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BIOL1040 > Module 3: Support and Movement > Flashcards

Module 3: Support and Movement Flashcards

1
Q

what is the skeletal muscle system made up of?

A 
> the (skeletal) muscle system constitutes 40-50% of human body mass
> organs
> tissues
> cells
>molecules and chemicals
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2
Q

What organs make up the skeletal muscle system?

A

> muscle tendon units
heart
visceral organs

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3
Q

What tissues make up the skeletal muscle system?

A

> skeletal muscle tissue
cardiac muscle tissue - not under conscious control
smooth muscle tissue - not under conscious control

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4
Q

What cells make up the skeletal muscle system?

A

myocytes

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5
Q

What molecules/chemicals make up the skeletal muscle system?

A

> actin
myosin
Ca2+

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6
Q

what are the functions of the muscular system?

A 
> to convert energy into mechanical work
> this has consequential roles for:
- movement (bones, blood, food, etc)
- support (bony and soft tissue
- protection (guarding of orifices)
- body temperature regulation
- nutrient storage
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7
Q

what are the characteristics of muscle tissue?

A 
>excitability and conductivity
- ability to respond to stimuli producing action potentials
> contractility
- ability to shorten and thicken
> extensibility
- ability to be stretched without damage
- skeletal muscles often work in pairs: when one contracts the other relaxes and is usually stretched
> elasticity
- strain energy storage
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8
Q

Describe muscle contraction?

A

> in essence, contraction results form relative sliding of filaments within a muscle
actin and myosin filaments have a regular arrangement within sarcomeres, and are orientated in one direction
muscle contraction occurs as each sarcomere shortens - there is a resultant ‘pull’ on both points of attachment of a muscle

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9
Q

Describe muscle structure

A 
Refer to diagram
> A-band ('dark' zone):
- M-line (binding of myosin)
- H-zone (myosin; no actin)
- zone of overlap (myosin and actin)
> I-band ('light' zone):
- actin, no myosin
- Z-line
(actin proteins)
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10
Q

describe joint structure and function

A 
Joints allow for relative movement of bones
> nonaxial
- gliding
> monoaxial/ uniaxial
- hinge
- pivot
> Biaxial
- Ellipsoid
- saddle
> Triaxial (Multiaxial)
- ball and socket
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11
Q

describe Synovial joints

A

> flexion and extension occur in the sagittal plane

> flexion decreases the joint angle, extension increases it.

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12
Q

Describe adduction and abduction

A

> occur in the coronal plane
adduction moves a body part towards the midline, abduction moves it away from the midline
rotation occurs around a long axis

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13
Q

what are the components of skeletal muscle?

A 
> muscle origin
> muscle belly
> muscle insertion
Connective tissue layers
>endomysium - fibre
> perimysium - fascicle
> epimysium - belly
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14
Q

what is excitation-contraction coupling?

A

> invloves motor units (MU)
- a motor neuron plus all the muscle fibres it innervates
small number of MU = fine movement
large number of MU = large movement

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15
Q

describe the process of contracting a muscle

A

1) acetylcholine released at synaptic terminal diffuses across synaptic cleft and binds to receptor proteins on the muscle fibre’s plasma membrane, triggering an action potential in muscle fibre.
2) action potential is propagated along plasma membrane and down t tubules.
3) action potential triggers the release of Ca2+ from the sarcoplasmic reticulum.
4) calcium ions bind to troponin in thin filament; myosin- binding sites exposed
5) cycles of myosin cross bridge formation and breakdown, coupled with ATP hydrolysis, slide thin filament towards centre of sarcomere
6) cytosolic Ca2+ is removed by active transport into SR after action potential ends
7) tropomyosin blockage of myosin-binding sites is restored; contraction ends, and muscle fibre relaxes.

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16
Q

what is electromyography?

A 
records the electrical activity of muscles via:
> surface electrodes
- for superficial muscles
> fine-wire electrodes
- for deep or small muscles
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17
Q

explain the cross-bridge cycle

A

1) ATP is attached to the myosin head and it is in its low energy configuration
2) the myosin head hydrolyses ATP to ADP and inorganic phosphate and is in its high energy configuration
3) the myosin head binds to the actin, forming a cross-bridge
4) releasing ADP +Pi, myosin returns to its low energy configuration, pulling the actin in a powerstroke.
5) binding of a new molecule of ATP releases the myosin head from the actin, and a new cycle can begin.

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18
Q

what happens to your muscles when you die?

A

> blood ceases to circulate
Ca2+ leaks out of the SR
Avaliable ATP is used to sustain muscle contraction due to excess Ca2+
once ATP stores are exhausted, myosin heads cannot unbind leading to stiffening of the body = rigor mortis
begins immediately (instantaneous appearance = cadaver spasm)
obvious 2-4hrs post-mortem
complete by 6-12 hours ppost mortem
lasts 15-25hrs
disappears with tissue decay

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19
Q

describe Rhabdomyolysis

A

> muscle damage
disintegration or dissolution of muscle, associated with excretion of myoglobin in the urine

Causes:
> vigorous exercise, alcoholism, drugs, heatstroke, seizures, crush injuries

Symptoms:
>dark urine, weakness, renal failure, compartment syndrome

Treatment:
> plenty of fluids, diuretics

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20
Q

what is muscle force affected by?

A

> the number and timing of stimulation
- twitch and wave summation
the ability to generate tension also depends on the sarcomere length ~ muscle fibre length
- skeletal muscle tends to operate at lengths where tension is high
passive tension also effects force
- provided by non-contractile connective tissue
- the more the CT is stretched, the more it resists that stretch.
- this contributes to tension that prevents muscle over extension
GRAPHS FOR ALL THESE CONCEPTS

21
Q

what is a skeleton?

A

> the framework of any structure

- does not always comprise of bones

22
Q

what types of skeletons are there?

A 
>hydroskeletons
- worms
> exoskeletons
- nautilus 
> endoskeletons
- humans
23
Q

describe skeletons role in classification

A

skeletal features have been and continue to be important for taxonomy

24
Q

describe hydroskeletons

A

> fluid held under pressure in closed, semi-rigid, body compartment
muscles anchor to compartment wall and change shape of the compartment
e.g., earthworms have longitudinal and circular muscles surrounding their body segments enabling elongation and contraction of compartments

25
Q

describe exoskeletons

A

> calcium carbonate shells or cuticle
muscles attached on the inside of the skeleton
arthropods either enlarge or shed and replace their exoskeleton as they grow

26
Q

describe endoskeletons

A

> inside the body

>rigid

27
Q

describe the components of the human skeleton

A 
>organs
- bones
- cartilage
- ligaments
- bone marrow
>tissues
- connective tissue
- including bone tissue
>cells
- bone has osteocytes, osteoblasts and osteoclasts
>molecules and chemicals
- especially Ca2+ in extracellular matrix
> around 200 bones
> 80 bones in axial skeleton (22 in skull)
> 126 bones in the appendicular skeleton
28
Q

what are skeletal roles?

A 
mechanical roles:
- support
- protection
- movement
Metabolic roles:
- nutrient store > minerals and lipids
- blood cell formation > haematopoiesis/heamopoeisis
- large role of axial skeleton in adults
29
Q

what are the different types of bone?

A 
>long
- shaft with ends; femur, phalanges, etc
- important for leverage/movement
> short
- square shaped; carpals, tarsals, sesamoid bones, etc
- important for movement
> flat
- as name suggests; sternum, scapula, ribs, etc
- protection/ haematopoiesis
> irregular
- as name suggests; vertebrate, as coxae, pelvic
- support, movement and hematopoiesis
30
Q

what is the composition and structure of bones?

A 
>compact bone
- lamellar or cortical bone
>trabecular bone
- spongy bone
>hydroxyapatite
- comprises about 2/3 of bone tissue
- stores/contains 99% of body's calcium
- bone brittleness
>collagen
-comprises roughly 1/3 of bone tissue
- bone flexibility
31
Q

how is the bone matrix maintained?

A 
via:
> osteocytes
- maintain bone matrix
> osteoblasts
- create bone matrix
> osteoclasts
- breakdown bone matrix
DIAGRAM
32
Q

what does ossification mean?

A

the process in which cartilage in turned into bone

33
Q

what is a bone modelling unit? (BMU)

A
  • osteoclasts excavate a tunnel ‘parallel’ with the diaphysis and osteoblasts subsequently refill the tunnel with osteoid, that gradually mineralises.
34
Q

what happens when resorption of bone outstrips deposition?

A

leads to loss of bone tissue and architectural change that increases the risk of bone fracture
> osteoporosis = bone mass less than 2.5 sd below the mean for young adults.

35
Q

why are bones hollow?

A

because they are more resistant to bending

36
Q

what are the different sources of movement?

A

> muscles
cilia/ flagella
cytoplasmic streaming

37
Q

what are the styles of locomotion in water?

A

> undulating
flapping
rowing
jet propulsion

38
Q

how do aquatic animals overcome gravity?

A 
> reasonably bouyant
> Gas bladders = shallow water 
> lift = physics
> Aspect ratio of tails
- high AR = efficient and faster
>KEY CONCEPT:
- use of the water column can be achieved via active or passive approches, each comes with its own advantages and disadvanages
39
Q

what are the styles of locomotion in air? also what are some important things to remember?

A

> friction and gravity are very important
birds have light bones, no teeth and, usually, no urinary bladder
STYLES:
flapping flight
bounding flight
- less than 300g body mass
- energetically- economical, muscles used at their optimum power output
soaring
- thermal and slope
- energically economical
- postural muscle use
- ‘large’ wings
- uses energy from the environment = hot thermals
hovering
- energetically demanding
- hummingbirds get lift on up and down strokes unlike other birds
KEY CONCEPT:
flight styles vary, with many adaptations relating to feeding ( search, predation and escape, migration)

40
Q

describe the styles of locomotion on land

A

> gravity is most important variable to overcome
STYLES:
crawling
walking

> running

> jumping

> climbing
- brachiating - monkeys swinging

41
Q

describe locomotion in primates

A 
> brachiation 
- gibbon/ orangutang
> quadrapedalism
- knuckle walking
- gorilla
- chimpanzee
- orangutang (modified)
> bipedalism
- human
42
Q

describe the styles of crawling

A
  • two-anchor - catepillar
  • pedal wave - retrograde or direct - snail
  • peristalsis - wave like
  • serpentine crawling, sidewinding, concertina
  • amoeboid crawling
43
Q

describe the styles of walking

A
  • cursorial (graviportal) walk - elephant
    KEY CONCEPT:
    > body form, posture and size strongly influence energetic costs. More muscle activity is needed to walk with a bent limb (non-cursorial) versus a straight limb (cursorial) posture.
44
Q

describe the styles of running

A
  • plantigrade - flat foot - humans
  • digitigrade - on toes - cats and dogs
  • unguligrade - on fingertips - horses
45
Q

describe the styles of jumping

A
  • bipedal hopping, (kangaroos) is a specialised form of jumping powered by muscle. however, elastic strain energy that is stored temporarily in stretched tendons makes the gait economically
46
Q

describe locomotion in humans

A

> efficient bipedal gait minimises energy cost by reducing movement of the centre of gravity as much as possible, increasing stride length, while maintaining balance
“During walking, more than 1000 muscles are
synchronized to move over 200 bones around
100 moveable joints”
Two periods of double limb
support & two periods of
single limb support
- Heel strike
- Stance
- Heel off
- Swing

47
Q

what are the benefits of bipedalism?

A

scanning, carrying, specialisation of upper limb

48
Q

how fast can a human walk?

A

> acceleration needed to move a mass in the arc of a circle = V2/r
gravitationla acceleration, g, acts on our centre of mass which moves in the arc of a circle with a radius equal to lower limb length, r, hence g=v2/h
vmax = sqrt(gh) = 3.1m.s-1
only when walking with a cursorial gait
when running we use achilles tendon as a spring to ‘bounce’ along
use the pendulum principle to conserve energy when walking
KE and GE are out of phase, conserving 60-75% of energy of CoM

BIOL1040 (7 decks)

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