Chapter 17 18 Musculature Digestive Systems The Musculature

Chapter 17 & 18 Musculature & Digestive Systems

The Musculature System

The Musculature System n Includes 3 types of Muscle: n n Function of the Muscles: n n Striated, Smooth & Cardiac Provide means of Movement Keeps blood pumping Moves food thru Digestive System Skeletal Muscle usually in Antagonistic Pairs n n Flexor (bicep) Extensor (tricep)

n n n n n Skeletal Striated Voluntary Organ Smooth Involuntary Heart Cardiac Involuntary The Musculature System 3 Types of Muscle Tissue Skeletal, Smooth and Cardiac

How Muscles Work n n n Muscles can only contract & get shorter They cannot push things, they only pull. They are attached to two different bones and cause them to bend at the joint n n n Origin They work in Antagonistic Pairs n n Insertion n Origin – place the muscle attaches or begins (proximal) Insertion – place on the other side of joint muscle attaches (distal side) Flexors – cause the joint to bend – bicep Extensor – causes the joint to extend ( straighten out) - tricep Muscles are attached to bones w/ tendons

Smooth & Cardiac Muscle n n Smooth Muscle – usually are not voluntarily controlled. Found in the walls of hollow organs of the digestive tract & blood vessels. n They assist in the movement of food thru the digestive system (peristalsis) and movement of blood thru the circulatory system. Cardiac Muscle – found only in the heart. Similar to both Striated & Smooth Muscle tissue. Involuntarily controlled by brain.

Skeletal Muscle Structure n n Skeletal muscles are made up of bundles of muscle fibers which in turn are made of myofibrals (multi-nucleated muscle cells). Each myofibral is made of n n n thin filaments called Actin and thick filaments called Myosin. Muscle Bundle Fibers Myofibrils Filaments Actin & Myosin Each fiber is divided into functional units called sarcomeres tendon Muscle Bundle Fiber Sarcomere Myofibril Filaments

Skeletal Muscle Sarcomere n n n Sarcomere is divided into various zones. Each Sarcomere is separated by Z discs Light colored bands are I bands Dark colored bands are A bands Middle of the dark A band is H zone Middle of H zone is the M line Muscle contraction begins after a nerve stimulates the muscle fiber. n Actin Myosin

Skeletal Muscle Contraction n. Muscle contraction begins after a nerve stimulates the muscle fiber. n Impulse causes Actin filaments to slide over (like a ratchet) the Myosin filaments. n This shortens the length of the sarcomere. n Once contracted, the H zone closes up. n. This shortening isn’t much until you add up the thousands of sarcomeres in each muscle bundle. Actin Myosin

Need-to-Know Skeletal Muscles Know these muscles: Masseter, Trapezius, Deltoid, Pectoralis, Latissimus dorsi, intercostals, Rectus abdominis, External obliques, Biceps brachii, Triceps, Gluteus, Rectus femoris, Biceps femoris, gastronemius

The Digestive System Mouth pharynx esophagus stomach duodenum jejunum ileum cecum ascending colon transverse colon descending colon sigmoid colon rectum anus n General info: n n Basic “tube-within-a-tube” Digestion by mechanical & chemical means Mechanical Digestion from cutting, grinding, chewing in mouth. From churning by peristalsis in stomach Chemical Digestion beginning in mouth through stomach & small intestines. n n n Acidic p. H in mouth & stomach Switches to basic p. H in small intestine Accessory Organs – food doesn’t pass thru them. They supply digestive “juices”. n Salivary glands, Liver, gall bladder & pancreas

Upper Digestive Tract n Mouth & Pharynx n Teeth n n n Incisors- slice Canines – tear Premolars – grind Molars - grind Tooth Structure n n n Crown, neck & root Enamel – hard for protection Dentine – softer, alive bone-like Pulp – soft blood & nerve tissue Cementum & Periodontal membrane “glue” tooth to the bony socket Chewed Food (smaller pieces w/ higher surface area) mixes w/ saliva becomes bolus. Enzyme Amylase begins Carbohydrate chemical digestion. Swallowed food passes thru pharynx, past epiglottis & into esophagus n

The Esophagus n n Involuntary contractions and relaxation of smooth muscle surrounding esophagus moves food down esophagus: Peristalsis Cardiac Sphincter: Ring shaped muscle separating the esophagus from the stomach q sphincters are muscles that squeeze the digestive tube closed and help move material in only one direction.

The Stomach n n Cardiac Sphincter n n n Mechnical & Chemical digestion Stomach secretes HCl – very acidic Mucus secretions protect lining from self-digestion Stomach lining w/ folds to increase surface area Bolus is mixed w/ acids for several hours – now called chyme. n n n Carbohydrate and protein digestion takes place. Enzyme Pepsin used in protein digestion Leaves thru Pyloric Sphyncter to the duodenum.

Small Intestine n n n About 20 ft long, 1”-2” in diameter Most chemical digestion takes place here 3 regions – duodenum, jejunum and ileum Chemical p. H 8 – protein, fats & carbohydrates are digested Increased surface area by millions of villi and microvilli Absorption into blood stream by highly vascular integration surrounding digestive tract.

Large Intestine (aka Colon) n n 5 -6 feet in length, 3”-4” in diameter Main Functions n n n Reabsorption of water Reabsorption of vitamins Waste elinination Very little digestion (most is done in the stomach & small intestine) Divided into Cecum, Ascending, Transverse, Descending, and Sigmoid Colon Undigested food & Wastes stored in the rectum before being eliminated thru the anus.

Accessory Digestive Organs n n Salivary Glands – secretes saliva and enzyme amylase. Mixes w/ food forms Bolus. Liver- filters blood & secretes Bile used to emulsify & digest Fats Gall Bladder – stores bile until needed Pancreas- 3 functions n n n Release & control of insulin in the Islets of Langerhans. Controls sugar blood levels Release digestive enzymes Produce sodium bicarbonate to convert stomach acid to a basic solution in the duodenum

Chapter 17 Muscle & Digestive Systems That’s all folks!!