Chapter 39: Bone and Muscle

Question 1

Connective tissue

Answer 1

Types: 
 - Connective proper 
    1) Loose connective ( adipose
        tissue)
    2) Dense connective
        ** Regular = tendons and
            ligaments)
        ** Irregular = organ
           capsules/muscle
            covers)
 - Special connective
    1) Cartilage
    2) Bone
    3) Blood

Question 2

Bone

Answer 2

Special connective tisse

- Hard and flexible

Question 3

Components of bone are either 1) ______ or 2) _______

Answer 3

1) Organic

2) Inorganic

Question 4

Organic components of bone

Answer 4

• Cells : osteoblasts, osteocytes, osteoclasts
• Osteoid: Unclassified bone matrix (1/3 mass). Responsible for flexibility and tensile strength of bone. Made of proteoglycans, glycoproteins, and collagen fibers.

Question 5

Inorganic components of bone

Answer 5

• Calcium phosphate
• 65% mass of matrix unit
• Responsible for hardness and resistance to compression

Question 6

Bone functions

Answer 6

Support, protection, movement, mineral stooge, structure, and blood cell formation (hematopoiesis in red marrow cavities)

Question 7

Structural unit of compact bone is 1)_________

Answer 7

1) Osteon

- Not ALL bones are like this

Question 8

Osteons: Not found in 1) ______.

Answer 8

1) Rats

Concentric rings of bone cells and layers of bone matrix around a central canal that carries blood, lymphatic vessels and nerves.

** Each osteon forms an elongated cylinder parallel to the long axis of the bone

Question 9

Volkmann’s canals

Answer 9

Canals that run at a right angle to the central canal

Question 10

Bone development and growth

Answer 10

Endochondral bone a.k.a cartilage or replacement bones.

• These make up most of the bones of the skeleton
• Bones are first formed as cartilage model, but are then replaced with bone

Intramembranous bone (no cartilage precursor)

• Forms directly from mesenchyme
  
  • ** Dermal
  • ** Sesamoid
  • ** Perichondral/periosteal

Question 11

Intramembranous bone

Answer 11

Dermal - bones of the skull (pectoral girdle ancestrally)
***Mesenchymal sources lie
within dermis of skin

Sesamoid - forms within tendons
*** Patella and pisiform bone of
wrist

Perichondral/periosteal - forms within deep layer of fibrous CT covering cartilage or bone

Question 12

Bone repair/remodeling

Answer 12

Bones are constantly being repairing because of natural fractures that occur throughout life (10 % bone repairing at any time in an adults life)

• Osteoclasts channel through existing bone
• Osteoblasts (blast = forming) lay downs new osteon, entombing themselves
• Osteoclytes are formed by entombing of osteoblasts of new bone

Question 13

Primary categories of adult tissues include 1) __________, 2) __________, 3) ___________, and 4) ____________.

Answer 13

1) Epithelium
2) Connective tisse (bones)
3) Muscle tissue (muscle)
4) Nervous tissue

Question 14

Mus

Answer 14

“Little mouse” - Latin origin

• Exerting of force by transforming chemical energy into mechanical energy.
• Present as skeletal muscle, cardiac muscle, and muscles found in hollow organs.

Question 15

Muscles “primary” functions

Answer 15

Producing movement, maintaining posture, act on viscera (i.e. heart & blood vessels, digestive tract, and respiratory channels), and stabilizes joints,

Question 16

Muscles “secondary” functions

Answer 16

Heat generation (byproduct of muscle contraction and thermogenesis), and electric organs in some fish.

Question 17

Striated muscle appears to have striations under 1) ________ microscopes

Answer 17

1) Light

Question 18

Striated muscles

Answer 18

Muscles under voluntary control due to somatic part of motor division in PNS.
**Associated with skeletal system

Individual cells are joined together end-to-end in order to form longer composite fibers.

Question 19

Each striated muscle cell is 1) _______ can be very 2) _______ in size (up to (3) _____), and is referred to as a 4) __________.

Answer 19

1) Multinucleate
2) Large
(3) 5 cm
4) Muscle fiber

Question 20

Cardiac muscle occurs 1) ________

Answer 20

1) only in the HEART!

Question 21

Cardiac muscle

Answer 21

Muscles are also striated, but they are also mono nucleate, they are involuntary, they are connected by intercalated disks (specialized regions), and are often branched.

– Waves of contraction spread through cells and across intercalated disks
– Waves of contraction can be initiated by nerve signals, or can arise intrinsically within muscle tissue itself

Question 22

Smooth muscle appears 1) ________ under 2) _______

Answer 22

1) smooth
2) light microscopy

** Smooth muscle fibers are less organized than others!

Question 23

Smooth muscle

Answer 23

Almost entirely concerned with visceral function:
• Digestivetract–peristalsis,sphincters
• Bloodvessels
• Lungs
• Piloerection in skin of mammals
• Muscles of iris and ciliary body of eye
– Accommodation, and constriction & dilation of pupil
• Muscles of uterus, and urinary and genital tracts

Question 24

Smooth muscle are 1) _________, they are 2) _______ and 3) _______ in shape, and are joined at 4) _________.

Answer 24

1) Involuntary; contractions are slow and sustained
2) Mononucleate
3) Fusiform
4) Junctions to form sheets

Question 25

Myofibrils of 1) _________ muscle are 2) _________, which consist of two kinds of 3) _________.

Answer 25

1) Striated
2) Repeated units called sarcomeres
3) Myofilaments.

Question 26

Myofilaments

Answer 26

Thick = myosin (a.k.a M line)
Thin = actin (a.k.a Z line)
- These filaments are interspersed in a regular 3-D arrangement.

Question 27

Thick filaments of striated (skeletal) muscle are 1) _________ structures. One unit is a 2) _______ and several units together make the 3) _________.

Answer 27

1) Bipolar
2) Molecule
3) Filament
Two myosin polypeptide chains coiled together, which has a globular “head”

Question 28

Thin filaments of striated (skeletal) muscle are 1) _______ structures.

Answer 28

1) Helical

1 chain of actin and 2 chains of tropomyosin, and repeated units of globular protein called troponin

Question 29

Striated muscle contractions part one -
Before contraction, 1) ________ bocks the binding of 2) ________ to 3) __________ located on the actin filaments. When a motor signal arrives at the muscle cell, the neurotransmitter 4) ______ is released which stimulates the muscle cell to release 5) ______ from the 6) ________.

Answer 29

1) Tropomyosin
2) Myosin
3) Troponin
4) Acetylcholine
5) Ca++
6) Sarcoplasmic reticulum

Question 30

Striated muscle contractions part two -
The released Ca++ binds to the 1) _________, changing its conformation and allowing the 2) __________ strand to move away from the myosin-binding sites on the actin. The now-exposed myosin binding sites bind to the myosin 3) ______. When bound to the actin, the myosin heads “flick back” and in so doing drive the actin and myosin molecules by each other in 4) ______ _________ (“SLIDING FILAMENTS). This 5) _________ the 5) _________ (and the length of the myofibril as a whole), which brings the 7) __ and 8) ___ lines closer.

Answer 30

1) Troponin
2) Tropomyosin
3) Heads
4) Opposite directions
5) Shortens
6) Sarcomere
7) M
8) Z

Question 31

Striated muscle contractions part three -
If the myosin binding sites on the actin filament still are 1) _______ the myosin head again can bind to the actin and “flick” again. If the muscle cell is not re-stimulated, its sarcoplasmic reticulum will pull 2) _______ out of the cytoplasm. Deprived of its Ca++, the troponin reverts to its previous conformation, and the tropomyosin reverts to its previous conformation, blocking the 3) _________ ______ on the actin. The myosin heads now can not bind to the actin filaments and contraction stops.

Answer 31

1) Exposed
2) Ca++
3) Myosin-binding sites

Question 32

Examples of importance of muscle contraction process

Answer 32

• Curare binds to acetylcholine receptors and so blocks nervous stimulation of skeletal muscle
• In Duchenne muscular dystrophy, the sarcolemma (plasma membrane) degenerates and so the muscle can not be stimulated and eventually atrophies (most common and serious form, inherited as sex- linked recessive and so expressed almost entirely in males, 1 in 3500 births.

Question 33

Fast twitch muscle fibers

Answer 33

– E.g., extrinsic eye muscles (move the eye) are fast twitch, with time to maximum tension of ~ 7.3 milliseconds

Question 34

Muscle fibers differ in the 1) _______ with which they contract, and can be classified as 2) ____ _____ or 3) ____ _____.

Answer 34

1) Speed
2) Slow twitch
3) Fast twitch

Question 35

Slow twitch muscle fibers

Answer 35

– E.g., soleus muscle of leg (deep to gastrocnemius) is slow twitch, with time to maximum tension of ~ 100 milliseconds

Question 36

Twitch speeds in muscle fibers

Answer 36

• Fast and slow twitch are relative terms. They do not refer to absolute contraction speed!

• What is classified as slow in one species may be fast in different species.
• Trade-off seems to be between speed and strength of contraction vs. sustainability of contraction.
• Degree of precision decreases in lager muscles**
• Differences in contraction speeds (fast vs. slow) seem to be related to differences in myosin types, activation of actin and myosin, and innervation.

Question 37

1) _______ is how a muscle organ varies its output to match a job and there are 2) _______ main way in which they do this: 3) _________ and 4) ___________.

Answer 37

1) Graded force
2) Two
3) Rate modulation
4) # of motor units

Question 38

Varying output: Rate (a.k.a degree of contraction) modulation

Answer 38

– Vary the frequency of nervous stimulation of the muscle organ
– To a point, more frequent stimulation produces more force. Smooth, sustained contraction is called fused or complete tetanus.

Question 39

Varying output: # of motor units

Answer 39

– A single motor neuron innervates a unique set of muscle cells in a particular muscle organ.
– Greater force can be generated by involving progressively more motor units
– Related but different phenomenon: size of motor unit
• For muscles that perform delicate movements, the motor unit includes fewer muscle cells
– E.g. laryngeal muscles (vocalization) or extrinsic eye muscles (move eye) have motor units with as few as 8-10 muscle cells
• Larger muscles, like the gastrocnemius (calf) have motor units of several thousand muscle cells per motor neuron.

Question 40

Bones of early fish called 1) _______ which has bony armor made of 2) _______.

Answer 40

1) Ostracoderms

2) Dermal

Question 41

Humans are not born with 1) ________.

Answer 41

1) Patella

Question 42

Electric organs are 1) _______ organs

Answer 42

1) Sensory

Question 43

The visible structures of striated muscles = 1) _________.

Answer 43

1) Sarcomeres

Question 44

Troponin has 1) __________ binding spots for 2) ___________.

Answer 44

1) Three

2) Actin, Tropomyosin, and Ca++

Question 45

The myosin head is 1) _________ and 2) ______ is released when it contracts.

Answer 45

1) Charged

2) Energy

Question 46

Smooth, sustained contraction is called 1)__________

Answer 46

1) fused or complete tetanus.