Digestive Pt 1 thru slide 85 Flashcards by Johnny B

Refers to the use of the nutrients gained from food to
Build and maintain the structures of the body
Provide energy needed to keep us alive

Metabolism

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Also refers to interactive set of chemical pathways that make life possible

Metabolism

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Before food can be used for energy, growth and maintenance, and regulation of bodily functions, the nutrients have to be ______

Assimilated

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when nutrient molecules enter cells and undergo many chemical changes

Assimilation

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The act of breaking food molecules down into smaller molecular compounds that, in-turn, releases energy

Catabolism (a decomposition process)

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The act of building nutrient molecules into large molecular compounds that requires the use of energy

Anabolism (a synthesis process)

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Catabolism released energy in two forms:

Thermal Energy (heat)

2. Chemical Energy

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Released in frequent, small bursts or otherwise it would “cook” the cell it is being released in

____ energy is practically useless as an energy source for cells because it can’t be used to carry out work

This heat that gets released from all cells collectively maintains the body temperature for homeostasis

Thermal energy (heat)

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Cannot be used directly for biological reactions

It first has to be transferred into the high-energy molecule of adenosine triphosphate (ATP)

Chemical Energy

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The “universal biological currency”

Adenosine Triphosphate (ATP)

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___ are readily absorbed in their original form:

Micronutrients

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____ need to e small enough to be absorbed

Macronutrients

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Micronutrients:

-28 considered essential

Do not provide calories of energy

Vitamins & Minerals

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Macronutrients:

Proteins
Fats
Carbohydrates

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Calories of energy per Macronutrient:

Protein 4 cals
Carbohydrate 4 cals
Lipids9 cals

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Cheif energy source fo the brain

Glucose

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Digestion of carbs requires ezymes called:

Amylases

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Principle monosaccharide
Basic source of energy for cells
Found in things like fruits

Glucose

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Principle monosaccharide (converted to glucose by liver)
Basic source of energy for cells
Found in things like fruits

Fructose

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Principle monosaccharide (converted to glucose by liver)
Found mostly in dairy products (milk, cheese, butter)

Galactose

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Absorb-able form of carbohydrates:

Glucose
Fructose
Galactose

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Byproduct of polysaccharide (starch) digestion

Found in excess in beer and some liquor (Barley)

Maltose

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Glucose + Galactose

Principle sugar found in milk

Lactose

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Glucose + Fructose

Ordinary table sugar

Sucrose

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Disaccharides unable to be absorbed as is:

Sucrose Lactose Maltose

Polysaccharides unable to be absorbed as is or at all:

Starches Glycogen Cellulose (no absorbed or broken down)

Amylose and amylopectin combined | Potatoes, Corn, Oats, Rice

Starches

The stored form of glucose in the body | Found in the liver, muscle tissue, and some glial brain cells

Glycogen

Chemical name for fiber Fruit skins, whole-grain rice (the husk is the fiber), legumes (the shell is the fiber), corn (skin on kernel is the fiber)

Cellulose

Carbohydrates can be classified in the diet as:

Simple Complex

Monosaccharides and disaccharides Fast source of energy Can be found in fruits and milk, but also additives to things like candy, soda This is why these can cause a quick burst of energy followed by a “crash” after because it is used so quickly

Simple Carbohydrate

More difficult to digest because of longer chain sizes Polysaccharides Provides a more consistent amount of energy while being broken down (if able to be broken down) Can be found in things like whole grains, legumes, starchy vegetables

Complex Carbohydrates

Are most common form of lipid found in the diet and in the body

Triglycerides (TAGS)

Triglycerides are required for absorption of fat-soluble vitamins including:

A, D, E, K

Consists of one glycerol subunit that is attached to three fatty acids A high-energy nutrient synthesized and stored in adipocytes (adipose cells) as well as hepatocytes (liver cells)

Triglycerides (TAGS) Lipids

all hydrogen bonds are used (solid at room temp) Found in animal meats and dairy fats Can also be found in coconut and palm oils

Saturated Fatty Acids

1 glycerol cluster + 3 fatty acids =

Triglycerides or 'fat'

not all hydrogen bonds are used (liquid at room temp)

Unsaturated

Olive, canola, peanut oils | Oils found in almonds, pecans, and avocados

Monounsaturated

Safflower, sunflower, soybean, corn oils

Polyunsaturated

Compound Lipids:

triglycerides combined with other components Phospholipids Glycolipids Lipoproteins

Fatty acids + phosphorus + nitrogen Lipid “bilayer” in cell membranes, part of the nerve sheath

Phospholipids

Fatty acids + carbohydrate + nitrogen Part of cell membrane, helps to facilitate cellular recognition

Glycolipids

Chylomicrons Very low-density lipoproteins (VLDL’s) Low-density lipoproteins (LDL’s) High-density lipoproteins (HDL’s)

Lipoproteins

Derived Lipids:

Steroids Terpenes Fat-soluble vitamins Ketone bodies

In order to be absorbed at the cellular level, triglycerides have to be _____(broken down) into smaller components - Fatty acids (FAs) - Monoglycerides (MGs)

Hydrolyzed

Lipids need to be hydrolyzed by certain ___ enzymes

Lipase

(Cholesterol primary one) | Found in egg yolks, red meat, organ meats, shellfish, and dairy products

Steroids

Helps to build plasma membranes Precursor in synthesis of Vitamin D Requires for synthesis of androgens/sex hormones

Steroids

During _____ state blood may contain so many chylomicrons that it can appear turbid, or yellowish

Absorptive

In post-absorptive state (usually ~4 hours after meal) few ______ exist in blood Contents have moved mostly into adipose tissue

Cholymicrons (lipoprotein)

Entering blood from adipose tissue or other cells, fatty acids combine with ____ to form FFAs When rate of fat-catabolism increases (i.e. starvation), FFAs levels in blood increase markedly

Albumin

Lipoproteins: Largest to smallest Low protein to High Least dense to most slide #33

``` Chylomicrons VLDL IDL LDL HDL ```

Delivers triglycerides to cells throughout the body Synthesized in enterocytes (intestinal cells) from fat and cholesterol absorbed in the small intestine Very triglyceride-rich Very large particle

Chylomicrons

Because of large size, have to enter lacteals (lymphatic capillaries) which carries them to thoracic duct to be dumped into blood

Chylomicrons

Delivers triglycerides to cells throughout the body Very triglyceride rich Large particle, smaller than chylomicron

Very Low-Density Lipoprotein (VLDL)

Synthesized in the liver from excess fats and cholesterol that have made it there from portal circulation

Very Low-Density Lipoproteins (VLDL)

Delivers cholesterol to cells throughout the body As VLDL’s are stripped of their triglycerides, the “leftovers” get remodeled in the liver to form LDL’s Smaller particles than VLDL’s

Low-Density Lipoproteins (LDL)

Reverse cholesterol transport for excess cholesterol Returns excess cholesterol to the liver for recycling Is made in both the liver and the small intestines

High-Density Lipoproteins (HDL)

Triglycerides are first hydrolyzed to yield fatty acids and a glycerol Fatty acids are broken down into two carbon pieces (acetyl-CoA) by a process called ___-____ These then enter the citric acid cycle

Beta-oxidation

Glycerol is then converted to glyceraldehyde-3-phosphate which is then either:

Converted to glucose OR | Enters the glycolysis pathway

``` Synthesis of various types of lipids: Triglycerides Phospholipids Cholesterol Prostaglandins ```

AKA Lipogensis (Anabolism)

'Building blocks' of all cells

Proteins

Involved in the synthesis of certain neurotransmitters and hormones Serotonin, epinephrine, melatonin, histamine

Protein

Absorption of proteins requires them to be broken down into any of the following:

1. Amino Acid 2. Dipeptide 3. Tripeptide

Anything larger than (#) amino acids together is too large for absorption therefore requiring something to break it down smaller

Proteins are broken down by _____

Proteases

Of the 20 Amino acids, how many are essential, conditionally, and non-essential:

9 essential 7 conditionally 4 non-essential

Constitutes the major process for growth, reproduction, tissue repair, and replacement of all cells destroyed by wear and tear

Protein metabolism | anabolism & catabolism

Food is our only source of ____ energy Most food particles are too large to be used by cells in their original form

Chemical

GI tract also known as:

Alimentary (nourishment) canal

Gastrointestinal tract (GI tract) Approximately (##-##) feet long in living human In a state of ____(sustained contraction) Approximately (##-##) feet long in cadaver -Variation is due to loss of muscular tone after death

16-23 feet Tonus 23-39 feet

Accessory digestive organs:

``` Teeth Tongue Salivary glands Liver Gallbladder Pancrease ```

Term: Liquids into the mouth

Ingestion

Everyday, cells within the GI tract and accessory organs secrete ~## L of water, acid, buffers, enzymes into lumen of tract

7 Liters

Alternating contraction/relaxation of smooth muscle in walls of tract mix food and secretions and propel towards anus

Mixing and propulsion

Term: mix and movement of material along tract

Motility

Six basic process of digestive system:

1. Ingestion 2. Secretion 3. Mixing & Propulsion 4. Digestion 5. Absorption 6. Defecation

2 Forms of Digestion:

Mechanical | Chemical

Teeth cut and grind food before swallowed, smooth muscles of stomach and small intestine churn food- this helps to mix with enzymes to dissolve food

Mechanical Digestion

Large carbohydrate, lipid, protein, molecules are split into smaller molecules by hydrolysis- enzymes produced by salivary glands, tongue, stomach, pancreas, small intestine catalyze these catabolic reactions

Chemical Digestion

A few substances can be absorbed without chemical digestion, these include:

Vitamins Ions Essential Fatty Acids Water

Entrance of ingested and secreted fluids, ions, and products of digestion into the epithelial cells lining the GI tract These substances pass into blood or lymph and circulate to various locations in the body

Absorption

Wastes, indigestible substances, bacteria, cells sloughed from lining of tract, digested materials not absorbed leave the body through the anus

Defecation

Wall of GI tract from lower esophagus to anal canal has same basic four-layered arrangement of tissue From outer layer to inner-most layer (contact with tract contents):

- Serosa or adventitia (depends on the location) - Muscularis - Submucosa - Mucosa

Found on almost all parts of the GI tract Serous membrane composed of areolar connective tissue and simple squamous epithelium (mesothelium)

Serosa

Also called the visceral peritoneum Forms from a portion of the visceral peritoneum

Serosa

Single layer of connective tissue for the esophagus and proximal duodenum

Adventitia

Layers in Mouth, pharynx, superior aspect of esophagus Also present in external anal sphincter, permits voluntary control of defecation

Muscularis - Skeletal (voluntary)

Found in the rest of the tract Involuntary contractions help break down food, mix it with secretions, and propel it forward Inner sheet of circular fibers, outer sheet of longitudinal fibers

Muscularis - Smooth (involuntary)

Network of neurons between the circular and longitudinal muscle layers

Myenteric Plexus (plexus of Auerbach) in Muscluaris

Consists of areolar connective tissue that binds the mucosa to muscularis Contains many blood and lymph vessels that receive absorbed food molecules

Submucosa

Contains submucosal plexus (plexus of Meissner) Extensive network of neurons

Submucosa

Inner lining of GI tract composed of 3 layers:

Mucosa 3. Muscularis mucosae (outer) 2. Lamina propria (middle) 1. Epithelium (inner)

Thin layer of smooth muscle fibers This layer is what causes the mucous membrane of the small intestine and stomach to have the folded appearance These folds increase surface area for digestion and absorption Movement of this layer ensures all absorptive cells are fully exposed to contents of GI tract

Muscularis Mucosae (outer Mucosa)

Areolar connective tissue containing many blood and lymphatic vessels which allow nutrients to reach other tissues of the body Supports the epithelium and binds to the muscularis mucosae Contains majority of mucosa-associated lymphatic tissue (MALT)

Lamina Propria (middle Mucosa)

This lymphatic nodular tissue contains immune cells that protect against disease ____ tissue present along GI tract especially tonsils, small intestine, appendix, and large intestine

Mucosa-Associated Lymphatic Tissue (MALT)

every 5-7 days these cells are replaced by new cells, old slough off and are excreted

Epithelium (inner Mucosa)

Nonkeratinized stratified squamous found in mouth, pharynx, esophagus and anal canal Protective function

Epithelium (inner Mucosa)

Simple columnar found in ___ and ___ Secretion and absorption function Tight junctions between cells here prevent leakage

Stomach and Intestines Epithelium (inner Mucosa)

Secrete mucous/fluid/enzymes into lumen

Exocrine cells

Secrete hormones into lumen

Enteroendocrine cells

Considered the 'brain' of the gut:

Enteric Nervous System

Enteric nervous system arranged in two plexuses: Both plexuses consist of neurons, interneurons, and sensory neurons

1. Myenteric (Auerbach) | 2. Submucosal Plexus (Plexus of Meissner)

Plexus located between longitudinal and circular smooth muscle layers of the muscularis

Myenteric (Auerbach)

Plexus found within the submucosa

Submucosal (Meissner)

Supply motor impulses to longitudinal and circular smooth muscle layers of muscularis This leads to this plexus controlling the majority of GI tract motility Particularly the frequency and strength of contraction of muscularis

Myenteric (Auerbach)

Motor neurons supply the secretory cells of the mucosal epithelium This leads to this plexus controlling secretions of the organs of the GI tract

Submucosal (Meissner)

Connect the myenteric and submucosal plexuses (ENS)

Interneurons

Sensory Neurons- supply the ___ ___ Some function as chemoreceptors Activated by certain chemicals in food located in the lumen of GI organs Others function as baroreceptors (stretch receptors) Activated when food stretches distends the wall of a GI organ

Mucosal Epithelium

Sympathetic nerve endings secrete _____ activating andrenergic receptors, stimulating cardia activity, yet inhibiting gastrointestinal activity

Nor-epinephrine

Vagus nerve endings secrete _____ activating cholinergic receptors, inhibiting cardiac activity, yet stimulating gastrointestinal activity

Acetylcholine (ACh)

Stimulation of the _____ nerves that innervate the GI tract causes an increase in GI secretion and motility by increasing activity of the ENS

Parasympathetic

Stimulation of the _____ nerves connected to the GI tract cause a decrease in GI secretion and motility by inhibiting the ENS neurons Emotions such as fear (fight or flight), anger, anxiety may slow digestion because they stimulate the sympathetic nerves that supply the GI tract

Sympathetic

Largest serous membrane in the body:

Peritoneum

Peritoneum divided into:

Parietal | Visceral

Lines the wall of the abdominopelvic cavity

Parietal

Covers some of the organs and cavity and is also considered serosa

Visceral

Space between the two layers that contains lubricating serous fluid (small amount)

Peritoneal Cavity

Space that is behind the peritoneum Organs in this space are anteriorly covered by the peritoneum:

Retroperitoneal: - Kidneys - Ascending colon (large intestine) - Descending colon (large intestine) - Duodenum (small intestine) - Pancreas

Contains large folds that weave between the viscera These bind organs together and then also to abdominal walls Contain blood vessels, lymph vessels, and nerves that supply the abdominal organs

Peritoneum

Five major peritoneal folds:

1. The greater omentum 2. Falciform ligament 3. Lesser omentum 4. Mesentery 5. Mesocolon

Largest peritoneal fold:

The Greater Omentum

Drapes over transverse colon and small intestine Attaches to portions of stomach and duodenum, extending downward, anterior to small intestines, folds and extends upwards to attach to transverse colon Contains considerable amount of adipose tissue which can expand with weight gain Characteristic “beer belly” Many lymph nodes here contribute macrophages and antibody-producing cells that combat GI tract infections

The Greater Omentum

Peritoneal “fold” that attaches the liver to the ventral surface (anterior) of the abdominal wall

Falciform Ligament

Free border of this ligament contains the ligamentum teres (aka round ligament; remnant of the umbilical vein)

Falciform Ligament

The ____ is the only digestive organ attached to anterior abdominal wall

Liver

lesser omentum

slides show

triglycerides combined with other components

Compound Lipids

Types of compound lipids

Phospholipids Glycolipids Lipoproteins

Food is our only source of chemical energy Most food particles are too large to be used by cells in their original form True or False?

True!

-Consists of all of the organs involved in the breakdown of food - This system is a tubular system - --Extends from the mouth to the anus - --Forms extensive surface area in contact with the external environment - --Closely associated with cardiovascular system because of the blood vessels involved in the digestive process

Digestive system

Cardiovascular... connection to digestive system?

Supplies digestive organs with O2 and processes nutrients

Endocrine | ... connection to digestive system?

Hormones help regulate multiple actions in digestive system

Integumentary | ... connection to digestive system?

Protects digestive organs; Helps with vitamin D for calcium absorption

Lymphatic | ... connection to digestive system?

MALT defends against pathogens; lacteals absorb lipids to be transported into blood stream

Nervous | ... connection to digestive system?

Sensory/motor neurons help regulate secretions and muscle contractions of GI tract

Respiratory | ... connection to digestive system?

Provides oxygen and waste removal of CO2

Urinary | ... connection to digestive system?

Kidneys make calcitriol which aids in calcium absorption in the GI system

Urinary | ... connection to digestive system?

Kidneys make calcitriol which aids in calcium absorption in the GI system

Continuous tube extending from mouth to anus | ----Travels through thoracic cavity, through abdominopelvic cavity

Gastrointestinal tract (GI tract)

Gastrointestinal tract (GI tract) consists of?

Mouth, most of pharynx, esophagus, stomach, small intestine, large intestine (and anus)

Accessory digestive organs?

Teeth Tongue Salivary Glands, liver, gallbladder, pancreas

Returning parasympathetic impulses stimulate salivation, returned along the fibers of both the _ and _ nerves

Facial (VII) nerve | Glossopharyngeal (IX) nerve