Unit 2 - Nutrition, Digestion, Excretion Flashcards
Carbohydrates - function
- important source of energy
- body prefers carbohydrates over all other available sources
- must be obtained from other organisms
Dehydration synthesis
glucose + glucose -> maltose + water
Hydrolysis
sucrose + water -> glucose + fructose
7 roles of proteins
- Structural
- Contractile
- Storage
- Defence
- Transport
- Signal
- Enzymes
Enzymes - function
- act to catalyze activation energies of chemical reactions
- digestive enzymes are enzymes that break down food into usable material
- shape of enzyme must match substrate
Enzymatic reaction
- Enzyme binds loosely to substrate at active site
- Chemical change takes place at active site, resulting in two products
- Products are released from active site
Lipids - function
- source of energy
- long term storage
- for making cell membranes and hormones, and for bringing in certain vitamins that are fat soluble
Fats and oils
- made from two different molecules, glycerol and fatty acids
- formula for fat formation is 1 glycerol, 3 fatty acids
Saturated fats
- carbon chains have single bonds; strong and hard to break down
- butter, lard, coconut oil
Monounsaturated fats
- one double bond between two carbons; less hydrogens present than in saturated fats
- olive oil, canola oil, peanut oil
Polyunsaturated fats
- more than one double bond between carbons; way less hydrogen
- fatty fish oil, avocado oil
Waxes
- long chained fatty acids combined with long chained alcohols
- creates insoluble molecules which act as waterproof coating for leaves, feathers, and fur
Steroids
- structurally different from other lipids
- consist of four linked rings of carbon atoms
- functions include chemical messengers (hormones), digestion (bile acids), and cell membrane structure (cholesterol)
Monosaccharides
- “one sugar”
- three types are glucose (aka blood sugar), fructose (aka fruit sugar), and galactose
Disaccharides
- “two sugars”
- formed chemically by the joining of two monosaccharides through dehydration synthesis
- sucrose (table sugar), lactose (milk sugar), and maltose (beer/bread making)
Polysaccharides
- few hundred to few thousand monosaccharides joined together by dehydration synthesis
- starch (plant storage), glycogen (animal storage), cellulose (plant fibre), chitin (protective exoskeletons of arthropods)
- can be split through hydrolysis
Mechanical digestion
Mouth: biting and chewing
Stomach: layers of muscle contract and churn
Chemical digestion
Mouth: saliva contains enzyme called amylase, digests starch molecules
Stomach: an enzyme called pepsin, and hydrochloric acid, digest large proteins into smaller proteins
Small intestine: pancreatic enzymes digest nutrients into simpler forms, bile assists in fat digestion (breaks down fat globules), protein digestion is accomplished by several enzymes
Where are carbs digested?
The mouth and small intestine
Where are proteins digested?
The stomach and small intestine
Where are lipids digested?
The small intestine
Examples of enzymes involved in digestion
Amylase digests starch
Pepsin digests proteins
Lipase digests lipids
Stages of digestion
- Mouth
- Esophagus
- Stomach
- Small intestine
- Large intestine
Digestion in the mouth
- food changed mechanically by biting and chewing
- saliva binds food particles together into a soft mass called a bolus
- amylase digests stars molecules into smaller molecules (maltose)
Digestion in the esophagus
- esophagus is a thick walled muscular tube
- bolus moves through esophagus by peristalsis: rhythmic series of muscular contractions
Digestion in the stomach
- layers of muscle contract and churn food with gastric juices to form chyme
- enzyme called pepsin, and hydrochloric acid, digest large proteins into smaller proteins
- alcohol and sugar are absorbed by the stomach into the blood stream
- stomach stores food and prepares it for further digestion
Digestion in small intestine
- chyme enters through sphincter
- pancreatic enzymes digest nutrients into simpler forms
- bile enters from gall bladder to assist in fat digestion
- polypeptides are broken into amino acids
- most absorption occurs in the ilium
- products enter cells of villi, enter capillaries
- diffusion accounts for movement of most nutrients, but active transport is responsible for movement of glucose and amino acids
- absorption is completed in the jejunum
Digestion in large intestine
- substances not absorbed pass into large intestine
- main functions are to absorb water and to store, process, and eliminate residue following digestion and absorption
- intestinal matter (feces) remaining are stored in the rectum and passed out through the anus
Pancreas - function
secretes many digestive enzymes
Liver
- produces bile; mixture of salts, pigments, and cholesterol that breaks down globules of fat in the small intestine
- bile stored in gall bladder
Villi
- fingerlike projections on inner surface of small intestine
- contain small blood vessels that absorb nutrients
Microvilli
projections of cells on each villus that increases the surface area
Duodenum
first part of small intestine
Ilium
middle of small intestine, where most absorption takes place
Jejunum
final part of small intestine, where absorption is completed
Adrenal glands
Produce hormone adrenal
Kidney
- humans have two kidneys, located one behind the stomach and one behind the liver, in the small of the back
- excretion of water is closely regulated by the kidneys, as well as the chemical composition of blood
- the kidneys filter blood
Ureter
- tube that carries urine from kidney to bladder
Urinary bladder
Muscular sac that stores urine until it can be excreted
Urethra
Tube that carries urine from bladder to outside of the body
Renal artery
Carries blood to kidney
Renal vein
Carries blood away from kidney
Renal pelvis
Inner portion of kidney that connects to ureter; funnels urine
Nephron
- basic structural and functional unit of the kidney is the nephron
- each kidney has about one million, located in the cortex
- primary function is to filter blood
- three major parts
Glomerulus
- bed of capillaries
- blood enters kidney from renal artery and moves into glomerulus where filtration occurs
Filtration
- process of water and dissolved particles being pulled out of the blood
- resulting liquid is called filtrate (contains water and toxic substances that might have accumulated in blood like ammonia, glucose, vitamins, etc.)
Bowman’s capsule
- glomerulus is enclosed by Bowman’s capsule
- small molecules and water pass through this area, larger molecules remain in capillaries
- filtrate is collected in Bowman’s capsule for transport
Tubules
- filtrate moves in proximal tubule, water and nutrients are reabsorbed into blood
- wastes remaining in blood even after filtration are passed to tubules
- filtrate flows into Loop of Henle, concentrated by removing more water, then passes to distal tubule
- waste and toxic substances are passed from blood into filtrate; process called secretion
- travels to collecting duct, now called urine, prepared for transport out of body
- collected in renal pelvis, enters ureter, then goes to bladder
Flow of filtrate through the nephron
glomerulus -> Bowman’s capsule -> proximal tubule -> Loop of Henle -> distal tubule -> collecting duct -> renal pelvis -> ureter -> bladder
