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How Animals Move Chapter 21. Pumping Up Muscles Androstenedione – Intermediate in testosterone and estrogen synthesis pathways – Taken as dietary supplement.

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Presentation on theme: "How Animals Move Chapter 21. Pumping Up Muscles Androstenedione – Intermediate in testosterone and estrogen synthesis pathways – Taken as dietary supplement."— Presentation transcript:

1 How Animals Move Chapter 21

2 Pumping Up Muscles Androstenedione – Intermediate in testosterone and estrogen synthesis pathways – Taken as dietary supplement – Doesn’t help add muscle – Does have negative side effects

3 Pumping Up Muscles Creatine phosphate – Short chain of amino acids – Donates phosphate to ATP when muscles need quick energy – Does enhance performance in sports that require short bursts of energy – Long-term effects unknown

4 p.349

5 3 Types of Skeletons 1.Hydrostatic skeleton 2.Exoskeleton feed me! resting

6 3 Types of Skeletons 3. Endoskeleton (vertebrates) pelvic girdle pectoral girdle Generalized mammal

7 Skull bones Rib Cage INTERVERTEBRAL DISKS Pectoral girdle and upper limb bones CLAVICLE SCAPULA HUMERUS RADIUS ULNA CARPALS METACARPALS PHALANGES Pelvic girdle and lower limb bones PELVIC GIRDLE FEMUR PATELLA TIBIA FIBULA TARSALS METATARSALS PHALANGES ligament bridging a knee joint, side view, midsection Vertebral Column VERTEBRAE STERNUM RIBS CRANIAL BONES FACIAL BONES Fig. 21-3, p.351 a b c d e

8 Functions of Bones Interact with muscle to enable movement Support and anchor muscles Enclose and protect internal organs Store calcium and phosphorus Produce blood cells

9 Long Bone Structure Compact bone Spongy bone Central cavity contains yellow marrow compact bone tissue spongy bone tissue nutrient canal central cavity (contains yellow marrow)

10 Compact Bone Structure Compact bone consists of many dense, cylindrical layers surrounding canals spongy bone tissue compact bone tissue outer layer of dense connective tissue blood vessel cylindrical layers

11 Bone Marrow Yellow marrow – Fills the cavities of adult long bones – Is largely fat Red marrow – Occurs in spongy bone of some bones – Produces blood cells

12 Bone Mass In adults, bone building and bone breakdown continue constantly Osteoblast secretions form bone Osteoclasts enzymes degrade bone Adding and removing minerals adjusts bone strength and helps maintain blood calcium levels

13 Bone Density Exercise can increase bone density Osteoporosis: Decrease in bone density – May occur when the action of osteoclasts outpaces that of osteoblasts – May also occur as a result of inability to absorb calcium

14 Osteoporosis

15 Where Bones Meet Joints: Areas of contact or near contact between bones Ligaments: Straps of connective tissue at joints Arthritis: Joint damage or inflammation – Osteoarthritis – Rheumatoid arthritis

16 Skeletal Muscle Bundles of muscle fibers Tendons attach muscles to bone Lever system Opposing muscle groups biceps triceps

17 Fig. 21-7, p.354

18 Skeletal Muscle Contraction A muscle is made up of bundles of muscle fibers Muscle fiber contains cross- banded myofibrils myofibril

19 Sarcomere Z band sarcomere Myofibril is made up of thick and thin filaments arranged in sarcomeres

20 Muscle Microfilaments Thin filaments Two actin strands twisted together Globular proteins Parallel with myofibril Thick filaments Myosin Motor protein Tail and double head

21 Sliding-Filament Model Myosin heads attach to actin filaments Myosin heads tilt toward sarcomere center, pulling actin with them

22 Sliding-Filament Model When actin filaments are pulled inward, toward sarcomere center, sarcomere shortens Filaments themselves do not shorten

23 Contraction Requires Calcium Skeletal muscles contract in response to signals from motor neurons Signals release calcium from sarcoplasmic reticulum Calcium allows actin and myosin to bridge

24 Contraction Requires Energy Muscle cells require huge amounts of ATP energy to power contraction Cells store only small amounts of ATP Three pathways supply ATP to power muscle contraction

25 ATP for Contraction pathway 1 dephosphorylation creatine phosphate pathway 2 aerobic respiration pathway 3 glycolysis alone creatine oxygen glucose from bloodstream and from glycogen break down in cells ADP + P i relaxation contraction

26 Motor Unit One neuron and all muscle fibers it controls When a motor neuron is stimulated, all fibers in muscle unit contract simultaneously, producing muscle twitch Rapid, repeated stimulus of motor unit produces tetanus

27 Twitch and Tetanus peak relaxation stimulus contraction starts time number of stimuli per second tetanic contraction repeated stimulation twitch

28 Muscle Tension Mechanical force exerted on an object by a contracting muscle For a muscle to shorten, muscle tension must exceed the load that opposes it Load may be the weight of an object or pull of gravity on muscle

29 Two Types of Contraction Muscle shortens as it contracts Isotonic contraction: Load is less than muscle’s peak capacity Muscle contracts but can’t shorten Isometric contraction: Load is greater than muscle’s peak capacity

30 Infection and Motor Neurons Bacterial toxins block motor neuron control – Clostridium botulinum, botulism – Clostridium tetani, tetanus

31 Muscle Fatigue Inability to maintain muscle tension Glycogen is depleted after a period of tetanic contraction Requires recovery time

32 Muscular Dystrophies Genetic disorders in which muscles weaken and degenerate Duchenne muscular dystrophy – Defective protein in muscle plasma membrane prevents normal binding of actin filaments to Z band Myotonic muscular dystrophy

33 Exercise Aerobic – Long duration, low intensity – Increases number of mitochondria, number of blood capillaries to all skeletal muscle Strength training – Intense, short duration – Makes fast-acting muscles form more myofibrils and enzymes for glycolysis

34 Aging Muscles shrink Number of muscle fibers decreases Slower healing time Aerobic exercise improves fitness and memory

35 Osteogenesis Imperfecta


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