1. Chapter 9 & 11 Review

2. The four characteristics of skeletal muscle:
1. Excitable (turned on by nerves)
2. Contractile (shorten when stimulated)
3. Extensible (can elongate without damage)
4. Elastic (can spring back to resting length)

3. Skeletal Muscles are vascular
Each muscle is served by 1 artery, at least
1 vein, and 1 nerve Mu S C L e
Spinal
cord

4. Each part of the muscle is wrapped in a connective tissue wrapping which protects the cells, and gives some stretch to the muscle
EPImysium
wraps whole muscle
Tendon
(b)
ENDOomysium
(wraps individual
muscle cells)
Fascicle:
A bundle of muscle cells
PERImysium
Wraps a bundle of
muscle cells
Muscle CELL
(somethimes
called a fiber)
Figure 9.1

5. This is ONE muscle cell. What are the clues?

6. MYOFIBRILS are broken into smaller units called SARCOMERES
SARCOMERES are made of smaller units called FILAMENTS (myofilaments)
Z disc
Z disc
(c)
Small part of one myofibril enlarged to show the myofilaments
responsible for the banding pattern. Each sarcomere extends from
one Z disc to the next.
Sarcomere
Z disc
Z disc
Thin (actin)
filament
Elastic (titin)
filaments
Thick
(myosin)
filament
(d)
Enlargement of one sarcomere (sectioned lengthwise). Notice the
myosin heads on the thick filaments.
Figure 9.2c, d

7. A single myosin molecule
A place to bind to the actin in the thin filament
A place for ATP to bind

8. Twisted double strand of G actin beads
G actin has active sites for myosin head attachment, but they are covered by tropomyosin
Tropomyosin and troponin: are proteins bound to actin that regulate whether or not the actin and myosin attach to each other and pull

9. Sliding filament model
Step 1: Calcium is released from the SR and binds Troponin.
Step 2: Troponin changes shape and moves tropomyosin exposing binding site for myosin
Step 3: Myosin binds actin and ADP + Pi is released and power stroke occurs
Step 4: ATP binds to myosin and releases it from actin
Step 5: ATP hydrolyzed into ADP + Pi releasing energy and re-cocking myosin head
Step 6: Muscle contraction ends when calcium actively pumped back into SR

10. WHY do the ions move the way they do?
Why does Ca+ move INTO the nerve cell?
Why does Na+ move INTO the muscle cell?
Why does K+ move OUT of the muscle cell?
HINT: you learned this in General Biology
OUTSIDE IN IN
Lo Na+
Lo Cl-
Lo Ca+
Hi K+
Hi Na+
Hi Cl-
Hi Ca+
Lo K+
Lo Na+
Lo Cl-
Lo Ca+
Hi K+

11. Steps at the NMJ         +   _ Ca2+ Na+ A Ch Na+ Ach-E K+
Brain has idea to move.
Action potential sent down motor neuron.
AP opens voltage-gated Ca2+ channels and Ca2+ flows into axon terminal.
Ca2+ causes synaptic vesicles to release Ach into synaptic cleft through exocytosis.
ACh binds to ligand-gated Na+/K+ channel (ACh receptor) on sarcolemma which opens and allows Na+ to flow in and K+ to flow out.
More Na+ flows in than K+ flows out causing the inside of the sarcolemma to become more positive.
Depolarization of motor end plate causes AP in sarcolemma.
AP opens voltage-gated Na+ channels in sarcolemma, Na+ flows down conc. Gradient, depolarizing membrane and further propagating AP.
AP flows through T-tubules to release Ca2+ from SR.
ACh broken down in synapse by AChE into acetic acid and choline which are reabsorbed by axon terminal which halts muscle contraction.  
Ca2+  
Na+   A Ch
Na+  + 
Ach-E K+  _

12. Ca++ is released from the SR into the cytoplasm
The Action potential is a signal that moves along the sarcolemma and down the T tubules, and then
Ca++ is released from the SR into the cytoplasm
Steps in
E-C Coupling:
Sarcolemma
Voltage-sensitive
tubule protein
T tubule
Ca2+
release
channel
Terminal
cisterna
of SR
Ca2+
Figure 9.11, step 3

13. Figure 9.11, step 8 Steps in E-C Coupling: The aftermath Sarcolemma
Voltage-sensitive
tubule protein
T tubule 1
Action potential is propagated along
the sarcolemma and down the T tubules.
Ca2+
release
channel
Calcium ions are released. 2
Terminal
cisterna
of SR
Ca2+
Actin
Troponin
Tropomyosin
blocking active sites
Ca2+
Myosin
Calcium binds to troponin and
removes the blocking action of
tropomyosin. 3
Active sites exposed and
ready for myosin binding 4
Contraction begins
Myosin
cross
bridge
The aftermath
Figure 9.11, step 8

14. Cross bridge formation.
Actin
Ca2+
Thin filament
ADP
Myosin
cross bridge Pi
Thick filament
Myosin 1
Cross bridge formation.
Figure 9.12, step 1

15. The power (working) stroke.
ADP Pi 2
The power (working) stroke.
Figure 9.12, step 3

16. Cross bridge detachment.
ATP 3
Cross bridge detachment.
Figure 9.12, step 4

17. ADP
ATP
hydrolysis Pi 4
Cocking of myosin head.
Figure 9.12, step 5

18. Spatial summation Temporal summation Best sarcomere length Go to gym
Large
number of
muscle
fibers
activated
Muscle and
sarcomere
stretched to
slightly over 100%
of resting length
Large
muscle
cells
High
frequency of
stimulation
FOUR WAYS TO INCREASE THE FORCE OF CONTRACTION
Figure 9.21

19. What does TRYING HARDER mean?!
Stimulus strength
Think harder
(stimulate
more brain
cells)
Maximal
stimulus
Threshold
stimulus
Turn on more
nerves going
to muscles
Proportion of motor units excited
Strength of muscle contraction
Turn on more
muscle cells to
create more
FORCE
Maximal contraction
Figure 9.16

20. Very low frequency of stimulation leads to low force production
Contraction
Relaxation
Stimulus
Single stimulus
SINGLE MUSCLE TWITCH
A single stimulus is delivered. The muscle
contracts and relaxes (muscle twitch) with low force
Figure 9.15a

21. The faster you stimulate the muscle, the more forcefully it contracts
Apply another stimulus before the first totally relaxes and the forces sum!
Stimuli
Partial relaxation
Low stimulation frequency
INCOMPLETE
TETANUS
The faster you stimulate the muscle, the more forcefully it contracts
…………….UP TO A POINT….
Figure 9.15b

22. Repeated fast stimulation makes the maximum force possible
Stimuli
High stimulation frequency
COMPLETE TETANUS
Probably because large amounts of calcium are entering the cell
and allowing very rapid thin and thick filament pulling.
Figure 9.15c

23. Sarcomeres excessively
4. INCREASE FORCE by changing the sarcomere length
Sarcomeres
greatly
shortened
Sarcomeres at
resting length
Sarcomeres excessively
stretched
75%
100%
170%
Optimal sarcomere
operating length
(80%–120% of
resting length)
Figure 9.22

24. Does muscle contraction always produce movement?
single cells
and
whole muscles
always produces FORCE
but
shortens a muscle (isotonics)
(you TRY to move, and do)
Or does NOT shorten a muscle(isometrics)
(you TRY to move, and don’t)

25. Short-duration exercise
Prolonged-duration
exercise
STORED ATP
ATP stored in
muscles is
used first.
ENZYMES
ATP is formed
from creatine
Phosphate
and ADP using
Enzymes in the
cytoplasm
GLYCOLYSIS
Glycogen stored in muscles is broken
down to glucose, which is oxidized to
generate ATP using enzymes in the
AEROBIC METABOLISM
ATP is generated by
breakdown of several
Nutrients in the mitochondria
And requiring oxygen.
Figure 9.20

26. Fuels: CP, ADP Produces: 1 ATP per CP Provides ATP for 15 seconds of
Coupled reaction of creatine
phosphate (CP) and ADP
Energy source: CP
(a) Direct phosphorylation
Oxygen use: None
Products: 1 ATP per CP, creatine
Duration of energy provision:
15 seconds
Creatine
kinase
ADP CP
ATP
Fuels: CP, ADP
Produces: 1 ATP per CP
Provides ATP for
15 seconds of
Activity.
Figure 9.19a

27. Fuel: glucose Produces: a. 2ATP per glucose and
b. Lactic acid-diffuses into the bloodstream and is used as fuel by the liver, kidneys, and heart, OR converted back into pyruvic acid by the liver.
Provides ATP for 60 seconds
of activity.
Energy source: glucose
Glycolysis and lactic acid formation
(b) Anaerobic pathway
Oxygen use: None
Products: 2 ATP per glucose, lactic acid
Duration of energy provision:
60 seconds, or slightly more
Glucose (from
glycogen breakdown or
delivered from blood)
Glycolysis
in cytosol
Pyruvic acid
Released
to blood
net gain 2
Lactic acid O2
ATP
Figure 9.19b

28. Fuels: glycogen, glucose, Fatty acids, amino acids
Energy source: glucose; pyruvic acid;
free fatty acids from adipose tissue;
amino acids from protein catabolism
(c) Aerobic pathway
Aerobic cellular respiration
Oxygen use: Required
Products: 32 ATP per glucose, CO2, H2O
Duration of energy provision: Hours
Glucose (from
glycogen breakdown or
delivered from blood) 32 O2
H2O
CO2
Pyruvic acid
Fatty
acids
Amino
Aerobic respiration
in mitochondria
ATP
net gain per
glucose
Fuels: glycogen, glucose,
Fatty acids, amino acids
Needs: Oxygen & Mitochondria!!!
Produces: 32 ATP per glucose
Produces 95% of ATP during rest and light to moderate exercise. BUT, if you go too fast, ATP production cannot keep up, and you FATIGUE.
Figure 9.19c

29. So, if you want to run for a long time you need the right resources……
You get them by aerobic (endurance) training:
-Makes chest muscles stronger to pull in more oxygen
-encourages capillary growth to bring oxygen to muscles
-increases myoglobin synthesis so cells hold more oxygen
-increases the number of mitochondria in cells, to make more ATP
Capillaries grow at
about the same
rate as grass.

30. Light colored cells are called FAST TWITCH MUSCLE CELLS
They have:
Few myoglobin ((oxygen holding molecule)
Few mitochondria
Higher glycogen stores
Fast speed of contraction
Based on their characteristics
are these aerobic or anaerobic cells?
Hint: think of how much ATP the
above ingredients could produce…

31. Dark colored muscle cells are called SLOW TWITCH MUSCLE CELLS
They have: 
Lots of myoglobin (oxygen holding molecule)
Many mitochondria
Lower glycogen stores
SLOW speed of contraction
Based on their characteristics
are they aerobic or anaerobic cells?
Hint: think of how much ATP the
above ingredients could produce…

32. Nervous System
Label the following neuron and describe the function of each numbered area. 1
Dendrites
1. Dendrites receive stimuli from sensations or other nerves thru NT.
2. Nucleus is responsible for storing DNA that codes for the many proteins neurons require 3
Cell body (Soma)
3. Cell body (Soma) integrates local potentials from the dendrites 2
4. Axon hillock has high conc. of
V-G Na+ channels and triggers AP
Nucleus
5. Axon carries AP from soma towards axon terminal
6. Schwann Cell insulates axon to speed up AP. 7
Node of Ranvier 5
Axon 8
7. Node of Ranvier is gap between Schwann cells that contain V-G Na+ channels to boost AP 4
Axon Hillock/ Trigger Zone 6
Axon Terminal
8. Axon terminal releases NT onto dendrites of neighboring neurons.
Schwann Cell

33. Nervous System
What are the three types of neurons? Where are the found and what is the function of each?
Multipolar
Found in the CNS (Brain and spinal cord)
Function as motor neurons (control muscle movements)
Bipolar
Found in the retina of eye
Function as specialized receptor cells in the retina
Unipolar
Found in the PNS
Function as sensory nerves (Send sensory information to the CNS)

34. Nervous System
List the 4 glial cells found in the CNS and describe their function.
Astrocytes
Creates the blood brain barriers and provides scaffolding to support the CNS neurons
Microglia
Related to immune cells, cleans up debris and fights infections through phagocytosis
Ependymal Cell
Related to epithelial cells it lines the ventricles of the brain and circulates CSF with cilia
Oligodendrocyte
Myelinates neurons in the CNS. One oligodendrocyte myelinates many neurons

35. Nervous System List the 2 Glial cells in the PNS Satellite cells
Function is unclear but they are believed to provide nutrients to PNS neuron cell bodies, similar to Astrocytes in the CNS
Schwann Cells
Myelinate axons of neurons in the PNS. Many Schwann cells per single axon.

36. Nervous System CNS PNS Sensory/Afferent Division Motor/Efferent
Somatic
Voluntary
Visceral
Involuntary
(ANS)
Sympathetic
Para-
Sympathetic

37. Nervous System Define these terms: Voltage: Membrane potential
The difference in charge between two compartments
Membrane potential
The relative voltage difference between the outside and inside of a cell
The resting membrane potential of a neuron is -70 mV
Threshold potential
The change in membrane potential required to initiate an action potential
+15mV or a membrane potential of -55mV
Action potential
A wave of depolarization that flows down an axon in a wave

38. Nervous System
What are three factors that contribute to the -70mV resting membrane potential of a neuron?
1. Large negatively charged proteins in the cell that cannot escape through channels
2. Leaky K+ channels allow for the slow movement of K+ out of the cell. When + ions leave the cell, it becomes more negative inside. The membrane potential is set at the point which the flow of K+ ions out is balanced by the force of attraction of K+ ions back in.
3. Na+/K+ pump moves Na+ out and K+ into the cells against their concentration gradients using ATP to maintain the membrane potential. Since 3Na+ are pumped out for every 2K+ in, more positive ions are leaving the cell making it more negative inside.

39. Nervous System What excites a neuron?
Opening of chemical gated ion channels in the dendrites and cell body of a neuron by NT or sensory receptor stimulation.
What ions will cause a depolarization of the neuron?
Na+ and Ca2+
What ions will cause a hyperpolarization of the neuron?
K+ and Cl-
Depolarizations occurring in the dendrites and cell body are called?
Local or graded potentials
Are local potentials the same as action potentials?
No. They can be excitatory or inhibitory. They decrease in strength as they travel across the membrane, travelling only a short distance.

40. Nervous System Channel locations in a neuron. K+ Leak channels
Chemical gated channels
Voltage gated channels

41. Nervous System
Describe the events leading up to and the process of an AP.
1. NT released at the synapses on dendrites and cell body of a neuron opens chemical gated channels allowing Na+ or Ca2+ to flow in depolarizing the area around the channel. This is called a local potential.
2. If the sum total of all local potentials in the dendrites/cell body add up to +15mV, bringing the membrane potential up to -55mV, voltage-gated ion channels in the trigger zone (axon hillock) open allowing Na+ to flow into the axon.
3. The rush of Na+ into the axon further depolarizes the membrane up to +30 mV. This depolarization causes V-G Na+ channels further down the axon to open, propagating the AP.
4. At +30 mV, V-G Na+ channels close and V-G K+ channels open allowing K+ to rush out if the cell. This repolarizes the membrane (brings it back down below -70mV).
5. Because the membrane potential drops below -70mV (hyperpolarization) it makes it difficult for another AP to occur, unless it is a very strong stimulus. V-G channels cannot open again right away which prevents the AP fro travelling back up the axon (refractory period).
6. The Na+/K+ pumps then restore the ion balances (High Na+ outside/High K+ inside) and the K+ leak channels restore the -70mV resting membrane potential.

42. Nervous System What does myelin do? What is saltatory conduction.
Insulates the axon so AP’s travel quickly underneath and do not decay as much as in a naked axon.
What is saltatory conduction.
AP flow down a myelinated axon. The AP flows quickly under the myelin to the next node of Ranvier where the membrane is depolarized again, boosting the AP strength where it slows quickly under the next myelin sheath. It is a fast-slow-fast-slow flow that is up to 30x faster than AP flow down a naked axon.
Which axons are the fastest?
Large diameter axons with myelin are the fastest. Neurons to the skeletal muscles.
Which axons are the slowest?
Small diameter, unmyelinated axons are the slowest. Nerves to organs.
Which is faster, a large unmyelinated axon or a small myelinated axon?
Small myelinated axon is faster. Myelin creates more speed than diameter does. This saves space in the brain.

43. Nervous System Neurotransmitters. What are the two NT actions?
Direct
Indirect
Describe direct NT action
NT binds to receptor, which is also an ion channel, and opens it. Fast and short lived.
Describe indirect NT action
NT binds receptor which actives G-protein. G-protein travels across membrane and binds to Adenylate cyclase and activates it. The enzyme converts ATP in to cAMP. cAMP is a messenger molecule which travels through the cytoplasm and opens an ion channel. It can also activate enzymes in the cytoplasm or genes in the nucleus. It is slower and longer lasting.

44. Nervous System Acetylcholine Skeletal Muscle Cardiac Muscle
Smooth Muscle
Excitatory or inhibitory?
Opens which ion channel?
Direct or Indirect?
Excitatory
Inhibitory
Excitatory
Na+ K+
Ca2+
Direct
Indirect
Indirect

45. Nervous System Drugs that affect ACh Receptors: Nicotine Nerve Gas
Curare
Botox
Agontist or Antagonist
Action
Effect
Agonist
Agonist
Antagonist
Antagonist
Causes dopamine release in the brain
Stops AChE breakdown in synapse
Prevents Na+ ch. From opening
Prevents release of ACh vesicles
Spastic paralysis
Flaccid paralysis
Flaccid paralysis
Addiction

46. Strategies for doing well on the test:
Read the test first, make sure you understand what is expected of you.
Manage your time! If you get stuck on a MC question, skip it and come back later.
Multiple Choice/Matching questions:
Your first instinct is usually correct.
If you get stuck, try and eliminate at least two responses you know are incorrect. That way you now have a 50/50 chance, and remember your first instinct.
You can also read the question before each response, this can help you to weed out answers if they don’t sound right.
Read the question CAREFULLY, make sure you know what it is asking before selecting an answer.

47. Strategies for doing well on the test:
Written questions:
Decide which questions you are going to answer at the beginning.
Make an outline of the points you want to cover.
Pay attention to information in MC questions that may help you answer written questions.
Use your outline to construct your response into sentences that tell a story.
Re-read your answers as you go and make sure you are answering the questions asked.
If you are not sure of something, raise your hand or come up and ask!