For sophomores and juniors interested in medical school and undergraduate opportunities: A visit by...

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.

Thursday, Oct 25 Friday, Oct 26 Saturday

Afternoon, Oct 27

Sunday, Oct 28in Acorn Cafe

9-11 am Biology Office Suite

with Sharon Guffy

1-2 pm Biology Office Suite

Miranda Stockman and Brooks Owens

by appointment with Polly Ketcham

ketchampd@email.wofford.edu

10-10 with Sejal Naik12- 2 with Miranda Stockman

2-4 with Polly Ketcham4-6 with Brooks Owens6-8 with Becca Bryson

Abstract Reviewers Schedule

Abstract due MondayAt start of class.

1QQ # 20 for 10:30Write each letter, and circle each correct response.

A person who trains to participate in the Tour de France would naturally acclimate bya) increasing the number of Type I myofibers b) increasing the density of capillaries in leg musclesc) synthesizing much more creatine than normald) 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 11:30Write each letter, and circle each correct response.

A person who trains to compete in weightlifting would naturally acclimate bya) increasing the number of Type I myofibers b) increasing the density of capillaries in chest and arm musclesc) synthesizing much more thick and thin myofilaments in Type II myofibersd) 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.

Fig. 09.26Relationship between recruitment and motor unit type

S 17

Size of somatic motoneuron cell body

The Size Principle

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 16

Length-tension Relationship

So….. Tension produced by a single myofiber varies

depending on sarcomere length.

S 13

Types of Contractions

Isometric =Same length

Isotonic =Same tension

S 6

Aka Lengthening contraction

Consider blood flow to skeletal muscles during isometric contractions.Consider blood pressure during isometric contractions.

S 9

Are there benefits of using trekking poles?

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)

S 10

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 multi-unit until just before labor and delivery when genes for gap junctions are expressed and the uterus become single-unit.

Control by neurotransmitters, hormones, local factors for some smooth muscles (02, NO, pH, stretch, vasodilators ….)

S 13

Slow waves and pacemaker potentials

Often with pacemaker cells

Intestinal tract, uterus, small diameter blood vessels Large airways of lungs, large arteries, ciliary muscle

Comparison of Single-Unit and Multi-Unit Smooth Muscles

Figure 9.34

Special situation: Dephosphorylation & latch bridge

from SR and influx during Action Potential or graded potential

Graded potentials result in graded

contractions

S 11

Slow twitch of SM due to slow action of myosin ATPase.

Lack troponin

Excitation-contraction coupling in Smooth Muscles

Ca++

Latchbridge =latch state

S 12 Comparison of Twitch Duration

Thankful for latch state!Crucial for long-term tension of sphincters.

Intercalated Discs: mechanical attachments of cardiac myofibers to each other, with gap junctions (electrical synapses) to conduct AP

Analogy: Falling dominoes

S 14 Cardiac Myofibers

Plateau phase

S 15

S 16

Why no tetanic contractions of cardiac muscle?

Figure 12.17

Calcium-induced calcium release

Ca++ channels blockers:

•How and where do they work?

•When are they used?

Excitation-Contraction Coupling

What ends the twitch?

S 17

Fig. 09.06Know this table p. 287S 18