Anatomy Notes Week 4 PDF

Organ systems The Integumentary System  skin, hypodermis, hair, nails, glands, muscle, and nervous system sense receptors 1. Skin – two layers A. Epidermis – stratified squamous epithelium  derived from ectoderm  avascular Primarily composed of keratinocytes  cells that produce lots of kerati...

Organ systems The Integumentary System  skin, hypodermis, hair, nails, glands, muscle, and nervous system sense receptors 1. Skin – two layers A. Epidermis – stratified squamous epithelium  derived from ectoderm  avascular Primarily composed of keratinocytes  cells that produce lots of keratin; a fibrous protein with protective properties A. Epidermis  separated into five distinct strata (four in thin skin) i) stratum basale – basal layer; attached to the dermis a) single row of keratinocytes (~90% of total)  stem cells that divide by mitosis  one daughter cell pushed toward surface following each cell division (takes ~25–45 days to reach surface) b) melanocytes (~10%)  produce melanin (pigment)  albinism – inability to produce the various melanins A. Epidermis ii) stratum spinosum – spiny layer  irregular shaped keratinocytes with many intermediate (pre-keratin) filaments iii) stratum granulosum – granular layer  thin (3–5 cell) layer containing many dark-staining keratohyaline granules (help form keratin) Note: cells above granulosum are far away from blood supply iv) stratum lucidum – clear layer  thin (2-3 cells thick) band of flat, dead clear keratinocytes A. Epidermis v) stratum corneum – surface layer  thick (~30 cells thick) band of flat, soft keratin containing cells  continually shed and replaced from below  glycolipids between cells creates waterproof layer Thin skin – hair follicles and sebaceous glands present  no stratum lucidum apparent Thick skin – palm of hand, sole of foot  no hair follicles or sebaceous glands The Integumentary System: skin B. Dermis – CT proper; derived from mesoderm i) papillary layer – outer, thin loose areolar layer  vascular – supplies epidermis with O2 and nutrients  has projections (dermal papillae and ridges) that extend into the epidermis of thick skin – create your ‘fingerprints’ ii) reticular layer  deep, thick dense irregular CT (fibrous collagen layer)  contains blood vessels, nerves, and glands (plus hair follicles and arrector pili muscles in thin skin) Hypodermis – subcutaneous layer (= superficial fascia)  layer of adipose and areolar CT underlying the skin  loosely binds integumentary system to underlying structures Skin colouration keratinocytes i) melanin – red, brown, and black pigment types melanin  responsible for most variation in skin colour among people (i.e. not number of melanocytes)  formed in melanocytes; transferred to keratinocytes  freckles, moles; tan (in response to UV exposure) ii) carotene – yellowish orange colour  accumulates in stratum corneum; dietary origin iii) hemoglobin – blood pigment  blood in dermal capillaries  most evident in fair-skinned people (e.g. blushing) melanocyte 2. Epidermal derivatives A. Hair – composed of hard-keratin containing epithelial cells  has a root (in dermal layer) and a shaft (projects from skin) B. Hair follicles – invagination of epidermis (root sheath) surrounded by a CT sheath shaft i) hair bulb – expanded region at base of the hair root ii) hair matrix – single layer of rapidly dividing cells sheath  are derived from stratum basale cells root bulb  site of hair growth; also contains melanocytes matrix iii) hair papilla – dermal tissue projecting into the matrix  contains blood supply for hair matrix cells and signals for its regulation papilla 2. Epidermal derivatives oil gland Associated with each hair follicle is: arrector pili a) root hair plexus – nerve endings b) sebaceous (oil) gland – opens into follicle c) arrector pili muscle – smooth muscle  contraction causes ‘goosebumps’ C. Nails – scale-like modification of the epidermis Heavily keratinized stratum corneum cells arising from the nail matrix nail root nail body free edge nerve sweat pore 2. Epidermal derivatives D. Exocrine glands i) sebaceous (oil)  found sebaceous mainly with hair follicles  secrete sebum (oil, salt, and protein mixture)  softens and lubricates hair and skin; antibacterial ii) sudoriferous (sweat) – secretion is ~99% H2O  secretory portion of gland found in dermis with a duct opening on the surface (sweat pore)  helps regulate body temperature via evaporation  removes some body wastes (urea, ammonia) sudoriferous D. Exocrine glands cerumen iii) ceruminous  modified sweat glands in the auditory canals  its secretion mixes with sebum to form cerumen (ear wax), a waxy substance with antimicrobial/antifungal properties iv) mammary (milk) – a nutritious secretion  modified sweat glands mammary glands adipose ducts 3. Cutaneous Sense Receptors Components of the nervous system specialized to respond to external stimuli A. Mechanoreceptors – sensitive to mechanical stimuli i) touch receptors  root hair plexuses around hair follicle  nonencapsulated (free) nerve endings that detect hair movement  Meissner’s corpuscles – fingertips, soles, nipples  encapsulated sensory neurons in the dermal papillae used for discriminative touch 3. Cutaneous Sense Receptors ii) pressure receptors  Pacinian corpuscles – fingertips, soles, nipples  large encapsulated receptors in the deep dermis and hypodermis  some free nerve endings deep in the dermis also sense pressure B. Thermoreceptors – sensitive to temperature changes  free nerve endings in dermal papillae C. Nociceptors – pain  typically free nerve endings in dermis, though all receptor types indicate ‘pain’ if overstimulated Skeletal and Muscular Systems Skeleton divided into axial and appendicular portions Homework: Learn and know directional terms  i.e. medial, lateral, proximal, anterior (ventral), etc. 1. Axial skeleton – skull, hyoid, vertebral column, and thorax  80 bones A) Skull i) cranial bones (8 bones); surround brain frontal (1) parietal (2) ethmoid (1) temporal (2) sphenoid (1) occipital (1) A) Skull ii) facial bones (14 bones) mandible (1) zygomatic (2) maxillae (2) lacrimal (2) nasal (2) vomer (1) inferior nasal conchae (2) palantine (2) ethmoid palantine (behind maxilla) A) Skull iii) auditory ossicles (6 bones) – used for sound transmission  malleus (2), incus (2), and stapes (2) B) Hyoid bone – assists in swallowing  does not articulate with any other bone  attachment site for muscles of the tongue, neck, and pharynx 1. Axial skeleton spinous process transverse process lamina C) Vertebral column General structure of most vertebrae 7 processes spinous (1) pedicle superior articular process foramen transverse (2) body superior (2) and inferior (2) articular processes (and their facets; sites of articulation with adjacent vertebrae)  arch composed of 2 laminae (between spinous and transverse process) and 2 pedicles (body to transverse process)  vertebral foramen (for  body spinal cord) (centrum); thick anterior region C) Vertebral column i) cervical region – 7 vertebrae (C1–C7) Smallest, lightest vertebrae a transverse foramen runs through each transverse process  for vertebral arteries, veins, and nerves transverse foramen a) atlas (C1)  has no centrum or spinous process  articulates with skull (occipital condyles)  allows for flexion and extension of neck (‘yes’ nod) atlas C) Vertebral column b) axis (C2) dens a knoblike dens (odontoid process) on body projects superiorly, articulating with the atlas  creates a pivot (swivel) joint, allowing a ‘no’ shake c) C3– C7  ‘typical’ vertebrae axis C) Vertebral column ii) thoracic region – 12 vertebrae (T1–T12)  possess long, slender spinous processes  body and transverse processes have costal facets  for articulation with ribs iii) lumbar region – 5 vertebrae (L1–L5)  large thick bodies; short, heavy spinous processes  provide support for upper body; limited rotation ability C) Vertebral column iv) sacrum – 5 fused vertebrae  articulates with ilium and 5th lumbar vertebra v) coccyx – 3-5 (but mostly 4) fused vertebrae  tailbone Intervertebral foramen – lateral openings between adjacent vertebrae  form the exit holes for spinal Intervertebral foramen nerves Curvature of the Spinal Column “S shaped” (lateral view) 1. Cervical and lumbar sections  are concave posteriorly (convex anteriorly) 2. Thoracic and sacrum sections  are convex posteriorly (concave anteriorly) Abnormal curvatures: i) scoliosis – lateral bend of the spinal column ii) kyphosis – extensive dorsal thoracic curve (hunchback) iii) lordosis – extensive lumbar curve (sway back) 1. Axial skeleton D) Thoracic cage – ‘bony thorax’  forms a protective cage around the vital organs of the thorax  attachment point for muscles of the neck, back, chest, and shoulder 1. Sternum – ‘breast bone’  fusion of three bones: i) manubrium – superior ii) body – middle iii) xiphoid process – inferior D) Thoracic cage 2. Ribs – ♂ 12 pairs; ♀___ pairs  articulate posteriorly with corresponding thoracic vertebra i) 7 pairs of true ribs – superior  directly attach anteriorly to sternum via costal cartilage (hyaline) 8 9 10 12 11 ii) 5 pairs of false ribs – inferior  ribs 8 to 10 attach to the sternum indirectly via costal cartilage of rib 7  ribs 11 and 12 are not attached to the sternum  ‘floating ribs’; are embedded in muscle 2. Appendicular skeleton  upper and lower limb girdles; 126 bones A. Pectoral girdle i) clavicle – ‘collarbone’  articulates with the manubrium  connects the and acromion process axial and appendicular skeletons ii) scapula – ‘shoulder blades’ a) spine – runs along posterior surface b) acromion process – articulates with clavicle c) glenoid fossa – articulates with the head of the humerus d) coracoid process – attachment point for chest and upper arm muscles 2. Appendicular skeleton B. Pelvic girdle – paired os coxae or ‘hips’ Three fused bones: ilium (superior), ischium (inferior), and pubis (anterior) Contains three key joints: ilium i) sacroiliac  synovial joint between the sacrum and ilium ii) pubic symphysis acetabulum ischium  cartilaginous joint uniting the anterior medial os coxae (i.e. between the pubic bones) pubis iii) acetabulum – point of fusion between the three coxal bones  synovial ball and socket joint for the head of the femur 2. Appendicular skeleton C. Upper and lower limbs (in the anatomical position) (left) Arm humerus ulna radius carpals (8) ‘wrist’ metacarpals (5) ‘palm’ phalanges (14) (right) Leg femur patella (anterior; ‘kneecap’) tibia fibula tarsals (7) ‘ankle’ talus; articulates with tibia/fibula calcaneus = heel bone metatarsals (5) ‘sole’ tibia fibula talus phalanges (14) calcaneus thumb (pollex) big toe (hallux)