Pharmacology Flashcards
What type of motor neurones innervate skeletal muscle?
myelinated axons
When do the myelinated axons become unmyelinated?
as they approach muscle to innervate an individual muscle fibre
they then split further into 5 to form the terminal bouton
What does the terminal bouton form?
a chemical synapse with the muscle membrane at the neuromuscular junction
How are action potentials transferred from the axon to the terminal bouton?
acetylcholine
What is the terminal bouton surrounded by?
Shwann cells
What is the pre synaptic process?
choline transported to the terminal bouton by a choline transporter
Ach is synthesised from acetyl CoA and choline in the cytosol by choline acetyltransferase
Ach is concentrated in vesicles
What does an action potential at the terminal bouton cause?
opening of Ca channels, into the terminal bouton
Ca causes vesicles to fuse with presynaptic membranes
Ach diffuses into the synaptic cleft and activates post synaptic nicotonic Ach receptors in the end plate region
Nicotonic Ach receptors only open when two Ach bind to the exterior
Gate opens, Na enters, K exits
end plate potential is generated
When is the end plate potential generated?
When Na>K
What is the post synaptic process?
each vesicle contains a quantum of Ach (certain amount)
one quantum of Ach = minature endplate potential
What do many minature endplate potentials cause?
endplate potential that causes an action potential that initiates contraction (opening of Na channels) - a twitch
How is Ach action terminated?
hydrolysis of Ach by acetylecholinerase to acetate and choline
What are bones seperated by?
cavity containing synovial fluid
What are bones united by?
fibrous capsules lined wiht a synovial membrane which is vascular connective tissue that contains cells that produce synovial fluid
What is a simple synovial joint?
one pair of articular surfaces - fingers
What is a compound synovial joint?
more than one pair of articular surfaces - elbow
What is the role of synovial fluid?
provides chondrocytes with O2 and nutrients and removes CO2 and waste products
aids in the nutrition of articular cartilage
lubricates and allows the movement of joins
How many mls of synovial fluid are there usually in a joint cavity?
3.5mls
How does synovial fluid have a high viscosity?
it has hyalauronic acid
What happens to synovial fluid viscosity and elasticity during rapid movement?
high elasticity
decreased viscosity
What is bone made up of?
23% collagen
10% water
2% non collagen proteins
65% bioapatite
What is the role of the water in articular cartilage?
maintains the resilience of tissue
What is the role of the collagen in articular cartilage?
provides stiffness and strength
What is the role of the protoglycan in articular cartilage?
compressive properties associated with load bearing
What performs catabolic breakdown of cartilage?
TNF alpha and IL-1
stimulates protelytic enzyymes and inhibits protoglycan synthesis
What performs anabolic build up of cartilage?
TGF beta and IGF-1
stimulates protoglycan synthesis and counteracts effects of IL-1
What are the markers of cartilage degradation?
increased levels of serum and synovial keratin sulphate (levels increase with age also)
increased type 2 collagen in synovial fluid
