Nutrition Unit 2 Flashcards
Body Cells (Definition)
The smallest unit in which independent life can exist. Need energy, oxygen, and nutrients to remain healthy and do work.
Regulators in the Body
- Genes
- Proteins
- Co-enzymes
Genes
- Units of a cell’s inheritance that act as a code or recipe
for the making of protein to do the body’s work. Proteins
of a cell determine a cell’s structure and the functions it
can perform. - Genes are segments of a cell’s DNA (deoxcyribomucleic
acid). Chromosomes are composed of the DNA and
protein. - Each cell contains all genes but different ones are active
in different cells.
Proteins
- Enzyme: Facilitates/speeds up a chemical reaction
without itself being altered in the process. Many in the
body. - Hormones: Chemical messengers that control the
activity of other organs. Produced by glands (specialized
cells).
Co-Enzymes
- Non-Protein, organic molecule that works with the
enzyme to promote the enzyme’s activity (aids the
action of the enzyme). - Many have B vitamins as part of their structure.
Organization of the Body
Cells-Tissue- Organs- Systems- Whole Body
Body Fluids and the Cardiovascular System
- Blood
- Extracellular Fluid
- Intracellular Fluid
- Lymph
Blood
- Fluid of the cardiovascular system composed of water,
red and white blood cells, platelets, nutrients, oxygen
and other constituents. - Blood travels in:
Arteries: Blood vessels that carry oxygen from the heart to the tissues.
Veins: Blood vessels that carry CO2 and other wastes from the tissues back to the heart.
Capillaries: Minute, weblike blood vessels that connect arteries to veins and permit transfer of materials (CO2, O2, nutrients, and fluid) between blood and tissues.
Extracellular Fluid
- Fluid outside the cells that bathes the cells and
transports materials to and from the cells.
Intracellular Fluid
- Fluid within the cell that provides the medium for cellular reactions and helps the cell to hold its shape.
Lymph (Fluid)
- Excess tissue fluid not reabsorbed by blood capillaries.
- Lymphatic capillaries take up excess tissue fluid and
return it to the blood stream.
Cardiovascular System
- Organ system composed of the heart and blood
vessels. Its function is to transport nutrient-rich,
oxygenated blood to the tissues and pick up CO2 and
other waste products, carrying them to points of
disposal. - Blood Flow Diagram (see page 75 of text):
Lungs: O2 picked up by the blood, CO2 released. Blood returns to the heart and is pumped to other parts of the body.
Liver: Filters toxins from the blood and accepts blood from the digestive system, altering the absorbed materials to make them better suited for use by other tissues (“Gatekeeper of the blood). Blood then returns to the heart.
Intestines: After food is broken down in the intestines, nutrients are picked up by the blood vessels in the intestines and transported to the liver. Large fats picked up by intestinal lymphatic vessels which then transport them to the blood.
Kidneys: Cleanses the blood of wastes. Blood then returns to the heart.
Lungs
O2 picked up by the blood, CO2 released. Blood returns to the heart and is pumped to other parts of the body.
Liver
Filters toxins from the blood and accepts blood from the digestive system, altering the absorbed materials to make them better suited for use by other tissues (“Gatekeeper of the blood). Blood then returns to the heart.
Intestines
After food is broken down in the intestines, nutrients are picked up by the blood vessels in the intestines and transported to the liver. Large fats picked up by intestinal lymphatic vessels which then transport them to the blood.
Kidneys
Cleanses the blood of wastes. Blood then returns to the heart.
The Hormonal (Endocrine) System, Nervous System, and Hunger Relations
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Homeostasis
The relatively constant, self-correcting internal environment of a living organism.
To maintain homeostasis, cells in the body must communicate with each other.
Each cell communicates with its neighbor or by releasing chemicals into the extracellular fluid.
Communication over long distances, however, is coordinated by the endocrine and nervous systems.
The nervous system joins the hormonal system to regulate body processes through communication among all organs.
Hormonal (Endocrine System)
- System of cells, tissues, and organs used for life
processes (growth, development, reproduction,
regulation) that require long-term (leisurely)
communication. - Uses hormones as the chemical messengers.
Examples:
Pancreas- monitors blood sugar levels. If blood sugar is high, insulin is released which helps glucose to enter cells. If blood sugar is low, glucagon is released which stimulates the liver to release its stored glucose into the bloodstream. Insulin and glucagon are examples of hormones.
Nervous System
- Organ System consisting of the brain, spinal cord, and
nerves that coordinate the other organ systems of the
body. The nervous system is our rapid method of
communication. - Uses neurotransmitters as the chemical messengers.
Hunger Regulation ( a joint effort by the hormonal and nervous systems)
- The sensation of hunger and fullness are perceived by
the cortex, the brain’s thinking, outer layer. We have the
ability to override these signals and choose not to eat
or ignore that we are full. - Deep inside the brain is the hypothalamus which
monitors many body conditions (including the availability
of nutrients) and communicates with the cortex and
other parts of the body. - Internal signals come to the hypothalamus from the
digestive tract by way of hormones and the nervous
system. Fat tissue produces a hormone that informs the
brain about the degree of body fatness that helps to
regulate appetite. The sight and smell of food can also
increase or decrease appetite.
Immune System
- Enables the body to resist diseases.
- Protects the body against antigens: foreign substances
that stimulate the immune system. Antigens can be a
pathogen (bacterium, virus), part of a foreign cell, toxin
or cancer cell.
Parts of the Immune System
- Barrier to Entry
- White Blood Cells
- Lymphoid Organs
Barriers to Entry
- Skin and mucous membranes lining the respiratory,
digestive, and urinary tracts.
-Oil glands on the skin- chemicals weaken or kill bacteria. - Hydrochloric Acid in the stomach inhibits/ kills bacteria.
- Helpful bacteria in the intestines inhibit growth of
pathogens (disease-causing agents).
White Blood Cells
- Phagocytes: Ingest and destroy antigens, old cells, and
cell debris by the process of phagocytosis (cell eating). - T Cells: Destroy cells infected by bacteria or viruses and
destroys cancer cells and tissue transplants. HIV-
attacks/destroys helper T Cells. - B Cells: Produce antibodies in response to antigen.
Antibodies: proteins designed to combine with and
inactive specific antigens.
Lymphoid Organs
- Lymph Nodes: Clean the lymph.
- Tonsils: 3 sets of tonsils.
- Spleen: Cleanses the blood. Removes debris and worn
out/ damaged cells. - Thymus: Along the trachea. Site where T Cells mature.
- Red Bone Marrow: Produces white blood cells, red
blood cells, and platelets.
Digestive System/ Gastrointestinal System (GI)
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Functions of the Digestive/GI System
- Ingestion of food
2.Breakdown of food into smaller particles by mechanical
processing, movement of food, and chemical digestion. - Absorption of nutrients into the cells lining the
digestive tract. - Elimination of undigested/ unabsorbed substances.
Digestive Enzymes Function
Digestive enzymes function at a particular pH: measure of acidity on a point scale.
pH below 7- acid
pH of 7- neutral
pH above 7- basic
Acids: Compounds that release hydrogen (H+) in a watery solution.
Bases: Compounds that either accepts hydrogens from solutions or releases hydroxide (OH) particles.
Parts of the Digestive Tract
- Mouth
- Swallowing and epiglottis
- Esophagus
- Stomach (gastric)
- Small Intestines
- Large Intestines (Colon)
Parts of the Digestive Tract: Mouth
- Mechanical processing: Teeth chew (masticate) food into
small pieces; tongue manipulates food into a bolus (ball
of food), mixes it with saliva. - Chemical digestion: Breakdown of starch is begun by
enzyme salivary amylase in saliva. Saliva is produced by
the salivary glands.
Parts of the Digestive Tract: Swallowing and Epiglottis
The epiglottis is a flap-like structure of cartilage that covers the opening of the larynx during swallowing so food doesn’t go down the trachea.
Parts of the Digestive Tract: Esophagus
- Passes food to the stomach by peristalsis: wavelike,
muscular contractions of the esophagus, stomach, and
intestines that push contents along. - Lower esophageal sphincter. A sphincter is a circular
muscle surrounding a body opening. It contracts to
close the opening.
Parts of the Digestive Tract: Stomach (Gastric)
- Has deep folds for expansion (rugae)
- Mechanical processing: Mixes and churns food into a
thick, soupy, acidic liquid: chyme. - Chemical digestion (Gastric Juice)
- Absorption: Absorbs aspirin, alcohol, some drugs.
- Pyloric Sphincter: Circular muscle at the lower end of
the stomach that regulates the flow of chyme into the
small intestine.
Gastric Juice Contains
- Pepsin enzyme that digests protein and gastric lipase
that digests some lipids (fats). - HCI: activates pepsin, kills bacteria, denatures protein.
- Mucus: lubrication and protection. Stomach protected
by a bicarbonate-rich mucus layer excreted from goblet
cells.
Small Intestines
- Mechanical Processing and propulsion: Mixes contents with digestive juices and moves contents along.
- Chemical Digestion:
-Villi: Finger-like projections of the cells that line the
intestinal tract for increased absorptive surface area.
House blood capillaries and lymphatic capillaries
(lacteals). The products of protein and CHO
digestion, and most vitamin and minerals are
absorbed directly into the blood stream while the
products of fat digestion (large fats) are absorbed
into the lacteals. The lacteals eventually carry them
to the blood steam.
- Microvilli: Tiny hair, hairlike projections on each cell of
every villus that can trap nutrients and
transport them into the cells. Called the “Brush
Boarder”. Houses intestinal enzymes.
Increases absorptive surface.
- Most digestion and absorption occurs in the small
intestine.
- With an under supply of energy and nutrients, the
absorptive surface of the small intestine shrinks
(atrophy).
Large Intestine (Colon)
Functions:
Absorption of water, electrolytes, and bile salts; secretion of mucus; compaction of intestinal contents; and storage of feces.
Feces: Waste material remaining after digestion and absorption are complete; eventually excreted.
Fiber: Some digested by bacteria in the colon. Most fiber unabsorbed. Fiber provides bulk against which the muscles of the colon can work.
Cecum: Blind end (pouch) of the large intestine that has the appendix (has lymphoid tissue to fight infection).
Rectum and Anal Canal: Last 20 cm of digestive tract. Stores feces prior to elimination.
Anus: Hold rectum closed. Opens to allow elimination.
Accessory Organs
- Pancreas
- Secretes pancreatic juice into the upper small intestine.
Pancreatic juice contains enzymes (to digest CHO, FAT,
PRO) and sodium bicarbonate (neutralizes the stomach
acid so enzymes can work).
- Secretes the hormones insulin and glucagon into the
blood to keep sugar (glucose) within normal limits. - Liver
- Accepts blood from the digestive system and alters the
absorbed materials to make them better suited for use
by other tissues.
- Produces bile: A substance made from cholesterol and Bilirubin that emulsifies fat. - Gallbladder
- Stores bile until needed.
- When fatty foods enter the small intestine, bile is
released.
Emulsifier:
A compound that breaks fat into tiny droplets so that enzymes can get to it. It can do this because it has a water-loving end and a fat-loving end.
Hormonal Control of Digestion
- Several hormones are released from the GI tract in
response to food. - Hormones either increase or decrease digestive juices,
bile, and peristalsis.
The Excretory System
Kidneys:
- Filters blood, adjusting the blood’s composition in
response to the body’s need, disposes wastes, removes
toxins, and regulates fluid volume.
- Nephrons: the working units of the kidneys, consisting
of inter-meshed blood vessels and tubules. Concentrate
wastes as urine.
Bladder:
Sac that holds urine until the time of elimination.
Storage Systems
Liver
Adipose
Bone
Muscle
Provides cells with a constant flow of needed nutrients between meals. All body systems need a constant supply of nutrients and are impaired by an under supply or over supply.
Storage Systems: Liver
- Converts excess energy- containing nutrients into
glycogen and fat. Glycogen: Storage form of
carbohydrates in animals and humans. - Glycogen stored in the liver is for short-term use to
help maintain blood glucose levels between meals. The
fat is shipped out in packages to be picked up by body
cells for energy use or for storage. - Stores fat-soluble vitamins (A, D, E, K), iron and B12.
Storage Systems: Adipose Tissue
- Fat tissue consisting of fat-storing cells and blood
vessels to nourish them. - Meets long-term energy needs. Supplies energy for days and weeks when no food is eaten.
Storage Systems: Bone
- Stores calcium and other minerals like phosphorus,
fluoride, and sodium. - The mineral reserves help to maintain normal
concentrations in body fluids.
Storage Systems: Muscle
Stores glycogen as a reserve for its own use.
