{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

L16 NPB 101 - Lecture 16 •  SmartSite: – ...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Lecture 16 •  SmartSite: –  Lecture 16 Notes •  Review –  Sleep/Wake •  Announcements: –  None •  Muscle –  Skeletal muscle •  Reading (Recommended): –  Relevant por<ons of Chapter 8 1 REV: Hypothalamus & Sleep •  Hypothalamus important in many regulatory func<ons. •  EEG provides electrical informa<on related to cor<cal synap<c ac<vity. •  Sleep defini<on based on EEG paOerns (along with Eye and Muscle electrical paOerns). •  Sleep is an ac<ve process ac<vated by the VLPO •  Sleep Depriva<on alters our physiological capacity in many systems 2 –  Slow Wave Sleep (80%) –  Paradoxical (REM) Sleep (20%) –  90 minute cycles for a total of about 7.5 hours/night Muscle Physiology 3 Muscle •  Comprises largest group of <ssues in body •  Three types of muscle –  Produce force; different control mechanisms –  Similar contrac<le mechanisms; different morphologies –  Skeletal muscle (40 ­50% of body mass) –  Smooth muscle (5 ­10% of body mass) –  Cardiac muscle •  Make up muscular system  ­ voluntary •  Appears throughout the body systems as components of hollow organs and tubes – involuntary; ANS control •  Found only in the heart •  Classified in two different ways –  Striated or unstriated –  Voluntary or involuntary 4 Categoriza<on of Muscle Fig. 8 ­1; pg. 258 5 Muscle •  Controlled muscle contrac<on allows –  Purposeful movement of the whole body or parts of the body –  Manipula<on of external objects –  Propulsion of contents through various hollow internal organs –  Emptying of contents of certain organs to external environment 6 Skeletal Muscle Contrac<on Fig. 8 ­13; pg. 268 7 Structure of Skeletal Muscle •  Muscle consists a number of muscle fibers lying parallel to one another and held together by connec<ve <ssue. •  Single skeletal muscle cell is known as a muscle fiber: –  Mul<nucleated –  Large, elongated, and cylindrically shaped –  Fibers usually extend en<re length of muscle 8 Structure of Skeletal Muscle •  Myofibrils –  Contrac<le elements of muscle fiber –  Regular arrangement of thick and thin filaments •  Thick filaments – myosin (protein) •  Thin filaments – ac<n (protein) •  Sarcomere –  Func<onal unit of skeletal muscle –  Found between two Z lines (connects thin filaments of two adjoining sarcomeres) 9 Structure of Skeletal Muscle Fig. 8 ­2ab; pg. 259 10 Structure of Skeletal Muscle 2 Kinds of Protein Contrac1le Regulatory Fig. 8 ­2cd; pg. 259 11 Myosin •  Component of thick filament •  Protein molecule consis<ng of two iden<cal subunits shaped somewhat like a golf club –  Tail ends are intertwined around each other –  Globular heads project out at one end •  Tails oriented toward center of filament and globular heads protrude outward at regular intervals –  Heads form cross bridges between thick and thin filaments •  Cross bridge has two important sites cri<cal to contrac<le process –  An ac<n ­binding site –  A myosin ATPase (ATP ­splifng) site 12 Structure and Arrangement of Myosin Molecules Within Thick Filament Fig. 8 ­4; pg. 260 13 Ac<n •  Primary structural component of thin filaments •  Spherical in shape •  Thin filament also has two other proteins –  Tropomyosin and troponin •  Each ac<n molecule has special binding site for aOachment with myosin cross bridge –  Binding results in contrac<on of muscle fiber 14 Ac<n & Myosin •  Ac<n and myosin are ohen called contrac<le proteins. Neither actually contracts. •  Ac<n and myosin are not unique to muscle cells, but are more abundant and more highly organized in muscle cells. 15 Tropomyosin and Troponin •  Ohen called regulatory proteins •  Tropomyosin –  Thread ­like molecules that lie end to end alongside groove of ac<n spiral –  In this posi<on, covers ac<n sites blocking interac<on that leads to muscle contrac<on –  Made of three polypep<de units •  One binds to tropomyosin •  One binds to ac<n •  One can bind with Ca2+ •  Troponin 16 Composi<on of a Thin Filament Fig. 8 ­5; pg. 261 17 Tropomyosin and Troponin •  Troponin –  When not bound to Ca2+, troponin stabilizes tropomyosin in blocking posi<on over ac<n’s cross ­bridge binding sites –  When Ca2+ binds to troponin, tropomyosin moves away from blocking posi<on –  With tropomyosin out of way, ac<n and myosin bind, interact at cross ­bridges –  Muscle contrac<on results 18 Role of Calcium in Cross ­Bridge Forma<on Fig. 8 ­6; pg. 262 19 Sliding Filament Mechanism •  Cross ­bridge interac<on between ac<n and myosin brings about muscle contrac<on by means of the sliding filament mechanism. 20 Sliding Filament Mechanism •  Increase in Ca2+ starts filament sliding •  Decrease in Ca2+ turns off sliding process •  Thin filaments on each side of sarcomere slide inward over sta<onary thick filaments toward center of A band during contrac<on •  As thin filaments slide inward, they pull Z lines closer together •  Sarcomere shortens •  All sarcomeres throughout muscle fiber’s length shorten simultaneously •  Contrac<on is accomplished by thin filaments from opposite sides of each sarcomere sliding closer together between thick filaments 21 Changes in Sarcomere During Shortening Fig. 8 ­8; pg. 263 22 ...
View Full Document

{[ snackBarMessage ]}