Systems Physiology Flashcards
1
Q
In controlling blood flow, what controls the resistance?
A
Arteriolar radius
Resistance is proportional to 1/r^4
2
Q
What local effect occurs with changes to arteriolar radius?
A
Regulates blood flow it tissues
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
4
Q
What are the intrinsic factors that control vascular smooth muscle?
A
- temperature
- transmural pressure
- local metabolites, endothelium derived factors and autocoids
5
Q
What is a precapillary sphincter?
A
A band of smooth muscle at the arteriolar end of the capillary
6
Q
what is the hypodermis?
A
the third layer of the skin - underneath the dermis and consist of loose CT - adipose cells
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
8
Q
which epidermal layer is not found in thin skin?
A
stratum lucidum
9
Q
which cell type is the most abundant in the epidermis?
A
keratinocytes
10
Q
which cell type are the most abundant in the dermis?
A
fibroblasts
11
Q
what are the two layers of the dermis?
A
papillary layer
reticular layer
12
Q
describe the cells in the stratum spinosum
A
many desmosomes = spiky appreance
express keratin
active protein synthesis
13
Q
how can you characterise the cells in the stratum granulosum
A
large granules of keratohyalin
cell death occurs in outermost aspect
14
Q
which type of connective tissue is found in dermal papillary layer?
A
type III collagen
elastin
15
Q
what type of CT is found in reticular layer of the dermis?
A
dense irregular CT
type I collagen and elastin
16
Q
what are the three phases of hair growth?
A
anagen (active)
catagen (regressive)
telogen (resting)
17
Q
what is a pilosebaceous unit ?
A
hair follicle and sebaceous gland
18
Q
which gland is found opening into the hair follicle?
A
appocrine gland
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
20
Q
what is the difference between vellus and terminal type of hair?
A
vellus: body hair
terminal: scalp, secondary sexual hair
21
Q
in the structure of the hair follicle, here do the hair follicle stem cells lie?
A
the bulge
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
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
24
Q
what are the five types of epithelial junctions?
A
tight adherens desmosomes hemisdesmosomes gap
25
what are mucous membranes composed of?
epithelium, basement membrane, lamina propria, smooth muscle
26
what are the 5 types of connective tissues?
```
fibrocollagenous
adipose
cartilage
bone
blood
```
27
what is ground substance composed of?
glycoaminoglycans (GAGs)
| proteoglycans
28
which collagen type is found in basement membranes?
type IV
29
what are the types of fibrocollagenous connective tissue?
LOOSE:
- areolar
- adipose
- reticular
DENSE:
- regular
- irregular
- elastic
30
where is dense irregular CT found?
dermis - reticular layer
31
where is dense regular CT found?
tendons, ligaments
32
what is the difference between white and brown adipose tissue?
WHITE:
- unilocular
- adults
- energy store, shock absorber, insulator
BROWN:
- multilocular
- newborns
- rich in mitochondria
- heat source
33
what are the three types of cartilage?
hyalin - type II collagen
elastic - type II collagen + elastic fibres
fibrocartilage - type II and type I collagen
34
three cells types in bones?
osteoclasts - resorb
osteoblasts - form
ostecytes - maintain
35
what are the types of glycoproteins found in ECM?
laminin and fibrolectin: cell adhesion
fibrillin : elastic fibre formation
osteocalcin: mineralisation
36
what is the precursor for elastin?
tropoelastin
37
which cells produce cartilage?
chondroblasts
38
where are chondrocytes found?
lacunae
39
where is fibrocartilage found ?
intervertebral disks
40
what is 'osteoid'?
the ground substance of bone - type I collagen
41
what are the types of bone?
spongy/trabecular/cancellous bone - spaces filled with bone marrow
lamellar bone - has layers/lamellae
compact bone - organised into osteons
42
what is periosteum?
dense vascular CT surrounding bone except at surface of joints
43
what is the perichondrium?
the fibrous tissue surrounding cartilage but not of developing joints
consists of two layers: inner chondrogenic
outer fibrous
44
where do the calcium ions come from in smooth muscle contraction?
extracellular calcium
45
what are the two types of bone growth?
ENDOCHONDRAL
- long bone
- requires hyalin cartilage for model
INTRAMEMBRANOUS
- flat bone formation
- formed within fibrous membrane
46
briefly list the steps of endochondral bone formation
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
47
briefly describe intramembranous ossification
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
48
what protein do calcium ions bind to in smooth muscle contraction?
calmodulin
49
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) periosteal arteries
b) Haversian and Volkmann's canals
c) i nutrient artery
d) epiphyseal arteries
50
what happens to smooth muscles in asthma?
hypertrophy and hyperplasia of smooth muscles
51
what controls smooth muscle contractions?
autonomic stimulation,
hormones,
local physiological conditions
52
what is found at the junction of A and I bands in sarcomeres?
T tubules
53
what controls skeletal muscle contraction?
alpha motor neurones
54
what does calcium bind to during contraction of skeletal muscle?
troponin
55
which muscle type has no stem cells?
cardiac
56
what is a sarcomere?
a unit of a myofibril from one Z-line to the next
57
what type of junctions are predominantly found at intercalated discs in cardiac muscle?
longitudinal component: gap
| transverse component: desmosomal junctions
58
which muscle type does not have an extracellular source of Calcium ions for contraction?
skeletal muscle - from sarcoplasmic reticulum
59
how is force of contraction regulated in skeletal muscles?
recruitment of motor units and frequency of action potentials
60
describe skeletal muscle contraction
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.
61
which component is NOT found in smooth muscle but is found in skeletal and cardiac muscles?
a) actin
b) myosin
c) troponin
d) tropomyosin
c) troponin (instead calcium ions bind to calmodulin)
62
what is leiomyoma?
benign neoplasms of smooth muscle
63
what are the zones of epiphyseal growth plate?
1) resting chondrocyte reserve
2) proliferating chondrocytes
3) mature chondrocytes
4) calcified chondrocytes - dying
64
what is the difference between woven and lamellar bone?
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
65
what is appositional growth and interstitial growth
appositional growth:
- growth in diameter
- at periosteal surface
interstitial growth:
- growth in length
- via epiphyseal growth plate
66
factors affecting remodelling of bone?
- change in mechanical stresses
- fracture
- hormones eg parathyroid hormone, calcitonin
67
what are the boundaries of the superior thoracic cavity?
body of thoracic vertebra 1
medial margin of rib 1
manubrium
68
what is the inferior thoracic cavity closed by?
diaphragm + structures passing through/posteriorly to it
69
at which point is the mediastinum divided horizontally into superior and anterior mediastinum?
horizontal line through sternal angle between T4 and T5
70
how are the lungs attached to the mediastinum?
via the root
71
what are the divisions of the mediastinum?
superior
| inferior -> post, middle, ant
72
what is the name given to the lining covering the thorax and enveloping the lungs?
pleura
73
describe the two types of pleura
visceral pleura - attached to lungs
| parietal pleura - attached to thorax
74
what are the boundaries of the thoracic wall?
anteriorly: sternum
posteriorly: thoracic vertebra + intervertbral discs
laterally: ribs and intercostal muscles
75
what are the main anatomical features of the sternum?
manubrium
sternal angle
body of sternum
xiphoid process
76
where do the intercostal nerves and blood vessels lie?
costal groove between the inner two intercostal muscles
77
which ribs are called "floating ribs"
ribs 11 and 12
| they do not articulate with anything anteriorly
78
what are the structures within the hilum of the lungs?
```
1 pulmonary artery
2 pulmonary veins
bronchus branch
bronchial vessels
nerves
lymphatics
```
79
what does the articulating facet of the tubercle on a rib articulate with?
the articulating facet on the transverse process of its corresponding verterbrae
80
which nerve innervates the diaphragm?
phrenic nerve
81
which muscles are involved in quiet breathing?
inspiration: diaphragm + external intercostal muscles
expiration: passive, recoil of elastic fibres in lungs
82
which nerve innervates the innermost and internal intercostal muscles?
segmental nerve
83
which muscles are the most important during forced expiration?
abdominal muscles
84
what is intrapleural pressure?
the pressure in the intrapleural fluid between the visceral and parietal pleura
usually negative with respect to the atmosphere
85
how is the intrapleural pressure affected during:
a) quiet inspiration
b) quiet expiration
c) forced expiration
a) intrapleural space becomes more negative
b) intrapleural pressure becomes less negative(returns to normal)
c) intrapleural pressure becomes positive
86
what is lung compliance dependent on?
surfactant
elastic fibres + collagen in tissue
87
what is lung compliance affected by?
disease:
- emphysema : increase in compliance
- fibrosis/inflammation : decrease in compliance
88
what factors affect ventilation of lungs ?
- 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
what is lung compliance?
change in volume
-----------------------------
change in pressure
90
what is airway resistance?
resistance to the flow of gas within the airways of the lungs
91
what are the two types of airflow
```
turbulent = chaotic
laminar = streamlined
```
92
what is airway resistance effected by?
obstructive pulmonary diseases
- inflammation or smooth muscle contraction (asthma)
- increased secretions blocking airways (bronchitis)
- collapse of airways (eg emphysema
93
what does Poiseuille's law suggest about airway resistance?
the wider the tube, larger the radius, the lower the resistance to airflow
94
what are the sites of airway resistance during breathing?
UPPER HALF:
- nose
- vocal folds of larynx
- mouth
LOWER HALF:
- " poiseuille's law"
- branches become smaller = resistance increases = decreased airflow)
95
describe the mechanism for quiet inspiration
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
which organ in the body receives the entire cardiac output?
lungs
97
what are the four functions of the pulmonary circuit?
- 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
list the properties of pulmonary blood vessels
- 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
is bronchial circulation part of systemic or pulmonary?
systemic
high BP
contains cartilage
100
what is " massive pulmonary embolism" ?
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
what is the ideal relationship between perfusion and ventilation in the lungs?
ventilation and perfusion closely matched:
| ratio - 0.8:1.0
102
what affects blood flow distribution in the systemic and pulmonary circulation?
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
define tidal volume
the volume of air inspired/expired at rest
0.5L/breath
104
define vital capacity
the total amount of air that is moved from full inspiration to full expiration
105
define inspiratory reserve volume
maximum volume of air that can be inspired above tidal volume
106
define expiratory reserve volume
maximum volume of air expelled below tidal volume
107
define functional residual capacity
air that remains in the lungs after a normal expiration
108
define residual volume
amount of air remaining in lungs after a full exhalation
109
what are lung volumes determined by?
- size
- elasticity of chest and lungs
- strength of respiratory muscles
110
what are the three pressures that are involved in pulmonary ventilation?
- atmospheric
- intra-alveolar
- intrapleural
111
what is anatomical dead space?
```
space that does not take part in gas exchange:
mouth
trachea
pharynx
bronchus
terminal bronchi
```
112
what is physiological dead space?
anatomical dead space (existing) + alveolar dead space (develops)
113
what is the respiratory quotient?
RQ = CO2 being eliminated/ O2 being consumed
(tells you about the fuel being metabolised)
1. 0 = carbohydrates
0. 8 = fats
0. 7 = proteins
114
how can diet and exercise affect the respiratory quotient?
diet: increase CO2 due to carbon from glucose
exercise: increases RQ (due to increased lactic acid)
115
what do central chemoreceptors in the medulla oblongata respond to?
pH of cerebral spinal fluid
116
why does an acute rise in blood Pco2 result in a greater Pco2 change in the cerebrospinal fluid?
in the CFS , there are only bicarbonate ions to act as buffers, no proteins or haemoglobin
117
where are the peripheral chemoreceptors located?
aortic arch
common carotid arteries
118
what are the two types of cells found in the carotid body?
glomus - detect Po2
- associated with sensory neurones
- contain neurotransmitter
sustentacular - wrap around glomus cells and nerve cells
119
describe the action of the glomus cell in a carotid body
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
what is the difference between the peripheral chemoreceptors in the aortic bodies and carotid bodies
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
what is meant by "hypoxic drive"? in terms of breathing
if CO2 is not removed from the blood, the chemoreceptors become unresponsive to Pco2 and so the Po2 becomes the principle respiratory stimulus
122
what is the 'Hering-Breur Reflex'?
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
explain how central chemoreceptors indirectly respond to change in arterial Pco2
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
what does the dorsal respiratory group in the medulla oblongata receive sensory input from?
peripheral mechanoreceptors, chemoreceptors, proprioreceptors
and from apneutic centres
125
what does the ventral respiratory group in the medulla oblongata send impulses to? and when is it active?
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
define asthma
chronic inflammatory disease of airways
episodic, reversible bronchospasms
due to exaggerated bronchoconstrictor response to various stimuli
127
which antibody is produced in asthma?
IgE
128
list the structural changes to the airways caused by asthma
- 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
what are the effects of sympathetic stimulation to the lungs? which receptor mediates this?
Beta 2 receptors - Gs coupled
cause bronchodilation
increased secretions
increased mucocilairy clearance
decreased mast cell release
less vascular leakage
130
what are the parasympathetic effects on the lungs?
bronchoconstriction
increased mucus secretions
increased ion transport
131
name the inflammatory cells involved in asthma
macrophages
T-lymphocytes
basophils
132
what are the effects of histamine
stimulation of parasympathetic nervous system
bronchoconstriction
chemotaxis (late phase)
oedema formation
narrowing of lumen = decreased airflow
133
what is the difference between the early and late phase of asthma?
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
what is the lifespan of RBC?
120 days
135
which cells break down RBC?
Kupffer cells : macrophages
136
what is the normal male and female haemocrit?
males: 40-54%
females: 37-47%
137
what is the normal blood cell count for males and females?
males: 4.5 - 6.3 million
females: 4.0- 5.5 million
138
what is the normal haemoglobin amount in males and females?
males: 14-18 g/dl
females: 12-16 g/dl
139
how many molecules of oxygen can each haemoglobin molecule carry?
4
140
what non-protein group is found in haemoglobin?
iron
141
what is methaemoglobin?
the iron is in the oxidised form Fe3+ - cannot bind to oxygen
142
when is haemoglobin in the R (relaxed) and T (tense ) states?
tense state: deoxyhaemoglobin
relaxed state: oxyhaemoglobin
143
why does CO and NO displace oxygen from haemoglobin?
CO and NO have a higher affinity for Fe2+ than oxygen
144
what is co-operativity of haemoglobin?
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
define allosterism
a change in the activity and conformation of a protein due to a substrate binding to an allosteric site (not the active site)
146
what is the Bohr effect?
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
what factors affect the haemoglobin binding to oxygen?
- 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
what is myglobin and its role?
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
what is 2,3-bisphosphoglycerate and its role?
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
how does hypoxia affect 2,3-bisphosphpglycerate levels in RBC?
increases levels so more oxygen is displaced and supplied to tissues
151
define the term: oxygen carrying capacity
the amount of oxygen carried by 1 litre of blood in equilibrium with room air
152
define: oxygen content
the amount of oxygen carried by 1 litre of blood at any given partial pressure of O2 (Po2)
153
define : oxygen/haemoglobin saturation
the percentage of oxygen carrying capacity at any given Po2
154
how does partial pressure affect gas diffusion?
the greater the difference in partial pressures, the greater the rate of diffusion
155
why is there more carbon dioxide dissolved in plasma than oxygen?
because carbon dioxide is more soluble
156
what is the difference between external and internal respiration?
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
how is carbon dioxide transported in the body?
- bicarbonate ions (70%)
- bind to haemoglobin = carboaminohaemoglbin (23%)
- dissolved directly in plasma (7%)
158
what does rate of gaseous exchange depend on in the luncgs?
- partial pressure difference
- surface area
- diffusion distance
- solubility of each gas
159
what is the haldane effect?
- 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
what is the chloride shift?
Cl- ions exit or move into RBC to maintain electric balance during movement of H+ ions
161
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
b) oxygen content
162
what does the pericardium consist of?
fibrous pericardium (outermost layer)
serous pericardium > parietal + visceral (attached to heart)
163
what are the functions of the pericardium?
- maintain position of heart
- prevent over expansion
- shock absorber + reducing friction
- limits motion
164
what is the coronary sulcus?
separates the atria from the ventricles on the external surface - contains the trunk of the nutrient vessels
165
what is the interventricular sulcus?
separates the left and right atria on the surface
166
which valve sepearates the right atrium and right ventricle?
tricuspid
167
which valve separates the left atrium and ventricle?
mitral valve
168
what prevents back flow of blood into the ventricles?
heart strings ( chordae tendinae)
169
where are the openings for the coronary arteries found?
two openings found on the left and right semilunar cusps of the AORTIC VALVE
blood enters during ventricular contraction
170
for the heart sounds, what causes the "lub" and "dub" sound?
"lub" -S1: closure of mitral and tricuspid valves (atrioventricular)
"dub"- S2: closure of pulmonary and aortic valves
171
what is systole?
contraction of ventricles
mitral and tricuspid valve closed
172
what is diastole?
ventricular filling
aortic and pulmonary valves close
173
what is a stetonic valve?
calcified valve
limits blood flow
narrowed valve
174
what is an incompetent valve?
valve cusps do not close properly
allows back flow of blood
175
when are the mitral and tricuspid valves open?
during diastole as ventricles are being filled
176
name two compounds important for mediating coronary blood flow
adenosine and nitric oxide
177
what causes ischemic heart disease?
plaque build up in coronary arteries = reduced blood flow to cardiac muscle
can cause tooth ache or jaw ache
178
what prevents tetanic contraction in cardiac muscles?
the long refractory period (plateau) prevents contractions from fusing together
179
list the types of pacemaker tissues
-SAN (primary)
AVN
bundle of His
Purkinje fibres
180
what is the difference between depolarisation in pacemaker tissue in the heart and neuronal tissue?
pacemaker depolarisation dependent on influx of calcium ions = slower
neuronal tissue depolarisation by influx of Na + ions = faster
181
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
Bachmann's bundle
182
where is the SAN found?
right atrium
183
what conducts the wave of excitation from the atria to the ventricles?
atrioventricular nose
| slow conductance = allows ventricular filling
184
what is Wolf-Parkinson-White syndrome?
| and how does it affect the ECG?
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
in an ECG, what is the PR interval?
the delay between atrial and ventricular contraction because of:
>repolarisation of atria
> AVN node delay of conductance
186
in an ECG, what does the T wave represent?
repolarisation of ventricles
187
in an ECG, what does the P wave represent?
atrial contraction
188
in an ECG what does the QRS complex represent?
ventricular contraction
189
what is the relationship between resistance and diameter of blood vessels?
resistance = 1/r^4
190
in which blood vessel does the main pressure drop occur?
arterioles - main resistance vessels
191
what is critical velocity? (in terms of blood flow)
the transition between laminar to turbulent blood flow
192
what factors increase likelihood of turbulent flow?
- increase in velocity
- increase in vessel radius
- increase in blood density
- decrease in blood viscosity
(when (reynolds no.) Re>200 = turbulent flow)
193
what are the three main layers of blood vessels?
- tunica intima
- tunica media
- tunica adventitia
194
which blood vessel layer controls the diameter of the vessels?
a) tunica intima
b) tunica media
c) tunica adventitia
tunica media - contains smooth muscle
195
which blood vessel layer filters out white blood cells?
a) tunica intima
b) tunica media
c) tunica adventitia
a) tunica intima
196
which blood vessel layer prevents over expansion of the vessel?
a) tunica intima
b) tunica media
c) tunica adventitia
c) tunica adventitia - contains fibrous tissue
197
which blood vessel layer contains the vasa vasorum?
a) tunica intima
b) tunica media
c) tunica adventitia
c) tunica adventitia
vasa vasorum - small blood vessels that supply the walls of larger vessels with nutrients
198
what are the sublayers of tunica media?
- internal elastic lamina
- smooth muscle
- external elastic lamina
199
what factors increase venous return?
-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
how do the parasympathetic and sympathetic innervations control the heart rate?
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
what is stroke volume dependent on?
preload
contractility
afterload
202
what is end diastolic volume
the volume of blood in the ventricles at the end of diastole before ventricles contract
203
what is end systolic volume?
the volume of blood in the ventricles left after their contraction
204
what is the stroke volume?
amount of blood pumped out from one ventricular contraction = EDV-ESV
205
what factors influence the end diastolic volume?
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
what factors influence the End systolic volume?
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
what is an inotrope?
a neurotransmitter/hormone/ drug that alters the force of contraction of heart muscle
208
what is left sided heart failure and what causes it?
= 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
what is right sided heart failure and what cases it?
inability for right side of heart to pump blood effectively out to the lungs
caused by
left sided heart failure
chronic bronchitis
210
what are the consequences of left and right sided heart failures?
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
describe the baroreceptor reflex
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
atrial stretch is detected by which fibres? and what does atrial stretch cause to release?
B fibres in the left atrium
release of atrial natriuretic peptide which is a vasodilator and a diuretic
213
how do the kidneys have a role in controlling blood pressure?
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
what substances cause relaxation of vascular smooth muscle?
- endothelin 1 (by binding to ETb receptors on endothelium = release of NO)
- nitric oxide
- prostacyclin
215
which type of capillaries are found in the brain, muscle, heart, skin, lungs and fat?
a) continuous
b) fenestrated
c) discontinuous
a) continuous
216
which type of capillaries are found in the kidney and gut?
a) continuous
b) fenestrated
c) discontinuous
b) fenestrated
217
which capillary type has a incomplete basement membrane?
a) continuous
b) fenestrated
c) discontinuous
c) discontinuous
218
what are the factors of oedema?
what is myxoedema and its causes?
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
how do sphincter muscles in metarterioles respond to hypoxic conditions?
low O2 = smooth muscle relaxation to allow more blood to flow through to that area
(also caused by K, adenosine and CO2)
