Flashcards in Module 3 - Support and Movement Deck (62):
Function and roles of muscular system
To convert chemical energy into mechanical work
- body temperature regulation
- nutrient storage
4 characteristics of muscle tissue
excitability and conductivity
- can response to stimuli
- produce an action potential
- carry a chemical or electrical signal
- can shortent and thicken
- can be stretched without damage
- muscles often work in pairs
- strain energy storage
What are the 2 types of filaments?
Actin - thin
Myosin - thick
What is the M-line?
mid line of myosin
What is the Z-line?
ends of sarcomeres
What is the H-zone?
myosin no actin including M-line
What is the A-band?
range of myosin
What is the I-band?
actin including Z line
4 types of joints
Examples of nonaxial joints
- carpels, vertebrae
Examples of monoaxial/uniaxial joints
- humerous and ulna
- radius and ulna
Examples of biaxial joints
Examples of triaxiak/multiaxial joints
ball and socket
What are the three planes of movement?
What is the sagittal/median plane of movement?
- forward and back
- cause flexion (decrease angle) and extension (increase angle) of joints
What is the coronal plane of movement?
- left and right
- causes adduction (body part moves toward midline) and abduction (body part moves away from midline)
What is the transverse plane of movement?
- rotation about the long axis (head to toe)
Define motor unit
a motor neuron plus all the muscle fibres it innervates
What is a muscle fibre?
A bundle of myofibrial (chains of sarcomeres)
In what manner do action potentials spread across motor units?
Like ripples in water
What is Rigor mortis?
Rigor mortis occurs when ATP stores deplete in a deceased body, causing the myosin heads to remain bound to the actin leading to the stiffening of the body.
- begins immediately
- obvious 2 - 4 hours post mortem
- complete by 6-12 hours post mortem
- lasts 15-25 hours
- disappears with tissue decay
What is Rhabdomyolysis?
Rhabdomyolysis is the disintergration or dissolution of muscle, associated with excretion of myoglobin in the urine.
What are the symptoms of Rhabdomyolysis?
- dark urine
- renal failure
- compartment syndrome
What are the causes of Rhabdomyolysis?
- vigorous exercise
- crush injuries
What are the treatments of Rhabdomyolysis?
- plenty of fluids
- diuretics (drugs to increase urination)
3 basic mechanical roles of skeletons
- support (against gravitation acceleration)
- protection (of internal organs)
- movement (of body)
2 metabolic roles of skeletons
- nutrient storage - minerals and lipids, particulary Ca2+ and P3-
- Blood cell formation - a large role of the axial skeleton in adults
Types of skeletons
Features of endoskeletons
- internal skeleton consisting of two parts: axial (skull, jaw, spine and ribs - 80 bones in humans (22 from skull)) and appendicular (limbs/anything coming off the axial skeleton - 126 bones in humans)
Features of exoskeletons
- calcium carbonate shells or cuticle (chitin - coat secreted by epidermis)
- provides protection from predators and the environment
- muscles attach to the inside of the skeleton
- arthropods either enlarge or shed and replace exoskeleton as they grow
Features of hydroskeleton
- fluid held under - pressure in a closed, semi-rigid body compartment
- muscles anchor to compartment wall and change shape of compartment
4 types of bone
Examples of irregular bones
- important for support, movement and hematopoiesis
- e.g. vertebrae, os coxae, pneumatic bones
Examples of flat bones
- important for protection/hematopoiesis
- e.g. sternum, scapula, ribs
Examples of short bones
- square shaped
- important for movement
- e.g. carpals, tarsals, sesamoid bones
Examples of long bones
- shaft with end
- important for leverage/movement
- e.g. femur, phalanges
Compact vs. trabecular bone
compact - hard outer of bone
trabecular - spongy inside, a 3D lattice
Both are made of same material, just organised differently to have different mechanical properties.
Primary vs secondary bone
Secondary bone is the new bone - produced as tubes up through the primary bone
What are the two components of bone tissue?
hydroxyapatite and collegen
What is hydroxyapatite?
- inorganic: Ca10(PO4)6(OH)2
- about 2/3rds of bone tissue
- stores/contains 99% of the body's calcium (1-2kg- the most abundant mineral in the body)
- bone brittleness
What is collegen?
- comprises roughly 1/3rd of bone tissue
- bone flexibility
- reinforcing material, like steel rods in concrete
What causes rickets?
A lack of hydroxyapatite makes the bone more flexible causing them to bend under the weight of the body
Osteoblasts vs osteoclasts vs osteocytes
Osteoblasts - create bone matrix
Osteoclasts - breakdown bone matrix
Osteocytes - maintain bone matrix
blast - build
clast - opposite of build
cytes - maintain
What percentage of bone mass is bone cells? What is the rest?
2% - the rest is matrix, which is hydroxyapatite and collegen
How does the number of bones change throughout life? Why does this happen?
11 weeks prior to birth - 800 ossification centres
At birth - 450 ossification centres
Mature adults - 206 bones
Growth plates fuse making bones become one.
How does bones grow or be repaired?
The bone wall stays the same thickness but the width increases.
Osteoclasts excavate a tunnel 'parallel' with the diaphysis and osteoblasts subsequently refill the tunnel with osteoid that gradually mineralises. This is the bone modeling unit (BMU). Damage is constantly repaired.
What shape of bone resists bending best?
Hollow oval bones is better than round or solid bone.
4 types of locomotion in water
-side to side motion
- side movements cancel each other out to push the animal forward
- can be restricted e.g. cuttlefish
- Jet propulsion
How is buoyancy controlled in water?
Gas bladders increase and decrease the density of the body and therefore its buoyancy to overcome gravity.
Important aspects in locomotion in air, features that make it possible and the 4 types
Friction and gravity are very important.
Birds have light bones (air pockets), no teeth and usually no bladder.
- for body mass less than 300g
- energetically economical
- muscles used at their optimum power output
- energetically economical
- postural muscle use
- large wings required
- energetically demanding
- hummingbirds get lift on up and down strokes unlike other birds
Important variable and 4 types of locomotion on land
Gravity is the most important variable to overcome, and friction is of lesser concern unless moving fast.
5 types of crawling
- pedal wave
- serpentine crawling, sidewinding, concertina
- amoeboid crawling
3 types of running
- plantigrade - flat foot
- digitigrade - on toes
- unguligrade - on fingertip (elongation of light distal limb)
With the same number of bone, is more or less skeletal elements better?
Less skeletal elements result in stronger bones as the bone is less distributed.
3 types of locomotion in primates
- pedulum swinging through trees
e.g. gibbon, orangutang
- knuckle walking (4 limbs)
e.g. baboon, gorilla, chimpanzee
- 2 limbs
4 stages of human gait cycle
2 periods of double limb support and two periods of single limb support
Benefits of bipedal gaits
- minimises energy costs by reducing movement of cenre of gravity
- increases stride length
- maintain balance
1000 muscles, 200 bones, 100 moveable joints
How fast can we walk, how fast do we walk and why?
Acceleration is needed to move a mass in the arc of a circle = v squared/r
Gravitational acceleration acts on our centre of mass which moves in the arc of a circle with a radius equal to the lower limb length. Therefore, g = v^2/r
v(max) = sqrt(gr) = 3.1m/s
How much energy of centre of mass can be conserved in walking?
How is lower limb length related to maximum walking speed?
Max walking speed is inversely proportional to lower limb length.
What are canaliculi?
The osteological features that allow osteocytes to communicate with each other