[B] (Pt 1) Human Musculoskeletal Anatomy: SKELETAL TISSUES Flashcards
(30 cards)
Germ Layers (x3)
Early embryonic pluripotent stem cells arranged in germ layers (cells will become all tissues body)
i.e. endoderm (inner), mesoderm, ectoderm (outer)
Connective Tissue
- Connects + supports organs/ other tissues
- Cells embedded in matrix w collagen fibres + elastic tissue
- Develops from mesoderm
e.g. cartilage/ bone
Cartilage
Hard, flexible connective tissue in respiratory airways + end of bones + anterior end ribs + nose + outer ear
1) Hyaline Cartilage
2) White Fibrous Cartilage (fibrocartilage)
3) Yellow Elastic Cartilage
Chondrocytes
Cells in cartilage:
- Secrete an extra-cellular matrix made of transparent protein chondroitin (may contain fibres collagen/ elastic material)
- In spaces in matrix (lacunae)
Properties Cartilage
- Rigid: hold open tube e.g. trachea/ Eustachian tube
- Flexible: allows ribcage movement
- Returns original shape after bending: role load bearing joints e.g. hips/ knees
(No blood vessels: nutrient acquisition/ gas exchange rely diffusion - diffusion slow so healing slow)
(No nerves)
Hyaline Cartilage
Weakest
Role: Prevents friction at joints
- High proportion collagen (in extra-cellular matrix)
- “Glassy”
- Surrounded fibrous coat connective tissue (perichondrium)
- If damaged replaced fibrocartilage scar tissue
- Ossifies in foetus (becomes bone) + in adults is articular cartilage at ends of bones
e. g. joining ribs w sternum/ nose/ larynx/ trachea/ bronchi
White Fibrous Cartilage (fibrocartilage)
Strongest
Role: Load bearing in intervertebral discs
- Collagen organised in dense fibres (higher tensile strength) + in direction of stress
- Makes intervertebral discs + ligaments
Yellow Elastic Cartilage
Intermediate Strength
Role: Maintains shape at epiglottis
- Chondrocytes surrounded collagen (in matrix) + network elastin fibres
(makes it elastic but maintains shape)
e.g. ear pinna/ epiglottis
Bone: Functions (x4)
- Structural support skeleton
- Movement (bones attachment sites for muscles)
- Physical protection organs e.g. brain
- Mineral regulation: storage (e.g. Ca/P), trapping harmful mineral (e.g. lead), regulation calcium content
Bone: Types (x2)
1) Spongy/ Cancellous Bone
2) Compact Bone
Spongy/ Cancellous Bone
Found end of long bones + in vertebrae
Light + porous and has network of spaces containing bone marrow (flexible tissue where RBCs made)
Compact Bone
Strong and rigid + surrounds most bones - gives white/shiny appearance (75% bone body)
Haversian + Volkmann canals run through bone so blood vessels can penetrate
OSTEOBLASTS: Continuously build it up
OSTEOCLASTS: Continuously degrade it
–> cells held in matrix secreted osteoblasts (30% organic collagen fibres to resist fracture + 70% inorganic hydroxy-apatite (mineral rich Ca and P) v hard and resists compression)
Haversian System/ Osteon
- Structural and functional unit of compact bone
- Separated by interstitial bone
- Formed concentric lamellae (rings made hydroxy-apatite secreted by osteoblasts in lacunae) around central Haversian canal
Periosteum > interstitial bone > lamellae > Haversian Canal > marrow cavity
(+ lacunae + Volkmann canals + Canaliculi)
Haversian Canal
- Centre of Haversian System
- Contains an arteriole, a venule, lymph vessels and nerve fibres
Volkmann Canal
[Haversian System]
Perforating canal that connects Haversian canals with each other and with the periosteum (carries blood vessels)
Canaliculi
[Haversian System]
Microscopic channels that radiate out of lacunae (containing osteoblasts) into bone matrix
–> forms 3D network between osteoblasts to supply nutrients via blood vessels + remove waste (also some exchange by diffusion through bone matrix)
Bone Formation: Cartilage Bones
e.g. limb bones/ vertebrae/ ribs
OSSIFICATION of hyaline cartilage in embryo:
(begins ends/ middle long limb bones)
- Cartilage cells flatten + Ca deposited around them
- Osteoblasts secrete layers bone matrix around cartilage while osteoclasts break down cartilage
- Blood vessels invade
Perichondrium surrounding cartilage –> periosteum surrounding bone (dense fibrous connective tissue)
Bone Formation: Membrane Bones
e.g. collarbone (clavicle)/ most skull (cranium)/ facial bones
–> form directly in embryonic connective tissue
Bone Diseases (x3)
1) Rickets + Osteomalacia
2) Brittle Bone Disease (osteogenesis imperfecta)
3) Osteoporosis
Rickets + Osteomalacia
Rickets: Childhood disease where Ca not absorbed into growing bones so become soft/ weak/ deformed
Osteomalacia: Milder rickets in adults
Symptoms: Tenderness/ fractures/ bone deformity e.g. bow legs toddlers/ knock knees/ less wide pelvic girth women (difficulty childbirth)
Diagnosis: Blood tests (low Ca)/ x-rays/ bone density scans
Cause: Lack vitamin D/ Ca (sunlight converts inactive to active vitamin D which incorporates Ca into bones)
Prevention: Exposure sunlight + Ca in diet + vit D (fat soluble so found butter/eggs/fish)
Treatment: Vitamin D/Ca supplements/ ultraviolet B light exposure/ surgery for bone deformities
Brittle Bone Disease [osteogenesis imperfecta (OI)]
Inherited disorder in balance organic vs inorganic components bone - leading increase risk fractures
Symptoms: Fractures/ poor muscle tone/ loose joints
Diagnosis: Test collagen from skin biopsy/ DNA analysis
(Normally collagen has high proportion smallest amino acid glycine but OI replace w bigger amino acids so cannot coil tightly so H-bonds holding triple helix weaker - interaction triple helix w hydroxy-apatite altered so brittle bones)
Cause: Genetic (mutations in type 1 collagen)
Treatment: No cure
- Drugs (increase bone mass, reduce pain/ fractures)
- Surgery (metal rods in long bones to walk)
- Physiotherapy (strengthen muscles, mobility)
Osteoporosis
Abnormal loss of bone mass + density due Ca leached from bones resulting increased risk fracture
Symptoms: Fractures arm, wrist, hip, vertebrae/ stooped posture/ chronic back pain
Diagnosis: Bone scan measure mineral density in hip
Causes/ Risk Factors:
- Age (post-menopausal women rapid loss bone density due drop oestrogen/ old men due drop testosterone)
- Lack Ca in diet
- Family history
- Inflammatory conditions e.g. rheumatoid arthritis
- Medical conditions/ drugs that affect hormone lvls
- Alcohol/ smoking
Prevention/ Treatment: No cure
- Diet rich Ca/ vit D
- Regular load bearing exercises (increase bone density)
- Drugs (increase Ca uptake in bones)
- Give up smoking/ less alcohol
- Prevent falls
Types of Muscle (x3)
- Skeletal (striped, striated, voluntary)
- Non skeletal (unstriped, non striated, smooth, involuntary)
- Cardiac
Skeletal Muscle: Structure of Muscle Tissue
(Muscle fibres = long thin cells)
Fascicle = Bundle of muscle fibres
(Surrounded by connective tissue - perimysium)
Muscle = Bundle of fascicles
(Surrounded by connective tissue - epimysium)
