BSC 109 Lecture 17: BSC 109 Chapter 14 Part 1
24 Oct 2016
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BSC 109 Chapter 14 Part 1
Digestive System and Nutrition
October 19, 2016
Clicker: Steroid (hydrophobic) hormones have the faster mechanism of action compared to non-
steroid hormones. False
Clicker: Which gland produces oxytocin? Hypothalamus
Clicker: Hyper secretion of growth hormone after puberty would most likely result in which
condition? Acromegaly
Clicker: Which hormone is considered a gonadotropin? FSH and LH
Clicker: Cushing’s syndrome results from an over secretion of which hormone? Cortisol
The Digestive System Brings Nutrients Into the Body
• The digestive system includes:
- Gastrointestinal (GI) tract (hollow tube)
o Lumen: space within this tube
o Includes mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum,
anus
- Accessory organs
o Salivary glands, liver, gallbladder, pancreas
Can be divided into two areas: GI and hollow tube
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Figure 14.1 Organs and Accessory Organs of the Digestive System and Their Functions
Right side: hollow tube
Left side: major accessory organs;
aid in the breaking down of food
The Walls of the GI Tract Are Composed of Four Layers
• Common layers throughout the system
1. Mucosa: innermost layer, mucous membrane in contact with the lumen
2. Submucosa: layer of connective tissue containing blood vessels, lymph vessels, nerves
3. Muscularis: two or three layers of smooth muscle, responsible for the movement,
motility
4. Serosa: outermost layer
• Sphincters: thick muscular rings that separate some of the organs
Muscularis is a double layer – longitudinal and latitudinal; involuntary, help with
churning the food up and propelling it forward
Serosa holds everything in place and makes sure the intestines do not get tangled up
The sphincters serve as a check point or a door throughout the system
Five Basic Processes Accomplish Digestive System Function
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1. Mechanical processing and movement
- Includes chewing and mixing
Breaking down food – physical breaking down, chewing, or the muscles that churn the
stomach
The food passes through a turbulent path
2. Secretion of the following:
- Fluid
- Digestive enzymes and hormones
- Bile, acid, alkali, mucus
Secrete a mixture of fluids that aid in the digestion of food; the four listed above
3. Digestion
- Breaking down food to smallest absorbable units
- Includes chemical and mechanical breakdown
Chemical and mechanical
Carried out by digestive enzymes
Break the bonds between the atoms in order to chemically digest or breakdown food
4. Absorption
- Occurs through mucosa
- Nutrients and water move into blood or lymph vessels
Food is too large to pass on, so it has to be broken down so it can be passed through the
blood
5. Elimination
- Undigested material is eliminated as feces
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Document Summary
Clicker: steroid (hydrophobic) hormones have the faster mechanism of action compared to non- steroid hormones. The digestive system brings nutrients into the body: the digestive system includes: Gastrointestinal (gi) tract (hollow tube: lumen: space within this tube, includes mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus. Accessory organs: salivary glands, liver, gallbladder, pancreas. Can be divided into two areas: gi and hollow tube. Figure 14. 1 organs and accessory organs of the digestive system and their functions. Left side: major accessory organs; aid in the breaking down of food. Muscularis is a double layer longitudinal and latitudinal; involuntary, help with churning the food up and propelling it forward. Serosa holds everything in place and makes sure the intestines do not get tangled up. The sphincters serve as a check point or a door throughout the system. Emily-paige montgomery epmontgomery@crimson. ua. edu: mechanical processing and movement. Breaking down food physical breaking down, chewing, or the muscles that churn the stomach.
