Human physiology muscular system
This presentation is the property of its rightful owner.
Sponsored Links
1 / 21

Human Physiology Muscular System PowerPoint PPT Presentation


  • 54 Views
  • Uploaded on
  • Presentation posted in: General

Human Physiology Muscular System. Muscle Classification. Functionally 1. Voluntarily 2. Involuntarily Structurally 1. Striated 2. Smooth Combined 1. Visceral 2. Cardiac 3. Skeletal. Sarcomere. Z. A. Z. A. Z. A (I). I. Z. Z. Z. Categories of skeletal muscle actions.

Download Presentation

Human Physiology Muscular System

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Human physiology muscular system

Human PhysiologyMuscular System


Muscle classification

Muscle Classification

  • Functionally

    • 1. Voluntarily

    • 2. Involuntarily

  • Structurally

    • 1. Striated

    • 2. Smooth

  • Combined

    • 1. Visceral

    • 2. Cardiac

    • 3. Skeletal


Human physiology muscular system

Sarcomere

Z

A

Z

A

Z

A (I)

I

Z

Z

Z


Categories of skeletal muscle actions

Categories of skeletal muscle actions

  • CategoriesActions

  • Extensor Increases the angle at a joint

  • Flexor Decreases the angle at a joint

  • Abductor Moves limb away from midline of body

  • Adductor Moves limb toward midline of body

  • Levator Moves insertion upward

  • Depressor Moves insertion downward

  • Rotator Rotates a bone along its axis

  • Sphincter Constricts an opening


Myofilaments

Myofilaments

  • 1. Myosin: 110Å thick; confined to the A-band. (Mole. wt. 500,000 deltons; 200 molecules/myofilament)

    • A. Tail- 800Å long, composed of a double helix

    • B. Head (cross bridges)-600Å terminating in a globular double structure. Contains binding sites for actin & ATP


Myofilaments1

Myofilaments

  • 2. Actin: 60A thick; runs from Z-line (disc) to just inside A-band. Mole wt. 60,000 deltons.

    • G-actin (globular units): contracted form

    • F-actin (fibrous polymers): relaxed form

  • Actin associated proteins

    • A. Tropomyosin

    • B. Troponin


Mechanics of muscle contraction

Mechanics of Muscle Contraction

  • 1. An action potential is generated by a motor nerve.

  • 2. This causes the release of acetylcholine from the axon terminals at the neuromuscular junctions.

  • 3. This Ach causes an increase in membrane permeability at the motor-end plate, causing the production of an end-plate potential (EPP).


Mechanics of muscle contraction1

Mechanics of Muscle Contraction

  • 4. The EPP depolarizes the fiber membrane (sarcolemma) causing a muscle action potential which spreads over the entire surface of the fiber membrane.

  • 5. This depolarizes the T-tubules, causing ionic conduction through their extracellular fluid, and the release of inositol triphosphate as a second messenger.


Mechanics of muscle contraction2

Mechanics of Muscle Contraction

  • 6. Ca++ is then released from the endoplasmic reticular fluid of the cisterns (lateral sacs) into the surrounding myofibril.

  • 7. Ca++ binds to the actin associated protein troponin, allowing the attachment of actin to the myosin-ATP complex to form a strong ATPase.

  • 8. The ATPase splits ATP, releasing the energy needed for the movement of the myosin cross bridges.


Mechanics of muscle contraction3

Mechanics of Muscle Contraction

  • 9. Energy from creatine phosphate replaces ADP on the myosin cross bridges, thereby breaking the A-M bond and allowing the cross bridges to relax.

  • 10. The Ca++ are forced back into the walls of the longitudinal tubules by active transport.

  • 11. This restores the inhibitory action of the troponin-tropomyosin complex.


Human physiology muscular system

A

I

H

Z


Selective terms

Selective Terms

  • 1. Motor Unit: consists of all the muscle fibers innervated by terminals from a single axon. (Range from 23 - 2,000 fibers)

  • 2. All or None Law: at or above threshold levels; the degree of contractile response of a single muscle fiber (or motor unit) is independent of stimulus strength

  • 3. Tension: force exerted by a contracting muscle

  • 4. Load: force exerted on a muscle by the weight of an object

  • 5. Isotonic contraction (same tension): the tension developed by the contracting is greater than the load. Therefore, the muscle shortens.


Selective terms1

Selective Terms

  • 6. Isometric contraction (same length): the strength of the load is greater than the tension of the muscle. Therefore, the muscle remains at the same length.

  • 7. Muscle spindle apparatus: a series of small spindle shaped fibers within the muscle for detecting changes in the length (stretch) of the muscle.

  • 8. Golgi tendon organ: tension receptors located in tendons, and activated by the pull of a contracting muscle


Human physiology muscular system

Flexor

Reflex

Cross

Extensor reflex

From

stimulus

source

Repetitive

after discharge

(oscillatory circuit)

Inhibitory

interneuron

excited

inhibited

Reciprocal

inhibition

excited

Vasodilation

Blood vessel

Antidromic

Reflex

Renshaw

cell

Red line

Red flare

wheel

No

motor activity


Human physiology muscular system

Impulse Responses of Skeletal Muscles

1) Twitch

Contraction phase (0.04 sec)

Relaxation phase (0.05 sec)

Latent period (0.002 sec)

2) Summation

a) wave (frequency)

fatigue

Tetanus


Human physiology muscular system

b) Multiple motor unit (recruitment) intensity

5

1. Subthreshold

2. Threshold

3. suprathreshold

4. Maximal

5. Supramaximal

4

3

2

1

Voltage

c) Treppe (staircase phenomenon)

2 stimuli/sec


Lactic acid in cellular respiration glycolysis

Lactic Acid in Cellular Respiration (Glycolysis)

  • (LDH: Lactic Acid Dehydrogenase)

2 NADH

Lactic Acid

Glucose

Pyruvate

LDH

O2

Acetyl CoA


Glycolysis cont

Glycolysis [cont.]

  • Fate of Lactic Acid

    • 1. Used by the heart for energy: it can convert lactic acid back to pyruvate.

    • 2. Decarboxylation (buffering action):  CO2 which  ventilation

    • 3. Converted back to pyruvate then to TCA


Glycolysis cont1

Glycolysis [cont.]

  • Pain

    • 1. Bradykinin: a peptide released from damaged tissue. It excites the pain nerve endings.

    • 2. Ischemia: If the brachial artery is occluded & the muscles of the forearm exercised, pain will begin in 15 seconds. With no exercise it takes 4 minutes.


Human physiology muscular system

Strength-Duration Curve

(Excitability Curve)

Utilization time (nerve)

Utilization time (muscle)

Chronaxie of nerve

2.0

Chronaxie of muscle

Strength of stimulus

1.5

1.0

.5

0.1

0.2

0.3

Duration of stimulus

(seconds)


Human physiology muscular system

2.25m

2.0m

1.65m

1.0

Relative tension

0.5

3.65m

1.25m

80100120 140 160

0

60

Percentage rest length

1.65 m

2.25 m

3.65 m


  • Login