Chapter 34.1-34.2, 41: Animal Digestion and Excretion

Animals are all

heterotrophs

Single-celled organisms/sponges digest their food

intracellularly

• Each cell digests for itself

• No digestion in a body cavity

Other multicellular animals digest their food

extracellularly

• within a digestive cavity

Cnidarians and flatworms, have a

gastrovascular cavity

Specialization occurs when the digestive tract has a separate

mouth and anus

• Known as an alimentary canal

Mouth

• Cavity where food enters

• Teeth start mechanical digestion

Tongue

moves food, mixes itwith saliva, and helps swallow

Esophagus

• Tube that delivers food to stomach

• Muscular contractions propel fooddown, known as peristalsis

Stomach

• Sack for preliminary digestion

• Secretes gastric juice to digest

Pepsinogen

breaks down proteins

Hydrochloric acid

reduces food

Small intestine

• Receives bile and pancreatic juicefor further digestion

• Absorbs majority of nutrients

• Has increased surface area toabsorb most efficiently

Villi =

finger-like projections of wall

Microvilli =

finger-like extensions of cell membrane

Large intestine

• Absorbs the remaining water

• Contain bacteria that

• convert cellulose into sugar, synthesize vitamin K

• End in rectum, and wastes are expelled through the anus

Liver:

produces bile that helps tobreak fat into smaller units

• Excess bile is stored in the gall bladder

Pancreas:

produces pancreaticjuice that digests most major typesof organic molecules

Monogastric

• One stomach

• Carnivores have this asdigestion of meat is easy

Ruminant

have a four-chambered stomach

Contents can be regurgitated and rechewed called

rumination

Avian

• No teeth

• Two chambered stomach

Proventriculus:

food is stored anddigestive juices are introduced

Gizzard:

muscular compartmentthat breaks down food with thehelp of rocks

Essential nutrients

substances that an animal cannot manufacture for itself but are necessary for health

Vertebrates have nutritional deficiencies,

and must gain a range of essential nutrients from food

To maintain osmotic balance, the animal’s body must

• be able to take water from the environment

• excrete excess water into the environment

• Exchange solutes to maintain homeostasis

Tonicity

the measure of a solution’s ability to change the volume of a cell by osmosis

Hypertonic:

more solute/less water; will take in water from surroundings

Hypotonic:

less solute/more water; will lose water to surroundings

Isotonic:

equal water exchange with surroundings

Water always moves from

hypotonic to hypertonic

Nitrogenous Wastes are produced when

amino acids andnucleic acids are broken down

The amino group is removed ,resulting in

ammonia

Bony fishes and immature amphibians

eliminate ammonia by diffusion via gills

Chondrichthyes, adult amphibians, and mammals

convert ammonia into urea, which is dissolved in water

Birds, reptiles, and insects

• convert ammonia into the water-insoluble uric acid

• Uses more carbon, but does not need water

Osmoconformers

• organisms that are in osmotic equilibrium (isotonic) with theirenvironment

• most marine invertebrates and chondrichthythes

Osmoregulators

• Maintain a constant blood osmolarity different than their environment (hypertonic/hypotonic) • Most vertebrates

• All terrestrial animals

Single-celled protists use

contractile vacuoles

Protonephridia are a

network of tubes which branch into bulb like flame cells

Flame cells

remove solutes and excess water from body

Nephridia

One on each segment

• A series of convoluted tubules that remove excess water and solutes from blood and produce urine

• Urine excreted through anephridiopore

Malpighian tubules

Insects

• extensions of the digestive tract

Nitrogenous wastes →

urea

(Cartilaginous fish Isotonic to

seawater

(Saltwater bony fish) Hypotonic to

seawater

(Saltwater bony fish) Water wants to leave their bodies

by osmosis across their gills

(Freshwater bony fish) Hypertonic to

fresh water

• Water wants to enter body from environment

Each kidney is made up

of about 1 million functioning nephrons

Urine is produced

from the blood and funneled into renal pelvis

(Nephron) Blood is carried into the

glomerulus

• Plasma is filtered as it is forced through porous capillary walls

• the result is filtrate

• Filtrate enters the Bowman’scapsule

(Nephron) Filtrate moves through the

renal tubules

• Proximal convoluted tubule

• Loop of Henle

• Distal convoluted tubule

• Collecting duct

Filtration

• Blood plasma is filtered out ofthe glomerulus into the tubule system

Reabsorption

• Selective movement of substances out of the filtrate back into the blood

Secretion

• Active movement of substancesfrom the blood into the filtrate

Epinephrine/norepinephrine

halt kidney function

• Renin

controls blood volume and kidney filtration

• Aldosterone

increases reabsorption of sodium in kidney

• Antidiuretic hormone

increases reabsorption of water in kidney