Chapter 3 - Section 2

Body Systems work together

- Circulatory, Respiratory, Digestive and Excretory are some of the body systems that work together to guarantee our health. - The Digestive System breaks down food into small molecules that

the cells can absorb and use to produce energy for all activities inside an organism.

- The Respiratory System obtains oxygen, that along with the digested food will be sent to various parts of the body by the circulatory system.

- Materials not needed by our bodies will be eliminated by our Digestive and Excretory systems.

- All these functions are coordinated by our Nervous System, that sends signals to the different organs, triggering the necessary responses.

- See chart

Cellular Respiration

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The food we eat follows a path:MouthEsophagus, stomach, small intestine, large intestine, rectum and anus

Digestive System

• Digestion is the breakdown of the foods that you eat into smaller and simpler molecules that can be used by the cells.

• There are 3 different mechanisms : ingestion, digestion, absorption

• Digestion – is a mechanical and chemical process

Digestive System

Mechanical Digestion – the action of chewing and the peristaltic movements ( contractions of the esophagus, stomach and intestines ), help break the food and mix with the gastric juices in the digestive system

Chemical Digestion – enzymes and gastric juices help break food into much smaller pieces that can be absorbed by the cells.

Helping Digestion

• Mouth – Digestion starts inside the mouth.Teeth break the food and the saliva softens and lubricates food. The saliva also contains an enzyme that helps the digestive process of carbohydrates.

• The stomach digests mainly proteins

How Your Body Works

Helping Digestion

• The small intestine digest the rest of the carbohydrates, proteins and the lipids

• The small intestine receives enzymes from the pancreas and the bile from the gallbladder.

• The bile has acids that are important in the digestion of lipids.

Interaction between Circulation and Digestion

The small intestine is not smooth. It is lined with tiny fingerlike projections called villi.

The connection between the digestive system and the circulatory system happens in the walls of the villi, where wanted materials are absorbed.

• The function of the villi is to maximize the process of absorption of nutrients by the bloodstream.

• The projections increase the surface contact of the circulatory and digestive systems.

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Circulation and Digestion

• The nutrients in the small intestine are absorbed in the walls of the villi.

• After they are absorbed into the bloodstream, nutrients are carried to our body cells.

• Materials that are not absorbed are released as body wastes.

Energy for the Body

• Cellular respiration is a series of chemical processes inside the cells, in which oxygen combines with food molecules and energy is released.

• A cell uses this released energy to perform all of its tasks.

• Carbon dioxide (CO2) and water are givenoff as wastes The carbon dioxide goes back to the circulatory system and to the respiratory system to be eliminated by the lungs

• Alveoli are clusters of tiny, thin-walled sacs, surrounded by capillaries that will absorb the Oxygen and release the carbon dioxide

The connection between respiratory system and circulatory system, called the exchange of gases, will happen in the alveoli. Oxygen is absorbed and carbon dioxide is realized.

Getting Rid of Wastes

• The removal of waste products, or excretion, is an important life process in all organisms.

• If wastes aren’t removed, they can build up to toxic levels and damage cells and eventually the whole organism.

Getting Rid of Wastes

the lungs

• Undigested material is removed by the digestive system and CO2 is eliminated by

• The body regulates itself:

The body can sense any changes in its environment and responds by making changes in body functions.

• Homeostasis – series of mechanisms that happen in the body to keep the body’s stable internal conditions.

• Homeostasis happens through 2 different processes:

1) Negative Feedback2) Positive Feedback wkst

Negative Feedback2

• In a negative feedback mechanism, the body changes an internal condition back to its normal state.

2• Regulation

of the blood pressure is controlled by a negative feedback system.

Negative Feedback

• Ex: sweating – the sweat on the surface of the skin evaporates, lowering your body temperature

• Flushing - dilation of vessels close to yourskin helps release heat, lowering your body temperature.

Positive Feedback

They are called positive because it does not stop the process, but it accelerates it until this process is over

Ex: contraction of the uterus during a baby delivery

Contraction of the uterus is not a normal process, but it is necessary for the birth, so the body does not stop it. It accelerates it until the baby is born.

2 Blood Clotting• Blood clotting is

usually not good for the body, but it is necessary when you have a cut.

• A positive feedback mechanism will guarantee that this process will happen to avoid the loss of blood.