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The Skeletal, Muscular and Levers System

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1 The Skeletal, Muscular and Levers System
Muscular Physics

2 Movement The physical constraints to movement
gravity and frictional drag occur in every environment, differing only in degree Involves skeletal and muscular systems Muscle have microtubules and microfilaments Needs energy

3 Types of Skeletal Systems
Changes in movement occur because muscles pull against a support structure, called the skeletal system -Zoologists recognize three types: -Hydrostatic skeletons -Exoskeletons -Endoskeletons

4 Hydrostatic Skeletons
Are found primarily in soft-bodied invertebrates, both terrestrial and aquatic Locomotion in earthworms -Involves a fluid-filled central cavity and surrounding circular & longitudinal muscles -A wave of circular followed by longitudinal muscle contractions move fluid down body -Produces forward movement

5 Longitudinal muscles contracted
Hydrostatic Skeletons Anterior Circular muscles Longitudinal muscles contracted Longitudinal muscles contracted contract, and anterior end moves forward contract, and segments catch up Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

6 Hydrostatic Skeletons
Locomotion in aquatic invertebrates -Occurs by fluid ejections or jetting -Jellyfish produce regular pulsations in bell -Squeezing some of water contained beneath it -Squids fill mantle cavity with sea water -Muscular contractions expel water forcefully through the siphon, and the animal shoots backward

7 Jellyfish propelled upward Contractile fibers Bell pulsates expelled
Water enters bell Contractile fibers expelled from bell Bell pulsates Jellyfish propelled upward Water expelled from siphon Squid backward b. a. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

8 Exoskeletons The exoskeleton surrounds the body as a rigid hard case
-Composed of chitin in arthropods An exoskeleton provides protection for internal organs and a site for muscle attachment -However, it must be periodically shed, in order for the animal to grow -It also limits body size

9 Endoskeletons Endoskeletons are rigid internal skeletons that form the body’s framework and offer surfaces for muscle attachment -Echinoderms have calcite skeletons, that are made of calcium carbonate -Bone, on the other hand, is made of calcium phosphate

10 Endoskeletons Vertebrate endoskeletons have bone and/or cartilage
-Bone is much stronger than cartilage, and much less flexible Unlike chitin, bone and cartilage are living tissues -They can change and remodel in response to injury or physical stress

11 Joints Joints are the locations where one bone meets another
-1. Immovable joints = Join bones -2. Slightly movable joints = Involve fibrous connective tissue or cartilage -3. Freely movable joints = Also called synovial joints -Contain a lubricating fluid

12 Slightly Movable Joints
Body of vertebra Fibrous joints Fibrous Joints Intervertebral disk Articular cartilage connective tissue Bone Suture Immovable Joint a. Slightly Movable Joints Cartilaginous Joints b. Synovial membrane Synovial fluid Fibrous capsule Articular cartilage Freely Movable Joint c. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

13 Joints Movable joints can be divided into four types
-Ball-and-socket joints = Permit movement in all directions -Hinge joints = Allow movement in only one plane -Gliding joints = Permit sliding of one surface over another -Pivot joints = Allow rotation

14 Ball-and-Socket Combination Joint Hinge Joint Gliding Joint a. d. b.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

15 The Muscular System Interactions of Skeletal Muscles in the Body
Muscles usually work in groups, i.e. perform “group actions” Muscles are usually arranged in antagonistic pairs flexor-extensor abductor-adductor, etc.

16 How Skeletal Muscles Produce Movement
Muscles exert force on tendons that pull on bones Muscles usually span a joint Muscle contraction changes the angle or position of one bone relative to another Brachialis flexes forearm

17 How Skeletal Muscles Produce Movement
origin Origin: the attachment of the muscle to the bone that remains stationary Insertion: the attachment of the muscle to the bone that moves Belly: the fleshy part of the muscle between the tendons of origin and/or insertion belly insertion

18 Naming Skeletal Muscles
Location of the muscle Shape of the muscle Relative Size of the muscle Direction/Orientation of the muscle fibers/cells Number of Origins Location of the Attachments Action of the muscle

19 Muscles Named by Location
Epicranius (around cranium) Tibialis anterior (front of tibia) tibialis anterior

20 Naming Skeletal Muscles
Trapezius Shape: deltoid (triangle) trapezius (trapezoid, 2 parallel sides) serratus (saw-toothed) rhomboideus (rhomboid, 4 parallel sides) orbicularis and sphincters (circular) Deltoid Rhomboideus major Serratus anterior

21 Muscles Named by Size Psoas minor maximus (largest) minimis (smallest)
longus (longest) brevis (short) major (large) minor (small) Psoas major

22 Muscles Named by Direction of Fibers
Rectus (straight)-parallel to long axis Transverse Oblique Rectus abdominis External oblique

23 Muscles Named for Number of Origins
Biceps (2) Triceps (3) Quadriceps (4) Biceps brachii

24 Muscles Named for Origin and Insertion
Sternocleidomastoid originates from sternum and clavicle and inserts on mastoid process of temporal bone insertion origins

25 Muscles Named for Action
Flexor carpi radialis (extensor carpi radialis) –flexes wrist Abductor pollicis brevis (adductor pollicis) –flexes thumb Abductor magnus – abducts thigh Extensor digitorum – extends fingers Adductor magnus

26 Movements Range of motion: depends on length of muscle fibers (fascicles); long fibers = large range of motion parallel and fusiform muscles Power: depends on total number of muscle fibers; many fibers = great power convergent, pennate, bipennate, multipennate

27 Lever Systems and Leverage
Lever: i.e. bones, a rigid rod that moves on some fixed point Fulcrum: i.e. joint, a fixed point Resistance: the force that opposes movement the load or object (bone or tissue) to be moved Effort: the force exerted to achieve a movement the effort is provided by muscle(s) Motion is produced when the effort exceeds the resistance (isotonic contraction)

28 Lever Systems and Leverage
Leverage: the mechanical advantage gained by a lever Power: muscle tension (effort) farther from joint (fulcrum) produces stronger contraction (opposes greater resistance) Range of motion (ROM): muscle tension (effort) closer to joint (fulcrum) produces greater range of motion.

29 Mechanical Advantage Load is near fulcrum, effort is far away
Only a small effort is required to move an object Allows a heavy object to be moved with a small effort Example: car jack

30 Mechanical Disadvantage
Load is far from the fulcrum, effort is near the fulcrum a large effort is required to move the object allows object to be moved rapidly, a “speed lever” throwing a baseball

31 Lever Systems and Leverage
First-class lever: (EFR) Effort-Fulcrum-Resistance

32 Leverage Systems and Leverage
Second class lever: (FRE) Fulcrum-Resistance-Effort

33 Leverage Systems and Leverage
Third-class lever: (FER) Fulcrum-Effort-Resistance

34 Skeletal Muscles

35 Web sites Interactive muscular system: 5-8th grade muscle activity:
5-8th grade muscle activity:

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