zoology( the book 1)

DIGESTION AND NUTRITION.

DIGESTION AND NUTRITION

All organism requires... ENERGY.

SUN – ultimate source of energy for life on earth.


Autrophic

Heterotrophic

prototrophs

chemotrophs


DIETARY HABITS:

- Herbivorous

- Omnivorous

- Carnivorous

- Saphrophagus


Few animals can absorb nutrients directly from their external environments.

-Feeding on Particular Matter-Feeding on Food Masses-Feeding on Fluids

FEEDING MECHANISMS:


(Feeding on Particular matter)

Suspension feeder- aquatic organisms that collect suspended food particles from the surrounding water; particles are filtered(filter feeding) or taken by other methods.

FEEDING MECHANISMS:


(Feeding on Particular matter)

Deposit feeder- aquatic organisms that consume detritus and small organisms on soil or other sediments

FEEDING MECHANISMS:

(Feeding on Food Masses)

predators most locate, capture, hold and swallow prey.

carnivorous animals seize food and swallow it while some employ toxins that paralyze or kill prey upon capture.

FEEDING MECHANISMS: DIGESTION AND NUTRITION

(Feeding on Food Masses)

fishes, amphibians, and nonavian reptiles use their teeth to grip prey and prevent it’s escape until they can swallow it.

birds lack teeth, nut their beaks are often provided with serrated edges, or upper beak is hooked for seizing and tearing prey.


Biting, cutting and stripping

Seizing, piercing, and tearing Grinding and crushing

(Feeding on Fluids)

Fluid-feeding is especially characteristic of parasites. But it is practiced among many free-living forms as well.



Purpose: reduce feed particles to molecules that can be absorbed into the blood

Digestion is the process of breaking down food into simple substances that can be absorbed by the body.

Absorption is the process of taking the digested parts of food into the bloodstream.

WHAT IS DIGESTION?


• Mechanical breakdown of food

• Chemical breakdown of food– HCl in the stomach– enzymes

• Contractions of digestive tract

WHAT IS DIGESTION?


In the mechanical phase, teeth or structures physically break down large pieces food into smaller pieces.

In the chemical phase, digestive chemicals called enzymes break apart individual molecules of food .

WHAT IS DIGESTION?


TYPES OF DIGESTION

Intracellular Digestion

The simplest invertebrates(animals without backbones)do not have specialized digestive organs. Single-celled organisms, such as amoebas, rely on intracellular digestion (digestion within the cell).

WHAT IS DIGESTION?


TYPES OF DIGESTION

Intracellular Digestion

A food particle is enclosed within a food vacuole by phagocytosis Food wastes are simply extruded from the cell by exocytosis.

WHAT IS DIGESTION?


TYPES OF DIGESTION

Intracellular Digestion more complex organisms require

systems that are more specialized. Animals such as jellyfish and nonparasitic flatworms combine the intracellular process with some specialized digestive organs.

WHAT IS DIGESTION?


TYPES OF DIGESTION

Extracellular DigestionMost of the more complex

invertebrates and all vertebrates (animals with a backbone) digest food entirely through extracellular (digestion outside the cell) processes.

WHAT IS DIGESTION?


TYPES OF DIGESTION

Extracellular Digestion Food moves in one direction, from

mouth to anus, through the series of organs that make up the alimentary canal.

WHAT IS DIGESTION?


TYPES OF DIGESTION

Extracellular Digestion Digestion is completed in the intestine . The

liver and pancreas pour their digestive juices into the anterior end of this organ. After the anterior intestine absorbs the usable products of digestion, the walls of the posterior intestine absorb leftover water.

WHAT IS DIGESTION?


TYPES OF DIGESTION

Extracellular Digestion In vertebrates the anterior intestine is

called the Small intestine ; the posterior intestine is the large intestine .Feces , composed of unabsorbed and indigestible food residues, form in the posterior intestine.

WHAT IS DIGESTION?


Animals classified by the type of stomach they have:

Monogastric or non-ruminants

Ruminants

Avian

Pseudo-ruminant

WHAT IS DIGESTION?


MONOGASTRIC ANIMALS• Monogastric(simple) – one or simple stomach

structure• mostly carnivores and omnivoresEg. Hogs, cat, dog

RUMINANT ANIMALS• Ruminant (polygastric)- 4 compartment stomach

with the compartments before the “true” stomach• • herbivoresEg. Cattle, sheep, goat

WHAT IS DIGESTION?


AVIAN ANIMALS• is found in poultry ;differs greatly from any other

type.• Since a bird has no teeth, no chewing is involved.• Eg. Chicken.

PSEUDO-ROMINANT• An animal that eats large amounts of roughage but

does not have a stomach with several compartments.

• can utilize roughages because of an enlarged cecum and large intestine.

• Eg. Horse

WHAT IS DIGESTION?

DIGESTIVE SYSTEM

DIGESTIVE SYSTEM TYPES OF DIGESTIVE SYSTEM

Incomplete Type -when anus is absent, mouth serves for ingestion of food and egestion of waste materials

Complete Type- mouth and anus are present; may be subdivided into the digestive tract, the digestive glands, and the accessory structures

DIGESTIVE SYSTEM DIVISIONS OF THE COMPLETE TYPE

OF DIGESTIVE SYSTEM:

I. Coelom, Peritoneum, and Mesenteries

DIGESTIVE SYSTEM Coelom – cavity containg the visceral organs

Divided into:

a. small pericardial cavity – contains the heart

b. larger pleuro-peritoneal cavity – which contains the rest of the visceral organs

DIGESTIVE SYSTEM Peritoneum – connective tissue membrane that lines the coelomTypes: a. parietal peritoneum – lines the

body wall b. visceral peritoneum – covers

most visceral organs

DIGESTIVE SYSTEM Mesenteries -two layers of the peritoneum that suspends viscera from the dorsal body wall - name of organ they suspend Omentum -double membrane continuous with the mesenteries that connect the visceral organs with one another - also named after organ they connect.

II. Buccal Cavity

DIGESTIVE SYSTEM II. Buccal cavity:- large cavity exposed upon opening the mouth Parts: maxillary teeth – in the upper jaw sticky tongue – located at the floor of the

cavity which captures food and passes it on the esophageal opening

glottis – slit-like opening to the respiratory system and is found at the region between the tongue and esophageal opening

DIGESTIVE SYSTEM vocal sacs – where pair of slits lead to

; slits are located lateral to the glottis and near angle of jaw

choanae or internal nares- pair of holes at the roof of the buccal cavity

vomerine teeth- pair of v-shaped formations at the root of the mouth

Eustachian tube – opening or recess near the angle

III. Digestive tube:

DIGESTIVE SYSTEM III. Digestive tube:1.esophagus

– short tube connecting the oral cavity to the stomach2. Stomach

– bag shaped muscle

Parts of stomach:a. cardiac end – anterior portion continuous with the esophagus b. pyloric end – posterior portion continuous with the small intestinec. greater curvature – outer curvatured. lesser curvature – inner curvaturee. rugae – lines of the inner wall of the stomach

DIGESTIVE SYSTEM 3. pyloric sphincter – constriction at the junction of the stomach

and the small intestine 4. Small Intestine - digestive tube that has become the long

coiled structure from the pylorus - where most chemical digestion and

absorption occurs Has 2 regions: a. duodenum – bends anteriorly from the

pylorus and runs parallel to the stomach b. ileum – longer and posterior

DIGESTIVE SYSTEM 5. Large Intestine - where digestive tube enlarges - further breakdown of undigested

material by bacterial action and the absorption of water occur here

6. Cloaca – short narrow tube which opens to

the outside through the anus - urine and gametes also pass

through the cloaca and anus

DIGESTIVE SYSTEM

Mesenteries found in digestive system

dorsal mesentery – digestive tube is suspended from the dorsal body

mesogaster – mesenteries in the stomach at its cardiac end

mesentery proper or mesenterium – suspends the ileum

mesorectum – suspends rectum

7. Spleen – dark lymphoid organ lying within the fold of the

mesorectum

DIGESTIVE SYSTEM IV. The digestive glands: Liver- largest gland in the body -function: secretes bile, and monitor and

controls the balance of the body by removing the toxins in the body.

- Has three lobes: a left lobe subdivided into anterior and posterior

lobules a small right lobe much reduced median lobe Gall bladder- stores the bile secreted by the liver Bile- emulsifies fat, neutralizes the acidic food

entering the intestine and creates pH favorable for pancreatic and intestinal enzyme action.

Pancreas- digestive gland and an endocrine gland

DIGESTIVE SYSTEM As a digestive gland: Secretes pancreatic juice which contains several

enzymes for the chemical breakdown of food. These enzymes include lipase,

deoxyribonuclease, amylase and carboxypeptidase

As an endocrine gland: Secretes insulin Common Bile Duct- formed by the union of the

cystic duct of the gall bladder, the hepatic duct, and the pancreatic ducts

- Enters the anterior portion of the duodenum

zoology( the book 1)

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