ANA2 Q3

Nervous system

an extensive network of
specialized cells that serves as
the body’s control center and
communications network

Parasympathetic nervous system

• constricts pupils and inhibits tear glands

• slows heart

• increases salvation

• constricts bronchi

• increases digestive functions

• allows bladder contraction

Sympathetic nervous system

• dilates pupils and stimulates tear glands

• decreases salvation

• increases heart rate

• decreases digestive functions

• inhibits bladder contraction

functions of nervous system

1. senses changes in the body and external environment

2. interprets these changes

3. initiates action in the form of muscle contraction or gland secretion

neurons

• basic cell that makes up the nervous system

• receives and sends messages

• neurogenesis

glial cells

• provides support for neurons to grow

• delivers nutrients to neurons

• produce myelin to coat axons

• cleans up waste products and dead neurons

terminal branches

forms junctions with other cells

cell body

the cell’s life-support center

neural impulse (action potential)

• electrical signal traveling down the axon

myelin sheath

• covers the axon of some neurons and helps speed neural impulses

neural impulse

• electrical charge that passes from one neuron to the next neuron or muscle fiber

• all or none principle

resting potential

• separation of charges across the membrane

• polarized

action potential

• rapid and substantial excitation of the neuron’s membrane

• depolarized (labo-labo na)

electromechanical delay

• time between an arrival of neural stimulus and tension development by the muscle

• used in the study of reaction time, physiological properties of muscle (pylometrics and population differences)

cerebellum functions

• motor learning

• sense of body position

• balance and equilibrium

• fine movement coordination

frontal lobe

cerebrum

• executive functions, thinking, planning, organizing, problem solving, emotions, behavioral control, personality

parietal lobe

• perception, making sense of the world, arithmetic, spelling

temporal lobe

• memory, understanding, language, hearing

biomechanical behavior of nerves

external trauma to the extremities and nerve entrapment may produce mechanical deformation of the nerves, resulting to deterioration of their function

Common modes of nerve injury:

• stretching

• compression

stretching (tensile) injury

• initial elongation of the nerve to its limit

• nerve fibers start to rupture inside

• disintegration of elastic properties and nerve behaves like a plastic material

• max elongation is at 20%

• complete structural failure elongation at 25 to 30%

stretching (tensile) injury

• there can be considerable structural damage without any visible injury on the surface

• result of gradual stretching is the growth of intra-neurons (schwannomas)

compression injury

• can induce symptoms like numbness, pain, and muscle weakness

• may be caused by impairment of blood flow

male brain

• 10% larger

• stronger front-to-back

• optimized for motor skills

male brain

• more likely to develop alcohol dependence

• 3x antisocial personality

• 4x autism

• 2x parkinsons

female brain

• stronger side-to-side

• optimized for intuitive thinking

• more grey matter

female brain

• 2x depression

• 2x alzheimers

• 4x multiple sclerosis

• stroke

bone

• extremely dynamic tissue that is continually modeled and remodeled

• fulfils 2 important mechanical functions:

  • rigid skeletal framework that supports and protects body tissues

  • forms system of rigid levers that can be moved

bone characteristics

• stiffness (can withstand stress/ strain)

• compressive strength (resist compression)

what contributes to the stiffness and compressive strength of bone?

1. calcium phosphate

2. calcium cabonate

^^ thhey constitute 60-70% dry bone weight

what contributes to flexibility and tensile strength (ability to resist tension)?

• collagen

^^ progressively lost and bone brittleness increases with aging

what affects bone strength?

• water (25-30% of bone weight)

  • carries nutrients to and waste products away

  • transports mineral ions

• bone porosity (amt of bone volume filled with pores or cavities)

resisting compression

bone is strongest

resisting shear

bone is weakest

cortical bone

types of bone (based on porosity)

• compact mineralized bone with low porosity

• found in the shaft of long bones

• stiffer, can withstand greater stress

trabecular (cancellous or spongy)

types of bone (based on porosity)

• less compact bone with high porosity

• found in the ends of long bones and vertebrae

• has honeycomb structure forming cells with marrow and fat

• can undergo more strain before fracturing

axial

type of bone based on location

skull, ribcage, vertebrae

appendicular

type of bone based on location

• bones of arms and legs

short bones

types of bones (based on shape)

• tarsals

• carpals

long bones

types of bones (based on shape)

• humerus, radius, femur, fibula, tibia, ulna, metacarpal, metatarsal, phalanges

flat bones

types of bones (based on shape)

• sternum, scapula, ribs, cranial

irregular bones

types of bones (based on shape)
* vertebrae, sacrum

sesamoid

types of bones (based on shape)

• patella

epiphyseal plates

• growth centers found near ends of bones where new cells are produced

• closes at around 18, some are present until 25

epiphyseal lines

• remnants of epiphyseal plates in mature bone

periosteum (inner layer)

• builds concentric layers of new bone of top of existing ones

osteoblasts

• build bone tissue

osteoclasts

• breakdowns bone tissue

• diameter of medullary cavity is enlarged when bone is broken down

ossification

• natural process of bone formation

1. Intramembranous - bone develops directly

2. endochondral - bone replaces cartilage

• All bones undergo this, except for the skull, mandible, and clavicles

calcification

• buildup of calcium in body tissues

• can form hardened deposits even in soft tissues, arteries, and other areas

bone growth development

• bone mineral peak at 33-40 women & 19-33 men

^^ at this peak age-related progressive decline in bone density and strength begins

• changes are more pronounced in women

^^ there is an increased rate of bone loss after menopause (estrogen deficiency)

hypertophying

bone response to stress

• wolff’s law: densities, sizes, and shapes of bones are determined by the magnitude and direction of forces acting on it

• mechanical loading causes strain on bones due to predominance of osteoblast or osteoclast activity (remodeling)

bone atrophy

• when normal stresses exerted on bone is reduced, this happens through remodeling

• calcium, bone weight & strength decrease

  • loss of bone mass

osteoporosis

• disorder involving decreased bone mass and strength with pain and one or more fractures

• begins as osteopenia (reduced bone mass without fracture)

• common symptom is back pain

dowager’s hump

• aka thoracic kyphosis

• result of osteoporosis

osteoporosis

risk factors

1. women

2. white or asian

3. older

4. small stature or frame

5. family history

^^ majority are postmenopausal and elderly women, men are also susceptible

connective tissues

• tissues that connect and support other tissues

functions

1. mechanical support

2. medium for exchange of nutrients and waste products

3. energy storage

4. thermal insulation

5. defensive functions (barrier, engulfs bacteria, contains antibodies)

collagen fibers

• large fibers made of protein collagen

  • promotes tissue flexibility

elastic fibers

• made of protein elastin

  • allows stretch and recoil

reticular fibers

• small and branched fibers

• forms structural framework of organs

fascia

• thin membrane of connective tissue that covers structure of the body (protecting and binding to a structural unit)

fasciitis

inflammation of fascia

superficial

• directly under dermis

• stores fat and water

• creates passageway for nerves and vessels

deep

• found around muscles and their internal structures

• aid in muscle movement

• provides passageway for nerves and vessels

• provides muscle attachment sites

• cushions muscle layer

subserous

• separates deep fascia from membranes that line thoracic and abdominal cavities

  • allows for flexibility and movement of internal organs

bursae

• small, flattened sacs (contains synovial fluid)

  • found in areas of friction (muscles or tendons)

bursitis

when bursa becomes enlarged and swollen due to excessive friction

tendons

• dense connective tissue that surrounds muscles

• connects muscle to bone

• contains abundant collagen fibers for strength and elasticity

ligaments

• fibrous structure made of dense connective tissue

• connects bones to each other

• composed of complex network of collagen fibers that resists stress

• prevent movement at joints and contribute to joint stability

cartilage

• connective tissue that varies in consistency and function by the proportion of proteins distributed through its matrix

  • does not contain blood vessels or nerves (limited ability to heal following injury)

elastic cartilage

• found in nose and ears

• does not have the same direct application to human movement as other cartilage

hyaline cartilage

• smooth and rubbery

• helps reduce friction

• damage can result in chronic inflammation of joint (osteoarthritis)

fibrous cartilage

• makes up disks between vertebrae and meniscus between femur and tibia at the knee

• cushions joint surfaces and enhances joint continuity