Skeletal tissues Flashcards
What are the three types of cartilage?
Yellow elastic cartilage
White fibrous cartilage
Hyaline cartilage
What type of cartilage is the most flexible?
Yellow elastic cartilage
What are the features of cartilage?
Hard, flexible, compressible, elastic, permeable
Which type of cartilage has the highest tensile strength?
White fibrous cartilage
What fibres does yellow elastic cartilage contain?
Elastin
What fibres does white fibrous cartilage contain?
Collagen
What is the function of hyaline cartilage?
Flexible support tissue made of chondrin protein, which is secreted by chondrocytes
What is it called when bones turn from cartilage to bone?
The bones ossify
Where is yellow elastic cartilage found?
Ears and nose
Where is white fibrous cartilage found?
Inter-vertebral disks
Where is hyaline cartilage found?
Coats the bone ends at joint (articular cartilage) and make up the supporting rings in the trachea and bronchi
What is the matrix/chondrin make of?
Glycoproteins
What is the function of the matrix/chondrin?
To reduce friction for bone articulation
What does compact bone do?
Forms a supporting tube to bone shaft and hard layers towards the outside of bone heads
What is the role of organic (squishy) bone and what is it made of?
Resist fracture. Made of collagen
What % of the bone is made up of organic bone?
30%
What % of the bone is made up of inorganic bone?
70%
What is the role of inorganic (brittle) bone and what is it made of?
Resist compression. Made of calcium phosphate and hydroxyapatite
What is the role of the periosteum?
Contain nerves and attaches to ligaments
Where is spongy bone found?
Inside the bone
Where is compact bone found?
Makes up the outer bone structure
What is the role of osteoclasts?
Digest/break down bones
What is the role of osteoblasts?
Deposit/build up bones
What materials do osteocytes exchange with blood vessels?
O2, CO2, glucose, amino acids, urea
Where are chondrocytes found?
In the chondrin/matrix of hyaline cartilage
Where are osteocytes found?
Within lacuna of compact bone
Is compact bone permeable or impermeable?
Impermeable
How do compact bones get nutrients?
By Haversian canals which perforate the compact bone and contain blood vessels and nerves
How do osteocytes and blood vessels connect?
Fine cytoplasmic threads (canaliculi)
What is each concentric ‘ring’ of osteocytes and collagen called?
Lamella
What is a set of lamella called?
An osteon/Haversian canal
What is another word to describe an osteon?
A Haversian canal
What do osteons/Haversian canals contain?
Venule, arteriole, nerves and a lymph vessel
Which direction do Haversian canals/osteons travel in compact bones?
Vertically
Which direction do Volkmann’s travel in compact bones?
Horizontally
What is rickets?
A childhood bone disorder where bones soften and become prone to fracture and deformity
What are the main causes of rickets?
Severe and long-term malnutrition
Lack of vit D/sunlight
What are the symptoms of rickets?
Enlarged wrists
Bones break easily
Low calcium blood levels (hypocalcaemia)
Bowed legs
Physical growth affected
What does low calcium blood levels (hypocalcaemia) lead to?
Deformities of bones and teeth
What foods are high in vit D?
Eggs, oily fish
What does vit D do?
Means calcium can be absorbed
What is the adult equivalent of rickets?
Osteomalacia
What is osteoporosis?
Major overly active osteoclasts to osteoblasts
What are the contributing factors to osteoporosis?
Old age
Smoking
Alcohol
Drugs
Family history
Arthritis
What is the cause of osteoporosis?
Abnormal loss of bone density (osteoclasts more active than osteoblasts).
What are the symptoms of osteoporosis?
More fragile
Increased fracture risk
Pain
Decline in bone density
What is the treatment of osteoporosis?
Regular load bearing exercise
Calcium and vit D foods
Drugs for calcium
Stop smoking and drinking
Hormone Replenishment Treatment (HRT)
What is the cause of brittle bone disease?
Imbalance between organic (collagen) and inorganic (calcium phosphate and hydroxyapatite) bone densities
Gene mutation - large amino acids meaning a less tight helix
What are the symptoms of brittle bone disease?
Increased risk of fracture
Loose joints
Poor teeth development
Spine curvature
Poor muscle tone
Shortened height
What is the treatment for brittle bone disease?
Drugs to increase bone mass
Surgery - metal rods to walk
Physio - strengthen muscles and improve mobility
What is the structure of muscles?
Muscles –> fibres –> myofibrils –> protein filaments (thick and thin)
What are the different types of muscle?
Skeletal, striped, striated
What is a bundle of muscle fibres called?
Fascicle
What is a single muscle fibre cell made up of?
Many cells joined together
What is the I band?
Just thin filaments (actin)
Small dots on a cross section picture
What is a sarcomere?
Distance between Z-lines
What is the A band?
Full length of thick filaments (myosin) which overlaps with the thin filaments at the end. A band overlap has large circles and small circles in a cross sectional image
What is the H zone?
Length of thick (myosin) filaments which don’t overlap with the thin filaments (actin)
Large dots in a cross sectional image
What is the I band made up of and what happens during contractions?
Actin - shortens
What is the A band made up of and what happens during contractions?
Myosin + actin - stays the same
What is the H zone made up of and what happens during contractions?
Myosin - shortens
What is the sarcomere made up of and what happens during contractions?
Myosin + actin - shortens
What happens in a neuromuscular junction?
Vesicles migrate to pre-synaptic membrane and release neurotransmitter into synaptic cleft via exocytosis. Acetylcholine diffuses across cleft.
Motor end plate is folded to give large SA and has ligand gated channels for acetylcholine Na+ channels open and Na+ floods in which depolarises the sarcolemma.
Sarcolemma carries depolarisation away from motor end plate to rest of myofibril
T-tubule carries depolarisation deep into myofibril
Sarcoplasmic reticulum releases Ca2+ by diffusion which triggers muscle contraction
Where do calcium ions come from to be used in muscle contraction?
Sarcoplasmic reticulum
What is the role of calcium ions in muscle contraction?
Change shape of troponin. Pushes tropomyosin to expose myosin binding sites
What is the role of ATP in muscle contraction?
ATP attaches to myosin head and breaks the cross bridge between actin and myosin
ATP hydrolysed by ATPase to ADP + Pi. Energy used to recock myosin head
What makes up the thin filament?
Mainly actin (big balls)
Troponin (Ca2+ binds to and causes tropomyosin to expose myosin binding sites) (binding site)
Tropomyosin (changes position to expose myosin binding sites)(long wire looking)
What happens in the power stroke of the rachet mechanism of the sliding filament hypothesis?
Myosin heads form cross bridges to the binding site. ADP and phosphate released from head which relaxes the head and rotates it causing the power stroke
What is the rachet mechanism of muscle contraction?
Sliding filament hypothesis where tropomyosin exposes myosin binding sites
How are the cross bridges between myosin head and myosin binding sites broken in the sliding filament hypothesis?
ATP attaches to myosin heads
What are the two different muscle types?
Slow twitch and fast twitch
What is the types of muscle fibre you have dependant on?
Genetics of the person
Training
Type of muscles
What type of respiration is used in slow twitch muscle fibres?
Aerobic (oxidative phosphorylation)
What type of respiration is used in fast twitch muscle fibres?
Anaerobic (glycolysis)
What are the contraction characteristics of slow twitch muscle fibres?
Continuous, slow muscle contraction over a long period of time
What are the contraction characteristics of fast twitch muscle fibres?
Short bursts of speed or strength
What sporting events are aided by slow twitch muscle fibres?
Endurance events: marathon, long cycling, long swimming
What sporting events are aided by fast twitch muscle fibres?
Sprint (100m)
Javelin
Jumping events
What is the colour of slow twitch muscle fibres?
Red
What is the colour of fast twitch muscle fibres?
White
Is there alot of mitochondria in slow twitch muscle fibres?
Yes there is many
Is there alot of mitochondria in fast twitch muscle fibres?
No very few
Is there alot of myoglobin in slow twitch muscle fibres?
Yes alot of myoglobin
Is there alot of myoglobin in fast twitch muscle fibres?
No, very little
What is the diameter of fibres in slow twitch muscle fibres?
Smaller diameter than fast twitch fibres
What is the diameter of fibres in fast twitch muscle fibres?
Larger diameter than slow twitch fibres
Is there alot of capillaries in slow twitch muscle fibres?
Yes there are many
Is there alot of capillaries in slow twitch muscle fibres?
No there are very few
Is there a high resistance to lactic acid in slow twitch muscle fibres?
No low resistance
Is there a high resistance to lactic acid in fast twitch muscle fibres?
Reasonably high levels of resistance
How can energy be supplied during exercise?
Through ATP-PC system
Aerobic respiration
Anaerobic respiration
How is the ATP-PC system used?
Provide 10-15 secs of ATP energy for muscle contraction.
ATP + Creatine ⇌(rest and exercise)⇌ Creatine phosphate + ADP
What is anaerobic respiration?
Glucose –> 2 ATP molecules + Lactate (muscle fatigue)
Glycolysis produces pyruvate reduced to lactate. Creates a lactic acid build up and makes power stroke less efficient (H+ ions present)
O2 used to oxidise lactate back to pyruvate in liver. Called 02 debt or EPOC
Results in increased stroke volume and heart rate
What is the perichondrium?
A dense layer of connective tissue that covers the external surface of most of the body’s cartilage
What secretes the matrix?
Osteoblasts
