Exam 3 - A&P 4-7; C ch 8,12,13

skeletal system functions

-support

-protection

-movement

-blood production

-mineral storage

osteocytes

mature bones cells that are inside each osteon

when osteoblasts become embedded in the bone matrix

spongy bone

cancellous bone; found in the epiphyses and inner part of diaphysis

red marrow as an infant, yellow in adults

red marrow in adults

found in bones of the skull, the vertebrae, ribs, sternum, clavicles, pelvis

red vs yellow marrow

-red: blood cells manufactured here, site of antibody production

-yellow: contains fat cells which store fat

endochondral ossification 

bone develops from cartilage templates

begins to ossify in diaphysis, secondary site is epiphyses 

intramembranous ossification

bone develops from noncartilage connective tissue scaffold

-bones of the skull, irregular vertebrae (clavicle), facial bones, mandible

osteoblasts

cells that produce bone

secrete collagen that forms strong, elastic fibers of bone

calcium phosphate salts crystalize around collagen fibers which form the hard matrix of bone

osteoclasts

large cells that resorb bone

secrete enzymes that digest collagen and hydrogen ions that dissolve the crystals

fractures

-incomplete: bone cracks

-complete: bones breaks in two or more pieces

-simple: bone does not break the skin

-compound: bone breaks through skin

sagittal suture

two parietal boned are joined in the midline

coronal suture

joins the parietal bones to the frontal bone

lambdoidal suture 

joins the parietal and occipital bones

regions of the vertebral column

-7 cervical

-12 thoracic

-5 lumbar

-sacrum and coccygeal

vertebral canal

contains the spinal cord

thoracic cage

formed by the sternum, thoracic vertebrae, and 12 ribs

pectoral girdle 

attaches the upper extremeties to the axial skeleton

-part of appendicular skeleton

-consists of scapula and clavicle

joint/articulation

point of contact between two bones

types of joints

-synarthroses: do not permit movement (sutures of skull)

-amphiarthroses: permits slight movement and help absorb shock (intervertebral joints)

-diarthroses/synovial: freely moveable (varies), hinge, ball and socket

connective tissue of the muscle 

-epimysium: covers the muscle

-perimysium: wraps each fascicle (bundle of muscle fibers)

-endomysium: surrounds individual muscle fibers 

energy for muscle contraction

immediate source comes from ATP

creatine phosphate is the backup energy storage

glucose is a fuel molecule that makes energy for creatine and ATP (last source)

muscle tone

muscles in a state of partial contraction when we are not moving

messages from nerve cells continuously stimulate muscle fibers

isotonic contraction 

muscles shorten and thicken, muscle tone remains the same (lifting a heavy object, bending your elbows)

isometric contraction

muscle tension increases but muscle length does not change (pushing against a heavy table or wall)

agonist

prime mover; the muscle that contracts to produce a particular action

antagonist

produces the opposite movement of the agonist

synergists and fixators 

muscles that help the prime mover by reducing unnecessary movement 

ergonomics

the science of matching workplace conditions and jobs demands to capabilities of workers

complications of immobility

-anorexia

-contractures

-disuse osteoporosis: lack of weight bearing on bones, causes bone demineralization

-hypostatic pneumonia: accumulation of secretions lead to inflammation and infection in lungs

-orthostatic hypotension: can lead to decreased cardiac output

-pulmonary embolism: blood clot that has traveled to the lungs

interventions for immobility 

-reposition every 2 hrs 

-encourage fluids and well-balanced diet

-early ambulation

-antiembolism measures

patient’s neurovascular function

circulation, movement, sensation (CMS)

compartment syndrome

occurs in the extremeties where the sheath of inelastic fascia partitions blood vessels, nerve and muscle tissue

disuse syndrome

a state in which an individual is at risk for deterioration of body systems as a result of prescribed or unavoidable inactivity 

central nervous system

consists of the brain and spinal cord

peripheral nervous system

twelve pairs of cranial nerves link the brain and thirty-one pairs of spinal nerves link the spinal cord with sensory receptors and the other parts of the body

neurons 

highly specialized to receive and transmit chemical and electrical signals 

-cell body, dendrite, axon, terminal branches that end in synaptic terminals 

astrocytes

cns

-support, protect and communicate with neurons

-regulate composition of extracellular fluid by removing excess K+

-may be important in memory and learning

oligodendrocytes

form insulating myelin sheaths around the neurons in the CNS

ependymal cells

-line cavities in the CNS

-produce and circulate CSF

microglia 

remove bacteria and cell debris by phagocytosis 

masses of cell bodies

PNS: ganglia; CNS: nuclei

bundle of axons

PNS: nerves; CNS: tracts/pathways

neural signaling events

1.reception

2.transmission: afferent (sensory) neurons

3.integration: info is sorted and interpreted

4.transmission: efferent (motor) neurons

5.actual response

synapse

a junction between two neurons

electrical gradient 

the difference in electrical charge across the plasma membrane 

resting potential

inner environment of the plasma membrane is negatively charged compared with extracellular fluid

-K+ leaks out more readily than Na+ ions

actions potential down a neuron

-depolarization brings neuron closer to transmitting a neural impulse

-threshold level

-repolarization occurs behind the action potential

-absolute refractory period: axon membrane cannot transmit another action potential no matter the stimulus

-relative refractory period: axon can transmit impulses but the threshold is higher

neurotransmitter: acetylcholine 

triggers muscle contraction; involved in cognitive function, memory 

catecholamines

epinephrine, norepinephrine, dopamine

seratonin

excitatory effect on pathways that control muscle contraction; regulates food intake, sleep and wakefulness; affects mood

endorphines

pain regulation

midbrain

motor coordination; visual and auditory relay centers 

pons

bridge; sleep and respiration

medulla

HB, RR, BP; sneezing, coughing, vomiting

hypothalamus

regulates stress, sleep, appetite, water intake

regulates autonomic responses

produces hormones ADH + oxytocin

thalamus 

relay center between spinal cord + cerebrum 

incoming messages are sorted and interpreted before sending to appropriate centers in cerebrum 

cerebellum

smooth, coordinated movements

maintains balance and equilibrium

maintains posture and muscle tone

cerebrum

center of consciousness, intellect, memory, and language

receives and interprets sensory info

controls motor functions

frontal lobe 

broca’s area directs the formation of words 

primary motor area controls voluntary movements of skeletal muscle 

parietal lobe

interpretation of pain, taste, touch, temperature, spatial perception

occipital lobe

visual area

temporal lobe

auditory centers; wernicke’s area for sensory and speech

limbic system 

important in motivation; plays a role in sexual behavior, biological rhythms, and autonomic responses 

hippocampus

limbic area

-formation and retrieval of memories

amygdala

limbic system

-filters incoming sensory information and evaluates its importance in terms of emotional needs and survival

meninges 

-dura mater

-arachnoid

-pia mater