EXAM 3

gastrointestinal tract

a continuous hollow tube extending from the mouth to the anus
-Its walls are constructed by the oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine
-approx. 30 ft long
-aka alimentary tract

1. ingestion
2. digestion
3. movement (mixing)
4. absorption
5. elimination

What are the 5 processes necessary to the digestion process?

ingestion

one of the processes of digestion; the taking of food or liquid into the body via the mouth

digestion

one of the processes of digestion; breaking down of large nutrient molecules into smaller molecules that can be absorbed; can be mechanical or chemical

mechanical digestion

specific type of digestion that entails the cutting and mastication (chewing) of food; peristalsis

chemical digestion

specific type of digestion; digestive enzymes hydrolyze macromolecules

movement (mixing)

one of the processes of digestion; food is passes from one organ to the next via peristalsis

absorption

one of the processes of digestion; taking in of subunit molecules by cells or membranes

elimination

one of the processes of digestion; process of expelling substances from the body via defecation

hard palate

bony anterior portion of the roof of the mouth

soft palate

entirely muscular portion of the back roof of the mouth

uvula

tissue tag hanging from soft palate

tongue

occupies the floor of the mouth and has 4 functions

1. grips food
2. repositions food between teeth
3. mixes food with saliva
4. movements from bolus

What are the 4 functions of the tongue?

salivary glands

glands associated with the mouth; secretes saliva

saliva

solution of water, mucus, salivary amylase, lysozyme, and bicarbonate; has 4 functions

1. cleanses the mouth
2. dissolves food chemicals for taste
3. moistens food & aids in compacting food into bolus
4. contains enzymes that begin chemical breakdown of starch

What are the 4 functions of saliva?

salivary amylase

the first enzyme to begin chemical digestion of starch

teeth

lie in sockets in the gum-covered margins of the maxilla and mandible; contains 2 main divisions: crown & root; there are 32 total in adults

enamel

hard material composed of calcium compounds and covers crown of tooth

dentin

thick layer of bone-like material beneath enamel of tooth

pulp

the inner tissue of the tooth containing blood vessels and nerves

dental caries (cavities)

results from acids produced by bacteria metabolizing sugar

periodontitis

inflammation of the periodontal membrane that lines tooth sockets; causes loss of bone and loosening of teeth

pharynx

portion of the GI tract between the mouth and the esophagus
-Serves as a passageway for food and also air on its way to trachea
-Trachea is parallel and anterior to the esophagus

esophagus

muscular tube for moving swallowed food from the pharynx to the stomach

swallowing

composed of a voluntary phase and involuntary phase (reflex action)
-Soft palate moves back to close off nasal passage via uvula
-Epiglottis covers the glottis, which is the opening to the larynx (voice box)

peristalsis

wavelike contractions that propel bolus along the esophagus

sphincters

muscle that surrounds a tube to open or close by relaxing or contracting

lower gastroesophageal sphincter

marks the entrance of esophagus to stomach
-Sphincter contracts to prevent acidic contents of stomach from backing into esophagus

heartburn

happens when lower gastroesophageal sphincter fails to open and allow food in the stomach or when it opens allowing stomach contents back into esophagus

stomach

a muscular sac that mixes food with gastric juices to from chyme, which then enters the small intestine
-1 L capacity; pH 2
-Stores food; does not absorb nutrients; empties in 2-6 hrs
-Initiates digestion of proteins with enzyme pepsin
-Controls the movement of food into the small intestine

gastric juice

produced by gastric glands of stomach; includes pepsin, mucus, & HCl

chyme

thick semi-liquid food material that passes from stomach to the small intestine

pyloric sphincter

regulates chyme entry into the small intestine

small intestine

long tubelike chamber of GI tract between stomach & large intestine
-Contains enzymes secreted by pancreas and enters via duct in duodenum to digest carbs, fats, and proteins
-Receives bile produced by the liver, stored in gallbladder & released into duodenum
-About 20 ft long
-Contains 3 sections: duodenum, jejunum, & ileum
-Nutrients are absorbed here (villus)

1. duodenum
2. jejunum
3. ileum

What are the 3 sections of the small intestine?

duodenum

first 10 inches of small intestine

jejunum

2nd part of small intestine; 8 ft long

ileum

3rd part of small intestine; 12 ft long

villus

small fingerlike projections of the inner small intestine wall (mucosa); increases surface area of small intestine
-Outer layer has cells that have microvilli (brush border)
-Blood capillaries and small lymphatic capillaries (lacteal) are present

lactose intolerance

inability to digest lactose because of an enzyme deficiency
-Do not have brush border enzyme (lactase)
-Symptoms include diarrhea due to fluid retention, gas, bloating, & cramps when bacteria breakdown lactose anaerobically

1. pancreas
2. liver
3. salivary glands
4. gallbladder

What are the 4 accessory organs of the digestive tract?

pancreas

internal organ that produces digestive enzymes; also produces hormones insulin & glucagon; accessory organ in the digestive system

type 1 diabetes

happens when pancreas does not produce sufficient amounts of insulin (onset typically before age 15)

type 2 diabetes

happens when pancreas does not make enough insulin or body's cells are insulin resistant (onset typically after age 40)

pancreatic amylase

enzyme in the pancreas that digests starch to maltose

trypsin

protein-digesting enzyme secreted by the pancreas

lipase

fat-digesting enzyme secreted by the pancreas

liver

large, dark-red internal organ; accessory organ in the digestive system and contains the following functions:
1. DETOXIFIES blood (hepatic portal vein brings blood to liver from GI tract capillaries
2. Stores GLUCOSE as glycogen, iron, vitamins A, D, E, K, & B12
3. Produces PLASMA PROTEIN and UREA
4. Produces BILE (stored in gallbladder) to emulsify fats
5. Regulates CHOLESTEROL

urea

primary nitrogenous waste derives from amino acid breakdown in liver

jaundice

yellowish tint to the skin caused by abnormal bilirubin (bile pigment) in blood, indicating liver malfunction

hepatitis

inflammation of the liver; often caused by \______ B virus

cirrhosis

chronic irreversible injury to liver tissue; caused by alcohol or Hepatitis C virus

large intestine

last major portion of the digestive tract; extending from the small intestine to the anus; approx. 5 ft long
-Function is to absorb water
-Does NOT absorb nutrients (exceptions are absorption of vitamins K and B-complex)
-Includes the cecum, vermiform appendix, colon, rectum, & anus

absorb water

What is the function of the large intestine?

cecum

the blind pouch at the beginning of the large intestine; has the vermiform appendix

vermiform appendix

small tubular appendage that extends out from the cecum; aids in fighting infections

colon

the major portion of the large intestine, consisting of the ascending colon, transverse colon, descending colon, and sigmoid colon

rectum

terminal end of the digestive tube; last 20 cm of large intestine; stores feces

anus

outlet of the digestive tract; where defecation occurs

skeletal system

system of protection & support
-Composed of bones, cartilages, joints, & ligaments
-Starts forming at about 6 weeks (embryo about 12 mm long)
-206 named bones
-Makes up 20% of body weight

1. supports body
2. protects soft body parts
3. produces blood cells
4. stores minerals & fats
5. permits flexible body movement (along with muscles)

What are the 5 main functions of the skeletal system?

axial skeleton

forms the long axis of the body and includes the bones of the skull, vertebral column, & the ribcage

appendicular skeleton

consists of bones of the upper and lower limbs and their girdles that attach the limbs to the axial skeleton

cartilage

white, flexible semi-opaque connective tissue
-CHONDROCYTES are the mature cell form of this
-Has NO NERVES OR BLOOD VESSELS; well suited for padding joints

ligament

band of fibrous tissue that connects bone to bone
-Contains cells called FIBROBLASTS

tendon

cord of fibrous tissue attaching muscle to bone
-Also contains cells called FIBROBLASTS

organic and inorganic compounds

What are the two groups of the chemical composition of bone?

organic

components of bone that include OSTEOBLASTS, OSTEOCYTES, & OSTEOCLASTS
-Bones are composed of living tissues

inorganic

components of bone that include HYDROXYAPATITES (mineral salts)
-Largely composed of calcium phosphate

ossification

process of bone formation

osteoblasts

bone-forming cells
-Secrete the organic matrix of bone (mucopolysaccharides & collagen fibrils)
-Promote the deposition of calcium salts into the matrix

osteocytes

mature bone cells derived from osteoblasts; they maintain the structure of the bone

osteoclasts

large cells that reabsorb or breakdown bone matrix; assist in returning CALCIUM & PHOSPHATE to the blood

diaphysis

elongated shaft of a long bone

medullary cavity (marrow cavity)

cavity inside shaft of long bone
-Walls composed of compact bone
-Filled with yellow bone marrow (stores fat)

epiphysis

the end of a long bone attached to the shaft
-Composed largely of spongey bone
-Contains RED BONE MARROW; produces all types of BLOOD CELLS
-Coated with cartilage

periosteum

fibrous connective tissue covering of long bone
-Contains blood vessels, lymphatic vessels, & nerves

compact bone

highly organized and composed of tubular units called OSTEONS
-Within osteons, osteocytes (mature bone cells) occupy small cavities (LACUNAE)
-CANALICULI connect lacunae to one another and to central canal
-The central canal contains small blood vessels and nerve fibers

spongy bone

has an unorganized appearance compared to compact bone
-Composed of numerous struts or thin plates (TRABECULAE) separated by uneven spaces
-Spaces are often filled with RED BONE MARROW

endochondrial ossification

bone replaces cartilaginous models of the bones

1. smooth
2. cardiac
3. skeletal

What are the 3 types of muscle tissue?

smooth muscle

consisting of spindle-shaped, nonstriated muscle cells
-Located in walls of hollow internal organs and blood vessels
-SINGLE NUCLEUS in cell
-INVOLUNTARY MUSCLE, slow to react, does not fatigue easily

cardiac muscle

specialized muscle of the heart; striated; has 1-2 nuclei per cell
-These cells interlock at INTERCALATED DISKS
-INVOLUNTARY muscle

skeletal muscle

composed of cylindrical multinucleate cells with obvious striations
-Consists of muscles attached to the body's skeleton
-VOLUNTARY muscle

1. support
2. Movement of bones & other body structures
3. Maintenance of constant body temp.
4. Movement of fluids in the cardiovascular and lymphatic systems
5. Protection of internal organs & stabilization of joints

What are the 5 functions of muscle?

pairs

Muscles work in \______

shorten

When muscles contract, they \______

pull

Muscles can only \______

origin

the end of a muscle attached to a stationary bone

insertion

the end of a muscle attached to a movable bone

antagonist

the muscle that acts opposite to the prime mover (ex: bicep vs tricep)

sarcolemma

plasma membrane of a muscle fiber; forms the tubules of the T system
-Encases hundreds of thousands of MYOFIBRILS

T (transverse) tubules

membranous channel that extends inward toward sarcoplasmic reticulum

sarcoplasmic reticulum

smooth endoplasmic reticulum of muscle cells; surrounds myofibrils and stores calcium ions

myofibril

rod-like bundle of contractile filaments found in muscle cells; contains a LINEAR arrangement of SARCOMERES; run the entire length of muscle fiber; composed of even smaller MYOFILAMENTS

fascicle

a bundle of muscle fibers surrounded by connective tissue; found in SKELETAL MUSCLE

myofiber (muscle fiber)

muscle cell

myofilaments

smaller cells within myofibrils; contain two types: actin & myosin