Transcript Monday Oct

For sophomores and juniors interested in medical
school and undergraduate opportunities:
• A visit by Dr. Paul Catalana, Al Squire, and other guests from
Greenville Hospital System University Medical Center.
• In RMSC 122 (The Pit) starting at 6:30pm, Tuesday Oct 30th.
• Presentation and discussion on the new medical school at Greenville and
undergraduate opportunities through their MedEx program, including
clinical experiences and preparation for medical school.
Abstract due Monday
At start of class.
Abstract Reviewers Schedule
Thursday, Oct 25
Friday, Oct 26
Saturday
Afternoon, Oct
27
Sunday, Oct 28
in Acorn Cafe
by appointment
10-10 with Sejal Naik
1-2 pm Biology Office
9-11 am Biology
with Polly
12- 2 with Miranda Stockman
Suite
Office Suite
Ketcham
2-4 with Polly Ketcham
Miranda Stockman
with Sharon Guffy
ketchampd@em
4-6 with Brooks Owens
and Brooks Owens
ail.wofford.edu
6-8 with Becca Bryson
1QQ # 20 for 10:30
Write each letter, and circle each correct response.
A person who trains to participate in the Tour de France
would naturally acclimate by
a) increasing the number of Type I myofibers
b) increasing the density of capillaries in leg muscles
c) synthesizing much more creatine than normal
d) Converting Type II glycolytic fibers to Type II
oxidative/glycolytic fibers.
e) Synthesizing more thick and thin myofilaments in
Type II myofibers.
1QQ # 20 for 11:30
Write each letter, and circle each correct response.
A person who trains to compete in weightlifting would
naturally acclimate by
a) increasing the number of Type I myofibers
b) increasing the density of capillaries in chest and arm
muscles
c) synthesizing much more thick and thin myofilaments
in Type II myofibers
d) Converting Type II glycolytic fibers to Type II
oxidative/glycolytic fibers.
e) Increasing the number of mitochondria in Type I
myofibers of the chest and arm.
S 15
But each motor unit
has myofibers of the
same type: I or IIA or
IIB.
S 17
Fig. 09.26
Relationship between
recruitment and
motor unit type
The Size Principle
Size of somatic
motoneuron cell
body
S 16
Increasing tension in a whole muscle
• Frequency of stimulation of motor neuron
• Recruitment: activate more motor units
• Activate larger motor units
• These factors also influence actual tension
– Fiber length (length-tension) relationship
– Fiber diameter
– Level of fatigue (state of activity)
S 13
Length-tension Relationship
So….. Tension produced by a
single myofiber varies
depending on
sarcomere length.
Types of
Contractions
S6
Isotonic =
Same tension
Isometric =
Same length
Aka Lengthening contraction
S9
Consider blood flow to skeletal muscles during isometric contractions.
Consider blood pressure during isometric contractions.
Are there benefits of using trekking poles?
S 10
Chapter 9 B Properties of
Smooth Muscle
How does smooth muscle differ from skeletal muscle?
(innervation, membrane potentials, excitation-contraction coupling, twitch
duration, fatigue, etc. (Table 9-6 p.287)
What are the features of membrane potential of smooth muscle?
(pacemakers and slow waves)
What are the differences between single-unit and multi-unit smooth muscle?
(location, spread of excitation)
Who cares about smooth muscles?
Two layers of smooth muscle in intestine
Classifying smooth muscle
• By location
–
–
–
–
–
–
vascular
gastrointestinal
urinary
respiratory
reproductive
ocular
• By contraction pattern
– Phasic: periodic contraction and relaxation
• Ex: esophagus and intestine
– Tonic: continuously contracting to some degree
• Ex: esophageal and urinary sphincters, vascular
Classifying smooth muscle
continued.
• By communication with neighboring myofibers
– Single-unit smooth muscle: gap junctions with
neighbors (function as a group)
• Ex: intestines
– Multi-unit smooth muscle: no gap junctions
(myofibers function independently)
• Ex: Iris and ciliary muscle of the eye
Interesting phenomenon: Uterine smooth muscle is multiunit until just before labor and delivery when genes for gap
junctions are expressed and the uterus become single-unit.
S 13
Comparison of Single-Unit and
Multi-Unit Smooth Muscles
Slow waves and pacemaker potentials
Intestinal tract, uterus, small diameter blood vessels
Large airways of lungs, large arteries, ciliary muscle
Often with pacemaker cells
Control by neurotransmitters, hormones, local factors for some smooth muscles
(02, NO, pH, stretch, vasodilators ….)
S 11
Excitation-contraction coupling in Smooth Muscles
Figure 9.34
from SR and influx during Action Potential or graded potential
Ca++
Graded potentials
result in graded
contractions
Slow twitch of SM
due to slow action
of myosin ATPase.
Lack troponin
Special situation:
Dephosphorylation &
latch bridge
S 12
Comparison of Twitch Duration
Latchbridge =latch state
Thankful for latch state!
Crucial for long-term tension of
sphincters.
S 14
Cardiac
Myofibers
Intercalated Discs: mechanical attachments of cardiac myofibers to
each other, with gap junctions (electrical synapses) to conduct AP
Analogy: Falling dominoes
S 15
Plateau phase
S 16
Why no tetanic contractions of cardiac muscle?
S 17
Figure 12.17
ExcitationContraction
Coupling
Calcium-induced calcium release
What ends the twitch?
Ca++ channels blockers:
•How and where do they work?
•When are they used?
S 18
this table p. 287
Fig.Know
09.06