Ch 4 - Body Basics

anatomy

study of cells and other body structures

physiology

study of how cells and body structures function

cell

smallest functional structure in living organism; made of molecules

• human has a/b 35-40 trillion ___ plus bacteria

• CANNOT get nutrients directly from food

  • must be broken down into nutrients

organelles

structures within cells that perform specialized functions

• AKA building blocks of cells

  • nucleus

  • mitochondria

  • ribosomes

  • plasma membrane

nucleus

where DNA (genetic material for cell’s proteins and other info) is located

DNA

genetic material for cell’s proteins and other info

mitochondria

where fuel is “burned” for energy

ribosomes

machines that make proteins in a cell

plasma membrane

separates cell from its environment, regulates intake and export of materials

DNA location

found in most cells of living organisms, w/ a few exceptions

• cells in multicellular organisms utilize different parts of ___

  • ex: eye cells use eye genes; liver cells use liver genes

tissue

collection of similar cells that perform specialized functions

• epithelial tissue → cells that form linings (ex: digestive system, skin)

• connective tissue → cells that hold together, protect, and support organs (ex: bone, fat, blood)

organ

collection of tissues that perform a specific function

system

collection of organs that work together to perform a major function

homeostasis

maintenance of approximately constant internal chemical and physical environment

• ex: body temp, blood pressure, acid-base balance, etc.

  • critical for good health and survival

from cells to organ systems to body

elements

substances that cannot be separated into simpler substances by ordinary chemical or physical means

• each type of atom is called an ___

• not made by human body

  • 118 in living organisms known

minerals

elements that are found in the earth’s crust, including some like calcium, iron, and zinc

• not made by humans

chemical bond

an attractive force that holds atoms together to form molecules

• can be single (-), double (=), or triple

molecules

cells are made up of these; and these are made of atoms

• biomolecules

  • carbohydrates

  • proteins

  • DNA

  • lipids

compounds

key chemical compounds in body (water, organic molecules, and minerals)

• water

• proteins

• lipids

• carbohydrates

• nucleic acids

• minerals

chemical reactions

processes that change atomic arrangement of molecules

digestion

all processes by which molecules in food are mechanically and chemically broken down

enzymes

proteins that make chemical reactions go faster (e.g., in metabolism and digestion)

• biological catalysts (recycled, not altered in chemical reaction)

• names of most end in “-ase”

  • ex: sucrase, lactase, lipase, protease

metabolism

all the chemical reactions that occur in living cells

• catabolism → break down molecules (releases energy)

• anabolism → build up molecules (supports growth, stores energy)

lymphatic system

helps maintain fluid balance, absorb many fat-soluble nutrients, and defend body against diseases (immune function)

• transports fat

• main organs

  • lymphatic vessels and lymph nodes, lymph (fluid that leaks out of blood plasma into spaces between cells, collected and transported in lymphatic vessels, “the sewer system”), white blood cells, spleen, thymus

absorption

process where digestive system moves essential compounds from digested food through intestinal lining into blood stream or lymphatic system

digestive system

breakdown of large food particles into smaller components (nutrients), and absorption of nutrients into bloodstream or lymphatic system

• main organs (GI tract)

  • mouth, esophagus, stomach, small and large intestines

• gastrointestinal (GI) tract → organ system

gastrointestinal (GI) track

hollow muscular tube extending from mouth through whole digestive system to anus

bioavailability

extent to which digestive tract absorbs a nutrient and how well the body uses it

• how good body is at absorbing nutrients

digestion process

mouth (mechanical/chemical digestion w/ enzymes) → esophagus (swallowing) → stomach (gastric juice) → small intestine (absorption of most nutrients - caught w/ villi and absorptive cells; digestive enzymes) + accessory organs (liver, gallbladder, pancreas) → liver (nutrients transported here) → large intestine (colon + rectum; microbes and bacteria, feces)

mouth digestion

• mechanical digestion

• chemical digestion

  • saliva mixes and lubricates food

  • salivary amylase → begins breakdown of starch in mouth

  • lingual lipase → begins breakdown of fat (in stomach)

• sense of taste and smell

  • taste buds

  • olfactory receptors, contribute to sense of taste

swallowing

• esophagus

• epiglottis (flap folds down over trachea (windpipe) when swallowing)

  • automatically stop breathing; prevents choking

• stimulates peristalsis

esophagus

tube connecting pharynx (behind/below mouth) w/ stomach

peristalsis

stimulated by swallowing

• waves of muscle contraction that move material through digestive tract

  • involuntary, not consciously controlled

stomach

• gastroesophageal sphincter (controls opening/closing of stomach; prevents esophageal reflux (acid from stomach into esoph.))

• secretes gastric juice (hydrochloric acid and ezymes)

  • acid activates enzymes and kills most microbes from food

• chyme

• mucus

• pyloric sphincter (controls rate of chyme release into small intestine)

gastric juice

AKA hydrochloric acid and enzymes

• secreted by stomach

  • acid activates enzymes and kills most microbes from food

chyme

mixture of gastric juice and partially digested food (stomach contents)

stomach mucus

lubricates and protects stomach walls from gastric juice

• if it breaks down, ulcers can form in stomach lining

pyloric sphincter

controls rate of chyme release into small intestine

small intestine

where most nutrients digested (broken down into smaller nutrients and released; catalyzed by digestive enzymes) and absorbed

• 20-25 ft long

• 3-5 hours for chyme to get through

• 3 sections

  • duodenum (acid contents of stomach mix w/ alkaline fluids secreted by pancreas (makes digestive enzymes) and gallbladder (bile salts, like detergents to break up fat)

  • jejunum (where most digestion and absorption occurs)

  • ileum (connects to large intestine)

    • things that cannot be absorbed, become waste

absorption of nutrients

in small intestine

• villi (tissue structure) → tiny projections that line small intestine; maximize space for digesting and absorbing nutrients

  • microvilli cover absorptive cells

• absorptive cells (cell type) → catch and transfer nutrients into blood

villi

tiny projections that line small intestine

• anatomical tissue projection; long-lasting tissue architecture

• cover absorptive cells

absorptive cells

in small intestine; remove nutrients from chyme and transfer them into intestinal blood or lymph

• short life-span, constantly dying and being replaced

  • need adequate nutrition to make new cells

    • malnutrition leads to poor absorption, worse malnutrition, reduce bioavailability

accessory organs for digestion

do not come into contact w/ chyme

• liver → processes and stores nutrients; produces cholesterol and bile to process fats

• gallbladder → stores and secretes bile (aids in fat digestion)

• pancreas → produces and secretes digestive enzymes and bicarbonate ions (increase pH)

bile

helps process fats; made by liver

• aids in fat digestion

transportation of nutrients to liver

nutrients enter capillary of villus/villi; transported to liver w/ portal vein (specialized food highway)

• after breakdown and absorption in small intestine, nutrients absorbed into blood

  • nutrient-rich blood funneled into large blood vessel (hepatic portal vein) and goes to liver

• chylomicrons → particles formed by small intestinal cells for transport of lipids through lymph and into bloodstream

large intestine

two major sections = colon and rectum

• where absorption of water and minerals occur AND feces forms

• contains microbes

rectum

lower part of large intestine; where feces are stored

gut microbiota

vast numbers in large intestine (AKA “friendly” bacteria)

• can…

  • metabolize undigested food material

  • make vitamin K and biotin (absorbed by host)

  • produce gas

• very important to good health

• symbiosis 1 (organism living inside another in mutually beneficial arrangement)

health and gut microbiota

very important to good health

• starvation, killing bacteria w/ antibiotics, emotional stress → diarrhea and cramps or infection w/ less beneficial bacteria (intestinal dysbiosis)

• yogurt w/ live bacteria reestablishes friendly microorganisms and balance

intestinal dysbiosis

occurs from infection w/ less beneficial bacteria in large intestine

• can happen b/c of starvation, killing bacteria w/ antibiotics, or emotional stress

probiotics

live, beneficial intestinal microbes

• mainly bacteria and yeast

• found in yogurt, cultured buttermilk, other fermented foods

  • also dietary supplements

• not approved by FDA

prebiotics

forms of dietary fiber that are poorly digested by human but support growth of beneficial gut microbes

adaptable human digestive tracts

• can handle combinations of foods

• can digest and absorb nutrients from wide variety of sources

• adjust kinds and amounts of different kinds of digestive enzymes made according to diet

  • ex: if eating a lot of sugar, body makes a lot of sucrase

auto-brewery syndrome

when there is too much yeast in gut (bacteria can’t keep under control), sugars can be fermented into alcohol

• treated w/ antifungal medication

colorectal cancer

cancer in colon or rectum

• 2nd leading cause of cancer deaths among adults

• primary cause of death for men under 50

  • African American men at higher risk

• nutrition may be risk factor

  • red/processed meat

  • % body fat

  • alcohol / cigarrete consumption

• easy to detect, treatable when caught early

GERD

gastroesophageal reflux disease

• symptoms = frequent heartburn, nausea, gagging, coughing, hoarseness)

• untreated → damage esophagus lining, esophageal ulcers (sores), esophageal cancer

peptic ulcer

sore in lining of stomach or duodenum

• deep, dull upper abdominal pain a/b 2 hours after eating

irritable bowel syndrome (IBS)

intestinal cramps and abnormal bowel function (diarrhea or constipation)

• unknown cause → linked to stress