Unit 5 Lec Flashcards
(183 cards)
1
Q
Exchange usually involve SOLUTES that
are dissolved in media including
A
- Blood Plasma
- Interstitial (Body) Fluid
- Intracellular (Cytoplasm) Fluid
2
Q
Thus, the EXCHANGE of Ions, Nutrients,
Wastes, etc. is going to affect both the
A
DIRECTION / RATE of DIFFUSION
3
Q
FORM of Digestive System is highly adapted to the
FUNCTION of
A
Breaking Down and Absorbing Nutrients
4
Q
FORM of “Brush Border” MAXIMIZES ? (Small intestine)
A
Surface area
5
Q
What maximizes surface area in small intestine
A
- Extreme length: long folded tract increase area
- Villi: tissue layer morphology
- Microvilli: cell membrane morphology
6
Q
Ultimately, maximizing surface area helps the digestive system do perform it function..
A
Of acquiring nutrients and energy
7
Q
Organic molecules from environment or other organisms are broken down to be used for
A
Energy (atp) and synthesis
8
Q
Diverse dietary modes
A
Carnivore: eat other animals
Herbivores: eat autotrophs (plants)
Omnivores: eat both animals and plants
Detritivores: eat dead/decaying matter
9
Q
Diet must satisfy need for — — —
A
Energy atoms nutrients
10
Q
Energy
A
Intake of food provides source of ATP to power biological reactions
11
Q
Atoms
A
Food brings in necessary energy organic carbon and nitrogen atoms that can be used to synthesis needed molecules
12
Q
Essential nutrients
A
Certain necessary molecules cannot be built by certain organisms, and thus must be ingested a,ready made from an outside source
13
Q
Essential nutrients that cannot be made by cells, but needed for life
A
Essential amino acids
Essential fatty acids
Vitamins
Minerals
14
Q
Essential amino acids (essential nutrient)
A
All organisms require a standard set of 20 amino acids
- most organisms make abt half of needed 20 amino acids
- remainder that that cannot make are called essential amino acids
15
Q
Essential fatty acids (essential nutrients)
A
Animals can synthesuze mist if needed fatty acids
- certain types of unsaturated fatty acids
- deficiencies in essential fatty acids are rare due to abundance food
16
Q
Vitamins (essential nutrient)
A
Organize molecules from diet that are required in very small amounts
- critical to major biological processes including but not limited to
* citric acid cycle: numerous
*visual system (vitamin A (retinol)
* collagen synthesis : vitamin C
17
Q
Minerals (essential nutrients)
A
Inorganic molecules from diet that are required in very small amounts
- critical to major biological processes including but not limited to :
*heme group (red blood cells): Fr (iron)
*water balance : sodium (Na+)
* neurons : sodium (Na+) and potassium (k+)
18
Q
digestive system : 2 sets of organs
A
Digestive tract
Accessory organ
19
Q
Digestive tract
A
- Passageway for Food
- Direct DIGESTION
- Direct ABSORBTION
20
Q
Accessory organs
A
- Produce Enzymes
- Produce Hormones
- Assist DIGESTION
- NOT along Tract
21
Q
Digestion
A
Food broken into small enough subunites to be absorbed and utilized at molecular level
22
Q
Extracellular digestion
A
Completely digest food before absorption into cells
23
Q
Humans completely breakdown food before
A
Molecules absorbed into cells
24
Q
Extracellular digestion occurs in compartments which are continuous with the
A
Outside body
25
Digestive tract has different organs but they all share general anatomical_ layer structure
4
26
Esophagus to anal canal, the organs of GI tract have the same general4 layer structure
Mucosa
Submucosa
Muscularis externa
Serosa
27
Mucosa
Innermost to lumen which has following functions
1. Secretion: mucus, enzymes, hormones
2. Absorption: nutrients and transfer to bloodstream
3. Protection: against pathogens
28
Lamina propria of mucosa
Connective tissue and stem cells to regenerate tissues
29
Muscularis mucosoe of mucosa
Additional thin muscle layer which is often present to propel mucus, to help lubrucation and protection
30
Submucosa
Surrounds mucosa
- large amount of CT which helps some organs distend and regain their shape (stomach)
- blood vessels, lymph vessels and nerve fibers (enteric nerves )
31
Muscularis externa
Smooth muscle
Peristalsis: propulsion of bolus
Segmentation: mechanical digest
Sphincter: tonic contraction
Circular layer: contracts and shrinks lumens circumference
Longitudinal layer: contracts and shortens tracts length
32
Serosa
Outermost layer
- visceral peritoneum that lines system along body cavity
- CT that is covered by single layer of squamous epithelia
33
What occurs in the oral cavity
Ingestion and mechanical breakdown
34
Cephalic stage
Mechanical digestion inside oral cavity
35
Salivary glands
Begin chemical digestion with amylase (starch breakdown)
- lubricators food (helps swallowing )
36
Tongue
Shapes food into bolus that is easier to move
37
Teeth
Distinct types of dentition based diet the species is adapted to
- vary in size shape and cutting surface
- vary in number of dif types (incisors, canines, premolar, molar
38
Special structure involves in swallowing
Pharynx, swallowing , esophagus , sphincter
39
Pharynx
Mammals havee a junction between both the esophagus and windpipe (trachea) to lungs
40
Swallowing
Relaxes sphincter that causes the epiglottis to block trachea
41
Bolus is moved the the stomach via
Peristalsis from smooth muscle
42
Processing in stomach
Glands in stomach secrete gastric juice
- gastric juice breaks down proteins with HCLamd pepsin
43
Two sphincters regulate what (stomach)
Bolus movement and keep the very acidic gastric juice contained within stomach
44
Small intestine three structural divisions
1. Duodenum (first part / entry)
2. Jejunum: (highest absorption)
3. Ileum(vitamins, salts/exits)
45
Small intestine is the major organ of both __ and __
Digestion and absorption
46
Duodenum
Digestive enzymes enter via ducts from pancreas and liver to assist breakdown of various nutrients
47
What does epithelais lining of duodenum make on its own
Digestive enzymes to fully breakdown additional nutrients
48
Peristalsis (small intestine/duodenum)
Smooth muscle
Move food along intestine
Next enter jejunum and then ileum
49
What do Jejunum and illeum perform most of the
Absorption
50
Large intestine
Important absorption occurs in cesium and colon
51
Small intestine connects to
Large intestine at cecum
52
Cecum
AIDS in plant fermentation so more material can be extracted
53
Colon (large intestine)
Remaining sections along large intestine that play critical role in absorbing water
54
Appendix (large intestine)
Immunity role
55
Rectum and anus
Undigested material is expel,ed
56
Large intestine terminates at the
Rectum and anus
57
Wastes of the digestive tract
Feces become more solid as they move through colon
58
Once waste reaches rectum,
Sphincter muscle move feces out of anus
59
Symbiotic bacteria
Organism usually have symbiotic bacteria living within intestines
- host :food delivered to bacteria: shelter provided
- bacteria: produces nutrients that are not normally available to host
60
Enteric Nervous System
network of Ganglia
and 100 Million Neurons that line GI-Tract
- actually more than the Spinal Cord!
61
Semiautonomous Neurons are arranged in
TWO major nerve plexuses in Walls of tract
- Submucosal Nerve Plexus
- Myenteric Nerve Plexus
- Largely control Propulsion/Motility
- Comprised of Ganglia that interconnect like
“Chicken-Wire” along GI-Tract
62
63
Short Reflexes: (enteric nervous system)
mediated by
the Enteric Plexuses, and are
largely INVOLUNTARY
- Pacemakers / Reflexes
- Internal Sensory Stimuli
64
Long Reflexes (enteric nervous system)
involve CNS
Integration Centers, and
“Extrinsic” ANS Divisions
- Parasympathetic Division
- Sympathetic Division
- Internal/External Stimul
65
Effectors of enteric nervous system
Secretory glands
Smooth muscle
66
Before we even bring food into
the Oral Cavity, visual/olfactory
STIMULI trigger the production of
Digestive Enzymes in the Saliva
- i.e. Chemical Digestion
67
Cephalic phase
Food brought to mouth and prepared for propulsion
68
Employ Teeth to break food into
smaller “chunks” that can fit into
our __ and __
69
Mechanical digestion assists with access of
Enzymes
70
What are walls of the mouth lined with
Thick Stratified Squamous Epithelia
- Protects against FRICTION
- Protects against CHEMICALS
- Reinforced with Keratin
71
What do lips/cheeks do?
help keep food in the
proper location during Ingestion and
Mechanical Digestion
72
Oral Vestibules with Gingivae (Gums)
hold Teeth
73
Hard Palate:
provides a rigid surface
for the Tongue to push against when
Chewing
- Ridges help create friction…
74
Soft palate
more mobile fold that
rises to block the Nasopharynx when
Swallowing
- Palatine Tonsil / Uvula at tip…
75
Tongue
made of Skeletal Muscle of
TWO Types, to perform:
- Mechanical Digestion of the Bolus
- Mixing Saliva into the Bolus
- Propulsion (Swallowing)
- Formation of Consonant Sounds
76
Intrinsic muscles
not attached to Bone,
they allow the Tongue to change SHAPE
- Important for Speech and Swallowing
77
Extrinsic muscles
attached to Bone,
they alter the POSITION of the Tongue
78
Tongue surface has peg-like projections called
Papillae
79
Filiform Papillae (tongue)
smallest and most
numerous, they provide FRICTION to
manipulate soft foods (Keratin)
80
Fungiform (tongue)
house TASTE BUDS
that can have chemosensory function,
and are supplied by vascular core
81
Vallate papillae
larger TASTE BUDS
that have more specific taste functions
82
Foliate papillae
more “pleat-like” they
have TASTE BUDS on the side of Tongue
83
Saliva performs a variety of roles
- cleanse mouth
- dissolve food for taste
- provide Electrolytes for GI-Balance
- Lubricate food Bolus
- Amylase: begin starch digestion
- Antimicrobial: Lysozymes / Antibodies
- Mucin Protein (thickening agent)
84
Three main glands of salivary glands
- Parotid Gland: largest, connecting
via duct to upper oral cavity
- Submandibular Gland: medium, its
duct enters under Frenulum (area in
front of the tongue)
- Sublingual Gland: almond shaped;
it has several ducts that enter under
the tongue and floor of mouth
85
Saliva begins the process of
Chemical digestion
86
Salivation Control is a point of
Digestive regulation
87
Minor Salivary Glands continuously
secrete
Saliva to keep mouth moist
88
Major Salivary Glands are ACTIVATED
when food enters
the Mouth, or other
Long Reflexes are initiated…
- Parasympathetic Division activated…
- Increases Watery / Enzyme components
- Irritation (Spicy!) also activates Saliva
89
if too much pain (Too Spicy!), the
Sympathetic Division will activate more
Mucus and shut down digestion
90
Teeth vary in cutting surface, size,
shape, and number!
- Incisors = cutting (meat)
- Canines = tearing/piercing (meat)
- Premolars = crushing (tough)
- Molars = grinding (vegetation)
91
Teeth in Humans are varied, due to
our mixed diet as
Omnivores
92
Primary (Milk) Teeth:
Baby
Teeth that we lose have slightly
different root structure, and are
less numerous
93
Permanent Teeth:
develop in the Oral Vestibule
and then erupt through Gingivae,
after Roots of Milk Teeth dissolve
94
Teeth: have the toughest material in the
body, called
Enamel, which is very highly
mineralized to protect against chewing…
- CANNOT be replaced…
95
Dentin
contains unique “Tubules” that
has an Odontoblast that can regenerate
the Tooth Tissue to prevent Tooth Decay
- CAN be replaced, to an extent…
96
Voluntary control mediated by
Motor neurons of cranial nerves
97
Involuntary control mediated by
Enteric plexuses that control smooth muscle
98
Smooth muscle two perpendicular layer
Circular and longitudinal
99
Circular layer
line circumference
the Lumen, so CONTRACTION will
CONSTRICT Cross-Section!
100
Longitudinal layer
runs parallel
to the Lumen, so CONTRACTION
will SHORTEN Tube!
101
Alternation contraction of circular and longitudinal layer will squeeze what
Bolus through pathaway
102
Smooth Muscle: contraction of TWO Layers does
Peristalsis and segmentation
103
TWO Methods of CONTRACTION by
Smooth Muscle in the organs of the
Digestive System
Tonic and phasic contraction
104
Tonic contractions
sustained for
long periods of time (up to Hours):
- Sphincters and Stomach Muscles
105
Phasic contractions
have cycles of
contraction / relaxation (few Seconds)
- Peristalsis and Segmentation
- Involve “Pacemaker” Cells
106
Smooth muscle pacemaker cells are located in
Myenteric plexus
107
Pacemaker cells in myenteric plexus
nterstitial Cells of Cajal (ICC)
108
interstitial Cells of Cajal (ICC)
these are
Neurons from Enteric Nervous System
(ENS) that act as Pacemakers
- Have UNSTABLE Membrane Potential
- Auto-Depolarize to generate rhythm…
- in myenteric plexus btwn muscle
109
110
What are ICC CONNECTED TO
Smooth Muscle Cells by
Gap Junctions, so electrical impulse is
relayed directly through cells
111
Although ICC auto rhythmic still innervated by
ENS/ANS at Varicosities
112
Smooth muscle cells visual
spindle”
shaped, and LACK Striations
- Do NOT form as long fibers…
- Connected via Gap Junctions
113
Do smooth muscle cells have sarcomeres
No instead contract using dense bodies
- “Dense Body” anchors Thick Filaments
- STILL use Actin-Myosin Contraction
114
Do smooth muscle cells have T tubules to propagate AP
No have Caveola instead
115
Smooth muscle is essential for what
Involuntary propulsion
116
How does smooth muscle cells function in swallowing
• Voluntary (Skeletal) Contractions begin the process in the Oral Cavity and Pharynx
• Involuntary Contractions continue the remainder of the process down Esophagus
117
Small intestine is the major organ of both __ and __
Digestion and absorption
118
Digestion
breakdown of food
into SMALLER Molecules is facilitated
by many enzymes…
119
Absorption
the exchange of
those digested nutrients across cell
membranes by DIFFUSION is aided by
MASSIVE Surface Area of the organ…
120
What is the beginning of the small intestines
Duodenum
121
Digestive enzymes enter via duct from the __ and __
Pancreas and liver to assist with breakdown of various nutrients
122
The Epithelial Lining of the Duodenum also
makes its OWN…
Digestive enzymes to fully breakdown additional nutrients
123
Peristalsis
Smooth muscle
Move food along intestine
Next enter the Jejunum and then ileum
124
Two sphincters of the stomach regulate what?
Bolus
movement INTO and OUT of Stomach
- Cardia / Gastroesophageal Sphincter
controls ENTRY of Food
- Pyloric Sphincter controls EXIT of the
Food Bolus
125
Sphincters (stomach)
keep acidic Gastric Juice
contained within the Stomach, and
allow for Storage of Food
126
Storage of stomach
can hold partially
digested Food for later…
- Fundus: “Dome” for Extra Storage
127
Mechanical digestion of stomach
to begin the
HARD task of Protein Digestion, the
Stomach has an EXTRA LAYER of the
Muscularis Externa
128
Oblique layer of stomach
added layer between
the Submucosa and Circular Layer of
the Muscularis Externa
- Pummel” the Bolus into Chyme,
which softens the Food further, and
makes Peptide Bonds easier to access!
129
130
Chemical digestion of stomach
are Gastric Glands
in Stomach that secrete Gastric Juice,
which can break down Peptide Bonds
through chemical reactions!
131
Mucosa layer is modified to have deep, branching of? (Stomach)
Gastric Glands with various
specialized Cell Types!
132
Is there absorption in stomach?
NO Substantial Absorption is done in
Stomach, to contain ACIDIC Juices
- Minimal Absorption of a few lipid-
soluble items, like Alcohol and Aspirin
133
What does gastric juice contain (stomach)
Hydrochloric acid
Pepsinogen = pepsin
134
Hydrochloric acid (gastric acid)
breaks up ECM
of cells, while low-PH DENATURES
Proteins such that Peptide Bonds
can be accessed…
135
Pepsinogen (gastric juice)
when secreted into
the Lumen, the HCl Acid converts
it to Pepsin
- Pepsin then Chemically Digests
Peptide Bonds, breaking Proteins
into Amino Acids
136
Chemical digestion
Food broken into subunits small enough to be absorbed via diffusion
137
When are amino acids absorbed
Small intestine
138
Gastric gland has dif cell types
1. Parietal Cells: secrete H+ & Cl- separately;
also secrete Intrinsic Factor
2. Chief Cells: secrete Pepsinogen, which
becomes Pepsin when mixed with HCl;
also secrete Lipases
3. Mucous Cells: secrete mucous to protect
lining from Gastric Juice
4. Enteroendocrine Cells: secrete a variety of
hormones, including Gastrin
139
Mucosal barrier of stomach
Essential to protect stomach lining from acid
1. Mucous cells
2. Epithelial cells
140
1. Mucous cells (mucosal barrier
secrete Mucus that is infused with
Bicarbonate to help NEUTRALIZE Acid along the
Stomach Wall
141
2. Epithelial cells of mucosal barrier
are joined by Tight Junctions to
prevent Gastric Juice from leaking into underlying
tissues.
142
What happens to damaged epithelial cells (mucosal barrier)
Shed and Replaced by
Stem Cells that reside where the Gastric Pits connect
to Gastric Glands.
143
If mucosal barrier is compromised what can happen?
it can cause
INFLAMMATION / DAMAGE, which leads to Ulcers!
144
What can the disruption of mucosal barrier lead to
Ulcers
145
Gastric ulcers (mucosal barrier)
damage to the Stomach Wall, including
Digestion by Stomach’s own Pepsin Enzymes!
146
How are gastric ulcers caused (mucosal barrier)
caused by Bacterial Overgrowth of Heliobacter Pylori
- H. Pylori disrupts gelatinous Mucus protection
- Allows Pepsin and HCl to Irritate / Digest Mucosa
- Can do a “Breath Smell” test to check for H. Pylori!
147
The stomach is involved in __ control of various reflexes in digestive system
Hormonal
148
Gastrin involved in numerous pathways, highlighting stomach’s involvement in
Complex reflexes
149
__ and __ stimuli can control levels of __ that circulate in blood
Positive, negative
Gastrin
150
Multiple responses of gastrin in stomach
- Short-Reflexes
- Long-Reflexes
- Local Effects
- Broad Effects
- etc.
151
Short reflexes of ENS
mediated by
the Enteric Plexuses, and are
largely INVOLUNTARY
- Pacemakers / Reflexes
- Internal Sensory Stimuli
152
Long reflexes of ENS
involve CNS
Integration Centers, and
“Extrinsic” ANS Divisions
- Parasympathetic Division
- Sympathetic Division
- Internal/External Stimuli
153
Does gastrin help open ileocecal valve?
Yes
- stomach mixes gastrin in chyme, proceeds to small intes
- chyme makes it to ileocecal valve
- gastrin hormone mixed in chyme , stimulate receptors in ileocecal valve to promote relaxation
- allows chyme to enter into large intestine
154
What pH does stomach require
Low pH to function
- helps break peptide bond of denaturing proteins
- ^ access to bonds by removing shape
- gastrin stimulates parietal cells to make HCL
155
Emptying of stomach is under __ control
Reflex
undergoes Peristalsis Movement like other parts of the GI-Tract, which is
under automatic control by Pacemaker Cells
156
What does duodenum release for emptying stomach
releases Secretin and CCK, which
DECREASE the Contractile Force and Stomach
Emptying, giving time for Digestive Tract to
“catch-up” with food that takes longer to
breakdown….
• Secretin and CCK, also stimulate the Liver and
Gallbladder to make more Bile, which helps to
digest lipids….
157
Both __ and __ regulate secretion of bile and pancreatic juice (bile breakup food)
Hormone and neural stimuli
- Vagus Nerve: basal response to food…
- Hormones: high response to Fat, if needed…
158
What does bile do
Bile emulsifies / BREAKS UP Fatty Food
- Bile STIMULATES production of MORE Bile
- fat is cleared, stomach clearing continues
159
MOST Digestion occurs in Duodenum, where
numerous enzymes enter via ducts from many
Accessory Organs
Accessory organs
- pancreas and liver secrete enzymes
160
161
What enzymes die pancreas secrete ? (Small intestine)
Lipases, Proteases, Nucleases to
breakdown Fats, Proteins, Nucleic Acids,
162
What enzymes does liver secrete (small intestine)
makes Bile Salts, which are first stored
in the Gallbladder (breakdown fats)
163
Duodenum also makes its OWN Enzymes,
which are ANCHORED to
Brush border
164
__and __perform most of the Absorption
Jejunum and ileum
165
Although DIFFUSION and SURFACE AREA are
eventually driving forces for Absorption and
exchanges of nutrients, often there is a
“coupling” with
Active transport
- energy free diffusion
- ATP driven active transport
166
Glucose absorption
- pancreatic amylase breaks down starches into disaccharides - where surface area comes into play
- brush border enzymes digest disaccharides into monosaccharides
* enterocytes only absorb monosaccharides
- cotranaporters couple diffusion of Na+ to bring in monosaccharides
* secondary active transport
- monosaccharides now diffuse from enterocytes into capillaries
*where diffusion comes into play
167
BUT, the Small Intestine and Large Intestine do more than
just Digestion and Absorption…
Secretion
168
Small intestine secretes material into
Lumen
• Intestinal Glands a.k.a. Mucosal Glands secrete Mucus from Mucosa
• Brunner’s Glands a.k.a. Duodenal Glands secrete Mucus from Submucosa
169
So why do we need to SECRETE Immunoproteins into the
Digestive Tract?
Keep bacteria in check
170
Cecum is a pocket below what
Ileocecal valve where chyme can be mixed further with mucus and be stored for a time
171
Fermentation and absorption are greatly assisted by
Symbiotic bacteria
172
Herbivores have much larger __ to perform more fermentation
Cecum
173
Where does symbiotic reside in
Small and large intestine
- enter via passage in food
- enter from colonization via anus
174
What does symbiotic bacteria assist with
Breakdown of plant material
- process is fermentation
- bacteria digest plant material
- humans absorb by products (fatty acids, vitamins)
175
What does symbiotic bacteria produce
Vitamins via their own metabolism
- release Vitamins as BY-PRODUCTS
- Vitamin B: diverse roles
- Vitamin K: blood clotting
176
Large intestine absorb
Vitamins
177
What does appendix store
Good bacteria - keep bacterial population in check
- lymphoid tissue
178
What is appendix susceptible to
to fecal
Blockage, due to twisted/narrow structure
- Can lead to infection and Appendicitis
- Inflammation blocks of drainage…
- Can burst, spreading of fecal matter
179
Role appendix highlights importance of ___ with __
Maintains homeostasis with gut bacteria
180
Immune system and gut bacteria live in
Dynamic equilibrium via
Homeostasis is maintained to PROMOTE
the growth of “good” Bacteria, so they can
outcompete more pathogenic strains
• Immune System ACTIVELY stops Bacteria
from entering inappropriate areas, via
MALT Structures (e.g. Peyer’s Patches,
Appendix, etc
181
Ileocecal Valve (Sphincter) is closed most of
the time, it RELAXES via TWO Mechanisms:
• Gastroileal Reflex: “Short Reflex” triggered
by sensors in Stomach lead to Propulsion in
Ileum and RELAXATION of Ileocecal Valve
• Gastrin Hormone is mixed into Chyme in the
Stomach, which stimulates receptors in the
Ileocecal Valve to promote RELAXATION
• BACKPRESSURE from Chyme/Bolus after it
passes into Cecum closes the valve.
182
Spicy Foods can trigger MORE
Mucus production
183
What does spicy food have in it
Capsaicin which bind/activates pain receptors
