Digestive System•Transport Quiz tomorrow

•Transport, Digestion, Homeostasis Test on 10/16 (Chapters 8, 41, 44)

•Set-up computers – digestion PPT is on website (save to computer)

•You can check the osmosis worksheet answers

Today

• Review – homeostasis, organic compounds, enzymes

• Types of feeding

• Types of digestion

• Know the parts of the mammalian digestive system

Homeostasis• Cells of the pancreas

monitor blood glucose levels

• High levels release insulin body cells and liver take up glucose stored as glycogen

• Low levels release glucagon liver breaks down glycogen releases glucose into blood

Feedback Mechanism

in pancreatic

cells

glucose

Problems when sugar is too high or too low

• Hyperglycemia (Diabetes) – blood sugar levels too high– Type II – fats cells are more resistant to

insulin over time

• Hypoglycemia – low blood sugar levels• Too much sugar in the blood

cardiovascular disease• Insulin (Diabetic) shock brain function

is affected first, disorientation, aggressiveness, slurred speech

Type I vs Type II Diabetes

Overnourishment

Undernourishment

Weight Regulation

Anorexia nervosa

• Medical consequences– Shrunken bones– Mineral loss– Low body temp.– Irregular heartbeat– Permanent failure of normal growth– Osteoporosis– Use of laxatives – increased risk of colon infection

and stretched colon– Miscarriages

Acid reflux/Bulimia

• Cancer• Ulcers• Scar tissue –

blockage of food• Asthma• Infection

Time for Digestion

30 sec

5-6 sec

2-4 hrs

5-6 hrs

12-24 hrs

Digestion

• Process of breaking down food into smaller molecules that can be used by the cell

• Digestion breaks down organic compounds (protein, carbs, etc.) into their components so the body can use to them for energy or building blocks for other compounds

• You are what you eat!

Amino Acids

Vitamins/Minerals• Vitamins – organic, required in small

amounts– Water-soluble (B,C) – coenzymes needed for

macromolecule metabolism, collagen synthesis

– Fat-soluble (A,D,E,K) – visual pigments, calcium absorption, blood clotting

• Minerals – inorganic molecules– Calcium – bone formation, muscle contraction– Iron – electron carriers, Oxygen transport

(hemoglobin)

Malnourishment – deficiency in a nutrient

• Scaly skin – deficiency of Biotin, Zinc

• Hair loss – vitamin A• Many deficiencies in

nutrients will cause irratibility

Feeding mechanismsSuspension-feeders

Bulk-feedersFluid-feeders

Substrate-feeders

Deposit-feeders

1. Stages of Food Processing

1. Ingestion

2. Digestion – hydrolytic enzymes

3. Absorption

4. Elimination

Intracellular Digestion

• Ingestion – phagocytosis, pinocytosis

• Digestion – hydrolytic enzymes contained in lysosomes

• Absorption – simple diffusion

• Elimination - exocytosis

Extracellular Digestion – can eat larger prey

Gastrovascular cavity

Complete digestive tracts(alimentary canals) – allow for systematicFood processing in specialized regions

1 opening2 openings

What you should know

• Each step of the digestive process– Name of organ– Structural adaptations– Type of digestion (mechanical, etc.)– Enzymes involved

a. Mechanical Digestion – the physical breakdown of large pieces of food into smaller pieces

b. Chemical Digestion – the process that turns complex molecules (fats, carbohydrates, proteins) into smaller molecules to be used by cells

II. Functionsa. Mouth

i. Teeth – used to tear, cut, and crush food into small fragments (Mechanical)

ii. Saliva –

1. Makes food slippery for easy swallowing

2. Begins chemical digestion of the food with help from enzymes – a protein that speeds up (catalyzes reactions)

a. Amylase – breaks bonds in starches to release sugar

b. Lysozyme – another enzyme that fights infection by breaking down the cell wall of bacteria that may be in the mouth

b. Esophagus

i. Tongue and throat muscles push the ball of food down your throat

ii. To ensure the food does not go down the trachea (windpipe), the epiglottis (flap of tissue) covers the opening to the trachea

iii. After passing through the throat, the food passes through the esophagus by peristalsis – rhythmic contractions of the smooth muscle

c. Stomachi. The food passes to the stomach

next where further mechanical and chemical digestion will occur1. Chemical Digestion

a. Hydrochloric Acid (HCL) and Pepsin – begin digestion of protein

2. Mechanical Digestiona. Stomach muscles contract to

churn and mix stomach fluids creating a mixture called Chyme.

Gastric Pits

d. Small Intestine

i. Completes digestion by dissolving the fat

1. Bile from the liver - breaks down the fat

2. Lipase – digests the fat

ii. Absorption of the nutrients into the bloodsteam occurs through villi (fingerlike projections lining the small intestine). Villi increase surface area and therefore the absorption rate

Positive feedback mechanism

e. Large Intestine

i. All that makes it to the large intestine is water, cellulose, and other undigested molecules

ii. Water is reabsorbed back into the body through the wall of the large intestine

iii. The concentrated waste material (feces) is then passed out of the body through the rectum

• http://kidshealth.org/PageManager.jsp?lic=1&article_set=59299&cat_id=20607

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter26/animation__organs_of_digestion.html

Digestive Enzymes

III. Disorders

a. Ulcers are caused by the destruction of the lining of the stomach by HCL

b. Infection with the bacterium Heliobactor pylori is said to play an important role in causing stomach ulcers

c. Strong antibiotics has become the most common treatment for stomach ulcers

• http://kitses.com/animation/swfs/digestion.swf

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter26/animation__organs_of_digestion.html