SKELETAL, MUSCULAR & INTEGUMENTARY SYSTEMS

CHAPTER 36 Biology

36-1 SKELETAL SYSTEM

FUNCTIONS:

bones provide rigid framework against which muscles can pull

give shape and structure to the body

support & protect internal organs

HUMAN SKELETON

•AXIAL SKELETON = skull, ribs, spine & sternum

•APPENDICULAR SKELETON = arms, legs, shoulder & pelvis

Bone Structure

solid network of living cells and protein

fibers that are surrounded by deposits of

calcium salts

Figure 6.3

Periosteum – tough membrane covering bone’s surface

Compact bone – hard material composed of cylinders underneath periosteum; enables bone to endure large amount of stress upon impact

Haversian Canal– central channel within cylinders containing blood vessels and nerves; carries nourishment to living bone tissue

Osteocytes – mature bone cells

Spongy Bone – network of connective tissue inside compact bone

Bone Marrow – soft tissue inside bones; red produces rbc’s and some wbc’s; yellow consists mostly of fat cells for energy reserve

Structure of Bone

Figure 6.6a, b

Bone Development

CARTILAGE: tissue that makes up

most of an embryo’s skeleton

OSSIFICATION: – process in which

cartilage is replaced with bone

Begins in embryos 7 mo’s before

birth

Bone growth until early adulthood

Bone thickness, remodeling, and

repair

•Bone cells replace cartilage in long bones of limbs

•Bones stop elongating when cartilage is replaced at plates

Hyaline

cartilage Spongy

bone

Blood

vessel

blood

vessel

Epiphyseal

plate

cartilage

Spongy

bone

Articular

cartilage

Bone Elongation

Figure 6.8

1. IMMOVABLE JOINTS: prevent

movement (ex) skull joints

2. SLIGHTLY MOVABLE JOINTS:

permit limited movement (ex)

vertebral column, ribs

3. FREELY MOVEABLE JOINTS –

permit movement in 1 or more

directions

JOINTS – where 2 bones meet

FREELY MOVABLE JOINTS

1. HINGE: elbows, knuckles, toes

2. BALL-AND-SOCKET: shoulders, hip

3. SADDLE: base of thumb

4. PIVOT: elbow, top of spine

JOINT STRUCTURE:

LIGAMENTS, SYNOVIAL FLUID, BURSA

Figure 8.3a, b

36.2

MUSCLE FUNCTION: movement, provides force that pushes substances (blood & food) through body

•Muscle Fibers: elongated muscle cells making up tissue

MUSCLE TISSUE Voluntary Muscle: contractions consciously

controlled (ex) skeletal

Involuntary Muscle: movements not consciously

controlled (ex) smooth & cardiac

SKELETAL SMOOTH CARDIAC

Skeletal Muscle

Figure 9.2 (a)

TENDON: tough

connective tissue

that connects

muscle to bone

MUSCLE STRUCTURE

MYOFIBRILS: muscle

fibers within a cell

SARCOMERE: unit of

myofibril

PROTEIN FILAMENTS:

ACTIN – thin

MYOSIN – thick

STRIATED MUSCLE:

striped due to

alternating light and

dark bands

Myofilaments: Banding Pattern

Figure 9.3 (c, d)

MUSCLE CONTRACTION: sliding-filament model

Thick myosin = purple

Thin actin = orange

(a) Partial overlapping

sarcomere is long

(b) Filaments slide past

each other

shortens sarcomere

(c) Totally overlapped,

Z lines closer

together

Neuromuscular

Junction

CONTROL OF MUSCLE CONTRACTION:

NEUROMUSCULAR JUNCTION: point of

contact between neuron and skeletal muscle cell

ACETYLCHOLINE: chemical released that

sends impulse to muscle fiber calcium

released muscles contract

36-3 The Integumentary System

Skin

Nails

Hair

Sweat & Oil glands

FUNCTIONS:

BARRIER AGAINST INFECTION & INJURY

REGULATE TEMP

REMOVES WASTE FROM BODY

PROTECTION AGAINST UV RADIATION

SKIN •EPIDERMIS: outer layer of skin

•Keratin - tough fibrous protein

•Melanin – dark brown pigment

•DERMIS: inner layer; has bv’s collagen, nerve endings, sensory receptors, hair follicles, glands

CROSS SECTION OF SKIN

FUNCTIONS:

•protects scalp form UV,

•provides insulation from cold

•hairs in nostrils, ears, and eyelashes prevent dirt from entering body

HAIR FOLLICLE: cluster of cells that produces hair

SEBACIOUS (OIL) GLANDS: secrete oily substance that helps maintain hair condition

HAIR

HAIR SHAFT EMERGING

FROM A FOLLICLE

KERATIN:

protein

that makes

up hair

MELANIN:

pigment

producing

hair color

NAILS •KERATIN: makes up nail

• FUNCTION: protects ends of fingers and toes

•NAIL ROOT: area of rapidly dividing cells

•CHANGES IN SHAPE, STRUCTURE & APPEARANCE MAY BE AN INDICATOR OF DISEASE