DIGESTIVE SYSTEMS



DIGESTIVE SYSTEMS Name_________ Date__________

In Animals the Digestive System has one Function:

*

3 Overall Steps to Accomplish Digestion:

1. _____________ 2. ________________ 3. ________________

Although only the second one is called "digestion" all three of these processes are considered functions of the digestive system.

1. ______________: Bringing food in; "eating."

ex.: mouths, lips, sucker lips on a fish, raspy teeth on a lamprey

2. __________________:

a) _____________: (or physical): shredding, biting, cutting, ripping, chewing, mashing, grinding

ex.: teeth, labrum (biting mouth parts in a grasshoppers, humans using knives, gizzards (in worms and birds), stomachs (very slightly)

b)________________: biological catalysts called enzymes (a type of protein) help large molecules get broken into molecules small enough to be absorbed into bloodstreams.

ex of enzymes: chemicals ending in "ase" : lactase digests lactose; lipase digest lipids

Occurs in mouths (enzymes in saliva), stomachs (enzymes in gastric or stomach "juice"), and intestines (enzymes from the intestines themselves and from the pancreas)

3. _________________: defecating (pooping)

ex.: anus, cloaca, vent (different names for almost the same thing)

All animals have to do the above tasks but have different structures to accomplish them. It is through evolutionary changes, that different animals have "solved" the problem of how to accomplish these basic tasks. Keep this in mind.

There are two basic body plans for digestive systems:

1. _____________________:

Ingestion and Egestion occur through the same hole!!!

(like what happens when you vomit). This is what some animals always do.

ex. Sea Anenomes (where Nemo lives) and hydra. Food goes in the mouth/anus and feces go out the same mouth/anus

[pic][pic] [pic]

2. ________________________:

Ingestion through a mouth and egestion through an anus (or equivalent).

These systems are called alimentary canals (by analogy, as a boat goes through a canal, food goes through the digestive tube)

[pic]

Most animals with this type of system have a mouth for ingestion, a stomach and intestines for digestion, and an anus for egestion.

There are two different general places that digestion occurs:

1. ____________________________________ (inside of cells)

Only single celled organisms like protista do this. Since they are only one cell to begin with, their digestive "systems" are just organelles inside themselves (inside a cell).

2___________________________________ (outside of cells)

All other organisms do this.

Even bacteria, although only single-celled, also digest their food outside of their selves by excreting digestive enzymes onto their food, and absorbing the smaller chemicals of food that result.

Humans and other animals do extracellular digestion but they do it intra"bodily",

i.e. inside of their bodies but outside cells in the hollow spaces of their digestive system.

HUMAN DIGESTIVE SYSTEM

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The digestive system - (also called the ________________) is a series of organs and glands that ______________. It breaks the _________________________________________.

Our body has to break food down into smaller molecules and _____________________.

The Digestive Process:

• The digestive process begins in the _____________.

• Food is partly broken down by the process of __________and by the chemical action of ________________ (physical and chemical digestion)

• After being chewed and swallowed, the food enters the _______________.

• The esophagus is a long tube that runs from ___________ to ______________.

Like all parts of the tube, it uses wave-like muscle movements (called _____________________) to force food from the _______________ into the _______________.

• The stomach is a large, sack-like organ that ______________ and bathes it in a very strong_________________ (_____________)

• There are also some ________________ in the stomach

• Food in the stomach that is partly digested and mixed with stomach acids is called ____________________.

• After being in the stomach, food enters the ______________.

• In the _______________, ______ (squirted from the ______and ________), and ___________________ (squirted from the _______), and other digestive enzymes (produced by the small intestine itself) cause the chemical breakdown of food.

• Three parts of the small intestine:

1.

2.

3.

• After passing through the __________________, food passes into the ____________.

• In the large intestine: _________________ (chemicals like _____________) are removed from the food. Many __________ (such as bacteria like Escherichia coil or E. coli for short) in the large intestine help in the digestion process.

[pic]

• The large intestine starts at the ________________ and ends at the ___________.

• Solid waste is then stored in the ______________________ until it is excreted via the ________.

Mixed Bag of Terminology

____________________________ - the passage through which food passes, including the mouth, esophagus, stomach, intestines, and anus.

____________ - the first part of the digestive system, where food enters the body. Chewing and salivary enzymes in the mouth are the beginning of the digestive process (breaking down the food).

_____________ - the long tube between the mouth and the stomach. It uses rhythmic muscle movements (called peristalsis) to force food from the throat into the stomach.

______________- a sack-like, muscular organ that is attached to the esophagus. Mostly chemical and a little bit of mechanical digestion takes place in the stomach. When food enters the stomach, it is churned in a bath of acids and enzymes.

Accessory Organs of Digestion

(not part of the alimentary canal (tube) – but produce chemicals that get squirted into the tube)

1. __________- a large organ located above and in front of the stomach. It filters toxins from the blood, produces some vitamins and makes bile (which breaks down fats) and some blood proteins

2______________ - a small, sac-like organ located in the liver. It stores and releases bile (a digestive chemical which is produced in the liver) into the small intestine.

__________ - a digestive chemical that is produced in the liver, stored in the gall bladder, and secreted into the small intestine. It emulsifies (makes smaller) large fat gobs into little goblets that can be more easily digested.

3. ____________- an enzyme-producing gland located below the stomach and above the intestines which helps in the digestion of carbohydrates, fats and proteins in the small intestine. It also produces sodium bicarbonate that neutralizes stomach acid as it enters the small intestine so that the acid does not corrode the small intestine lining. It also produces the hormone insulin, which keeps blood sugar (glucose) at the proper levels.

Other terms:

4._______________ - food in the stomach that is partly digested and mixed with stomach acids.

5.______________ - the flap at the back of the tongue that keeps chewed food from going down the windpipe (larynx and trachea) to the lungs. When you swallow, it automatically closes. When you breathe, it opens so that air can go in and out of the windpipe.

6.__________________ - rhythmic muscle movements that force food in the esophagus and the other parts of the tube from the mouth to the anus. This movement is involuntary - you cannot control it. It is also what allows you to eat and drink while upside-down.

7.________________________ - glands located in the mouth that produce saliva. Saliva contains enzymes that break down carbohydrates (starch) into smaller molecules.

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