Muscles

Question 1

On muscle contraction

Answer 1

H zone reduced (bw actin fillaments)
A band unchanged (myosin fillament)
I zone reduced (bw myosin fillaments)

Question 2

Transverse Tubule

Answer 2

Propagates muscle action potential

Question 3

Ca2+ released from?

Answer 3

Lateral Sac of Sarcoplasmic Rediculum

Question 4

MOTOR UNIT?

Answer 4

MOTOR NEURONS + MUSCLE FIBRES

Question 5

TENSION

Answer 5

FORCE EXERTED BY MUSCLE

Question 6

LOAD

Answer 6

FORCE EXERTED ON MUSCLE

Question 7

ISOMETRIC

Answer 7

CONTRACTION WITH CONSTANT LENGTH (WEIGHTLIFTING)
SHORTER LATENT PERIOD
LONGER CONTRACTION EVENT

Question 8

ISOTONIC

Answer 8

CONTRACTION WITH SHORTENING LENGTH (RUNNING)

Question 9

LENGHTENING

Answer 9

CONTRACTION WITH INCREASING LENGTH (SITTING DOWN)

Question 10

LATENT PERIOD

Answer 10

TIME BEFORE EXCITATION CONTRACTION STARTS

Question 11

AS LOAD INCREASES CONTRACTION VELOCITY AND DISTANCE SHORTENED?

Answer 11

DECREASES

Question 12

OPTIMAL LENGTH

Answer 12

MUSCLE LENGTH FOR GREATER ISOMETRIC TENSION

Question 13

FACTORS CAUSING FATIGUE

Answer 13

HIGH K+ - CONDUCTION FAILURE, DEPOLARISATION?
HIGH LACTIC ACID - ACIDIFIES PROTEINS
HIGH ADP + P - DELAYS MYOSIN DETACHMENT FROM ACTIN (INHIBITS X-BRIDGE CYCLE)

Question 14

Excitation-Contraction Coupling.

Answer 14

An action potential in the skeletal muscle cell is what triggers muscle cell contraction through the action of calcium ions being released from sarcoplasmic rediculum.

Question 15

FAST TWITCH

Answer 15

MYOSIN HAS HIGH ATPase ACTIVITY

Question 16

SLOW TWITCH

Answer 16

MYOSIN HAS LOW ATPase ACTIVITY

Question 17

OXIDATIVE

Answer 17

HIGH MITOCHONDRIA - HIGH OXIDATIVE PHOSPHORYLATION (ETC)
HIGH VASCULARISATION TO DELIVER MORE O2 AND NUTRIENTS
CONTAINS MYOGLOBIN FOR HIGH 02 DELIVERY
RED FIBRES WITH LOW DIAMETERS

Question 18

GLYCOLYTIC

Answer 18

FEW MITOCHONDRIA
HIGH GLYCOLYTIC ENZYMES AND GLYCOGEN
LOWER BLOOD SUPPLY
WHITE FIBRES WITH LARGE DIAMETERS

Question 19

3 TYPES OF MUSCLE FIBRES?

Answer 19

SLOW OXIDATIVE (I) - RESIST FATIGUE
FAST OXIDATIVE (IIa) - INTERMEDIATE RESIST FATIGUE
FAST GLYCOLYTIC (IIb) - FATIGUE QUICKLY

Question 20

NEURAL CONTROL DEPENDS ON?

Answer 20

FREQUENCY OF APs TO MOTOR UNITS

RECRUITMENT OF MOTOR UNITS

Question 21

DENERVATION ATROPHY

Answer 21

DESTROY NERVE/NMJ

Question 22

DISUSE ATROPHY

Answer 22

MUSCLE NOT USED

Question 23

SMOOTH MUSCLE

Answer 23

NO STRIATIONS 
SPINDLE SHAPED
MONONUCLEATE
INNERVATED BY ANS NOT SOMATIC NS
IN HOLLOW ORGANS 
X-BRIDGE CYCLE THAT USES Ca2+
FILAMENTS ARRANGED DIAGONALLY ACROSS CELLS AND ARE ANCHORED TO MEMBRANES AND CELL STRUCTURES BY DENSE BODIES (Z-LINES)

Question 24

SMOOTH MUSCLE X-BRIDGE CYCLE ACTIVATION

Answer 24

INCREASE Ca2+
Ca2+ BINDS CALMODULIN
Ca2+ - CALMOLDULIN BINDS TO MYOSIN LIGHT CHAIN KINASE
KINASE PHOSPHORYLATES MYOSIN X-BRIDGES WITH ATP
PHOSPHORYLATES X-BRIDGES BIND TO ACTIN
CONTRACTION + TENSION
CONTRACTION IS GRADED DEPENDING ON AP THAT REACH THE CELLS
ONLY SOME SITES ACTIVATED BUT
CONSTANT TENTION LEVEL

Question 25

SMOOTH MUSCLE RELAXATION

Answer 25

MYOSIN LIGHT CHAIN PHOSPHATASE - DEPHOSPHORYLATES X BRIDGES

Question 26

*PERSISTENT STIMULATION IN SMOOTH MUSCLE?

Answer 26

PHOSPHORYLATED X-BRIDGES MAY BE DEPHOSPHORYLATED WHEN STILL BOUND TO ACTIN? DECREASES RATE ATP SPLITTING SLOW X-BRIDGE CYCLE MAINTAIN TENSION FOR LONGER WITH LESS ATP USEFUL FOR BLOOD VESSEL WALLS THAT STAY OPEN FOR LONG PERIODS

Question 27

SMOOTH MUSCLE Ca2+

Answer 27

LESS SR IN SMOOTH MUSCLE, NO T-TUBULES | EXTRACELLULAR Ca2+ through voltage activated Ca2+ channels

Question 28

Factors affecting contractile activity?

Answer 28

Dynamic balance of all the following: Pacemaker activity Autonomic Neurotransmiters from varicosities (end points) Hormones (e.g. oxytocin) Local factors control relaxation (paracrine agents, pH, O2, osmolarity, ions, NO) Stretch (stretch stimulates further contraction harder)

Question 29

Single Unit smooth muscle

Answer 29

``` (GIT, uterus, small blood vessels) Many cells linked by gap junctions Signals travel between cells Contract synchronously May contain pacemaker cells Stretch evokes contraction ```

Question 30

Multiunit smooth muscle

Answer 30

(airways, large arteries, hairs) Few or no gap junctions Richly innervated by ANS Don’t respond to stretch