Bio 449 Lecture 15 - Endocrinology III / Muscle I Oct. 4, 2010

Endocrinology IIIHypothalamic-pituitary system (cont'd)

Hormonal control of growth (conclusion)Temporal patterns of GH release Hypo- and hypersecretion

Muscle IFunctions and types of muscleStructure of skeletal muscle

Myofiber structureSarcomere structure

Contraction of the sarcomere Cross-bridge cyclingLength-tension relationship

Terms to KnowAnabolismIGF-I OsteoblastOsteoclastChondrocyteEpiphyseal plate GigantismAcromegalyDwarfism

Smooth muscleStriated muscleSkeletal muscleCardiac muscle MuscleTendon

ReadingsLectures 15-16: Chapter 11, pages 396-401Chapter 12

Muscle fiber (myofiber)Sarcolemma MitochondriaSarcoplasmic reticulumMyofibrilSarcomereThick filamentThin filamentZ-disc (or Z-line)ActinMyosinCross-bridgeContractionSliding-filament theory

Hypothalamic-pituitary system

Hormonal control of growth

Bone growth

Fig. 23-16

Epiphysis

Diaphysis

Epiphyseal plate

Diaphysis

Compactbone

Osteoblast

Chondrocyte

Cartilage

Bone growth

Newlycalcifiedbone D

irecti

on o

f gro

wth

Osteoblasts

Old chondrocytes

Chondrocytes

Dividing chondrocytes

Acromegaly

Fig. 23-14

Poodles!

Muscle Physiology

Functions and Types of Muscles

Functions of muscle

Fig. 12-2

Flexion

Extension

Biceps musclecontracts (flexor)

Tricepsmusclerelaxes

Triceps musclecontracts (extensor)

Bicepsmusclerelaxes

Functions of muscle

Fig. 12-2

PeristalsisVasoconstriction

Hydrostatic Pressure

Types of muscle

Fig. 12-1

Nucleus

Muscle fiber(cell)

Striations

Skeletal muscle

Types of muscle

Fig. 12-1

Muscle fiber

Nucleus

Striations

Cardiac muscle

Intercalated disk

Types of muscle

Fig. 12-1

Muscle fiber

Nucleus

Smooth muscle

Muscle structure

Fig. 12-3

Skeletal muscle

Muscle fascicle:bundle of fibers

Muscle fiber

Connective tissue

Connectivetissue

T endon Nerve andblood vessels

Nucleus

Muscle structure

Fig. 12-3

T-tubules

Sarcoplasmicreticulum

Sarcolemma

Mitochondria

Myofibril

Thickfilament

ThinfilamentNucleus

ULTRASTRUCTURE OF MUSCLE

Muscle structure

Myofibril

Z disk

Z disk Z disk

Z diskSarcomere

Thin filaments

Tropomyosin

Troponin

Actin chain G-actin molecule

Myosin tail

Myosin heads

Myosin molecule

Thick filaments

Hingeregion

Titin

Titin

M line Myosincrossbridges

M line

Fig. 12-3

Cross-bridge cycle

Fig. 12-9

ADP ADP

Actinmoves

Cytosolic Ca2+

Tropomyosin shifts,exposing bindingsite on actin

TN

Power stroke

Initiation of contraction

Troponin G-Actin

Tropomyosinblocks binding

site on actin

Myosin head

TN

Relaxed state. Myosin head cocked.

Pi

Pi

1

2 3

4

5

Sarcomere contraction

Fig. 12-8