anatomy unit 2

atom

smallest unit of matter; most are neutral

element

substance made from 1 type of atom

valence electrons

outermost electrons in atom that interact with other atoms, often losing, gaining, or sharing electrons in bonds

compound

substance formed by the chemical combination of more than 2 elements that are chemically bonded

chemical bonds

lasting attraction between atoms, ions, or molecules that enables them to form chemical compounds

ionic bonds

2 ions bond because of opposite charges

ion

molecule that has gained or lost an electron and has a charge

covalent bond

atoms share electrons

molecule

group of covalently bonded atoms

polar covalent bond

unequal share of electrons, leads to partial charges

nonpolar covalent bond

equal share of electrons

electronegativity

the pull on shared valence electrons

hydrophilic

water soluble (polar molecules and ionic compounds)

hydrophobic

avoids water (nonpolar molecules, fats & lipids)

metabolism

the sum of all reactions occurring in a cell or organism

catabolism

nutrients or cell constituents are broken down to release energy or components (hydrolysis)

anabolism

larger molecules built or made from 2 or more atoms, ions, or molecules (dehydration synthesis)

ATP

energy transfer molecule with 3 phosphates

ADP

the low energy version of ATP, has 2 phosphates

organic compound

molecule with chains or rings of carbon

macromolecule

large molecule

polymer

long molecule made of many similar building blocks

monomer

small building blocks making up polymers

carbohydrates

source of energy, water balance, secretion; sugar monomer; water soluble; CHO

lipids

energy storage, insulation, waterproofing, hormones; glycerol/fatty acid monomer; not water soluble; CH(O)

proteins

structures, reactions, transport, hormones, movement; amino acid monomer; sometimes water soluble; CHONS

nucleic acids

holds genetic information, makes proteins; nucleotide monomer; water soluble; CHONP

saturated fats

no double bonds between carbons, solid at room temperature

unsaturated fats

at least 1 double bond between carbons, liquid at room temperature

phospholipids

hydrophilic (polar) head and hydrophobic (nonpolar) tail

steroid

fused rings form of lipids used as hormones or in membranes

cholesterol

used for membranes, modified into other hormones and vitamin D

hormones

signal molecules that travel via blood

enzymes

catalyst; proteins that speed up chemical reactions

activation energy

amount of energy required to start a reaction

substrate

reactant that enzyme acts on and changes

denaturation

enzyme shape changes causing it to not work on a reaction

inhibition

slows and disrupts enzyme work

activation

improves enzyme work temporarily

buffers

materials that prevent pH changes; needed for pH homeostasis

coenzyme

helps enzyme work better; “on switch”

inhibitor

blocks enzyme from doing a reaction, “off switch”

reaction rate

how fast the enzyme changes the substrate

active site

specific region on enzyme where substrate binds and catalysis takes place

ingestion

taking in food to the digestive tract

digestion

breaking down food into simpler molecules

absorption

bring nutrients from digested material to the blood (or lymph) to be delivered to cells

elimination

removal of undigested materials from body via defecation

defecation

feces

secretion

release of enzymes and chemicals material to facilitate digestion, or hormones to regulate digestion

motility

muscular movement of materials through GI tract

regulation

coordinating digestive organ activity

alimentary canal (GI tract)

organs that digested food passes through, the “tube” for food; mouth, pharynx, esophagus, intestines, stomach

accessory organs

organs that contribute to the digestive process in the main alimentary canal organs; teeth, salivary glands, liver, gallbladder, pancreas

mechanical digestion

physical breaking down of food into smaller pieces to increase surface area of food for exposure to chemical digestion

chemical digestion

chemical reactions assisted by enzymes that break chemical bonds in the macromolecules to make them smaller (monomers) to be absorbed into blood

mucosa

protective inner layer that produces mucus (thick in the stomach) and provides a barrier against foreign particles and captures them in mucus and clears them out

submucosa

layer that is made of connective tissue and contains blood, nerves, and lymph vessels

muscularis

layer of smooth muscle that is important for peristalsis

serosa

outermost layer of the wall

mesentary

special peritoneal membranes that line the cavity and anchors digestive organs to the abdominal cavity

sphincter

muscular doorway between GI tract organs to control when things enter or exit

lower esophageal sphincter

(cardiac) prevents stomach acid from entering esophagus (involuntary)

pyloric sphincter

controls when stomach contents enter duodenum (involuntary)

anal sphincter

controls exit of feces from body (involuntary/voluntary)

mouth

used to take in food

mastication

chewing food and mixing in saliva and its enzymes (amylase and some lipase) from salivary glands

bolus

ball like mix of saliva and food that will be swallowed

pharynx

“throat” that leads from mouth and nose to esophagus or trachea

epiglottis

flap of tissue at end of pharynx/throat that blocks off trachea (windpipe) to make sure food goes into esophagus

esophagus

moves bolus of food from mouth to stomach

peristalsis

rhythmic wavelike contraction of muscles that helps push food forward in GI tract

segmentation

breaking of food by “swishing” from similar peristalsis-like contraction of muscles in GI tract

stomach

allows chemical and mechanical digestion through gastric juices and churning; can briefly store food from large meals

chyme

liquid mix of gastric juices and food (from bolus)

gastric juices

mix of enzymes, acids, and hormones made by stomach

hydrochloric acid

kills bacteria, creates acidic pH of 2-4, activates stomach enzymes

pepsin

enzyme made by stomach that digests proteins in the stomach

gastrin

hormone in stomach that regulates digestion

churning

strong movement of stomach contents by muscles

rugae

folds in the stomach that allow it to expand

small intestine

key organ that does majority of chemical digestion and nutrient absorption in the body

duodenum

initial segment of small intestine leading from stomach, receives enzymes and chemical from gallbladder and pancreas

villi

finger-like projections lining intestines that increase surface area for absorption into blood vessels

large intestine

absorbs remaining water and helps form feces, has bacteria that help release vitamins

feces

POOP

microbiome

beneficial bacteria communities that help release nutrients, such as vitamin K and B

appendix

contains bacteria that replenish intestinal flora

rectum

stores feces at the end of the large intestine

anus

opening allowing elimination of feces from body

fundus

dome shaped “hump” at the top of the stomach, located inferior to the diaphragm and to the left of the cardia

pylorus

funnel-shaped “end” of the stomach that connects the stomach to the duodenum

lumen

hollow space in the middle of an organ, lined by the mucosa in the GI tract

gastric pits

dots on the internal surface of the stomach, makes digestive gastric fluid

teeth

helps with mastication in mouth and used for grinding and tearing food

salivary gland

produces saliva that is secreted into mouth to soften food (amylase + very little and ineffective lipase)

amylase

starts breakdown of carbohydrate starches in the mouth and duodenum, produced by pancreas and salivary glands

lipase

digests lipids (fats) but needs bile, digests very little in mouth and mostly in duodenum, produced by salivary glands and pancreas

bile

critical secretion that helps emulsify fat; produced in liver and stored in gallbladder

emulsification

helps cut fat globs separate into smaller droplets so it can be accessed by digestive enzymes in the small intestine