

separates the left and right atria on the surface

166
Q

which valve sepearates the right atrium and right ventricle?

A

tricuspid

167
Q

which valve separates the left atrium and ventricle?

A

mitral valve

168
Q

what prevents back flow of blood into the ventricles?

A

heart strings ( chordae tendinae)

169
Q

where are the openings for the coronary arteries found?

A

two openings found on the left and right semilunar cusps of the AORTIC VALVE

blood enters during ventricular contraction

170
Q

for the heart sounds, what causes the “lub” and “dub” sound?

A

“lub” -S1: closure of mitral and tricuspid valves (atrioventricular)

“dub”- S2: closure of pulmonary and aortic valves

171
Q

what is systole?

A

contraction of ventricles

mitral and tricuspid valve closed

172
Q

what is diastole?

A

ventricular filling

aortic and pulmonary valves close

173
Q

what is a stetonic valve?

A

calcified valve

limits blood flow

narrowed valve

174
Q

what is an incompetent valve?

A

valve cusps do not close properly

allows back flow of blood

175
Q

when are the mitral and tricuspid valves open?

A

during diastole as ventricles are being filled

176
Q

name two compounds important for mediating coronary blood flow

A

adenosine and nitric oxide

177
Q

what causes ischemic heart disease?

A

plaque build up in coronary arteries = reduced blood flow to cardiac muscle

can cause tooth ache or jaw ache

178
Q

what prevents tetanic contraction in cardiac muscles?

A

the long refractory period (plateau) prevents contractions from fusing together

179
Q

list the types of pacemaker tissues

A

-SAN (primary)

AVN

bundle of His

Purkinje fibres

180
Q

what is the difference between depolarisation in pacemaker tissue in the heart and neuronal tissue?

A

pacemaker depolarisation dependent on influx of calcium ions = slower

neuronal tissue depolarisation by influx of Na + ions = faster

181
Q

what facilitates the transmission of an electrical wave from the right atrium to the left atrium?

a) bundle of His
b) Purkinje fibres
c) Bachmann’s bundle
d) Bundle of Kent
e) AVN

A

Bachmann’s bundle

182
Q

where is the SAN found?

A

right atrium

183
Q

what conducts the wave of excitation from the atria to the ventricles?

A

atrioventricular nose

slow conductance = allows ventricular filling

184
Q

what is Wolf-Parkinson-White syndrome?

and how does it affect the ECG?

A

presence of an abnormal ‘bundle of Kent’ that joins the right atrium with right ventricle

produces premature ventricle contraction

early ventricular contraction means = shorter PR interval on ECG

185
Q

in an ECG, what is the PR interval?

A

the delay between atrial and ventricular contraction because of:

> repolarisation of atria
AVN node delay of conductance

186
Q

in an ECG, what does the T wave represent?

A

repolarisation of ventricles

187
Q

in an ECG, what does the P wave represent?

A

atrial contraction

188
Q

in an ECG what does the QRS complex represent?

A

ventricular contraction

189
Q

what is the relationship between resistance and diameter of blood vessels?

A

resistance = 1/r^4

190
Q

in which blood vessel does the main pressure drop occur?

A

arterioles - main resistance vessels

191
Q

what is critical velocity? (in terms of blood flow)

A

the transition between laminar to turbulent blood flow

192
Q

what factors increase likelihood of turbulent flow?

A
  • increase in velocity
  • increase in vessel radius
  • increase in blood density
  • decrease in blood viscosity

(when (reynolds no.) Re>200 = turbulent flow)

193
Q

what are the three main layers of blood vessels?

A
  • tunica intima
  • tunica media
  • tunica adventitia
194
Q

which blood vessel layer controls the diameter of the vessels?

a) tunica intima
b) tunica media
c) tunica adventitia

A

tunica media - contains smooth muscle

195
Q

which blood vessel layer filters out white blood cells?

a) tunica intima
b) tunica media
c) tunica adventitia

A

a) tunica intima

196
Q

which blood vessel layer prevents over expansion of the vessel?

a) tunica intima
b) tunica media
c) tunica adventitia

A

c) tunica adventitia - contains fibrous tissue

197
Q

which blood vessel layer contains the vasa vasorum?

a) tunica intima
b) tunica media
c) tunica adventitia

A

c) tunica adventitia

vasa vasorum - small blood vessels that supply the walls of larger vessels with nutrients

198
Q

what are the sublayers of tunica media?

A
  • internal elastic lamina
  • smooth muscle
  • external elastic lamina
199
Q

what factors increase venous return?

A

-EXERCISE:
> skeletal muscle pump: as the muscles contract, they compress the veins that pumps blood towards the heart. valves create unilateral flow.

-BREATHING RATE+DEPTH
> the abdomino-thoracic pump: as you inspire, the intrapleural pressure decreases, this causes the lungs and heart chambers [right atrium] to expand. the pressure in the right atrium drops causing a greater difference in pressure gradient between veins and arteries and so theres an increase in venous return

200
Q

how do the parasympathetic and sympathetic innervations control the heart rate?

A

parasympathetic: inhibits SAN resting tone to 70bpm
(inhibition of parasymp tone = small increase in HR)
Ach act on M2 receptors Gi coupled = decrease HR)

sympathetic on RIGHT side: decreases stage 4 spontaneous depolarisation phase of SAN conduction = quicker SAN depolarisations

sympathetic on LEFT side:

201
Q

what is stroke volume dependent on?

A

preload

contractility

afterload

202
Q

what is end diastolic volume

A

the volume of blood in the ventricles at the end of diastole before ventricles contract

203
Q

what is end systolic volume?

A

the volume of blood in the ventricles left after their contraction

204
Q

what is the stroke volume?

A

amount of blood pumped out from one ventricular contraction = EDV-ESV

205
Q

what factors influence the end diastolic volume?

A

FILLING PRESSURE
increased venous return = increased atrial filling = increased EDV

FILLING TIME:
increased HR =reduced filling time of ventricles = reduced EDV

VENTRICULAR COMPLIANCE:
as ventricle compliance (stretch) increases = more ventricular filling = increased EDV

206
Q

what factors influence the End systolic volume?

A

CONTRACTILITY
increase contractility = decreased ESV

HEART RATE:
increase in heart rate = increased contraction of ventricles = reduced ESV (-the amount of blood remaining in ventricles)

PRELOAD:
increasing venous return = increasing EDV = muscles more stretch = increased rate of contraction (frank starlings law) = decreased ESV

AFTERLOAD:
increase in peripheral resistance = decrease in EDV = increase in ESV

207
Q

what is an inotrope?

A

a neurotransmitter/hormone/ drug that alters the force of contraction of heart muscle

208
Q

what is left sided heart failure and what causes it?

A

= decrease in blood pumped out to the body and so blood fluid backed up in the lungs

  • heart attack
  • chroninc blockage of arteries
  • severe alcoholism
  • narrow heart valves
  • hypothyroidism
  • damage to heart muscle
209
Q

what is right sided heart failure and what cases it?

A

inability for right side of heart to pump blood effectively out to the lungs

caused by
left sided heart failure
chronic bronchitis

210
Q

what are the consequences of left and right sided heart failures?

A

RIGHT SIDED:
( blood not effectively pumped into lungs)
= fluid backed up in body = oedema
= decreased left ventricle filling

LEFT SIDED?
( blood not effectively pumped to body)
= decreased O2 transport to cells
= tiredness
= pulmonary oedema
= shortness of breath
211
Q

describe the baroreceptor reflex

A

high blood pressure stretches the carotid arteries and aorta = detected by the carotid bodies and aortic bodies that contain baroreceptors (also contain chemoreceptors)

the baroreceptors increase stimulation of their associated afferent nerves
( carotid bodies = glossopharyngeal)
( aortic bodies = vagus)

the afferent nerves stimulate the vasomotor and cardiovascular centres (cardioinhibitory) which increase parasympathetic stimulation to the heart = reducing HR
and decrease sympathetic stimulation to heart = reduced stroke volume and HR
decrease sympathetic stimulation to blood vessels = vasodilation

all of this reduces the BP

212
Q

atrial stretch is detected by which fibres? and what does atrial stretch cause to release?

A

B fibres in the left atrium

release of atrial natriuretic peptide which is a vasodilator and a diuretic

213
Q

how do the kidneys have a role in controlling blood pressure?

A

sympathetic stimulation controls renin production (beta 1 receptors)

therefore increase in BP will cause a decrease in symp stimulation and so decrease in renin production

= less angiotensin II
= less ADH
= less aldosterone
= vasodilation

214
Q

what substances cause relaxation of vascular smooth muscle?

A
  • endothelin 1 (by binding to ETb receptors on endothelium = release of NO)
  • nitric oxide
  • prostacyclin
215
Q

which type of capillaries are found in the brain, muscle, heart, skin, lungs and fat?

a) continuous
b) fenestrated
c) discontinuous

A

a) continuous

216
Q

which type of capillaries are found in the kidney and gut?

a) continuous
b) fenestrated
c) discontinuous

A

b) fenestrated

217
Q

which capillary type has a incomplete basement membrane?

a) continuous
b) fenestrated
c) discontinuous

A

c) discontinuous

218
Q

what are the factors of oedema?

what is myxoedema and its causes?

A

oedema - excess accumulation of ECF

  • high blood pressure
  • venous obstruction eg heart failure
  • leakage of plasma proteins into ECF

myxoedema - excess glycoprotein in ECF production due to hypothyroidism

  • low plasma proteins from liver disease
  • obstruction of lymphatic drainage
219
Q

how do sphincter muscles in metarterioles respond to hypoxic conditions?

A

low O2 = smooth muscle relaxation to allow more blood to flow through to that area

(also caused by K, adenosine and CO2)

year 1 (8 decks)

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