block b lecture 3 Flashcards
exercise physiology and pharmacology
how to calculate flow
=change in pressure/resistance
=(Palveoli-Patmosphere)/R
what is partial pressure
pressure of a gas in a mixture
what does 5 litres of blood contain
15mL physically dissolved O2
remainder (985 mL O2) bound to haemoglobin
4 x subunits =4 x globin haeme (Fe 2 binds O2)
what occurs when taking an in breath
diaphragm contracts
external intercostal muscles pull up ribs an dout
what occurs when taking an out breath
diaphragm relaxes and abdominal organs press upwards
lung elasticity recoils inwards
what occurs when taking maximum inspiration
sternum moves up and out
diaphragm contracts more
what occurs when taking maximum expiration
internal intercostal muscles pull ribs down and out
abdominal muscles compress organs and force diaphragm higher
3 chemical inputs that stimulate ventilation
decrease arterial PO2
increase production of non-CO2 acids
increase arterial PCO1
3 chemical inputs that stimulate ventilation
decrease arterial PO2
increase production of non-CO2 acids
increase arterial PCO1
what are bronchi – bronchioles both surrounded by
smooth muscle
what are alveolar sacs surrounded by
pulmonary capillaries
what is O2 in/CO2 out in alveoli driven by
pressure differences caused by breathing
what is breathing controlled and modulated by
motor neurons from medulla
modulated by chemoreceptors
what does haemoglobin Fe3 bind and where does it release at
98.5% of arterial O2
released at tissues (lower PO2), helps transport CO2 out
example of b agonists (adrenoceptors)
pulmonary smooth muscle relaxation
salbutamol (asthma)
example of a agonists (adrenoceptors)
vascular smooth muscle contraction
phenylephrine, pseudoephrine
(decongestants)
what is beclomethasone (asthma inhaler)
glucocorticoid receptor agonist that inhibits pulmonary inflammation
what does supplementary O2 increase
increases driving force for O2 uptake
what occurs during CO poisoning
haemoglobin binds CO more readily than O2 and loses cooperativity when it does
what is skeletal muscle controlled by
somatic motor nerves
what is skeletal muscle controlled by
somatic motor nerves
what are the 3 types of muscle fibres
myosin
actin
troponin
1 cell= 1 skeletal muscle fibre, how many nuclei and myofibrils each
multiple nuclei
hundreds of myofibrils each
what are the thick contractile filaments
myosin
what are the thin contractile filaments
actin
troponin
what do transverse-/T tubules extend
extend plasmalemma deep into cell
what is the Ca2 store in skeletal muscle
sarcoplasmic reticulum
in neuromuscular junction afferent what innervation from brainstem/spinal cord
cholinergic
what released binds nicotinic ACh-receptors
ACh
what occurs after Na influx from binding of nicotinic ACh receptors
Na influx
end plate potential
action potential propagates
what binding drives contraction
myosin bind actin
where does action potential propagate into
T-tubules
voltage sensor activates what receptor on SR
ryanodine
what does Ca2 bind
troponin
what energises myosin
ATP hydrolysis
what does the cycle of ATP binding, hydrolysis, ADP/Pi release drive
drives myosin like a ratchet
the fibres ATP supplies are all consumed within a few seconds, resupply via
phosphorylation of ADP by phosphocreatine
mitochondrial oxidative phosphorylation
glycolysis
what are the 3 skeletal muscle ATP supplies
phosphocreatine
mitochondrial oxidative phosphorylation
glycolysis
name of the fibres that contain lots of mitochondria
many small blood vessels
red, oxidative fibres
name of the fibres what have few mitochondria
lots of glycolytic enzymes
large glycogen stores
white, glycolytic fibres
name of the fibres that contain slower acting myosin ATPase
slow twitch fibres
name of the fibres that contain very fast acting myosin ATPase
fast twitch fibres
what type are slow oxidative fibres
type I
what type are fast oxidative glycolytic fibres
type IIa
what type are fast glycolytic fibres
type IIb/x
what is whole muscle tension
sum of recruitment of motor units
what are whole skeletal muscles made up of
many motor units, never just one type
what generates muscle action potential
motor nerves
Ca 2 rises
allows myosin actin cross bridge cycling to contract muscle
what does skeletal muscle use lots of and how
ATP
cycling Ca, Na, K pumping
how is ATP restored in skeletal muscle
phosphocreatine
glycolysis
mitochindria
what are the 3 fibre types
-I slow oxidative
-IIa fast-oxidative-glycolytic
-IIb/x fast-glycolytic
what are NMJ blockers
cause paralysis
some used alongside anesthetics during surgery
how do depolarising NMJ blockers work, and example
ACh mimic but much slower hydrolysis, cause sustained contraction= paralysis
suxamethonium
how do non depolarising NMJ work and example
competitive inhibitors of nAChR that block ACh binding and EPP formation
atracurium
tubocurarine
what does dantrolene inhibit
ryanodine receptor Ca2 release, sometimes used to treat muscle spasticity or malignant hyperthermia
how is thermo regulation carried out
increasing peripheral blood flow
sweating
what does low intensity; aerobic increase
mitochondria
capillaries
what occurs to skeletal muscle fibres in endurance training
fast glycolytic fibres become fast oxidatice glycolytic fibres
(IIb-IIa)
what occurs in high intensity strength training
increased diameter of fast twitch fibres
increased expression of glycolytic enzymes
greater synchronisation of motor unit recruitment
how does contracting skeletal muscles lead to increase in local blood flow in muscle
contracting skeletal muscles
local chemical changes
dilates muscle arterioles
increase local blood flow in muscle
does blood O2 increase or decrease during exercise
decrease
what is the limiting factor in oxygen consumption
cardiac output
what is VO2 max
maximal O2 consumption
increases in proportion to exercise intensity, up to a point
how to calculate VO2 max
(aterial O2 content - venous O2 content) x CO
