The Human Body Plan

I. Tissues

tissue- collection of cells that are similar in structure that work together for perform a specific function

4 main tissues:

Muscle Tissue:  composed of cells that can contract in coordinate

fashion

3 Types: Skeletal- (striated) moves bones in trunk, limbs        

and face.  Responsible for deliberate motion

                        Smooth- responsible for body functions you do not

consciously control (ex. digestion)

                        Cardiac- found in heart

Nervous Tissue: composed of cells that can receive and transmit

messages in form of electrical impulses (neurons)

Epithelial Tissue: layers of cells that line or cover all internal and

external body surfaces.  Tightly bound together to form

protective barrier.  Can be ciliated.

Connective Tissue: binds, supports, protects structures.  Most

abundant tissue- include bone cartilage, tendons, fat, blood

 and lymph.Cells embedded in large amounts of extracellular

substance called matrix (solid [bone], semi-solid [tendons/

ligaments], or liquid [blood])

II. Organ Systems

Organ- various tissues that work together to carry out specific

function

Organ system- organs work together, not in isolation

There is overlap between the systems

        ex: pancreas produces digestive juices and hormones

III. Body Cavities

compartments that house organs, protect from daily wear and tear, allows expansion and contraction of organs

Cranial cavity: encases brain

Spinal cavity: supports spine, extends from cranial cavity to base of

spine

Thoracic or Pleural cavity: contains heart, esophagus, resp. system

Abdominal or Peritoneal cavity: contains digestive, reproductive,

excretory

Diaphragm: wall of muscle that separates abdominal and thoracic

Protection, Support and Locomotion

IV. Skeletal System  (p930)

skeleton- internal framework, 206 bones, composed of 2 parts

        rigid framework against which muscles can pull

        gives shape and structure to body

        supports and protects internal organs

        bone marrow- produces RBC and WBC

Axial Skeleton: skill, ribs, spine, and sternum

Appendicular Skeleton: arm, leg, scapula, clavicle, pelvis

Bone structure: less than 20% of body mass

        periosteum- tough membrane, contains blood vessels, to

supply nutrients, and nerves, to signal pain

        compact bone- under periosteum

                hard material, enables bone to withstand stress

                cylinders of mineral crystals and protein fibers- lamellae

        Haversian canal- canals distributed thru-out compact bone

                blood vessels run thru

                wrapped by protein layers that house osteocytes (living

bone cells- secrete minerals)

        spongy bone- network of connective tissue inside compact

bone

        bone marrow- soft tissue

                Red- found in spongy tissue, end of long bones

                        produces RBC and some WBC

                Yellow- fills shaft of long bones

                        fat cells, energy reserve, can be converted into Red

Development: most bones develop from cartilage

        as embryo, skeleton first cartilage

Ossification- osteocytes begin to release minerals between

cartilage cells, solidifying

        Some bone, such as skull, is not cartilage first.

                osteocytes scattered randomly, bones grow and fuse

        Elongation: takes place near end of bones

epiphyseal plate (growth plates)- cartilage cells that divide

and form columns, pushing old cells to middle of bone, old cells die, replaced with new. Continues until all cartilage is replaced by bone (full height)

Joints: a place where bones meet

        Fixed Joints- prevent movement, skull, connective tissue

between to absorb impact

        Semimovable Joints- limited movement- vertebral column, rib

cage, separated by cartilaginous tissue

        Movable Joints- wide range of movements

                Hinge Joint- 2D movement (elbow, knee)

                Ball and Socket- 3D movement (shoulder, hip)

                Pivot Joint- side to side, up and down- base of skull

                Saddle Joint- rotate and grasp, base of thumb

                Gliding Joints- bones slide over one another, foot

Ligaments- bone to bone connective tissue

Synovial fluid- lubricates end of bones

Rheumatoid arthritis- immune system attacks joints

Osteoarthritis- degeneration of cartilage in joints

V. Muscular System

Types of Muscle:

Skeletal- called voluntary b/c you can consciously control

contractions

        muscle fibers- elongated, multinucleate cells

        striations- light and dark stripes along fiber

        fascicles- fibers grouped into dense bundles

Smooth- called involuntary- no conscious control, reflex

        walls of organs

        spindle shaped, 1 nucleus, no striations

interlace to form sheets, not bundles

Cardiac- makes up walls of heart

        striated, one nucleus, involuntary

        pacemaker bundle

Structure of Muscles:

Muscle, connective tissue, nerves, blood vessels

Each skeletal muscle has a nerve ending that controls its

activity

Myofibril- makes up muscle fiber

                made of 2 types of protein filaments

                Thick- made of protein called myosin

                Thin- made of actin

                The two overlap (striations)

                Z-line- actin filaments anchored at midpoints

                Sarcomere- 1 Z-line to the next

Contraction:

Muscular Movement of Bones:

        Muscles attached to bone by tendons

        Origin- point where muscle attaches to stationary bone

        Insertion- point where muscle attaches to moving bone

        Muscles arranged in opposing pairs- flexors (bends joint) and

                extensor (straightens a joint)

Integumentary System

Consists of skin, hair and nails

Epidermis- outer layer of skin

        many sheets flattened, scaly epithelial cells (mostly dead)

        Keratin- protein that fills cells, gives them rough, leathery

texture and waterproofness

        Melanin- pigment in skin

                produced by cells in lower epidermis

                absorbs UV

                amount of melanin depends on heredity & exposure

                released in response to damage to skin by UV

Dermis- inner layer of skin

        living cells

sensory neurons- sense conditions and signals

blood vessels- provide nourishment, regulates temp.

muscle fibers- attach to hair follicles (pinoerection)

hair follicles- origin of hair growth          

glands- produce sweat and oil

Subcutaneous fat- energy, shock-absorption, insulation

Nails and Hair

        Grow from roots (hair follicles)

        Made of keratin

Glands:

        Exocrine- release secretion thru ducts

        Sweat Glands- release excess water, salts, and urea

                                Cools skin

        Oil Glands- secrete fatty substance called sebum

                usually connected by tiny ducts to hair follicles

                prevent excess water loss

                toxic to some bacteria

                acne- ducts clogged with sebum, dead cells, bacteria

                sebum production controlled by hormones