anat Flashcards
what does the skeletal system consist of
- bones
- cartilage
- joints
how many bones are there in a human adult
around 206
what are the categorisation of skeletons in the human body
- AXIAL skeleton (80 bones)
- skull (29)
- vertebral column (26)
- thorax [ribs & sternum] (25) - APPENDICULAR skeleton (126)
- Pectoral girdle & upper limbs (64)
- Pelvic girdle & lower limbs (62)
Types of bones
- Long
- Short
- Flat
- Irregular
Functions of bones
- Support
- Movement
- Protection
- Blood formation (bone marrow)
- Electrolyte balance (in blood)
- Acid-base balance
- Storage of energy
Composition of bones
- BONE TISSUE
- PERIOSTEUM: fibrous outer & osteogenic underneath layer (not on articular cartilage)
- ENDOSTEUM: covering the yellow bone marrow
*lines MARROW CAVITY (holding red/yellow bone marrow) - Articular cartilage: covers ends of bones
- Blood vessels
- Nerves
*BONE MARROW (in centre of bone):
- Yellow: fat tissue (MAY redifferentiate to RED marrow at stress)
- Red [in FLAT, IRREGULAR bones and ENDS of adult femur/humerus: Hematopoietic
Segments of a (long) bone (end -> middle): EPIphysis -> METAphysis -> DIAphysis (shaft)
*growth place for children
Composition of Bone tissue
*bone tissue: MAIN component of bones
HARD connective tissue composition:
1. Cells
- Osteocytes (trapped in lacunae/space within BONE MATRIX): bone maintenance, remodeling, mechano-sensing
- Osteoclasts: bone resorption & remodeling, dissolves bone matrix (related to WBCs)
- Osteoblasts: generate NEW bone matrix & osteocytes
- Mineralised matrix
- ORGANIC: protein fibers (primarily collagen) & other materials
- Inorganic: hydroxypatite (specialised crystals) Ca2+ salts, Mg2+, Na+, K+, F-, SO42-, CO32-, OH-) - Compact bone tissue *osteon (structural unit)
> found at OUTER layer of bones (+ shafts/diaphysis of long bones) - Spongy bone tissue
> found in INTERIOR of skull bones, vertebrae, sternum, pelvis (+ ends of long bones)
*resembles sponge due to cavities between trabeculae (beams/plates of bone); cavities contain BONE MARROW
*OSTEOPOROSIS (porous bone): bone has too much RESORPTION and/or too little bone formation -> Ca2+/ PO43-/ Vit D/ diet/ Hormones/ exercise/ therapeutics
important bones of the body
Cranium -> skull
Mandible -> jaw
clavicle -> collarbone
scapula -> shoulder blade
sternum -> central chest bone
rib
vertebrae -> lower back (spinal cord)
humerus -> upper arm
ulna -> lower/ INNER arm (smaller)
radius -> lower/OUTER arm (bigger)
hip bone
femur -> upper thigh
patella -> knee cap
tibia -> calf/ INNER (bigger)
fibula -> calf/ OUTER (thinner)
Cartilage composition, location, features, types
Composition: made of TOUGH cartilaginous connective tissue
Location: in articulating ENDS of bones, thorax, nose, trachea, outer ear, larynx *structures not related to bone directly
Cells involved: chondrocytes (in lacunae, arise from perichondrium) - secrete cartilage matrix
- in lacunae, extracellular matrix
*EXTRACELLULAR MATRIX
> collagen/elastic fibers
> ground substances: H2O, glycosaminoglycans (chondoitin sulfates, keratan sulfate, hyaluronic acid etc), proteoglycans
*almost always covered by PERICHONDRIUM
** NO BLEED VESSELS/ NERVE (except in perichondrium)
Types:
1. Elastic cartilage (elastic fibers in matrix)
2. FIBROcartilage (COLLAGEN fibers in ground substance)
3. HYALINE cartilage (associated with perichondrium)
Muscle tissue features, types
Mainly composed of SPECIALISED cells -> MUSCLE FIBERS
- Contracts/ shortens with force
- Moves human body, organs, pumps blood
Types:
1. SKELETAL muscle tissue: Striated, Voluntary
2. CARDIAC muscle tissue: Striated, INVOLUNTARY
3. Smooth muscle tissue: non-striated, INVOLUNTARY
function: regulates all movements of human body (muscle contraction)
*except: cilia, flagellum, ameboid movement (some WBCs)
Skeletal muscle tissue features
- Elongated
- Cylindrical
- UNBRANCHED
- Striated muscle fibers
- Plasma membrane -> sarcolemma
- Cytoplasm -> Sarcoplasm (contents: myofibrils/ myofilaments, mitochondria, Golgi complex, ER/ sarcoplasmic reticulum)
- MULTI-NUCLEI: FLATTENED (near periphery beanth sarcolemma)
How muscles are formed (->: bundling): myofilaments -> myofibrils -> muscle fibers (cells) -> fasicles -> muscle fibers
Sacromere components/ feature
SARCOMERE: contractile unit of myofibril
I band (light) -> Z line(disc)
A band (dark) -> M line, H zone
made of thin & thick myofilaments
THIN: mainly made of ACTIN (attached to Z line), TROPOMYOSIN, TROPONIN [ATT]
THICK: mainly made of MYOSIN (attached to M line)
- as muscle contrcts -> filaments on thick & thin (within A band) interact with one another
*Myofibril: formed by a bundle of thick & thin filaments
Terminology (skeletal muscle): Origin, Insertion, Action, Agonist, Synergist, Antagonist
Origin: muscle attachment that remains STATIONARY while the muscle contracts
Insertion: Muscle attachment that MOVES while the muscle contracts
Action: specific MOVEMENT (eg. flexion, extension) produced by a muscle contraction
Agonist: muscle(s) responsible for producing a particular movement
Synergist: muscle(s) ASSISTING agonist in performing the particular movement
Antagonist: muscle(s) OPPOSING the action of agonist - to control (eg. speed/ smoothness of movement)
impt muscles in human body
Face
Buccinator (around cheek) - for blowing/ smiling
Masseter (jaw) - for chewing
Neck
Sternocleidomastoid (from skull to chest, diagonal) - for bending/ tilting neck
[Chest] Pectoralis major
[Stomach] Rectus abdominus
Arm
deltoid* -> shoulder
biceps brachii
Triceps brachii
Leg
Gluteus maximus*
Adductor longus -> hip/thigh
Biceps femoris -> back of upper thigh
Quadriceps femoris -> above knee cap, front
Tibialis anterior -> front of calf
Gastrocnemius -> calf
*deltoid/ gluteus maximus - used for IM injection
> Gluteus: at upper outer corner - AVOID sciatic nerve (biggest nerve of body)
Functions of skeletal muscles
- Produce movements (skeletal muscles act on joints & bones)
eg. walking, pinching, respiration, facial expression (subtle) - Maintain posture, position & stability
eg. sitting, standing steady - Support & protect
- Abdominal wall - protects internal organs
- Pelvic diaphragm - protects pelvic organs (from prolapse) - Guards entrances/ exits
- Sphincters - enable voluntary control of swallowing, micturition (urination), defecation & parturition - Maintain body temperature
- Chemical energy converted to heat during muscle contraction & shivering
