Anatomy and Physiology Test 3
describe various functions of the skeletal system
support, protection, movement, electrolyte balance, blood formation, energy storage
describe the structure and functions of each part of a typical long bone
diaphysis - bone shaft
epiphyses - ends of the bone at the joints
metaphyses - region between diaphyses and epiphysis
articular cartilage - covering both epiphyses
periosteum - connective tissue surrounding the diaphysis
medullary cavity - hollow space within diaphysis, contains the yellow marrow
endosteum - thin membrane lining the medullary cavity
explain why bone is classified as a connective tissue
the matrix is materially similar to other connective tissue, including some amount of collagen and elastic fibres. this gives strength and flexibility to the tissue
describe the cellular composition of bone tissue and the functions of each type of cell
the matrix is hardened by calcium phosphate and other minerals
individual bones consist of many types of tissue
• bone tissue
• blood
• bone marrow
• cartilage
• adipose tissue
• nervous tissue
• fibrous connective tissue
continually remodels itself and interacts with all of the other organ systems of the body
compare the structural and functional differences between compact and spongy bone tissue
compact bone - provides protection and support. shaft of long bones and external layer of all bones.
spongy bone - strong but lightweight. provides tissue support. ends of long bones and inside flat bones
compare the steps of intramembranous and endochondral ossification
intramembranous ossification
• occurs in flat bones when a connective tissue membrane is replaced by bone
• flat bones of skull, clavicle
endochondral ossification
• bone develops from a preexisting model of hyaline cartilage
• most bones of the body
• also seen in epiphyseal growth plates
summarize how mature bone continues to grow and remodel itself
from birth through adolescence, more bone is produced than is lost during remodeling.
older individuals, especially post-menopausal women, experience a decrease in bone mass when resorption outpaces deposition
describe the role of the bones in regulating blood calcium homeostasis
PTH released when blood calcium levels are low to raise calcium blood levels by four mechanisms.
adequate calcium and phosphate are needed for bone deposition. Calcitonin lowers blood calcium concentration in two ways: osteoclast inhibition which lessens the calcium liberated from the bones and osteoblast simulation which deposits calcium into the skeleton
describe the effect of age and exercise on bone
exercise later in life may delay the progression of osteoporosis as it slows down the rate at which bone mineral density is reduced
The axial skeleton
describe how the skeleton is organized into axial and appendicular divisions
the axial skeleton has 80 bones - central supporting axis of the body.
• 22 skull bones
• 8 cranial bones
• 14 facial bones
• hyoid
• 6 auditory ossicles
• 26 vertebral columns (in adult)
• 7 cervical
• 12 thoracic
• 5 lumbar
• 1 sacral
• 1 coccyx
• thorax : sternum and 24 ribs
the appendicular skeleton has 126 bones - upper limb and pectoral girdle, lower limb and pectoral girdle
• pectoral girdles: 2 clavicle and 2 scapula
• upper limb: humerus, radius, ulna, 8 carpals, 5 metacarpals, 14 phalanges
• pelvic girdle: hip (2-each composed of ilium, ischium, pubis)
• lower limb: femur, tibia, fibula, patella, 7 tarsals, 5 metatarsals, 14 phalanges
classify bones based on their shape or location
flat bones - protect soft organs, curved but wide and thin
long bones - longer than wide, muscles act on rigid levers
short bones - equal in length and width, glide across one another in multiple directions
irregular bones - elaborate shapes that do not fit into other categories
sesamoid bones - bones that develop in tendons or ligaments
The skull
identify the various cranial and facial bones on a diagram and indicate whether they are paired or single
• cranium - frontal, parietal, temporal, occipital, sphenoid, ethmoid
paired - parietal and temporal
unpaired - frontal, occipital, sphenoid, and ethmoid
• facial bones - zygomatic, maxilla, mandible, nasal, palantine, vomer, lacrimal, inferior nasal concha
paired - maxilla, palantine, zygomatic, nasal, lacrimal, inferior nasal concha
unpaired - vomer and mandible
describe the following special features of the skull: sutures, paranasal sinuses, and fontanels
sutures - thin layer of dense fibrous connective tissue unites the bone of the skull. little to no movement
paranasal sinuses - composed of sphenoid sinus, frontal sinus, ethmoid, sinus, maxillary sinus. sinus cavities allow the skull to increase in size without an increase in weight. increase the surface area of the nasal mucosa. serve as resonating chambers to intensify and prolong sound.
fontanels - provide some flexibility to the body's skull to allow the head to fit through the mothers pelvic outlet during birth
The vertebral column and thoracic cage
identify the regions and normal curves of the vertebral column
the vertebrae are divided into three regions: cervical C1-C7 vertebrae, thoracic T1-T12, and lumbar L1-L5 vertebrae. the vertebral column is curved, with two primary curves (thoracic and sacrococcygeal) and two secondary curves (cervical and lumbar)
primary curvatures are formed at birth and secondary curvatures are developed later in childhood
describe a typical vertebra
a typical vertebra consists of a vertebral body, a vertebral arch, as well as seven processes. the vertebral bodies progressively increase in size and thickness going down the vertebral column
describe the structural and functional features of the bones in various regions of the vertebral column
cervical vertebrae - 7 bones form the curve
thoracic vertebrae - 12 bones form the curve
lumbar vertebrae - 5 bones form the curve
sacral - 1 (5)
coccyx - 1 (4)
describe the basic structure and function of intervertebral discs
• cartilaginous pad located between the bodies of 2 adjacent vertebrae
• the inner gelatinous material is called the nucleus pulposus and is surrounded by a ring of fibrocartilage called the annulus fibrosis
• the discs bind adjacent vertebrae together, support body weight, and absorb shock
joints
describe the structural and functional classification of joints
a joint is a point of contact between two or more bones, cartilage and bone, teeth and bone.
joints link the bones of the skeletal system, permit effective movement, protect softer organs
describe the structure and functions of the 3 types of fibrous joints
the 3 types of fibrous joints:
synarthrosis - little to no movement
amphiarthrosis -slightly moveable
diarthrosis - freely moveable
structural classification:
• fibrous joints - lack joint cavity, bones held tightly together by connective tissue rich in collagen
• cartilaginous joints - lack a joint cavity, bones held together by cartilage
• synovial joints - bones forming the joint are united by an articular capsule and often accessory ligaments, forms a joint cavity
describe the structure and functions of the 2 types of cartilaginous joints
synchondroses - bones are united by hyaline cartilage
symphyses - bones are united together by a disk of fibrocartilage
describe the structure of synovial joints
have a synovial cavity, structurally complex, and permit a large range of movement
recognize and state each of the function of: articular discs, menisci, tendons, ligaments, bursae and tendon sheaths
• articular disc - layer of hyaline cartilage that covers the facing surfaces of two bones
• meniscus - absorbs shock and pressure, stabilizes joints
• tendon - connective tissue that attaches muscle to bone, most important structure in stabilizing a joint
• ligaments - attaches one bone to another
• bursae - sac filled with synovial fluid, located between adjacent muscles, where tendon passes over bone or between bone and skin
• tendon sheaths - protective covering that enables tendons to move back and forth more freely in tight spaces such as wrist and ankle
name and briefly describe the 6 sub-classes of synovial joints
plane joints - flat articular surfaces in which bones slide over each other with relatively limited movement
hinge joints - one bone with convex surface that fits into a concave depression on other bone
pivot joints - one bone has a projection that is held in place by a ring-like ligament
condylar joints - oval convex surface on one bone fits into a cup-shaped depression on the other
saddle joints - both bones have an articular surface that is shaped like a saddle, concave in one direction and convex in the other
ball-and-socket joints - smooth, hemispherical head fits within a cup-like socket
describe the movements permitted by the synovial joints
flexion - movement that decreases joint angle
extension - movement that straightens joint (zero point)
hyperextension - further extension of joint beyond zero
circumduction - combination of flexion, extension, adduction, abduction and one end of the appendage remains stationary while the other moves in a circular motion
abduction - movement of a body part in the frontal plane away from the midline of the body
adduction - movement in the frontal plane back toward the midline
pronation - forearm movement that turns palms to face either posteriorly or downwards
supination - forearm movement that turns palms to face either anteriorly or upwards
plantar flexion - extension of the foot away from the shin (toes pointing down)
dorsiflexion - bending of the foot superiorly (toes pointing up)
inversion - movement of the soles of the foot medially (soles in)
eversion - movement of the soles of the foot laterally (soles out)
identify the major anatomical features of the shoulder, hip and knee joints
the shoulder joint - most freely movable joint in the body
the hip joint - point at which the head of femur inserts into the acetabulum of the hip bone
the knee joint - is the largest and most complex joint of the body, consists of 3 joints within a single synovial cavity.
Muscular tissue
recall the characteristics and function of the 3 types of muscle tissue (skeletal, cardiac, smooth)
skeletal - attached to bones, striated, voluntary
cardiac - heart wall, striated, involuntary
smooth - walls of hollow internal structures, smooth, involuntary
define the following characteristics of muscle tissue
• excitability - muscle has the ability to respond to stimuli and produce electrical signals called action potential
• extensibility - ability of muscle tissue to stretch without being damaged
• elasticity - returns to its original resting length and shape after contraction or stretch
• contractility - ability of muscle tissue to contract forcefully when stimulated
list the functions of the skeletal muscle
• producing body movements
• stabilizing body positions
• storing and moving substances within the body
• generating heat
describe the connective tissue components and their relationship to bundling of fibres (epimysium, perimysium, endomysium)
endomysium - loose connective tissue surrounding each muscle fibre
perimysium - wraps 10-100 muscle fibres into bundles called fascicles
epimysium - fibrous sheath surrounding the entire muscle
these tissues separate neighbouring muscles or muscle groups from each other and the subcutaneous tissue
differentiate between a tendon and an aponeurosis
tendons are continuations of the connective tissue that connects the muscle to bone
an aponeurosis is a broad sheet of connective tissue that joins muscle to bone or another muscle
describe the basic microscopic anatomy of a skeletal muscle fibre
• sarcolemma, t-tubule, sarcoplasm, myofibrils, sarcoplasmic reticulum, filaments, sarcomere
sarcolemma - the plasma membrane that surrounds the muscle fibre
sarcoplasm - the cytoplasm
sarcoplasmic reticulum - each myofibril is encircled by a membranous sac called the sarcoplasmic reticulum
myofibrils - numerous long protein cords within muscle fibre
myofilaments - arranged in the cell into small units called sarcomeres
t-tubule - permit rapid transmission of the action potential in the cell, and also play and important role in regulating cellular calcium concentration
sarcomere - shortens and the muscle cells contracts
outline the 4 basic steps involved in the sliding filament mechanism of muscle contraction
• ATP hydrolysis
• cross-bridge formation
• powerstroke
• detachment
define a motor unit. explain the relationship between the size of a motor unit and the degree of control
the motor unit is one nerve fibre and all the muscle fibres innervated by it. 200 muscle fibres for each motor unit. there is an average, small and large motor unit
overview the sequence of events that occur at the neuromuscular junction that cause muscle contraction and subsequent relaxation
Upon depolarization, an action potential travels down the axon, causing voltage-gated calcium channels to open, resulting in an influx of calcium ions into the nerve terminal. This causes the vesicles to migrate towards the nerve terminal membrane and fuse with the active zones
state the role of calcium in muscle contraction
the electrical signal initiates the release of calcium within the cell which activates the muscle contraction process
define muscle tone
even when at rest, a skeletal muscle exhibits a small amount of tension, called tone. muscle tone is established by neurons in the brain and spinal cord. flaccid is the loss of muscle tone
compare isotonic and isometric muscle contraction
isotonic - tension is constant while muscle length changes
isometric - muscle contracts but does not change length
differentiate between hypertrophy and hyperplasia
muscle growth is due to hypertrophy however some smooth muscles can grow via hyperplasia such as the uterus
compare the structural and functional differences between cardiac and skeletal muscle and understand why there differences are important to cardiac function
cardiac muscle is involuntary as it is responsible for contracting the heart, whereas cardiac muscle is voluntary
compare the structural and functional differences between smooth muscle and skeletal muscle
skeletal muscle fibres are cylindrical, multinucleated, striated, and under voluntary control. smooth muscle cells are spindle shaped, have a single, centrally located nucleus, and lack striations
excitation and contraction steps
1. electrical impulse travels down a motor neuron to the neuromuscular junction
2. the change in voltage opens membrane channels allowing calcium to enter the motor neuron
3. the influx of calcium causes vesicles to release acetylcholine (ach) into the neuromuscular junction
4. ach diffuses across cleft, binds to receptors on the muscle fibre and creating an electrical signal that spreads over the muscle fibres
5. the electrical signal initiates the release of calcium within the cell which activates the muscle contraction process
6. the sarcomere shortens and the muscle cell contracts
muscular system
define:
- origin
- insertion
- belly
- action
- innervation
• origin - the attachment to the stationary bone
• insertion - the attachment to the moveable bone
• belly - thicker, middle region between origin and insertion
• action - happens when the more mobile bone is brought towards the one that is more stable during a muscle contraction
• innervation - stimulates a nerve or an organ to do a certain movement or create activity
define lever and fulcrum and compare the 3 types of levers
bones serve as levers and joints serve as fulcrums. fulcrum, load, effort. FLE=123
briefly describe how the shape of skeletal muscle relates to their function
muscles can only pull, they can't push. the action is the effect produced by a muscle to either produce or prevent movement. most muscle movements are coordinated by several skeletal muscles acting in groups rather than individually. must skeletal muscles are arranged in opposing pairs at joints
define:
- agonist
- synergist
- fixator
how do they work together?
• agonist - muscle that produces most of force during a joint action
• synergist - muscle that aids the prime mover, stabilizes the nearby joint, modifies the direction of movement
• fixator - muscle that prevents unwanted movement of bone
each play an important role in movement or preventing a movement from happening
understand the features used in naming muscles
• location
• size
• number of origins
• appearance
• direction of fibres
• origin and insertion
• muscle action