Ch.14: The Digestive System and Body Metabolism Flashcards
1
Q
What is ingestion?
A
Taking in food
2
Q
What is digestion?
A
Breaking food into nutrient molecules
3
Q
What is absorption?
A
Movement of nutrients into the bloodstream
4
Q
What is defecation?
A
Excretes to rid the body of indigestible waste
5
Q
What are the two main groups of organs in the digestive system?
A
Alimentary canal (gastrointestinal, or G I, tract)—continuous, coiled, hollow tube
• These organs ingest, digest, absorb, defecate
Accessory digestive organs
• Include teeth, tongue, and several large digestive organs
• Assist digestion in various ways
6
Q
What are the organs of the alimentary canal?
A
- Mouth
- Pharynx
- Esophagus
- Stomach
- Small intestine
- Large intestine
- Anus
- The alimentary canal is a continuous, coiled, hollow tube that runs through the ventral cavity from stomach to anus
7
Q
What is the anatomy of the mouth?
A
• Mouth (oral cavity)—mucous membrane–lined cavity
• Lips (labia)—protect the anterior opening
• Cheeks—form the lateral walls
• Hard palate—forms the anterior roof
• Soft palate—forms the posterior roof
• Uvula—fleshy projection of the soft palate
• Vestibule—space between lips externally and teeth and gums internally
• Oral cavity proper—area contained by the teeth
• Tongue—attached at hyoid bone and styloid processes of the skull, and by the lingual frenulum to the floor of the mouth
• Tonsils
*Palatine—located at posterior end of oral cavity
*Lingual—located at the base of the tongue
8
Q
What are the functions of the mouth?
A
- Mastication (chewing) of food
- Tongue mixes masticated food with saliva
- Tongue initiates swallowing
- Taste buds on the tongue allow for taste
9
Q
Concept Link 1
A
Recall that papillae containing taste buds, or taste receptors, are found on the tongue surface (see Chapter 8, p. 300). So, besides its food-manipulating function, the tongue allows us to enjoy and appreciate the food we eat.
10
Q
The _____ serves as a passageway for foods, fluids, and air.
A
Pharynx
11
Q
Food passes from the mouth posteriorly into the:
A
- Oropharynx—posterior to oral cavity
* Laryngopharynx—below the oropharynx and continuous with the esophagus
12
Q
Food is propelled to the esophagus by what two skeletal muscle layers in the pharynx?
A
- Longitudinal outer layer
- Circular inner layer
- Alternating contractions of the muscle layers (peristalsis) propel the food
13
Q
What is the anatomy of the esophagus?
A
- About 10 inches long
* Runs from pharynx to stomach through the diaphragm
14
Q
What is the physiology of the esophagus?
A
- Conducts food by peristalsis (slow rhythmic squeezing) to the stomach
- Passageway for food only (respiratory system branches off after the pharynx)
15
Q
What are the four layers from innermost to outermost, from esophagus to the large intestine? (Alimentary canal)
A
- Mucosa
- Submucosa
- Muscularis externa
- Serosa
16
Q
What is the mucosa? (Alimentary canal)
A
Innermost, moist membrane consisting of:
• Surface epithelium that is mostly simple columnar epithelium (except for esophagus—stratified squamous epithelium)
• Small amount of connective tissue (lamina propria)
• Scanty smooth muscle layer
Lines the cavity (known as the lumen)
17
Q
What is the submucosa? (Alimentary canal)
A
- Just beneath the mucosa
* Soft connective tissue with blood vessels, nerve endings, mucosa-associated lymphoid tissue, and lymphatic vessels
18
Q
What is the muscularis externa? (Alimentary canal)
A
- Smooth muscle
- Inner circular layer
- Outer longitudinal layer
19
Q
What is the serosa? (Alimentary canal)
A
- Outermost layer of the wall; contains fluid-producing cells
- Visceral peritoneum—innermost layer that is continuous with the outermost layer
- Parietal peritoneum—outermost layer that lines the abdominopelvic cavity by way of the mesentery
20
Q
Alimentary canal wall contains what two intrinsic nerve plexuses that are part of the autonomic nervous system?
A
- Submucosal nerve plexus
* Myenteric nerve plexus
21
Q
Alimentary canal nerve plexuses regulate _____ and _____ activity of the GI tract organs
A
- Mobility
* Secretory
22
Q
What is the stomach and where does food enter from and where does food empty into?
A
- C-shaped organ located on the left side of the abdominal cavity
- Food enters at the cardioesophageal sphincter from the esophagus
- Food empties into the small intestine at the pyloric sphincter (valve)
23
Q
Concept Link 2
A
Recall that valves control the flow of fluids, including blood flow in veins and through the heart (see Chapter 11, pp. 361–363). The valves of the digestive system (formed by sphincter muscles) control the flow of food and digestive juices through the GI tract.
24
Q
What are the regions of the stomach?
A
• Cardial (cardia)—near the heart and surrounds the cardioesophageal sphincter
• Fundus—expanded portion lateral to the cardiac region
• Body—midportion
*Greater curvature is the convex lateral surface
*Lesser curvature is the concave medial surface
• Pylorus—funnel-shaped terminal end
25
The stomach can stretch and hold __ L (__ gallon) of food when full
* 4
| * 1
26
What is the rugae?
Internal folds of the mucosa present when the stomach is empty
27
What is the lesser omentum?
* Double layer of the peritoneum
| * Extends from liver to the lesser curvature of stomach
28
What is the greater omentum?
* Another extension of the peritoneum
* Covers the abdominal organs
* Fat insulates, cushions, and protects abdominal organs
29
What is the structure of the stomach mucosa?
• Simple columnar epithelium composed almost entirely of mucous cells
• Mucous cells produce bicarbonate-rich alkaline mucus
• Dotted by gastric pits leading to gastric glands that secrete gastric juice, including:
*Intrinsic factor, which is needed for vitamin B12 absorption in the small intestine
• Chief cells—produce protein-digesting enzymes (pepsinogens)
• Parietal cells—produce hydrochloric acid that activates enzymes
• Mucous neck cells—produce thin acidic mucus (different from the mucus produced by mucous cells of the mucosa)
• Enteroendocrine cells—produce local hormones such as gastrin
30
What are the functions of the stomach?
* Temporary storage tank for food
* Site of food breakdown
* Chemical breakdown of protein begins
* Delivers chyme (processed food) to the small intestine
31
What is the small intestine and what is its function and structure?
* The body’s major digestive organ
* Longest portion of the alimentary tube (2–4 meters, or 7–13 feet, in a living person)
* Site of nutrient absorption into the blood
* Muscular tube extending from the pyloric sphincter to the ileocecal valve
* Suspended from the posterior abdominal wall by the mesentery
32
What are the subdivisions of the small intestine?
* Duodenum
* Jejunum
* Ileum
33
How does chemical digestion begin in the small intestine?
* Enzymes produced by intestinal cells and pancreas are carried to the duodenum by pancreatic ducts
* Bile, formed by the liver, enters the duodenum via the bile duct
* Hepatopancreatic ampulla is the location where the main pancreatic duct and bile ducts join
34
What are structural modifications in the small intestine?
• Increase surface area for food absorption
• Decrease in number toward the end of the small intestine
1. Villi—fingerlike projections formed by the mucosa
*House a capillary bed and lacteal
2. Microvilli—tiny projections of the plasma membrane (brush border enzymes)
3. Circular folds (plicae circulares)—deep folds of mucosa and submucosa
35
What are Peyer’s patches and where are they located?
* Collections of lymphatic tissue
* Located in submucosa
* Increase in number toward the end of the small intestine
* More are needed there because remaining food residue contains much bacteria
36
What is the large intestine?
* Larger in diameter, but shorter in length at 1.5 meters, than the small intestine
* Extends from the ileocecal valve to the anus
37
What are the subdivisions of the large intestine?
* Cecum
* Appendix
* Colon
* Rectum
* Anal canal
38
What is the cecum?
Saclike first part of the large intestine
39
What is the appendix?
* Hangs from the cecum
| * Accumulation of lymphoid tissue that sometimes becomes inflamed (appendicitis)
40
What is the colon?
* Ascending—travels up right side of abdomen and makes a turn at the right colic (hepatic) flexure
* Transverse—travels across the abdominal cavity and turns at the left colic (splenic) flexure
* Descending—travels down the left side
* Sigmoid—S-shaped region; enters the pelvis
41
Sigmoid colon, rectum, and anal canal are located in the:
Pelvis
42
What is the anus?
* Opening of the large intestine
* External anal sphincter—formed by skeletal muscle and is voluntary
* Internal anal sphincter—formed by smooth muscle and is involuntary
* These sphincters are normally closed except during defecation
43
The large intestine delivers _____ to the _____.
* Indigestible food residues
| * Body’s exterior
44
Goblet cells produce _____ to lubricate the passage of feces.
Alkaline mucus
45
Muscularis externa layer is reduced to three bands of muscle, called:
Teniae coli
46
The bands of teniae coli cause the wall to pucker into:
Haustra (pocketlike sacs)
47
What are the accessory digestive organs?
* Teeth
* Salivary glands
* Pancreas
* Liver
* Gallbladder
48
Humans have what two sets of teeth during a lifetime?
Deciduous (baby or milk) teeth
• A baby has 20 teeth by age 2
• First teeth to appear are the lower central incisors
Permanent teeth
• Replace deciduous teeth between ages 6 and 12
• A full set is 32 teeth (with the wisdom teeth)
49
Teeth are classified according to _____ and _____.
* Shape
* Function
* Incisors—cutting
* Canines (eyeteeth)—tearing or piercing
* Premolars (bicuspids)—grinding
* Molars—grinding
50
What are the two major regions of a tooth?
* Crown
| * Root
51
What is the crown of a tooth?
* Exposed part of tooth above the gingiva (gum)
* Enamel—covers the crown
* Dentin—found deep to the enamel and forms the bulk of the tooth, surrounds the pulp cavity
* Pulp cavity—contains connective tissue, blood vessels, and nerve fibers (pulp)
* Root canal—where the pulp cavity extends into the root
52
What is the root of a tooth?
* Cement—covers outer surface and attaches the tooth to the periodontal membrane (ligament)
* Periodontal membrane holds tooth in place in the bony jaw
* Note: The neck is a connector between the crown and root
* Region in contact with the gum
53
What are the three pairs of salivary glands that empty secretions into the mouth?
```
1. Parotid glands
• Found anterior to the ears
• Mumps affect these salivary glands
2. Submandibular glands
3. Sublingual glands
• Both submandibular and sublingual glands empty saliva into the floor of the mouth through small ducts
```
54
What is saliva?
• Mixture of mucus and serous fluids
• Helps to moisten and bind food together into a mass called a bolus
• Contains:
*Salivary amylase—begins starch digestion
*Lysozymes and antibodies—inhibit bacteria
• Dissolves chemicals so they can be tasted
55
What is the pancreas?
• Soft, pink triangular gland
• Found posterior to the parietal peritoneum
*Mostly retroperitoneal
• Extends across the abdomen from spleen to duodenum
• Produces a wide spectrum of digestive enzymes that break down all categories of food
• Secretes enzymes into the duodenum
• Alkaline fluid introduced with enzymes neutralizes acidic chyme coming from stomach
• Hormones produced by the pancreas
*Insulin
*Glucagon
56
What is the liver?
* Largest gland in the body
* Located on the right side of the body under the diaphragm
* Consists of four lobes suspended from the diaphragm and abdominal wall by the falciform ligament
57
The digestive role of the liver is to produce:
• Bile
• Bile leaves the liver through the common hepatic duct and enters duodenum through the bile duct
• Bile is yellow-green, watery solution containing:
*Bile salts and bile pigments (mostly bilirubin from the breakdown of hemoglobin)
*Cholesterol, phospholipids, and electrolytes
• Bile emulsifies (breaks down) fats
58
What is the gallbladder?
Green sac found in a shallow fossa in the inferior surface of the liver
• When no digestion is occurring, bile backs up the cystic duct for storage in the gallbladder
• While in the gallbladder, bile is concentrated by the removal of water
• When fatty food enters the duodenum, the gallbladder spurts out stored bile
59
What are the two gastrointestinal processes and controls?
* Digestion
| * Absorption
60
What are essential processes of the GI tract?
1. Ingestion
2. Propulsion
• Peristalsis
• Segmentation
3. Food breakdown: mechanical breakdown
4. Food breakdown: digestion
5. Absorption
6. Defecation
61
What is propulsion?
* Swallowing and peristalsis
| * Movement of foods from one region of the digestive system to another
62
What is peristalsis?
Alternating waves of contraction and relaxation that squeeze food along the GI tract
63
What is segmentation?
Movement of materials back and forth to foster mixing in the small intestine
64
What are examples of mechanical breakdown?
* Mixing of food in the mouth by the tongue
* Churning of food in the stomach
* Segmentation in the small intestine
* Mechanical digestion prepares food for further degradation by enzymes
65
Digestion occurs when _____ chemically break down large molecules into their building blocks.
Enzymes
66
Each major food group uses different:
* Enzymes
* Carbohydrates are broken down to monosaccharides (simple sugars)
* Proteins are broken down to amino acids
* Fats are broken down to fatty acids and glycerol
67
Concept Link 3
Recall that these enzymatic reactions are called hydrolysis reactions because a water molecule is added to each bond to be broken (see Chapter 2, p. 43). Water is also necessary as a dissolving medium and a softening agent for food digestion.
68
What is absorption?
* End products of digestion are absorbed in the blood or lymph
* Food must enter mucosal cells and then move into blood or lymph capillaries
69
What is defecation?
Elimination of indigestible substances from the G I tract in the form of feces
70
Food placed into the mouth is:
* Physically broken down by chewing
* Mixed with saliva, which is released in response to mechanical pressure and psychic stimuli
* Salivary amylase begins starch digestion
* Essentially, no food absorption occurs in the mouth
71
The pharynx and esophagus have no:
Digestive function
| Serve as passageways to the stomach
72
The pharynx functions in:
• Swallowing (deglutition)
• Two phases of swallowing
1. Buccal phase
2. Pharyngeal-esophageal phase
73
What is the buccal phase of food deglutition?
* Voluntary
* Occurs in the mouth
* Food is formed into a bolus
* The bolus is forced into the pharynx by the tongue
74
What is the pharyngeal-esophageal phase of peristalsis?
* Involuntary transport of the bolus by peristalsis
* Nasal and respiratory passageways are blocked
* Peristalsis moves the bolus toward the stomach
* The cardioesophageal sphincter is opened when food presses against it
75
Gastric juice is regulated by _____ and _____ factors.
* Neural
| * Hormonal
76
Presence of food or rising pH causes the release of the hormone:
Gastrin
77
Gastrin causes stomach glands to produce:
* Protein-digesting enzymes
* Mucus
* Hydrochloric acid
78
_____ makes the stomach contents very acidic.
• Hydrochloric acid
• Acidic pH
*Activates pepsinogen to pepsin for protein digestion
*Provides a hostile environment for microorganisms
79
What are protein-digestion enzymes?
* Pepsin—an active protein-digesting enzyme
| * Rennin—works on digesting milk protein in infants; not produced in adults
80
_____ and _____ are virtually the only items absorbed in the stomach.
* Alcohol
| * Aspirin
81
What are the three main steps of food propulsion?
* Peristalsis: waves of peristalsis occur from the fundus to the pylorus, forcing food past the pyloric sphincter
* Grinding: the pylorus meters out chyme into the small intestine (3 milliliters at a time)
* Retropulsion: peristaltic waves close the pyloric sphincter, forcing contents back into the stomach; the stomach empties in 4–6 hours
82
Intestinal enzymes from the brush border function to:
* Break double sugars into simple sugars
* Complete some protein digestion
* Intestinal enzymes and pancreatic enzymes help to complete digestion of all food groups
83
Pancreatic enzymes play the major role in the digestion of _____, _____, and _____.
* Fats
* Proteins
* Carbohydrates
84
_____ content neutralizes acidic chyme and provides the proper environment for the _____ to operate.
* Alkaline
| * Pancreatic enzymes
85
Release of pancreatic juice from the pancreas into the duodenum is stimulated by:
• Vagus nerves
• Local hormones that travel via the blood to influence the release of pancreatic juice (and bile)
*Secretin
*Cholecystokinin (CCK)
86
Hormones (secretin and CCK) also target the _____ and _____ to release bile
* Liver
| * Gallbladder
87
Bile acts as a fat:
* Emulsifier
| * Needed for fat absorption and absorption of fat-soluble vitamins (K, D, E, and A)
88
Water is absorbed along the length of the:
Small intestine
89
What are the end products of digestion?
* Most substances are absorbed by active transport through cell membranes
* Lipids are absorbed by diffusion
90
Substances are transported to the liver by the _____ vein or _____.
* Hepatic portal
| * Lymph
91
_____ is the major means of moving food
Peristalsis
92
What are segmental movements?
* Mix chyme with digestive juices
| * Aid in propelling food
93
During nutrient breakdown and absorption:
• No digestive enzymes are produced
• Resident bacteria digest remaining nutrients
*Produce some vitamin K and some B vitamins
*Release gases
• Water, vitamins, ions, and remaining water are absorbed
• Remaining materials are eliminated via feces
94
Feces contains:
* Undigested food residues
* Mucus
* Bacteria
* Water
95
What is propulsion of food residue and defecation in the large intestine?
* Sluggish peristalsis begins when food residue arrives
* Haustral contractions are the movements occurring most frequently in the large intestine
* Mass movements are slow, powerful movements that occur three to four times per day
96
Presence of feces in the rectum causes a:
* Defecation reflex
* Internal anal sphincter is relaxed
* Defecation occurs with relaxation of the voluntary (external) anal sphincter
97
Most foods are used as:
* Metabolic fuel
* Foods are oxidized and transformed into adenosine triphosphate (ATP)
* ATP is chemical energy that drives cellular activities
98
What is a nutrient?
Substance used by the body for growth, maintenance, and repair
99
What are major nutrients?
* Carbohydrates
* Lipids
* Proteins
* Water
100
What are minor nutrients?
* Vitamins
| * Minerals
101
What are carbohydrates?
* Dietary carbohydrates are sugars and starches
* Most are derived from plants such as fruits and vegetables
* Exceptions: lactose from milk and small amounts of glycogens from meats
102
What are lipids?
* Saturated fats from animal products (meats)
* Unsaturated fats from nuts, seeds, and vegetable oils
* Cholesterol from egg yolk, meats, and milk products (dairy products)
103
What are proteins?
Complete proteins—contain all essential amino acids
• Most are from animal products (eggs, milk, meat, poultry, and fish)
• Essential amino acids: those that the body cannot make and must be obtained through diet
• Legumes and beans also have proteins, but the proteins are incomplete
104
What are vitamins?
* Most vitamins function as coenzymes
| * Found mainly in fruits and vegetables
105
What are minerals?
* Mainly important for enzyme activity
| * Foods richest in minerals: vegetables, legumes, milk, and some meats
106
What is metabolism?
All of the chemical reactions necessary to maintain life
107
What is catabolism?
Substances are broken down to simpler substances; energy is released and captured to make adenosine triphosphate (ATP)
108
What is anabolism?
Larger molecules are built from smaller ones
109
_____ are the body’s preferred source to produce cellular energy (ATP).
Carbohydrates
110
What is glucose (blood sugar)?
* Major breakdown product of carbohydrate digestion
| * Fuel used to make ATP
111
As glucose is oxidized, _____, _____, and _____ are formed.
* Carbon dioxide
* Water
* ATP
112
What are the events of three main metabolic pathways of cellular respiration?
1. Glycolysis
• Occurs in the cytosol
• Energizes a glucose molecule so it can be split into two pyruvic acid molecules and yield ATP
2. Citric acid cycle (Krebs cycle)
• Occurs in the mitochondrion
• Produces virtually all the carbon dioxide and water resulting from cellular respiration
• Yields a small amount of ATP
3. Electron transport chain
• Hydrogen atoms removed during glycolysis and the citric acid cycle are delivered to protein carriers
• Hydrogen atoms are split into hydrogen ions and electrons in the mitochondria
• Electrons give off energy in a series of steps to enable the production of ATP
113
What is hyperglycemia?
* Excessively high levels of glucose in the blood
| * Excess glucose is stored in body cells as glycogen or converted to fat
114
What is hypoglycemia?
* Low levels of glucose in the blood
| * Glycogenolysis, gluconeogenesis, and fat breakdown occur to restore normal blood glucose levels
115
What are the functions of fats?
* Insulate the body
* Protect organs
* Build some cell structures (membranes and myelin sheaths)
* Provide reserve energy
116
Excess dietary fat is stored in _____ and other fat depots.
Subcutaneous tissue
117
When _____ are in limited supply, more fats are oxidized to produce ATP.
Carbohydrates
118
Excessive fat breakdown causes blood to become:
```
• Acidic (acidosis or ketoacidosis)
• Breath has a fruity odor
• Common with:
*“No carbohydrate” diets
*Uncontrolled diabetes mellitus
*Starvation
```
119
_____ form the bulk of cell structure and most functional molecules.
Proteins
120
_____ are carefully conserved by body cells.
Proteins
121
_____ are actively taken up from blood by body cells.
Amino acids
122
_____ are oxidized to form ATP mainly when other fuel sources are not available.
Amino acids
123
_____, released as amino acids are catabolized, is detoxified by _____ that combine it with carbon dioxide to form _____.
* Ammonia
* Liver cells
* Urea
124
_____ is the body’s key metabolic organ.
Liver
125
What are the roles in digestion of the liver?
* Manufactures bile
* Detoxifies drugs and alcohol
* Degrades hormones
* Produces cholesterol, blood proteins (albumin and clotting proteins)
* Plays a central role in metabolism
126
Liver can _____ if part of it is damaged or removed.
Regenerate
127
To maintain homeostasis of blood glucose levels, the liver performs:
* Glycogenesis
* Glycogenolysis
* Gluconeogenesis
128
What is glycogenesis?
* “Glycogen formation”
| * Glucose molecules are converted to glycogen and stored in the liver
129
What is glycogenolysis?
* “Glycogen splitting”
| * Glucose is released from the liver after conversion from glycogen
130
What is gluconeogenesis?
* “Formation of new sugar”
| * Glucose is produced from fats and proteins
131
Fats and fatty acids are picked up by the:
* Liver
* Some are oxidized to provide energy for liver cells
* The rest are either stored or broken down into simpler compounds and released into the blood
132
Blood proteins made by the liver are assembled from:
* Amino acids
* Albumin is the most abundant protein in blood
* Clotting proteins
133
Liver cells detoxify:
* Ammonia
| * Ammonia is combined with carbon dioxide to form urea, which is flushed from the body in urine
134
Cholesterol _____ used to make ATP.
* Is not
| * Most cholesterol (85%) is produced in the liver; only 15% is from the diet
135
What are the functions of cholesterol?
* Structural basis of steroid hormones and vitamin D
| * Building block of plasma membranes
136
Cholesterol and fatty acids cannot freely circulate in the:
* Bloodstream
| * They are transported by lipoproteins (lipid-protein complexes) known as LDLs and HDLs
137
Low-density lipoproteins (LDLs) transport cholesterol to:
* Body cells
| * Rated “bad lipoproteins” since they can lead to atherosclerosis
138
High-density lipoproteins (HDLs) transport cholesterol from _____ to the _____.
* Body cells
* Liver
* Rated “good lipoproteins” since cholesterol is destined for breakdown and elimination
139
Energy intake =
* Total energy output
| * (Heat + Work + Energy storage)
140
What is energy intake?
* The energy liberated during food oxidation
| * Energy produced during glycolysis, citric acid cycle, and the electron transport chain
141
What is energy output?
* Energy we lose as heat (60%)
| * Energy stored as fat or glycogen
142
Interference with the body’s energy balance leads to:
* Obesity
| * Malnutrition (leading to body wasting)
143
Body weight is usually relatively:
* Stable
| * Energy intake and output remain about equal
144
Mechanisms that may regulate food intake include:
* Levels of nutrients in the blood
* Hormones
* Body temperature
* Psychological factors
145
Nutrients yield different amounts of:
• Energy
• Energy value is measured in kilocalories (kcal)
*Carbohydrates and proteins yield 4 kcal /gram
*Fats yield 9 kcal /gram
146
What is basic metabolic rate (BMR)?
* Amount of heat produced by the body per unit of time at rest
* Average BMR is about 60 to 72 kcal /hour for an average 70-kg (154-lb) adult
147
What are factors that influence BMR?
• Surface area—a small body usually has a higher BMR
• Gender—males tend to have higher BMRs
• Age—children and adolescents have higher BMRs
• The amount of thyroxine produced is the most important control factor
*More thyroxine means a higher metabolic rate
148
What is total metabolic rate (TMR)?
* Total amount of kilocalories the body must consume to fuel ongoing activities
* TMR increases dramatically with an increase in muscle activity
* TMR must equal calories consumed to maintain homeostasis and maintain a constant weight
149
When foods are oxidized, more than __% of energy escapes as heat, warming the body.
60
150
The body has a narrow range of homeostatic temperature must remain between:
35.6°C and 37.8°C
| 96°F and 100°F
151
The body’s thermostat is in the:
Hypothalamus
152
Hypothalamus initiates mechanisms to maintain:
* Body temperature
* Heat loss mechanisms involve radiation of heat from skin and evaporation of sweat
* Heat-promoting mechanisms involve vasoconstriction of skin blood vessels and shivering
153
What is a fever?
* Controlled hyperthermia
* Results from infection, cancer, allergic reactions, CNS injuries
* If the body thermostat is set too high, body proteins may be denatured, and permanent brain damage may occur
154
The alimentary canal is a continuous, hollow tube present by the _____ week of development
Fifth
155
Digestive glands bud from the _____ of the _____ tube.
* Mucosa
| * Alimentary
156
The developing fetus receives all nutrients through the:
Placenta
157
In newborns, _____ must be frequent, _____ is inefficient, and _____ is common.
* Feeding
* Peristalsis
* Vomiting
158
What are newborn reflexes?
* Rooting reflex helps the infant find the nipple
| * Sucking reflex helps the infant hold on to the nipple and swallow
159
Teething begins around age:
6 months
160
What are problems of the digestive system?
Gastroenteritis
| Appendicitis
161
What is gastroenteritis?
Inflammation of the gastrointestinal tract; can occur at any time
162
What is appendicitis?
Inflammation of the appendix; common in adolescents
163
What are middle-age digestive problems?
* Ulcers
| * Gallbladder problems
164
What are later middle-age problems?
* Obesity
| * Diabetes mellitus
165
What is the activity of the digestive tract in old age?
* Fewer digestive juices
* Peristalsis slows
* Diverticulosis and gastrointestinal cancers are more common
