Exam 3 Flashcards
(320 cards)
1
Q
How do oxygen and carbon dioxide transport down gradients in tissues and capillaries?
A
Passive diffusion
2
Q
What is ventilation?
A
Transport of external gas across or into a gas exchange area (bringing air into the lungs or water over gills).
3
Q
What is respiratory exchange?
A
Gas diffusion between the external environment and the animal internal body (diffusion of air oxygen from the lungs or gills into blood vessels).
4
Q
What are the steps of external respiration?
A
- Ventilation
- Respiratory exchange
- Circulation
- Cellular exchange
5
Q
Describe the circulation step of external respiration.
A
The transport of gas throughout the body in the extracellular fluid.
6
Q
Describe the cellular exchange step of external respiration.
A
Gas diffusion between the extracellular fluid and the tissue cell.
7
Q
What is tidal ventilation?
A
Air moves in and out through the same opening by inhalation and exhalation (mammals)
8
Q
What is flow-through ventilation?
A
Water or air enters one opening and leaves through a separate opening (fish)
9
Q
What is more efficient, tidal ventilation or flow-through ventilation?
A
Flow-through ventilation
10
Q
Describe ventilation in birds (simple description).
A
A combination of tidal and flow-through ventilation.
11
Q
In bats during flight, __% of body CO2 is exchanged through the ____.
A
12, wings
12
Q
1-2% of CO2 and O2in other animals can be exchanged through the ___.
A
skin
13
Q
Describe the flow of the respiratory tract in mammals.
A
Nasal passages, pharynx, larynx, trachea, primary bronchi, secondary bronchi, bronchioles, and alveoli
14
Q
What increases tidal volume in horses and cheetahs?
A
Pliable nostrils
15
Q
What are maxilloturbinals?
A
Thin curls of cartilage and bone covered skin deep in the nasal cavity that help retain animal heat and moisture.
16
Q
What is the pharynx?
A
The common passageway for food and air before the trachea and esophagus.
17
Q
What is the larynx?
A
The gatekeeper of the trachea and respiratory tract
18
Q
What does the larynx consist of?
A
Many articulating cartilage structures including the epiglottis, glottis, thyroid cartilage, and vocal folds/cords.
19
Q
What is the trachea?
A
The long tube with collagen rings for which air passes leading into the lungs.
20
Q
What does the trachea divide into?
A
The left and right primary bronchi, each entering a lung (has collagen rings).
21
Q
What do the primary bronchi branch into?
A
The secondary bronchi entering different lung lobes (has collagen rings).
22
Q
What do the secondary bronchi branch into?
A
Bronchioles
23
Q
What are bronchioles wrapped with?
A
Smooth muscle
24
Q
What controls the diameter of bronchioles?
A
The autonomic nervous system
25
What do the bronchioles end with?
Alveoli
26
27
What are alveoli?
Hollow sacs where air gas is exchanged with pulmonary capillaries.
28
Alveoli _______ distance of gas diffusion and _______ lung surface area.
decrease, increase
29
How many cells layers make up the alveolar wall?
One (thin, type 1 alveolar cells)
30
How big is the space between air in alveolus and RBC in capillaries?
50x thinner than a piece of paper
31
What is the purpose of type II alveolar cells?
They secrete pulmonary surfactant
32
What is pulmonary surfactant?
A solution that reduces surface tension inside of alveolus so it remains open or expanded for gas exchange.
33
What do alveolar microphages do?
Provide a defense mechanism against microorganism and foreign material.
34
How many alveoli do human lungs have?
300 million
35
Smaller animals have ____ alveoli and alveolar capillaries.
more
36
What is pleura?
Connective tissue that lines outside each lung and is continuous with thoracic wall.
37
What is visceral pleura?
Pleura covering the lungs
38
What is parietal pleura?
Pleura covering the thoracic wall and diaphragm.
39
What is the pleural sac?
The space between visceral and parietal pleura with lubricating fluid. The space is sometimes referred to as the intrapleural space or cavity.
40
What is the atmospheric pressure at sea level?
760 mmHg at sea level
41
What is atmospheric pressure?
The pressure of atmospheric gas on earth's surface at sea level
42
What is intra-alveolar pressure?
Pressure in alveoli (760 mmHg when equilibrated with atmosphere)
43
What is pleural cavity pressure?
Pressure in the pleural cavity (756 mmHg)
44
Why do lungs tend to expand with the thoracic wall?
Intrapleural fluid cohesiveness and intramural pressure gradient
45
What is intrapleural fluid cohesiveness?
Fluid along the thoracic wall (intrapleural fluid) sticks to the lungs. When the thoracic cavity expands, it pulls lungs with it.
46
What is the intramural pressure gradient?
Pressure in lungs is greater than in the thoracic cavity. When the thoracic cavity expands, the lungs expand with it.
47
Describe what happens/the conditions present before inhalation.
Intra-alveolar pressure equals atmospheric pressure. Air does not move into the lungs.
48
Describe what happens when inhalation begins.
Contraction of thoracic muscles (intercostal and diaphragm) expands thoracic cavity (pleural cavity) and intrapleural pressure decreases to 754 mmHg
49
Describe what happens during inhalation.
Lungs expand to fill the larger thoracic cavity and intra-alveolar pressure becomes sub-atmospheric (759 mmHg). Air is pulled into the lungs.
50
Describe what happens/the conditions present when inhalation ends.
Atmospheric pressure moves air down its gradient into lungs until atmospheric and intra-alveolar pressures equilibrate.
51
Describe what happens during exhalation.
The thoracic muscles relax and recoil, Intra-alveolar pressure increases about 1 mmHg (761 mmHg) above atmospheric, and air moves out of the lungs.
52
What does lung recoil allow for?
It allows for the lungs to return to pre-inhalation size
53
What is lung recoil contributed to?
Stretchy elastin protein in lung tissue and a thin layer of fluid over intra-alveolar surface.
54
What is the importance of pulmonary surfactant?
It slightly reduces surface alveolar liquid tension so that it is not too great. It prevents alveolus from collapsing during exhalation and allows it to expand during inhalation.
55
What comprises pulmonary surfactant?
Proteins and lipids
56
What is total lung capacity (TLC)?
The max amount of air lungs can hold
57
What is the total lung capacity of a horse?
42 L
58
What is the total lung capacity of a human?
5.7 L
59
What is resting tidal volume (rTV)?
The volume of air entering or leaving the lungs during a single breath.
60
What is the resting tidal volume of a horse?
4-6 L
61
What is the resting tidal volume of a human?
0.4-0.5 L
62
What is functional residual capacity (FRC)?
The volume of air remaining in lungs after normal passive exhalation.
63
What is the functional residual capacity of a horse?
24 L
64
What is the functional residual capacity of a human?
2.2 L
65
What is residual volume (RV)?
The minimal volume of air remaining in the lungs even after a maximal exhalation.
66
What is the residual volume of a horse?
12 L
67
What is the residual volume of a human?
1.2 L
68
What is vital capacity (VC)?
The maximal volume of air that can be moved out during a single breath following a maximal inhalation.
69
What is the vital capacity of a horse?
30 L
70
What is the vital capacity of a human?
4.5 L
71
What is the pulmonary or minute ventilation (PV)?
The volume of air breathed in and out of respiratory tract in one minute.
72
How is pulmonary ventilation calculated and measure?
Measure in L/min and calculated with resting tidal volume (L/breath) x respiratory rate
73
Why is pulmonary ventilation unable to provide a precise estimate of gas exchange?
Anatomical dead space
74
What is anatomical dead space?
The part of the respiratory system not involve in gas exchange but can hold air.
75
What is the anatomical dead space of a horse?
1.8 L
76
What is the anatomical dead space of a human?
0.15 L
77
What is alveolar ventilation?
The volume of air exchanged between the atmosphere and alveoli per minute. More accurate measurement for ventilation.
78
What is the alveolar ventilation of a horse?
50.4 L/min
79
What is the pulmonary ventilation of a horse?
72 L/min
80
How is alveolar ventilation calculated?
(Tidal volume -dead space volume/ breath) x respiratory rate.
81
What does anatomical dead space cause?
Mixing of old and fresh inhaled air during tidal ventilation
82
The atmosphere consists of __% oxygen gas and __% nitrogen gas.
29, 71
83
What is oxygen's partial pressure in atmospheric air at sea level?
160 mmHg (21% of 760 mmHg)
84
How does gas tend to move?
From an area of high pressure to an area of low pressure.
85
In humans, after inhalation only __% of alveolar air is fresh.
15
86
Why is the percentage of fresh alveolar air so low?
Fresh inhaled air is mixed with a large volume of old air in lung dead space.
87
What is the partial pressure of inhaled O2 in the lungs?
100 mmHg
88
What is the partial pressure of CO2 in the lungs?
40 mmHg
89
What does lung and tissue gas diffusion depend on?
Gas partial pressure gradients
90
What gases bind to hemoglobin?
O2, CO2, and hydrogen
91
What adaptation does the hemoglobin in animals adapted to higher altitudes have?
A greater affinity for O2
92
What protein do horseshoe grabs use to transport oxygen?
Hemocyanin
93
Hemoglobin in mammals appears ____ when oxygenated and ___ when deoxygenated.
red, blue
94
Hemocyanin in horseshoe crabs appears ___ when oxygenated and ___ when deoxygenated.
blue, colorless
95
Antarctic icefish have no ________ or _______.
erythrocytes, hemoglobin
96
What factors effect hemoglobin's affinity for O2?
Increased CO2, Low pH/acidity, increased temperature.
97
What is CO2 converted to?
Carbonic acid
98
What is temperature important for in relation to affinity of O2 for hemoglobin?
It is important for ectoderms
99
__% of O2 in blood is bound to hemoglobin.
99
100
What is the O2 that is not bonded to hemoglobin dissolved in?
Plasma
101
How much CO2 is bound to hemoglobin?
25%
102
What enzyme in red blood cells converts carbonic acid to bicarbonate?
Carbonic anhydrase
103
What percentage of CO2 is converted to bicarbonate?
60%
104
Why is bicarbonate important?
It is transported back into the plasma to act as a pH buffer
105
What does low ventilation and too much CO2 result in?
A build up of carbonic acid
106
What extrinsic factors regulate airways in mammals?
Parasympathetic stimulation and sympathetic stimulation
107
How does parasympathetic regulation effect airways?
It promotes bronchoconstriction and airway resistance
108
How does sympathetic stimulation effect airways?
It promotes bronchodilation and decreased airway resistance
109
What intrinsic factors regulate airways in mammals?
Local increase in CO2 increases relaxation of airway smooth muscle.
110
Large blood flow causes small airflow to tissue, which causes an increase in CO2. How does the body counteract that?
Relaxation of local airway smooth muscle and dilation of local airways, causing a decrease in airway resistance.
111
Large blood flow causes small airflow to tissues, which causes a decrease in O2. How does the body counteract that?
Increased contraction of local pulmonary-arteriolar smooth muscle and constriction of local blood vessels, causing an increase in vascular resistance.
112
Where is the respiratory center in the brain?
The brains stem medulla oblongata
113
What does the dorsal respiratory group (DRG) contain?
Inhalation neurons that terminate on motor neurons supplying inhalation muscles
114
Inhalation requires ______ neuron activity and exhalation requires _______ neuron activity (DRG)
increased, decreased
115
What is respiratory rhythm driven by?
Higher order neurons with pacemaker activity
116
What does the ventral respiratory group (VRG) contain?
Inhalation neurons and exhalation neurons
117
When is the VRG utilized?
During active breathing when demands for ventilation increase
118
What does the medulla adjust the rate and depth of ventilation in response to?
Input from central and peripheral chemoreceptors
119
What is arteriole O2 monitored by?
Peripheral chemoreceptors in carotid and aortic arteries.
120
What is increased arterial CO2 detected by?
Central chemoreceptors in medulla near respiratory center
121
What is the most powerful stimulus for increased ventilation?
Increased arterial CO2 detected by central chemoreceptors in the medulla.
122
What are peripheral and central chemoreceptors sensitive to (other than O2 or CO2)?
Hydrogen ions
123
What helps to control animal acid-base balance?
Increase CO2 or lactic acid increases ventilation, increasing pH.
124
What are immediate changes in ventilation due to exercise caused by?
Anticipation, stress responses, and body movement
125
What does increased ventilation do to animal body temperature?
It decreases the temperature/ cools the animal down
126
What is hypoxic hypoxia?
Reduction in available O2
127
What is anemic hypoxia?
Reduction in O2 carrying capacity of blood
128
What causes anemic hypoxia?
Decrease in RBC, hemoglobin (Hb), Hb poising (carbon monoxide)
129
What is histotoxic hypoxia?
Reduction in tissue's ability to use O2
130
What is a cause for histotoxic hypoxia?
Cyanide poisoning blocks oxidative phosphorylation
131
What are hypercapnia and hypocapnia?
Increased and decreased CO2
132
What causes hypercapnia and hypocapnia?
Hypoventilation and hyperventilation
133
What is apnea?
Cessation or reduced breathing
134
What is the function of the digestive system?
To transfer nutrients and water from the external environment to the internal animal environment
135
What is the foregut?
The region of the digestive system before the stomach
136
What is the midgut?
The stomach
137
What is the hindgut?
The region of the digestive system after the stomach
138
What does the digestive system use to aid in digestion?
Enzymes, acidic molecules, and bacteria.
139
Where are nutrients absorbed?
Across the digestive tract epithelium into animal blood or lymphatic vessels.
140
Describe carnivores.
Animals that eat other animals. Have a high protein and fat diet. Simple, one chambered stomach. Uses enzymes and acidic molecules to digest protein.
141
Describe omnivores.
Animals that eat plants and other animals. Simple, one-chambered stomach. Food type may depend on animal's life stage and food availability. Includes most birds.
142
Describe herbivores.
Eat mostly plants. Microbes aid in digestion through fermentation and break down tough plant polysaccharides (cellulose). Includes one bird.
143
What is hindgut fermentation?
Animals with a simple stomach but with an enlarged cecum that houses bacteria for fermentation.
144
What animals are hindgut fermenters?
Horses and rabbits
145
What is foregut fermentation?
Animals with a multi-chambered stomach that houses bacteria in some chambers for fermentation. Found in ruminants.
146
What are some examples of foregut fermenters?
Cattle, sheep, deer, and giraffe
147
What are the regions of the large intestine in horses?
The cecum, the large colon, and the small colon
148
What is the valve that leads to the cecum in rabbits called?
The Ileo-caecal valve
149
What are the regions of the cecum in rabbits?
The cecum and the caecal appendix
150
What are the regions of the large intestine in rabbits?
The cecum, the proximal colon, the fusus coli, and the distal colon.
151
What is motility?
Mixing and moving food through the digestive tract.
152
How is motility achieved?
Digestive tract smooth muscle
153
How do pacesetter cells effect digestive tract smooth muscle?
They initiate slow-wave potentials that cause rhythmic, spontaneous fluctuations in membrane potential.
154
What triggers true action potentials in digestive tract smooth muscle?
Endocrine hormones, the nervous system, or food within the digestive tract.
155
What is secretion?
Digestive tract epithelium secretes water, ions, enzymes, mucus, and/or acidic molecules into the digestive tract lumen.
156
What is mucosa?
Epithelium specialized for secretion
157
What is digestion mostly accomplished by?
Hydrolase enzymes and enzymatic hydrolysis
158
What is enzymatic hydrolysis?
The separation of molecules using water
159
What is gastric juice?
Acid molecules (HCl) in the stomach that denatures proteins and activates enzymes
160
Where does absorption occur in the digestive tract?
The mid and hindgut regions, particularly the small and large intestine.
161
What are intestines?
Long organs with many folds along lumen to increase surface area for absoprtion
162
How are food molecules and water transported through epithelium?
By assisted membrane transporters
163
Proteins are broken down into _________ which are broken down into _____ ____.
polypeptides, amino acids
164
Fats are broken down into _________, which are broken down into ________, which are broken down into ____ _____ _____.
triglycerides, monoglycerides, free fatty acids
165
DNA and RNA are broken down into _____ ____.
nucleic acids
166
What are some examples of complex glucose polysaccharides?
Starch and cellulose from plants, chitin from fungi and exoskeletons of crustaceans and insects, and glycogen stored in animal tissues.
167
What are some examples of disaccharides?
Lactose (glucose and galactose), maltose (glucose and glucose), and sucrose (glucose and fructose)
168
What kind of receptors can be found in the digestive system and what do they activate?
Chemoreceptors, mechanoreceptors, and osmoreceptors. They activate the enteric and autonomic nervous systems.
169
What is the enteric nervous system?
Two nerve networks in the digestive tract wall.
170
What are the two networks of the enteric nervous system?
The myenteric plexus and the submucous plexus
171
What does the enteric nervous system involve and do?
It involves sensory receptors, interneurons, and effector neurons that allows the digestive tract to self regulate. It influences the activity of digestive smooth muscle, epithelial secretions, and release of endocrine hormones.
172
What nervous system can step in and control the enteric nervous system?
The autonomic nervous system
173
What does the digestive tract in most vertebrates include?
The mouth, pharynx, esophagus, stomach, small intestine, large intestine and cecum, and anus.
174
What are the chambers in ruminants?
The rumen, reticulum, omasum, and abomasum
175
What does the stomach in birds include?
The proventriculus and ventriculus (gizzard)
176
What are accessory organs to the digestive system in most vertebrates?
Salivary glands, the pancreas, and the biliary system
177
What does the biliary system include?
The liver and in some species the gallbladder
178
What are the components of the digestive system before the esophagus?
Nasal passages, hard and soft palate, the bolus, the tongue, the uvula, the pharynx, and the epiglottis
179
What are lips?
Pliable tissue important for prehension (seizing food)
180
What does the tongue consist of and what is its function?
Consists of skeletal muscle. Has many functions including prehension, drinking, moving food, vocalization, and secretion of antibiotic molecules
181
What do the hard and soft palates do?
Separate the oral cavity from the nasal cavity. The allow for chewing and suckling simultaneously when breathing
182
What is the function of the uvula?
It closes the nasal passages when swallowing
183
Which is harder, enamel or bone?
Enamel
184
What is the function of incisors?
Cutting food
185
What is the function of molars?
Grinding food
186
What is the function of canine teeth?
Catching and killing prey
187
What teeth do ruminants not have?
Canines or upper incisors. Grasses are pressed against upper dental pad to tear
188
What are the different salivary glands?
Parotid, sublingual, and submandibular
189
What is the function of saliva?
Acts as a solvent and helps food molecules stimulate taste buds
190
What does saliva contain?
Antibiotics and salivary amylase which begins digestion of starch and glycogen
191
What are other functions of saliva?
pH neutralization, animal thermoregulation, and depending on the type of animal, containing venom, anti-coagulants, or pheromones
192
What does ruminant saliva contain?
The saliva itself is alkaline. Contains bicarbonates and phosphates to support microbes in rumen
193
How much saliva do cattle produce?
140L, half of the animal's body water passes through the salivary glands
194
What is salivation controlled by?
The autonomic nervous system
195
What is the pharynx?
The area where nasal and oral cavities meet and where digestive and respiratory tracts meet.
196
What is the esophagus?
The organ that serves as a food/water passageway between the pharynx and stomach
197
What is the pharyngoesophageal sphincter?
Skeletal muscle that acts as a gate between pharynx and esophagus. Keeps are out of esophagus
198
What is the gastroesophageal sphincter?
Skeletal muscle that acts as a gate between the esophagus and stomach. Keeps stomach acid out of esophagus
199
How is swallowing achieved?
When a bolus (mass of food) is forces by the tongue into the pharynx, triggering mechanoreceptors to send signals to the medulla oblongata and a series of highly coordinated events in the throat.
200
What is the oropharyngeal stage of swallowing?
Closure of the nasal passage with uvula, epiglottis covers glottis, glottis closes and contraction of pharynx muscle forces food into esophagus.
201
What is the esophageal stage of swallowing?
Activation of ENS within the esophagus. Results in peristaltic waves of smooth muscle contraction dow the esophagus toward the stomach. Gastroesophageal sphincter relaxes.
202
What is peristalsis?
Waves of ring like contraction of smooth muscle around organs of the digestive tract that progressively moves the food bolus forward.
203
What is the bird crop?
An enlarged region of the bird esophagus in some species that acts as a temporary food storage center.
204
What is the stomach?
Muscular chamber between the esophagus and small intestine. Functions to mix, store, and digest food, particularly protein. Produces chyme.
205
What is chyme?
A thick liquid food mixture
206
What are the three regions of the animal stomach?
Fundus (upper region where food is stored), corpus or body (middle region where food is mixed with gastric juices), and the antrum or pyloric (lower thick muscular region where chyme is mixed and expelled through pyloric sphincter into small intestine)
207
What is the pyloric sphincter?
Skeletal muscle that acts as a gate between the stomach and duodenum of small intestine
208
What happens during stomach filling?
Folds in the stomach wall flatten and the stomach relaxes with food. The fundus and body have weak smooth muscle contractions, allowing for food storage, mostly in the fundus.
209
What is the most important promoter of stomach emptying?
The volume of chyme (stretch activates smooth muscle activity)
210
What factors other than chyme volume effect gastric emptying?
Fat, acid, hypertonicity, and distension
211
What is the greatest inhibitor of gastric emptying?
Fat (it takes time to absorb)
212
What are enterogastrones?
Hormones produced by the duodenum that reduce pyloric region smooth muscle activity.
213
What is secretin?
An enterogastrone that is produced by S cells in the duodenum and jejunum mucosa. The first endocrine hormone discovered.
214
What is cholecystokinin?
An enterogastrone that is produced by I cells in the duodenum and jejunum mucosa
215
Mucous cells secrete _____.
Mucus
216
Chief cells secrete ______.
pepsinogen
217
Parietal cells secrete ____.
HCl
218
Which cells are in gastric pits in the fundus and body regions (oxyntic mucosa)?
Mucous cells, chief cells, and parietal cells
219
Which cells are in gastric pits in the antrum/pyloric region (pyloric gland area)?
G cells and D cells
220
G cells secrete _____, and endocrine hormone.
gastrin
221
D cells secret _________, an endocrine hormone.
somatostatin
222
How is gastric juice produced?
H+ and Cl- are transported by assisted membrane transporters into stomach lumen. H+ and OH- are produced from water in parietal cell and H+ is transported into lumen by H+/K+ ATPase pump. Cl- concentration is greater in cell than in lumen, causing movement of Cl-.
223
What is the pH of the stomach?
As low as 2
224
What is the function of HCl?
Kills harmful microorgansims and denatures protein, converts pepsinogen to pepsin.
225
What is pepsin?
A proteolytic enzyme that breaks peptide bonds and digests protein in low pH environments
226
What causes carbohydrate digestion?
Swallowed salivary amylase
227
Why doesn't salivary amylase break down?
It is protected by the food it is in.
228
How is the stomach protected?
Chief cells make pepsinogen in inactive form to protect their own cytoplasm. Stomach mucosa secretes alkaline mucus several layers thick. Tight junctions between epithelial cells block H+ and HCl reentry into stomach tissue.
229
How often is stomach mucosa in humans replaced?
Every 3 days
230
What is the cephalic phase of gastric juice production and what is it related to?
Related to the brain. Anticipation of food stimulated secretion of HCl and pepsinogen . Involves activation of vagus nerve, enteric nervous system, and the release of ACh and gastrin.
231
What is the gastric phase of gastric juice production and what is it related to?
Related to the stomach. Stomach stretch and protein within stomach stimulates HCl and pepsinogen. Involves release of ACh and gastrin.
232
What is the intestinal phase of gastric production and what does it relate to?
Relates to the small intestine. Protein in small intestine stimulates small intestine to release gastrin.
233
What inhibits gastric juice production?
Decrease in protein within stomach, increase in stomach acidity (stimulates D cells to secret somatostatin, inhibiting HCl and gastrin secretion), and MOST IMPORTANTLY an increase in fat, stretch, or hypertonicity in small intestine
234
Who studied human digestion?
William Beaumont and Alexis St. Martin
235
What is the gizzard?
The bird muscular stomach to mechanically breakdown food
236
What is the connective tissue lining of the gizzard?
Koilin
237
How does the pancreas aid in dugestion?
It secretes enzymes into duodenum to help further digest chyme
238
What are the major proteases?
Trypsinogen, chymotrypsinogen, and procarboxypeptidase.
239
What is the function of trypsinogen?
It is converted by enterokinase to trypsin in duodenum. Trypsin converts more trypsinogen into trypsin. Helps to digest protein.
240
What is converted by trypsin into chymotrypsin?
Chymotrypsinogen
241
What is converted by trysin into carboxypeptidase
Procarboxypeptidase
242
What are the functions of amylase and chitinase?
Break down of carbohydrates
243
What is the function of lipase?
Break down of fat into triglycerides
244
What do high levels of acid in the duodenum cause?
Release of secretin hormone, stimulating pancreas duct cells to secrete sodium bicarbonate, increasing pH.
245
What do high levels of fat and protein in the duodenum trigger?
Triggers the release of CCK hormone, reducing gastric emptying and stimulating pancreatic acinar cells to secrete digestive enzymes, lipases, and proteases.
246
What is the most important metabolic organ in animals.
The liver
247
What does the liver consist of?
Hepatocytes and kupffer cellls
248
What are the functions of the liver?
Sampling and processing of carbohydrates, lipids, and proteins from digestive tract and detoxification/break down of body molecules considered waste. Glucose synthesis and storage as glycogen, secretion of bile salts into gallbladder to emulsify and break down fats. Fat, iron, copper and vitamin storage, and activation of vitamin D. Synthesis of plasma proteins, particularly clotting factors. Removal of bacteria and old RBCs
249
Where do nutrient absorbed from the digestive system travel?
They enter blood venous system
250
Where does blood leaving the stomach and intestines travel?
The hepatic portal vein which branches into sinusoids.
251
What are sinusoids?
Small capillaries in the liver.
252
What happens to digestive products leaked out of sinusoids?
They are sampled by hepatocytes that help with digestive molecule storage, processing, and detoxification
253
What forms bile salts?
Hepatocytes
254
Where does bile exit the liver?
The hepatic vein, which joins the vena cava
255
What do hepatic ducts do?
Trasport bile salts to gallbladder.
256
What is the function of bile salts?
To emulsify and separate fat for digestion, absorption, and pancreatic lipase digestion
257
Where are bile salts released from the gallbladder?
Into the duodenum
258
How much bile do human produce a day?
1 liter
259
What are bile salts produced from?
Cholesterol, amino acids, glycerine, or taurine
260
Why are bile salts able to break down fats?
They have hydrophobic and hydrophilic regions
261
Where is the rabbit gallbladder?
At the base of the liver
262
Why is bilirubin grenish/yellow?
RBC breakdown
263
What other than bile salts allows for cholesterol, fatty acid, and monoglyceride absorption?
Micelles
264
What are the three segments of the small intestine?
The duodenum, the jejunum, and the ileum
265
What is submucosa?
Connective tissue for stretch, includes the ENS submucosal plexus.
266
What is the muscularis externa?
Circular and longitudinal smooth muscle layers, includes the ENA myenteric plexus.
267
What is the visceral peritoneum (serosa)?
The outer connective tissue covering the digestive tract that secretes serosal fluid. Attached to mesentery that suspends intestine in abdominal cavity.
268
What is the brush border?
Epithelial cells with microvilli
269
How much doe the small intestine folds, villi, and microvilli increase the length of the small intestine?
600 x
270
What is transport of digested nutrients largely driven by?
Secondary active transport due to the sodium-potassium ATPase pump along basolateral side
271
What do soidum-glucose (SGLT), sodium-amino acid, and glucose transporters aid in?
The transport of molecules towards blood.
272
What does the transport of sodium aid in?
The transport/absorption of Cl- and water
273
How is fat transported in small intestine?
Passive diffusion (unassisted membrane transport)
274
Large fat droplets are emulsified into smaller units by _____ ____, broken down by ________ _____ into monoglycerides and free fatty acids which form ______ and are absorbed by epithelial cells.
Bile salts, pancreatic lipase, micelles
275
What are chylomicrons?
Fat droplets coated with phospholipids and proteins inside the cell formed by monoglycerides and fatty acids that reform triglycerides
276
What do chylomicrons undergo?
Exocytosis on the basolateral side and enter the lymphatic vessels on the way to the vena cava
277
Which vitamins are fat soluble and located in micelles during absorption?
A,D,E, and K
278
Where does most nutrient absorption occur in the intestine?
On the duodenum and jejunum
279
What is the ileum important for?
Absorption of vitamin B12 and reabsorption of bile salts
280
What factors of the small intestine match animal diet?
The type of pancreatic and small intestine enzymes, length of small intestine, and types of cell membrane transporters.
281
What does the hummingbird small intestine contain?
Large amounts of sucrose enzyme
282
What is the function of segmentation?
To mix and propel chyme through the small intestine in 3-5 hours. Involves smooth muscle contractions a few centimeters apart, forming contraction rings
283
What does segmentation aid in?
Helps to expose chyme to small intestine surface for absorption
284
The human small intestine contains ___ L of water from the diet and _ L from gastric juices. Approximately _ L of water is absorbed back into body.
2.5, 7, 9
285
How does the small intestine help maintain animal acid-base balance and water and ion concentrations?
Water and ion absorption
286
What is the cecum?
A blind pouch between the small intestine and large intestine. Important for microbial fermentation of cellulose.
287
What is the appendix?
Lymphatic tissue with no digestive function but stores some leukocytes. Considered a vestigial organ with little to no function.
288
What is the large intestine or colon?
The long organ between the cecum and rectum. Important for remaining water and ion absorption. Has ascending, transverse, and descending regions in humans.
289
What is the rectum?
The end of descending region, digestive exit.
290
What is the cloaca?
Renal, reproductive, and digestive exit in amphibians, birds, and egg laying animals
291
What is the purpose of the ileocecal valve and ileocecal sphincter?
Ensures transport of contents into cecum and not back into ileum.
292
What helps open ileocecal valve?
Gastrin
293
How much can the horse cecum hold?
7-8 gallons of food
294
What is the function of the colon?
Receive undigested cellulose, remaining bile salts, sodium, and water. Sodium is absorbed and water follows through osmosis. Some fermentation.
295
What is taeniae coli?
Bands of smooth muscle that run the length of the cecum and colon, resulting in the formation of haustra pouches
296
How does eating stimulate colon emptying?
Through the gastrocolic reflex. Food triggers the release of stomach gastrin and autonomic nervous system, causing strong smooth muscle contractions called mass movements.
297
What triggers the defecation reflex?
Fecal induced stretch.
298
What happens during the anal reflex?
The internal anal sphincter relaxes, the rectum and colon contract more vigorously, and animal has the urge to defecate. The external anal sphincter is voluntarily controlled.
299
What does fecal material consist of?
Undigested cellulose, bilirubin, sodium, water, and bacteria
300
What are fatty acids stored as?
Triglycerides in fat
301
What are amino acids used for?
Protein synthesis in animal
302
________ and ________ blood glucose levels are needed for animal survival.
Constant, consistent
303
What does too much glucose result in?
Negative osmotic effects and protein alterations to hemoglobin and collagen, negative effects on eyesight.
304
What does too little glucose result in?
Utilization of amino acids as fuel, starvation, and death
305
What are major storage sites for glucose as glycogen?
Liver and skeletal muscle
306
What happens during feasting?
Ingested nutrients are being absorbed by gut and enter the blood. Glucose is used for energy and then stored as glycogen. Fatty acids and amino acids are stored as triglycerides and protein.
307
What happens during fasting?
Nutrient absorption has finished, and nutrients decrease in blood. Glucose released from liver and muscle glycogen stores is used for energy.
308
What happens during continued fasting?
Triglycerides and protein are used for energy.
309
What are the roles of insulin and glucagon?
Regulate glucose, fatty acid, and amino acid storage and utilization during feasting and fasting cycles.
310
What are islets of langerhans?
Clusters of endocrine cells in pancreas.
311
Beta cells produce ______.
Insulin
312
Alpha cells produce _______.
Glucagon
313
What does insulin do?
Lowers blood glucose, fatty acids, and amino acids and stores them. Promotes activity of cell enzymes involve d in nutrient storage. Promotes cellular glycogen, triglyceride, and protein synthesis.
314
Increased blood glucose levels _______ insulin secretion from beta cells - _______ control.
increase, major
315
What other factors increase insulin production?
Increased amino acids in blood, food in digestive tract, and food induced parasympathetic activity.
316
Sympathetic activity ________ insulin release, glycogen synthesis, and _______ blood glucose for energy.
decreases, increases
317
What does glucagon do?
Antagonizes or counter balances insulin action. Increases fuel in blood by increasing liver glucose production and secretion, fat breakdown, inhibits triglyceride synthesis and liver protein synthesis, and promotes degradation of protein in liver.
318
What is diabetes mellitus?
Inadequate insulin action and hyperglycemia
319
What is diabetes mellitus type 1?
Insulin dependent. Near or total lack of insulin production by pancreatic beta cells. Often related to autoimmune disease targeting beta cells. Insulin provided as treatment.
320
What is diabetes mellitus type II?
Non-insulin dependent. Insulin secretion normal or even greater, but tissues don't respond to insulin. Caused by inactive or unresponsive insulin receptors because of receptor genetic mutation or disruption in receptor signaling. Chronic insulin secretion results in a decrease in a decrease in tissue insulin receptors over time.
