Maintenance Physiology Information for Nutrition

Joshua, Chigozie, and Jazmean

April 2015

Accomplishing Nutrition 

Plants

1. Autotrophic: Plant makes its own food from simple raw materials

1. Photosynthesis

2. Heterotrophic: Plants obtain nutrients and minerals from other organisms

1. Parasitic: Connects with their host’s vascular system through the roots
2. Insectivorous: These plants trap insects or other small organisms for nutrients
3. Plants obtain mineral nutrients from the soil

Unicellular Organisms (Fungi)

1. Most fungi are saprophytic (obtains nutrients from dead or decaying organisms)
2. Fungi can also be parasitic

1. Mycorrhizal: This fungi is able to take nutrients from the roots of the trees while the tree is able to gain nutrients from the surrounding soil by the fungi

Animals (Non Vertebrates) like Earthworms swallow dirt, decayed leaves, and other organic material while they burrow. The food passes through their pharynx and esophagus into their gizzard where the food is grinded up. 

Why is it Needed?

It is needed for growth and development. Plants, animals, and other unicellular organisms also use the process of nutrition to gain energy.

Dependent on other Body Systems (Mammals)?

The digestive system depends on other systems to accomplish the process of nutrition. The digestive tract functions by using muscular contractions to break up food and move it along the tract. Smooth muscle in the stomach churns food into a liquid, and contractions of the intestine move food through the system. Without the oxygen gained from the respiratory system, this would not happen. Large amounts of blood is needed for ongoing digestive functions due in part of the absorptive properties of the intestines and because it is almost constantly occurring. Without the circulatory system providing the blood, the digestive system would cease in function. Lastly, there needs to be a system that can take post digestive waste out of the body. This is where the excretory system comes into play. This system takes undigested nutrients and post digestive waste out of the body so it is not recycled back into the bloodstream.  

Dependent on other Life Systems?

Movement

1. Plants: Roots move in the soil and the stem moves towards the light which allows for better exposure to light.
2. Animals: Move their bodies quickly which gives them the ability to search and obtain their food, obtain shelter, or even escape danger

Respiration

1. Extracting energy out of food which is necessary for growth and mobility

1. Aerobic and anaerobic respiration both release energy as a result of an intake or lack of an intake of oxygen.

Growth

1. All organisms grow usually up until adulthood. As you grow and when you stop growing, materials in your body are being replaced by the food you intake.

Transportation into Circulatory System

In the stomach, proteins are broken down into amino acids by using the enzyme pepsin and are absorbed into the bloodstream (which is a part of the circulatory system) by the small intestine.

Carbohydrates are digested into disaccharides in the mouth due to amylase. It is then further digested into monosaccharides by using enzymes secreted from the pancreas. It is here where the monosaccharides are able absorbed across the intestine into the bloodstream to be transported to different parts of the body.

Water soluble vitamins are able to be absorbed directly into the bloodstream through the small intestine.

Regulatory Feedback Loop in Digestive System

Gastrin Feedback Loop (Positive)

1. Presence of food in the stomach, stretching of the stomach, and/or hydrogen ions in the stomach trigger the release of the hormone gastrin

1. Gastrin triggers the gastric glands to release pepsin and HCI which digests food

1. This causes the release of more gastrin

2. This is a positive feedback loop because the response (the release of pepsin and HCI) causes the stimulant (gastrin) to increase

Disruptions in Digestive System?

What happens when the system gets all wonky?

1. Ulcers

1. Cause: Helicobacter pylori bacterium
2. Symptoms: Burning sensation in upper abdomen
3. Treatment: Antibiotics, diet modification

2. Diarrhea/Constipation

1. Cause

1. Diarrhea: Too much water in feces which leads to decreased absorption by large intestine
2. Constipation: Too little water in feces which means that feces stay in the large intestine longer than normal

2. Symptoms

1. Diarrhea: Cramping
2. Constipation: Tenesmus (feeling of having to poop although you already did)

3. Treatment: Laxatives, increased fiber intake, diet modification

Microvillus: Microscopic, Finger-like Protrusions

Why do Nutrients Move into the Blood at the Microvillus? What is an example of a substance that is absorbed in the digestive system at another location?

• The lining of the small intestine is covered in tiny microvilli

• Give the lining of the small intestine a massive surface area for absorption of nutrients to occur across
• Each microvillus contains a minute blood capillary. When nutrients are absorbed into a microvillus, they enter its blood capillary. This is how nutrients from food enter blood.

• Example: Fats

• The first step in digestion of a fat such as butter is to dissolve it into the watery content of the intestinal cavity
• Bile acids produced by the liver act as natural detergents to dissolve fat in water and allow the enzymes to break the large fat molecules into smaller molecules, some of which are fatty acids and cholesterol

• Combine with the fatty acids and cholesterol and help these molecules to move into the cells of the mucosa

• In these cells the small molecules are formed back into large molecules, most of which pass into vessels (called lymphatics) near the intestine
• These small vessels carry the reformed fat to the veins of the chest, and the blood carries the fat to storage depots in different parts of the body.