new and very important pdf in anatomy

1. Muscular Tissue

2. MUSCLES
• Muscle is one of the 4 basic tissue types.
• Muscle cells are contractile cells. What are other contractile cells?
• They are elongate elements
Contraction  long axis of cell
• What do you understand by the following terms?
• MUSCLE FIBER
• SARCOPLASM
• SARCOLEMMA
• SARCOPLAMIC RETICULUM
• MYOFIBRILS
• MYOFILAMENTS

3. Muscle Functions
1. Production of
Movement
2. Maintenance of
posture
3.Thermogenesis
4. Stabilization of
joints

4. Muscle Functions
1. Production of Movement
– Movement of body parts and of the environment
– Movement of blood through the heart and the
circulatory vessels.
– Movement of lymph through the lymphatic
vessels
– Movement of food (and, subsequently, food
waste) through the GI tract
– Movement of bile out of the gallbladder and into
the digestive tract
– Movement of urine through the urinary tract
– Movement of semen through the male
reproductive tract and female reproductive tract
– Movement of a newborn through the birth canal

5. Muscle Functions
2. Maintenance of posture
– Muscle contraction is constantly
allowing us to remain upright.
– The muscles of your neck are
keeping your head up right now.
– As you stand, your leg muscles
keep you on two feet.
3. Thermogenesis
– Generation of heat. Occurs via
shivering – an involuntary
contraction of skeletal muscle.

6. Muscle Functions
4. Stabilization of joints
– Muscles keep the tendons
that cross the joint nice
and taut. This does a
wonderful job of
maintaining the integrity
of the joint.

7. 3 TYPES OF MUSCLE

8. CLASSIFICATION OF MUSCLE
STRUCTURAL and FUNCTIONAL
Functional: Voluntary or Involuntary
Structural: Striated or Smooth
Combined:
Smooth involuntary muscle = smooth muscle
Striated involuntary muscle = cardiac muscle
Striated voluntary muscle = skeletal muscle

9. Classification
Functional type
Skeletal m.
Cardiac m.
Smooth m
Striated m.
Unstriated m.
Voluntary m.
Involuntary m.
Morphologic type

10. The muscle cells can be classified into 3 major groups based on their:
1. shape,
2. number and position of nuclei,
3. presence of striations, and
4. whether they are under voluntary or involuntary control.
•Elongated cell
•Multiple peripheral nuclei
•Visible striations
•voluntary
•Branching cell
•Single central nucleus
•Visible striations
•involuntary
•Spindle shaped
•Single central nucleus
•Lack of visible striations
•involuntary

11. Characteristics of Muscle Tissue
1. Excitability
– The ability to receive and respond to a stimulus
• In skeletal muscle, the stimulus is a neurotransmitter
(chemical signal) release by a neuron (nerve cell).
• In smooth muscle, the stimulus could be a neurotransmitter,
a hormone, stretch, pH, Pco2, or Po2. (the symbol 
means “a change in”)
• In cardiac muscle, the stimulus could be a neurotransmitter,
a hormone, or stretch.
– The response is the generation of an electrical
impulse that travels along the plasma membrane of
the muscle cell.

12. Characteristics of Muscle Tissue
2. Contractility
– The ability to shorten forcibly when adequately
stimulated.
– This is the defining property of muscle tissue.
3. Extensibility
– The ability to be stretched
4. Elasticity
– The ability to recoil and resume original length after
being stretched.

13. MUSCLE
TISSUE
 4 basic tissues.
 Contractile cells,
 Elongate elements, muscle fibers,
 Excitability and contractitility,
 Origin
 Terminology:
 Functions: movement, maintenance of
posture, thermogenesis, stabilization of joint.
 Classification: 3 major groups based on
their: shape, nuclei (position and number),
striations, voluntary or not

14. Skeletal muscle

18. Muscle fiber
PM is
known as
sarcolemma
Muscle fiber
cytoplasm is
known as
sarcoplasm
Sarcoplasm has lots of mitochondria (why?), lots of glycogen granules
(to provide glucose for energy needs) as well as myofibrils and
sarcoplasmic reticuli.
Sarcolemma has invaginations that penetrate through the cell called
transverse tubules or T tubules.

19. Skeletal muscle
LM：
Shape: long cylindrical；diameters : 10 to 100 µm.
Nuclei: ovoid & flattened;
many peripherally placed nuclei.
Sarcoplasm:
* regular transverse / longitudinal striation
* myofibrils
myofibril
Muscular cell
nucleus

20. EM:
1. Myofibril
2.Transverse tubule
3. Sarcoplasmic reticulum
4. Other inclusions
mitochondria
myoglobin
glycogen
ribosome
1
2
3

21. Muscle fiber & myofibril
———muscular fiber
(muscular cell)
myofibril
dark band (A band)
Light band （I band)

22. Myofibril
* long , parallel , cylindrical filamentous bundles
*consisting of two types of myofilament (thin & thick).

23. Sarcomere: A segment between two adjacent Z line.
It is a structural and basic contractile unit.

24. • Z line: zone of apposition of actin filaments
belonging to two neighbouring sarcomeres
• M-line: band of connections between myosin
filaments

25. Banding
I band：only thin filament
H band (central region of A band): only thick
filament without cross bridges
Extremities of A band：both thin & thick filament
Z Z

26. Molecular configuration of myofilaments
* thick filament ----myosin
* thin filament: actin, tropomyosin, troponin.

27. Myosin (thick filament)
—head (adenosine triphosphatase, ATPase）
—shaft

28. Myosin 肌球蛋白 (thick filament)
—head (adenosine triphosphatase, ATPase）
—shalf
横桥 Cross bridge

29. Myosin 肌球蛋白 (thick filament)
—head (adenosine triphosphatase, ATPase）
—shalf
横桥 Cross bridge

30. Thin filament

31. Troponin
Actin
肌
Tropomyosin
Components of a thin filament

32. —binding site to myosin
Two strands of actin molecule arranged in a helix
Actin
Actin

33. Tropomyosin 原肌球蛋白

34. Tropnin
—TnT
—TnI
TnC—
binding Ca2+

37. Transverse tubule
* invaginations of the surface
sarcolemma
* lying as rings around each
myofibril
* located at A-I junction
* providing for rapid spread
of surface membrane
excitation throughout the entire
muscle fiber
A
I
Z
myofibril

38. Sarcoplasmic reticulun
* SER forming cylindrical sheaths
around each myofibril
(longitudinal tubule)
* at A-I junction, tubules connect to
channels of larger caliber called
terminal cisternae
Triad
* A T tubule is sandwiched
between two terminal cisternae.

39. Muscle Fiber Types
2 main types:
1. Slow fibers
2. Fast fibers

40. Slow Fibers
• Contract slowly because its myosin
ATPases work slowly.
• Depends on oxygen delivery and aerobic
metabolism.
• Is fatigue resistant and has high
endurance.
• Is thin in diameter – large amt of
cytoplasm impedes O2 and nutrient
diffusion.
• Cannot develop high tension – small diameter means few myofibrils.
• Has rich capillary supply and lots of mitochondria.
• Contains lots of the O2-storing protein, myoglobin which gives it a
red color.
• Uses lipids, carbs, and amino acids as substrates for it aerobic
metabolism.
• Best suited for endurance type activities.
• A.k.a. red fibers, slow oxidative fibers, type I fibers.

41. Fast Fibers
• So named because they can
contract in 0.01 seconds or less
after stimulation.
• Fast fibers are large in diameter;
they contain densely packed
myofibrils, large glycogen
reserves, and relatively few
mitochondria.
• Able to develop a great deal of tension b/c they contain a large number
of sarcomeres.
• Use ATP in massive amounts. Supported by anaerobic metabolism.
Fatigue rapidly.
• A.k.a., fast fatigue (FF) fibers, fast glycolytic (FG) fibers, white fibers.
• Best suited for short term, power activities.

42. Myasthenia Gravis
• My=muscle, asthen=weakness, gravi=heavy
• Autoimmune disease where antibodies attack the
ACh receptors on neuromuscular junctions.
• Results in progressive weakening of the skeletal
muscles. Why?
• Treated w/ anticholinesterases such as neostigmine
or physostigmine. These decrease the activity of
acteylcholinesterase.
– Why would this help someone with myasthenia gravis?

43. Muscular Dystrophy
- a group of diseases involving muscle deterioration.
-Duchenne muscular dystrophy related to deletions in
a huge gene coding for the protein dystrophin.
-The gene is linked to the X
chromosome, so it appears
predominantly in males.

44. ROLE OF MOTOR NEURON
In order for skeletal
muscle to contract, each
cell must be stimulated by
a process of a motor
neuron

45. Excitation
• In general each muscle is
served by one nerve – a bundle
of axons carrying signals from
the spinal cord to the muscle.
• W/i the muscle, each axon will
go its own way and eventually
branch into multiple small
extensions called telodendria.
Each telodendrium ends in a
bulbous swelling known as the
synaptic end bulb.
The site of interaction btwn a neuron and any other cell is
known as a synapse. The synapse btwn a neuron and a
muscle is known as the neuromuscular junction.

46. NEUROMUSCULAR JUNCTION

47. NEUROMUSCULAR JUNCTION ACTIVITY

48. ARRIVAL OF ACTION POTENTIAL AT AXON TERMINAL

49. FUSON OF SYNAPTIC VESICLES

50. RELEASE OF ACETYLCHOLINE

51. ACETYLCHOLINE BINDS TO RECEPTOR SITES

52. ACETYLCHOLINE BINDS TO RECEPTOR SITES

53. BREAKDOWN OF ACETYLCHOLINE

54. BREAKDOWN OF ACETYLCHOLINE

55. ACTION POTENTIAL PROPAGATION

56. CALCIUM RELEASE FROM TERMINAL CISTERNAE

57. CALCIUM RELEASE FROM TERMINAL CISTERNAE

58. SUMMARY

59. CONTRACTION OF THE MUSCLE CELL

60. CARDIAC MUSCLE

61. LM
- short cylindrical shape
- branched
-central nucleus, one or two nucleus per fiber
- cross striation
- myofibril
- intercalated disks
Cardiac muscle

62. Cardiac muscle（transverse section）

63. Cardiac muscle
intercalated disk
nucleus

65. EM:
*myofibril is not well defined;
*sarcoplasmic reticulum less developed;
*T tubules much wider;
located in the Z lines;
*Diad
* intercalated disk
T tubule
z
z
terminal cisternae
M

66. Intercalated disc
*Specialized cell junctions located at Z lines
*Stepwise pattern:
transverse region: intermidiate/desmosomes j.
longitudinal region: gap junction
z G.J.
I.J.
D.J.

67. Intercalated disk: Stepwise pattern
Transverse region : desmosome, intermediate J.
Longitudinal region : Gap J

68. Cardiac muscle
Skeletal muscle
？

69. Specialized cardiac muscle
fibers called purkinje fibers
(green) are located throughout
the heart ventricle. They
conduct the electrical impulse
from the pacemaker region of
the heart to cause the ventricle
to contract forcefully. Like all
healthy tissue, heart muscle
cells need an abundance of
oxygen and nutrients. Tiny
capillaries (orange), containing
red blood cells, course through
the muscle carrying nutrients,
oxygen, and fluids. Other
capillaries carry out carbon
dioxide and waste materials to
veins and the lymph system.

70. SMOOTH MUSCLE

71. Smooth muscle
* spindle-shape with single central nucleus
* sarcoplasm appears acidophilic
* no transverse striation and intercalated disc.

73. EM:
* invagination of sarcoplasm
* sarcoplasmic reticulum poorly developed
* there are myofilaments, but no myofibrils
caveola
Dense patch
Dense body
myofilaments

74. SMOOTH MUSCLE
• LOCATION OF SMOOTH MUSCLE
• Involuntary, non-striated muscle tissue
• Occurs within almost every organ, forming sheets,
bundles, or sheaths around other tissues.
• Cardiovascular system:
– Smooth muscle in blood vessels regulates blood flow
through vital organs. Smooth muscle also helps
regulate blood pressure.
• Digestive systems:
– Rings of smooth muscle, called sphincters, regulate
movement along internal passageways.
– Smooth muscle lining the passageways alternates
contraction and relaxation to propel matter through the
alimentary canal.

75. Smooth Muscle
• Integumentary system:
– Regulates blood flow to the superficial dermis
– Allows for piloerection
• Respiratory system
– Alters the diameter of the airways and changes the
resistance to airflow
• Urinary system
– Sphincters regulate the passage of urine
– Smooth muscle contractions move urine into and out of
the urinary bladder

76. Smooth Muscle
• Reproductive system
– Males
• Allows for movement of sperm along the male reproductive
tract.
• Allows for secretion of the non-cellular components of semen
• Allows for erection and ejaculation
– Females
• Assists in the movement of the egg (and of sperm) through the
female reproductive tract
• Plays a large role in childbirth

77. Smooth Muscle
• Elongate, tapering spindle cells:
– Are smaller: 5-10um in diameter
and 30-200um in length
– Are uninucleate: contain 1 centrally
placed nucleus
– Lack any visible striations
– Lack T-tubules
– Have a scanty sarcoplasmic
reticulum
• Smooth muscle tissue is innervated by the autonomic nervous
system unlike skeletal muscle which is innervated by the
somatic nervous system (over which you have control)
• Only the endomysium is present. Nor perimysium or
epimysium.

78. EM:
* invagination of sarcoplasm
* sarcoplasmic reticulum poorly developed
* there are myofilaments, but no myofibrils
caveola
Dense patch
Dense body
myofilaments

80. Types of Smooth Muscle
• Smooth muscle varies widely from organ to organ
in terms of:
– Fiber arrangement
– Responsiveness to certain stimuli
• How would the types of integral proteins that a smooth muscle
cell contained contribute to this?
• Broad types of smooth muscle:
– Single unit (a.k.a. visceral)
– Multi unit

81. Single Unit Smooth Muscle
• More common
• Cells contract as a unit
because they are all connected
by gap junctions - protein
complexes that span the PM’s
of 2 cells allowing the passage
of ions between them, i.e.,
allowing the depolarization of
one to cause the
depolarization of another.
• Some will contract
rhythmically due to
pacemaker cells that have a
spontaneous rate of
depolarization.

82. Single Unit Smooth Muscle
• Not directly innervated.
Diffuse release of
neurotransmitters at
varicosities (swellings
along an axon).
• Responsive to variety of
stimuli including stretch
and concentration changes
of various chemicals
• Found in the walls of the
digestive tract, urinary
bladder, and other organs

83. Multi-Unit Smooth Muscle
• Innervated in motor units
comparable to those of skeletal
muscles
• No gap junctions. Each fiber is
independent of all the others.
• Responsible to neural & hormonal
controls
• No pacemaker cells
• Less common
• Found in large airways to the lungs,
large arteries, arrector pili, internal
eye muscles (e.g., the muscles that
cause dilation of the pupil)
• Why is good to have the digestive
smooth muscle single unit and the
internal eye muscles multi-unit?

84. SMOOTH
• Shape: Elongate, tapering spindle cells:
• Size: Are smaller: 5-10um in diameter and 30-200um in length
• Nucleus: 1 centrally placed nucleus
• Striations: Lack any visible striations
• T-tubules
• Sarcoplasmic reticulum
• Involuntary,
• Locations:
• Cardiovascular system:
• Digestive systems:
• Integumentary system:
• Respiratory system
• Urinary system
• Males
• Females hypertrophy &hyperplasia, pregnancy, oxytocin