DIGESTIVE SYSTEM Flashcards by Secret acc

Q

GI provides the body with a continual supply of water, electrolytes, vitamins, and nutrients, which requires the following:

A

Movement
Secretion
Absorption
Circulation
Control

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Q

Adaptation of Parts:
______: Facilitates simple passage of food.

A

Esophagus

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Q

Adaptation of Parts:
______: Acts as temporary storage for food.

A

Stomach

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Q

Adaptation of Parts:
______: Specialized for digestion and absorption.

A

Small Intestine

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Q

Physiologic Anatomy of the Gastrointestinal Wall
- Cross Section of the Intestinal Wall (from outer surface inward):

A

Serosa
Longitudinal Smooth Muscle Layer
Circular Smooth Muscle Layer
Submucosa
Mucosa

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Q

______: Sparse bundles of smooth muscle fibers located in the deeper layers of the mucosa.

A

Mucosal Muscle

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Q

______: Executed by the various smooth muscle layers.

A

Motor Functions of the gut

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Q

GASTROINTESTINAL SMOOTH MUSCLE FUNCTIONS AS A ______

A

SYNCYTIUM

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Q

GASTROINTESTINAL SMOOTH MUSCLE FUNCTIONS AS A SYNCYTIUM

Length: ______-______ µm

A

200, 500

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Q

GASTROINTESTINAL SMOOTH MUSCLE FUNCTIONS AS A SYNCYTIUM

Diameter: ______-______ µm

A

2, 10

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Q

GASTROINTESTINAL SMOOTH MUSCLE FUNCTIONS AS A SYNCYTIUM

______ connections enable coordinated activity

A

Inter-layer

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Q

GASTROINTESTINAL SMOOTH MUSCLE FUNCTIONS AS A SYNCYTIUM

Made up of bundles of ______ fibers (______ and ______ layers)

A

parallel, longitudinal, circular

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Q

GASTROINTESTINAL SMOOTH MUSCLE FUNCTIONS AS A SYNCYTIUM

Fibers are ______ connected (via ______)

A

electrically, gap junctions

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Q

GASTROINTESTINAL SMOOTH MUSCLE FUNCTIONS AS A SYNCYTIUM

Functions as a single unit (______)

A

syncytium

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Q

GASTROINTESTINAL SMOOTH MUSCLE FUNCTIONS AS A SYNCYTIUM

Allows synchronized ______ and ______ for digestion

A

contractions, relaxations

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Q

______: Continuous slow electrical activity along muscle membranes

A

Intrinsic Electrical Activity

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Q

TYPES OF ELECTRICAL WAVES:

A

Slow Waves
Spike Potentials
Changes in Voltage of the Resting Membrane Potential
Entry of Calcium Ions Causes Smooth Muscle Contraction
Tonic Contraction of Some Gastrointestinal Smooth Muscle

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Q

TYPES OF ELECTRICAL WAVES:

______:
- Gradual changes in resting membrane potential (______-______ mV)

A

Slow Waves, 5, 15

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Q

TYPES OF ELECTRICAL WAVES:

______:
- Frequency varies by region:
Stomach: ~______/min
Duodenum: ~______/min
Terminal Ileum: ~______-______/min

A

Slow Waves, 3, 12, 8, 9

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Q

TYPES OF ELECTRICAL WAVES:

______:
- Caused by interactions between smooth muscle cells and pacemaker cells (Interstitial cells of ______)

A

Slow Waves, Cajal

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Q

TYPES OF ELECTRICAL WAVES:

______:
- Typically don’t cause contraction directly

A

Slow Waves

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Q

TYPES OF ELECTRICAL WAVES:

______:
- True action potentials exceeding -40 mV

A

Spike Potentials

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Q

TYPES OF ELECTRICAL WAVES:

______:
- Frequency: ______-______ spikes/second, lasting ______-______ milliseconds

A

Spike Potentials, 1, 10, 10, 20

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Q

TYPES OF ELECTRICAL WAVES:

______:
- ______ slow wave peaks = ______ spike potential frequency

A

Spike Potentials, Higher, increased

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TYPES OF ELECTRICAL WAVES: ______: - Generated by calcium-sodium channels

Spike Potentials

TYPES OF ELECTRICAL WAVES: ______: - Calcium influx initiates muscle ______

Spike Potentials, contractions

TYPES OF ELECTRICAL WAVES: ______: - The resting membrane potential of a muscle cell is typically around ______ millivolts. Changes in this voltage can affect how easily the muscle can be ______.

Changes in Voltage of the Resting Membrane Potential, -56, excited

TYPES OF ELECTRICAL WAVES: ______: - Depolarization makes muscles ______ excitable, while hyperpolarization makes them ______ excitable.

Changes in Voltage of the Resting Membrane Potential, more, less

TYPES OF ELECTRICAL WAVES: ______: - ______ occurs when calcium ions enter muscle fibers.

Entry of Calcium Ions Causes Smooth Muscle Contraction, Contraction

TYPES OF ELECTRICAL WAVES: ______: - Calcium activates ______ filaments through a ______ control mechanism, allowing contraction.

Entry of Calcium Ions Causes Smooth Muscle Contraction, myosin, calmodulin

Role of Slow and Spike Potentials - Slow waves primarily allow ______ entry and do not directly cause muscle ______.

sodium, contraction

Role of Slow and Spike Potentials - Significant ______ occurs during spike potentials, leading to ______.

calcium influx, contraction

TYPES OF ELECTRICAL WAVES: ______: - Continuous contraction not linked to the ______ activity, lasting several ______ to ______.

Tonic Contraction of Some Gastrointestinal Smooth Muscle, rhythmic slow wave, minutes, hours

TYPES OF ELECTRICAL WAVES: Tonic Contraction of Some Gastrointestinal Smooth Muscle - Causes of Tonic Contraction:

1. Continuous repetitive spike potentials 2. Hormonal stimulation 3. Continuous calcium ion entry

TYPES OF ELECTRICAL WAVES: Tonic Contraction of Some Gastrointestinal Smooth Muscle - Causes of Tonic Contraction: Continuous repetitive spike potentials: ______ frequency leads to ______ contraction.

Higher, greater

TYPES OF ELECTRICAL WAVES: Tonic Contraction of Some Gastrointestinal Smooth Muscle - Causes of Tonic Contraction: Hormonal stimulation: Causes partial ______ without ______.

depolarization, action potentials

TYPES OF ELECTRICAL WAVES: Tonic Contraction of Some Gastrointestinal Smooth Muscle - Causes of Tonic Contraction: Continuous calcium ion entry: Occurs independently of ______.

membrane potential changes

NEURAL CONTROL OF GASTROINTESTINAL FUNCTION— ______ SYSTEM

ENTERIC NERVOUS

The ______ is a complex network of over ______ million neurons embedded in the ______, extending from the ______ to the ______. It controls gastrointestinal ______ and ______.

enteric nervous system (ENS), 100, gastrointestinal tract, esophagus, anus, movements, secretions

Plexuses:

1. Myenteric Plexus (Auerbach’s Plexus) 2. Submucosal Plexus (Meissner’s Plexus)

Plexuses: ______ Plexus (______ Plexus): - Located between the longitudinal and circular muscle layers.

Myenteric, Auerbach’s

Plexuses: ______ Plexus (______ Plexus): - Primarily controls gastrointestinal motility.

Myenteric, Auerbach’s

Plexuses: ______ Plexus (______ Plexus): - Extends along the gastrointestinal tract.

Myenteric, Auerbach’s

Plexuses: Myenteric Plexus (Auerbach’s Plexus): Controls: - Increased ______. - Enhanced ______. - Increased ______ and ______. - Contains both ______ and ______ neurons.

tone of the gut wall, rhythmic contractions, contraction frequency, speed of peristalsis, excitatory, inhibitory

Plexuses: ______ Plexus (______ Plexus): - Found in the submucosa.

Submucosal, Meissner’s

Plexuses: ______ Plexus (______ Plexus): - Mainly regulates gastrointestinal secretion and local blood flow

Submucosal, Meissner’s

Plexuses: ______ Plexus (______ Plexus): - Focuses on local control within segments of the intestine.

Submucosal, Meissner’s

Plexuses: ______ Plexus (______ Plexus): - Integrates sensory signals for regulating secretion, absorption, and local contractions.

Submucosal, Meissner’s

Plexuses: ______ Connections: - ______ and ______ fibers connect to both plexuses, ______ or ______ gastrointestinal functions.

Extrinsic, Sympathetic, parasympathetic, enhancing, inhibiting

Plexuses: ______: - Originate from the ______, relaying information to both plexuses and other nervous system components.

Sensory Nerve Endings, gastrointestinal epithelium

Types of Neurotransmitters Secreted by Enteric Neurons Over ______ neurotransmitters identified, including: - ______ - ______

25, Excitatory, Inhibitory

Types of Neurotransmitters Secreted by Enteric Neurons Over 25 neurotransmitters identified, including: - Excitatory: ______, certain ______.

Acetylcholine, peptides

Types of Neurotransmitters Secreted by Enteric Neurons Over 25 neurotransmitters identified, including: - Inhibitory: ______, ______, vasoactive intestinal ______

Norepinephrine, epinephrine, polypeptide

AUTONOMIC CONTROL OF THE GASTROINTESTINAL TRACT ______ Stimulation: - Divided into ______ (______ nerve) and ______ divisions.

Parasympathetic, cranial, vagus, sacral

AUTONOMIC CONTROL OF THE GASTROINTESTINAL TRACT ______ Stimulation: - ______ enteric nervous system activity, ______ gastrointestinal functions.

Parasympathetic, Increases, enhancing

AUTONOMIC CONTROL OF THE GASTROINTESTINAL TRACT ______ Stimulation Usually Inhibits Gastrointestinal tract Activity

Sympathetic

AUTONOMIC CONTROL OF THE GASTROINTESTINAL TRACT ______ Stimulation: - Originates from the spinal cord (______ to ______).

Sympathetic, T5, L2

AUTONOMIC CONTROL OF THE GASTROINTESTINAL TRACT ______ Stimulation: - Generally inhibits gastrointestinal activity through ______ release.

Sympathetic, norepinephrine

AUTONOMIC CONTROL OF THE GASTROINTESTINAL TRACT ______ Stimulation: - Can block peristalsis if strongly stimulated.

Sympathetic

Afferent Sensory Nerve Fibers From the Gut Sources of Stimulation: - ______, ______, and ______.

Gut mucosa irritation, excessive distention, specific chemicals

Afferent Sensory Nerve Fibers From the Gut Sensory Pathways: - ______ fibers transmit signals to the ______ and ______, influencing ______ and ______ control.

Afferent, spinal cord, brain stem, reflexes, gastrointestinal

Gastrointestinal Reflexes:

1. Local Reflexes 2. Long-Distance Reflexes 3. CNS-Connected Reflexes

Gastrointestinal Reflexes: ______: Integrated within the ENS, controlling secretion and motility.

Local Reflexes

Gastrointestinal Reflexes: ______: From gut to prevertebral ganglia and back, such as the gastrocolic reflex.

Long-Distance Reflexes

Gastrointestinal Reflexes: ______: Involving the spinal cord or brain stem, including gastric control and defecation reflexes.

CNS-Connected Reflexes

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY - Gastrointestinal hormones play crucial roles in regulating ______ processes, including ______ and ______. They are released into the ______ circulation and act on specific target cells, even when nervous connections are severed.

digestive, secretion, motility, portal

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones:

1. Gastrin 2. Cholecystokinin (CCK) 3. Secretin 4. Glucose-dependent Insulinotropic Peptide (GIP) 5. Motilin

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ - Secreted by "G" cells in the ______ of the ______.

Gastrin, antrum, stomach

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Stimuli for Secretion: - Stomach distention.

Gastrin

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Stimuli for Secretion: - Presence of protein products.

Gastrin

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Stimuli for Secretion: - Gastrin-releasing peptide from gastric mucosa nerves (______ stimulation).

Gastrin, vagal

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Actions: - Stimulates gastric acid secretion.

Gastrin

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Actions: - Promotes growth of gastric mucosa.

Gastrin

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ - Secreted by "I" cells in the ______ of the ______ and ______.

Cholecystokinin (CCK), mucosa, duodenum, jejunum

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Stimuli for Secretion: - Digestive products of fat (fatty acids and monoglycerides).

Cholecystokinin (CCK)

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Actions: - Contracts the gallbladder, releasing bile into the small intestine.

Cholecystokinin (CCK)

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Actions: - Inhibits gastric motility, slowing stomach emptying.

Cholecystokinin (CCK)

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Actions: - Suppresses appetite by signaling the brain through sensory afferent fibers.

Cholecystokinin (CCK)

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ - Secreted by "S" cells in the ______ of the ______.

Secretin, mucosa, duodenum

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Stimuli for Secretion: - Acidic gastric juice entering the duodenum.

Secretin

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Actions: - Promotes pancreatic secretion of bicarbonate to neutralize acid.

Secretin

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Actions: - Has a mild effect on gastrointestinal motility.

Secretin

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ - Secreted by the mucosa of the upper small intestine.

Glucose-dependent Insulinotropic Peptide (GIP)

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Stimuli for Secretion: - Fatty acids, amino acids, and to a lesser extent, carbohydrates.

Glucose-dependent Insulinotropic Peptide (GIP)

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Actions: - Decreases gastric motility, slowing emptying into the duodenum.

Glucose-dependent Insulinotropic Peptide (GIP)

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Actions: - Stimulates insulin secretion at lower blood levels.

Glucose-dependent Insulinotropic Peptide (GIP)

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ - Secreted by the stomach and upper duodenum during fasting.

Motilin

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Stimuli for Secretion: - Occurs cyclically every 90 minutes during fasting.

Motilin

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Actions: - Increases gastrointestinal motility.

Motilin

HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY Hormones: ______ Actions: - Stimulates interdigestive myoelectric complexes that move through the stomach and small intestine.

Motilin

FUNCTIONAL MOVEMENTS IN THE GASTROINTESTINAL TRACT - The gastrointestinal tract exhibits two main types of movements essential for digestion and absorption: ______ movements and ______ movements.

propulsive, mixing

FUNCTIONAL MOVEMENTS IN THE GASTROINTESTINAL TRACT Propulsive Movements: ______ - Is the primary propulsive movement in the gastrointestinal tract. It's a coordinated contraction that pushes food forward, similar to squeezing a tube.

Peristalsis

FUNCTIONAL MOVEMENTS IN THE GASTROINTESTINAL TRACT Propulsive Movements: Peristalsis - Stimuli: Peristalsis is triggered by the distention of the ______, ______ or ______ irritation, and strong ______ signals.

gut, chemical, physical, parasympathetic

FUNCTIONAL MOVEMENTS IN THE GASTROINTESTINAL TRACT Propulsive Movements: Peristalsis - Role of the Myenteric Plexus: The myenteric plexus is essential for ______ peristalsis.

effective

FUNCTIONAL MOVEMENTS IN THE GASTROINTESTINAL TRACT Propulsive Movements: Peristalsis - Direction: Peristalsis generally moves food towards the ______, following the "______."

anus, law of the gut

FUNCTIONAL MOVEMENTS IN THE GASTROINTESTINAL TRACT Mixing Movement: ______ - Are responsible for mixing intestinal contents. Unlike peristalsis, which moves food forward, these contractions create intermittent constrictions along the gut wall, chopping and mixing the contents.

Segmentation Contractions

FUNCTIONAL MOVEMENTS IN THE GASTROINTESTINAL TRACT Mixing Movement: Segmentation Contractions - Mixing vs. Propulsion: In some areas, ______ contractions can also assist in mixing, especially when a ______ blocks forward movement.

peristaltic, sphincter

FUNCTIONAL MOVEMENTS IN THE GASTROINTESTINAL TRACT Mixing Movement: Segmentation Contractions - Variability: The specific mixing movements can ______ throughout the gastrointestinal tract, adapting to the needs of each segment.

differ

GASTROINTESTINAL BLOOD FLOW— SPLANCHNIC CIRCULATION - The splanchnic circulation supplies blood to the ______, ______, ______, and ______. A unique feature of this system is that all blood from these organs flows through the ______ via the ______ before entering general circulation. This allows the liver to filter and process substances absorbed from the gut.

gastrointestinal tract, spleen, pancreas, liver, liver, portal vein

Blood Flow through the Liver Filtration: As blood passes through the liver ______, ______ cells remove bacteria and other harmful particles.

sinusoids, reticuloendothelial

Blood Flow through the Liver Nutrient Processing: The liver processes ______, ______ nutrients absorbed from the gut, ______ a portion and ______ the rest.

non-fat, water-soluble, storing, metabolizing

Blood Flow through the Liver Fat Absorption: Fats are initially absorbed into the ______ system and enter ______ through the ______, bypassing the ______.

lymphatic, systemic circulation, thoracic duct, liver

ANATOMY OF THE GASTROINTESTINAL BLOOD SUPPLY Arterial Supply: The gastrointestinal tract is supplied by major arteries including the ______ and ______, with smaller arteries branching out to supply the walls of the ______ and ______.

superior mesenteric artery, inferior mesenteric artery, small, large intestines

ANATOMY OF THE GASTROINTESTINAL BLOOD SUPPLY Vascular Organization: Arteries branch within the ______, forming a network that ensures adequate blood supply to the ______ and ______.

gut wall, muscle layers, intestinal villi

EFFECT OF GUT ACTIVITY AND METABOLIC FACTORS ON GASTROINTESTINAL BLOOD FLOW ______ Blood Flow: Blood flow in the gastrointestinal tract correlates directly with ______ levels. For example, during nutrient absorption, blood flow can increase up to ______. After meals, blood flow rises significantly but decreases over ______-______ hours back to resting levels.

Activity-Dependent, local activity, eightfold, 2, 4

MECHANISMS OF INCREASED BLOOD FLOW DURING GASTROINTESTINAL ACTIVITY:

1. Vasodilator Substances 2. Metabolic Demand

MECHANISMS OF INCREASED BLOOD FLOW DURING GASTROINTESTINAL ACTIVITY: Vasodilator Substances: - Hormones like ______, ______, ______, and ______ released from the ______ promote ______ during digestion.

cholecystokinin, vasoactive intestinal peptide, gastrin, secretin, intestinal mucosa, vasodilation

MECHANISMS OF INCREASED BLOOD FLOW DURING GASTROINTESTINAL ACTIVITY: Vasodilator Substances: - ______ (______ and ______) released from ______ also contribute to increased blood flow.

Kinins, kallidin, bradykinin, glands

MECHANISMS OF INCREASED BLOOD FLOW DURING GASTROINTESTINAL ACTIVITY: Metabolic Demand: - ______ oxygen levels in the gut wall during active digestion lead to ______ blood flow, aided by the accumulation of ______ like ______.

Decreased, increased, vasodilators, adenosine

“______” BLOOD FLOW IN VILLIS Vascular Arrangement: In the intestinal villi, ______ and ______ run ______ but in ______ directions, allowing significant oxygen to diffuse from the ______ blood to the ______ blood before reaching the tips of the villi. This "______" mechanism can lead to ______, especially in conditions like ______, resulting in potential ______ damage to the villi.

COUNTERCURRENT, arterioles, venules, parallel, opposite, arterial, venous, countercurrent, oxygen deficits, circulatory shock, ischemic

NERVOUS CONTROL OF GASTROINTESTINAL BLOOD FLOW ______: Increases blood flow and glandular secretion during digestion, primarily as a secondary effect of enhanced glandular activity.

Parasympathetic Stimulation

NERVOUS CONTROL OF GASTROINTESTINAL BLOOD FLOW ______: Causes vasoconstriction in the gastrointestinal tract, reducing blood flow. This is particularly useful during exercise or shock when blood needs to be redirected to vital organs like the heart and brain.

Sympathetic Stimulation

NERVOUS CONTROL OF GASTROINTESTINAL BLOOD FLOW ______: After initial sympathetic vasoconstriction, local metabolic mechanisms can override this effect, restoring blood flow to essential areas.

Autoregulatory Escape

PROPULSION AND MIXING OF FOOD IN THE ALIEMENTARY TRACT Ingestion of Food - Food intake is driven by ______, while the choice of food is influenced by ______. Both mechanisms are vital for nutritional health.

hunger, appetite

PROPULSION AND MIXING OF FOOD IN THE ALIEMENTARY TRACT Mastication (Chewing) - ______ play a central role in chewing, with ______ cutting food and ______ grinding it. Chewing is largely controlled by the ______ and is often a ______ action. Chewing enhances digestion by breaking down food, especially tough fruits and vegetables, making it easier for digestive enzymes to act.

Teeth, incisors, molars, brainstem, reflex

Swallowing (______) is a complex process divided into three stages: ______, ______ (______), and ______ (______).

Deglutition, voluntary, pharyngeal, involuntary, esophageal, involuntary

Swallowing is a complex process divided into three stages: voluntary, pharyngeal (involuntary), and esophageal (involuntary). The pharyngeal stage involves closing the ______ to prevent food from entering the ______ tract, while the esophageal stage uses ______ to move food to the stomach.

trachea, respiratory, peristaltic waves

Esophageal Stage of Swallowing Two types of peristalsis move food through the esophagus: - ______ peristalsis (______) and - ______ peristalsis (triggered by ______). The lower ______ prevents stomach acid from flowing back into the esophagus.

primary, continuous movement, secondary, food retention, esophageal sphincter

Stomach Motor Functions The stomach has three primary motor functions:

(1) storing food, (2) mixing it with gastric secretions to form chyme, and (3) gradually releasing chyme into the small intestine for further digestion and absorption

The stomach has two parts: the ______ (upper) and ______ (lower) portions. When food stretches the stomach, ______ reflex relaxes the stomach wall, allowing it to store up to ______ liters of food.

orad, caudad, vagovagal, 1.5

Stomach ______ mix the food, forming ______, which is gradually emptied into the ______.

Peristaltic waves, chyme, small intestine

Stomach ______ occur when the stomach is empty, the person sometimes felt ______ in the ______ of stomach called ______.

Hunger contractions, mild pain, pit, hunger pangs

Stomach Emptying is regulated by the ______ and ______ reflexes.

pyloric pump, duodenum enterogastric

Stomach Hormones like cholecystokinin (CCK) and gastrin play key roles in controlling ______.

stomach motility

MOVEMENT OF THE SMALL INTESTINE The small intestine has two main types of movements: ______ and ______, both contributing to food digestion and movement.

mixing contractions, propulsive contractions

MOVEMENT OF THE SMALL INTESTINE MIXING CONTRACTIONS (SEGMENTATION) - Segmentation contractions occur when the intestine is stretched by ______, causing ______. These contractions divide the intestine into segments, promoting mixing of food with ______. Frequency is controlled by ______, with a maximum of ______ per minute in the duodenum and proximal jejunum and ______-______ per minute in the ileum. ______ reduces contraction strength by blocking the enteric nervous system.

chyme, localized contractions, intestinal secretions, electrical slow waves, 12, 8, 9, Atropine

MOVEMENT OF THE SMALL INTESTINE PROPULSIVE MOVEMENTS - Peristalsis propels chyme toward the ______ at ______–______ cm/sec, slower in the ______. Nervous and hormonal control increases ______ post-meal, driven by factors like ______ and ______. Peristalsis spreads chyme for ______ and may be blocked at the ______ until triggered by the ______ reflex. Peristaltic rush occurs during severe irritation, rapidly clearing the small intestine. Contractions of the ______ and ______ aid in absorption by increasing surface area and promoting lymph flow.

anus, 0.5, 2.0, terminal ileum, peristaltic activity, gastrin, CCK, absorption, ileocecal valve, gastroileal, muscularis mucosae, villi

MOVEMENT OF THE COLON The colon has two main functions:

(1) absorbing water and electrolytes to form solid feces and (2) storing fecal matter for expulsion

MOVEMENT OF THE COLON Its movements are sluggish and include:

1. Mixing Movements (Haustrations) 2. Propulsive Movements (Mass Movements) 3. Defecation

MOVEMENT OF THE COLON Its movements are sluggish and include: Mixing Movements (Haustrations): Contractions form ______ haustrations, rolling ______ to expose them to the ______ for ______.

sac-like, feces, colon's surface, absorption

MOVEMENT OF THE COLON Its movements are sluggish and include: Propulsive Movements (Mass Movements): Occur ______-______ times daily, moving feces down the ______, often triggered by ______ and ______ reflexes after meals.

1, 3, colon, gastrocolic, duodenocolic

MOVEMENT OF THE COLON Its movements are sluggish and include: Defecation: Involves reflexes that stimulate ______, relax the ______, and, with ______ control, lead to ______ of feces.

peristalsis, anal sphincters, voluntary, expulsion

Other Autonomic Reflexes Affecting Bowel Activity:

Peritoneointestinal Reflex Renointestinal Reflex Vesicointestinal Reflex

Other Autonomic Reflexes Affecting Bowel Activity: ______ Reflex: Triggered by peritoneal irritation, inhibiting enteric nerves and potentially causing intestinal paralysis, especially in peritonitis.

Peritoneointestinal

Other Autonomic Reflexes Affecting Bowel Activity: ______ Reflex: Inhibits intestinal activity due to kidney irritation.

Renointestinal

Other Autonomic Reflexes Affecting Bowel Activity: ______ Reflex: Inhibits intestinal activity as a result of bladder irritation.

Vesicointestinal

GENERAL PRINCIPLES OF ALIMENTARY TRACT SECRETION TYPES OF ALIMENTARY TRACT GLANDS:

single-cell mucous glands pits deep tubular glands Several complex glands

GENERAL PRINCIPLES OF ALIMENTARY TRACT SECRETION TYPES OF ALIMENTARY TRACT GLANDS: Surface of the epithelium in most parts of the gastrointestinal tract are billions of ______ called simply ______ or sometimes ______.

single-cell mucous glands, mucous cells, goblet cells

GENERAL PRINCIPLES OF ALIMENTARY TRACT SECRETION TYPES OF ALIMENTARY TRACT GLANDS: Many surface areas of the gastrointestinal tract are lined by ______ (______).

pits, crypts of lieberkühn

GENERAL PRINCIPLES OF ALIMENTARY TRACT SECRETION TYPES OF ALIMENTARY TRACT GLANDS: In the stomach and upper duodenum are large numbers of ______.

deep tubular glands

GENERAL PRINCIPLES OF ALIMENTARY TRACT SECRETION TYPES OF ALIMENTARY TRACT GLANDS: Several complex glands-the ______ glands, ______, and ______.

salivary, pancreas, liver

Basic Mechanisms of Stimulation of Alimentary Tract Glands:

A) Contact of Food with the Epithelium Stimulates Secretion-Function of Enteric Nervous Stimuli B) Autonomic Stimulation of Secretion C) Regulation of Glandular Secretion by Hormones

Basic Mechanisms of Stimulation of Alimentary Tract Glands: A) Contact of Food with the Epithelium Stimulates Secretion-Function of Enteric Nervous Stimuli: - local epithelial stimulation also activates the enteric nervous system of the gut wall by: 1. ______ stimulation, 2. ______ irritation, and 3. ______ of the gut wall.

Tactile, Chemical, Distention

Basic Mechanisms of Stimulation of Alimentary Tract Glands: B) Autonomic Stimulation of Secretion: • ______ Stimulation Increases the Alimentary Tract Glandular Secretion Rate - (______ and ______) such as: salivary glands, esophageal glands, gastric glands, pancreas, and Brunner's glands in the duodenum, distal portion of the large intestine (pelvic).

Parasympathetic, glossopharyngeal, vagus

Basic Mechanisms of Stimulation of Alimentary Tract Glands: B) Autonomic Stimulation of Secretion: • ______ Stimulation Has a Dual Effect on the Alimentary Tract Glandular Secretion Rate. 1. sympathetic stimulation alone usually slightly ______ secretion and 2. if ______/______ stimulation is already causing copious secretion by the glands, superimposed sympathetic stimulation usually ______ the secretion usually by means of ______.

Sympathetic, increases, parasympathetic, hormonal, reduces, vasoconstriction

Basic Mechanisms of Stimulation of Alimentary Tract Glands: C) Regulation of Glandular Secretion by Hormones: • The hormones are liberated from the ______ in response to the presence of food in the ______ of the ______.

gastrointestinal mucosa, lumen, gut

Basic Mechanism of Secretion of Glandular Cells:

1. Secretion of Organic Substances 2. Water and Electrolyte Secretion

Basic Mechanism of Secretion of Glandular Cells: 1. Nutrient material from ______. 2. ______ produce atp. 3. ATP is used for ______ of protein by the help of er and ribosome. 4. This protein fuse with the ______ for processing then forming into a secretory vesicles. 5. This vesicle will remain in the cell until ______ and ______ stimulation. 6. ______ will cause release of these vesicles by ______.

base Mitochondria synthesis golgi complex hormonal, neural Ca, exocytosis

SALIVA SECRETION TYPES OF SECRETION:

Serous type of secretions Mucus secretions

SALIVA SECRETION TYPES OF SECRETION: ______ contains ______, an enzyme for the digesting starches.

Serous type of secretions, ptyalin

SALIVA SECRETION TYPES OF SECRETION: ______ contain ______ for lubrication and for surface protective purposes.

Mucus secretions, mucin

SALIVA SECRETION GLANDS OF SALIVATION:

Parotid glands Submandibular glands Sublingual glands Buccal glands

SALIVA SECRETION GLANDS OF SALIVATION: Parotid glands: secrete entirely ______ type

serous

SALIVA SECRETION GLANDS OF SALIVATION: Submandibular glands: both ______ and ______ type

serous, mucus

SALIVA SECRETION GLANDS OF SALIVATION: Sublingual glands: both ______ and ______ type

serous, mucus

SALIVA SECRETION GLANDS OF SALIVATION: Buccal glands: secrete only ______

mucus

Nervous Regulation of Salivary Secretion - Salivary glands are controlled mainly by ______ all the way from the ______ and ______ in the brain stem.

parasympathetic nervous signals, superior, inferior salivatory nuclei

Nervous Regulation of Salivary Secretion - The salivatory nuclei are located approximately at the juncture of the ______ and ______ and are excited by both ______ and ______ stimuli from the tongue and other areas of the mouth and pharynx. Many taste stimuli, especially the ______ taste (caused by acids), elicit copious secretion of saliva-often ______ to ______ times the basal rate of secretion.

medulla, pons, taste, tactile, sour, 8, 20

Nervous Regulation of Salivary Secretion - Salivation also occurs in response to reflexes originating in the ______ and upper ______, particularly when irritating foods are swallowed or when a person is nauseated because of some gastrointestinal abnormality.

stomach, small intestines

______ • Function: entirely mucous that provides lubrication for swallowing.

Esophageal Secretion

2 types of mucous glands:

1. Simple Mucous Glands 2. Compound Mucous Glands

2 types of mucous glands: Simple Mucous Glands: lines most of the ______

esophagus

2 types of mucous glands: Compound Mucous Glands: a. Upper esophagus: Protects against ______. b. Lower esophagus: Protects from ______. • Risk: ______ can occur near the ______ junction despite mucus protection.

food excoriation, acidic gastric reflux, Peptic ulcers, esophagogastric

GASTRIC SECRETION GLANDS:

1. Oxyntic glands 2. Pyloric glands

GASTRIC SECRETION Oxyntic glands - these secrete ______, ______, ______ and ______. These are located on the ______ surfaces of ______ and ______ of the ______.

hydrochloric acid, pepsinogen, intrinsic factor, mucus, inside, body, fundus, stomach

GASTRIC SECRETION Pyloric glands - mainly secrete ______ and hormone ______. These are located in the ______ portion of the ______.

mucus, gastrin, antral, stomach

SECRETIONS FROM THE OXYNTIC (GASTRIC) GLANDS: 1. ______, which secrete mainly mucus. 2. ______, which secrete large quantities of pepsinogen. 3. ______, which secrete hydrochloric acid and intrinsic factor.

mucous neck cells, peptic (or chief) cells, parietal (or oxyntic) cells

BASIC MECHANISM OF HYDROCHLORIC ACID SECRETION - ______ secrete HCl into the ______ of the stomach and, concurrently, absorb ______ into the blood stream as follows.

Parietal cells, lumen, bicarbonate ion

BASIC MECHANISM OF HYDROCHLORIC ACID SECRETION - In the parietal cells, ______ and ______ are converted to ______ ions and ______ ions, catalyzed by ______.

CO2, water, hydrogen, bicarbonate, carbonic anhydrase

BASIC MECHANISM OF HYDROCHLORIC ACID SECRETION - Hydrogen ion is secreted into the lumen by ______ pump (______). ______ is secreted along with the hydrogen ions, thus the secretion product of parietal cells is ______.

H+-K+, H+-K+ ATPase, Chloride, HCl

BASIC MECHANISM OF HYDROCHLORIC ACID SECRETION - The ______ ions produced in the cells is absorbed into the bloodstream in exchange for ______ ions (______). As bicarbonate ion is added to the venous blood, the pH of the blood ______ ("______"). (Eventually this bicarbonate ion will be secreted in pancreatic secretions to neutralize ______ ions in the ______.)

bicarbonate, chloride, Cl- HCO3 exchange, increases, alkanline tide, hydrogen, small intestine

BASIC FACTORS THAT STIMULATE GASTRIC SECRETIONS ARE:

(A) Acetylcholine (B) Gastrin (C) Histamine

BASIC FACTORS THAT STIMULATE GASTRIC SECRETIONS ARE: Acetylcholine - pepsinogen by ______ cells - hydrochloric acid by ______ cells. - mucus by ______ cells.

peptic parietal mucous

BASIC FACTORS THAT STIMULATE GASTRIC SECRETIONS ARE: Gastrin and Histamine - strongly act ______ cells. - little effect of other

parietal

SECRETION AND ACTIVATION OF PEPSINOGEN - When pepsinogen is first secreted, it has no ______. However, as soon as it comes in contact with ______, it is activated to form ______.

digestive activity, hydrochloric acid, active pepsin

SECRETION AND ACTIVATION OF PEPSINOGEN - Pepsin functions as an ______, a highly acid medium (optimum pH ______ to ______), but if above a pH of about ______, it has almost no ______ and becomes completely ______ in a short time.

active proteolytic enzyme, 1.8, 3.5, 5, proteolytic activity, inactivated

Secretion of Intrinsic Factor by ______ Cells - Intrinsic factor is essential for ______ absorption in the ______. It is produced by ______ along with ______. When the acid-producing parietal cells of the stomach are destroyed, as often occurs in ______, ______ (lack of stomach acid) and ______ (due to failure of red blood cell maturation without vitamin B12) can develop.

Parietal, vitamin B12, ileum, parietal cells, hydrochloric acid, chronic gastritis, achlorhydria, pernicious anemia

Pyloric Glands Secrete ______ and ______ - The pyloric glands are structurally similar to ______ glands but contain few ______ cells and almost no ______ cells. They predominantly consist of ______ cells, which secrete a small amount of ______ and a large amount of thin ______. This mucus lubricates food movement and protects the stomach wall from digestion by gastric enzymes. Additionally, the pyloric glands secrete the hormone ______, which is crucial for controlling gastric secretion.

Mucus, Gastrin, oxyntic, peptic, parietal, mucous, pepsinogen, mucus, gastrin

Surface Mucous Cells - Surface mucous cells cover the entire surface of the ______ between glands. They secrete large quantities of viscid, alkaline ______ that coats the stomach mucosa with a thick gel layer, providing significant protection for the stomach wall and aiding in the lubrication of food transport. This secretion is stimulated by contact with food or irritation of the mucosa.

stomach mucosa, mucus

Stimulation of Gastric Acid Secretion ______ Cells of the ______ Glands - Only cells that secrete hydrochloric acid (HCl). The acidity of the fluid can be as low as pH ______ and is regulated by ______ and ______ signals.

Parietal, Oxyntic, 0.8, endocrine, nervous

Stimulation of Gastric Acid Secretion Stimulation of Acid Secretion by ______ - ______, a hormone secreted by G cells in the ______ glands, exists in two forms: ______ (______ amino acids) and ______ (______ amino acids, more abundant). ______ in food stimulate gastrin cells to release gastrin into the blood, which is then transported to ______ cells, causing histamine release. ______ stimulates parietal cells to secrete HCl.

Gastrin, Gastrin, pyloric, G-34, 34, G-17, 17, Proteins, ECL, Histamine

Regulation of Pepsinogen Secretion ______ cells in the ______ glands are stimulated by ______ from vagus nerves or the gastric enteric nervous plexus, and by ______ in the stomach (indirectly via enteric nervous reflexes). The amount of acid in the stomach strongly influences ______ secretion. Reduced acid secretion leads to ______ pepsinogen secretion, even if peptic cells appear normal.

Peptic, oxyntic, acetylcholine, acid, pepsinogen, decreased

PHASES OF GASTRIC SECRETION:

Cephalic Phase Gastric Phase Intestinal Phase

PHASES OF GASTRIC SECRETION: ______ Phase - This phase occurs before food enters the stomach, triggered by the sight, smell, thought, or taste of food. Neurogenic signals from the ______, ______, and ______ are transmitted via the ______ nerves to the stomach, accounting for about ______% of gastric secretion during a meal.

Cephalic, cerebral cortex, amygdala, hypothalamus, vagus, 30

PHASES OF GASTRIC SECRETION: ______ Phase - This phase begins once food enters the stomach, exciting long vagovagal reflexes (stomach to brain and back), local enteric reflexes, and the gastrin mechanism. It accounts for about ______% of gastric secretion during a meal, approximately ______ ml daily.

Gastric, 60, 1500

PHASES OF GASTRIC SECRETION: ______ Phase - This phase occurs when food is in the upper small intestine (______). Small amounts of ______ released by the duodenal mucosa continue to stimulate gastric secretion, accounting for about ______% of the acid response to a meal.

Intestinal, duodenum, gastrin, 10

PANCREATIC DIGESTIVE ENZYMES Pancreatic secretion contains multiple ______ for digesting proteins, carbohydrates, and fats. It also contains large quantities of ______, which play an important role in neutralizing the acidity of the chyme emptied from the stomach into the duodenum.

enzymes, HCO3−

PANCREATIC DIGESTIVE ENZYMES Enzymes of the pancreatic juice are secreted entirely by the ______ of the ______ glands.

acini, pancreatic

PANCREATIC DIGESTIVE ENZYMES HCO3− and water, are secreted mainly by the ______ cells of the ______ and ______ that lead from the ______.

epithelial, ductules, ducts, acini

Pancreatic Digestive Enzymes for Carbohydrate Digestion:

Pancreatic Amylase

Pancreatic Digestive Enzymes for Protein Digestion:

Trypsin and Chymotrypsin Carboxypolypeptidase

Pancreatic Digestive Enzymes for Lipid Digestion:

Pancreatic Lipase Cholesterol Esterase Phospholipase

Pancreatic Digestive Enzymes Carbohydrate Digestion ______ - hydrolyzes starches, glycogen, and most other carbohydrates (except cellulose) to form mostly disaccharides and a few trisaccharide.

Pancreatic Amylase

Pancreatic Digestive Enzymes Protein Digestion ______ is the most abundant.

Trypsin

Pancreatic Digestive Enzymes Protein Digestion ______ and ______ - split whole and partially digested proteins into peptides of various sizes but do not cause release of individual amino acids

Trypsin, Chymotrypsin

Pancreatic Digestive Enzymes Protein Digestion ______ - splits some peptides into individual amino acids, thus completing digestion of some proteins all the way to the amino acid state.

Carboxypolypeptidase

Pancreatic Digestive Enzymes Lipid Digestion ______ - capable of hydrolyzing neutral fat into fatty acids and monoglycerides

Pancreatic Lipase

Pancreatic Digestive Enzymes Lipid Digestion ______ - causes hydrolysis of cholesterol esters

Cholesterol Esterase

Pancreatic Digestive Enzymes Lipid Digestion ______ - splits fatty acids from phospholipids

Phospholipase

Enzymes for protein digestion become activated only after they are secreted into the intestinal tract - Trypsinogen is activated by an enzyme called ______ - Trypsinogen also can be auto catalytically activated by ______ that has already been formed from previously secreted trypsinogen. - Chymotrypsinogen is activated by ______ to form ______; - ______ is activated in a similar manner

enterokinase, trypsin, trypsin, chymotrypsin, Carboxypolypeptidase

SECRETION OF ______ PREVENTS DIGESTION OF THE PANCREAS. It is important that the proteolytic enzymes of the pancreatic juice not become activated until after they have been secreted into the ______ because the ______ and the other enzymes would ______ the pancreas.

TRYPSIN INHIBITOR, intestine, trypsin, digest

______ - prevents activation of trypsin inside the secretory cells and in the acini and ducts of the pancreas.

Trypsin Inhibitor

Trypsin Inhibitor - formed in the ______ of the ______ cells

cytoplasm, glandular

______ - This happens when large quantities of pancreatic secretion sometimes become pooled in the damaged areas of the pancreas, thus overwhelming the trypsin inhibitor. Activated pancreatic secretions digest the entire pancreas within a few hours.

Acute Pancreatitis

______ - This condition is sometimes lethal because of accompanying circulatory shock

Acute Pancreatitis

Secretion of Bicarbonate Ions When the pancreas secretes large amounts of pancreatic juice, the ______ concentration can rise to ______ mEq/L, providing a large quantity of ______ in the pancreatic juice, neutralizing stomach acid in the duodenum.

HCO3−, 145, alkali

Steps in secreting sodium bicarbonate solution:

1. Carbon dioxide diffusion and carbonic acid formation 2. H+ and Na+ exchange 3. Osmotic pressure gradient and water movement

Steps in secreting sodium bicarbonate solution: 1. Carbon dioxide diffusion and carbonic acid formation: - ______ diffuses into the cell and combines with ______ to form ______ (______), which dissociates into HCO3− and H+. - HCO3− enters the cell with ______ and is exchanged for ______ into the duct lumen. ______ is recycled back into the lumen.

CO2, water, carbonic acid, H2CO3, Na+, Cl−, Cl−

Steps in secreting sodium bicarbonate solution: 2. H+ and Na+ exchange: - H+ is exchanged for Na+ through the ______ membrane. Na+ also enters with ______ and moves into the ______, pulled by the ______ voltage.

basolateral, HCO3−, negative

Steps in secreting sodium bicarbonate solution: 3. Osmotic pressure gradient and water movement: - The movement of ______ and ______ creates an osmotic pressure gradient, causing water to move into the ______, forming an ______ bicarbonate solution.

Na+, HCO3−, duct, isosmotic

Pancreatic Digestive Enzymes Regulation of Pancreatic Secretion Three basic stimuli are important in causing pancreatic secretion:

Acetylcholine Cholecystokinin (CCK) Secretin

Pancreatic Digestive Enzymes Regulation of Pancreatic Secretion Three basic stimuli are important in causing pancreatic secretion: ______ - Released from the parasympathetic vagus nerve endings and other cholinergic nerves in the enteric nervous system.

Acetylcholine

Pancreatic Digestive Enzymes Regulation of Pancreatic Secretion Three basic stimuli are important in causing pancreatic secretion: ______ - Secreted by the duodenal and upper jejunal mucosa when food enters the small intestine.

Cholecystokinin (CCK)

Pancreatic Digestive Enzymes Regulation of Pancreatic Secretion Three basic stimuli are important in causing pancreatic secretion: ______ - Secreted by the duodenal and jejunal mucosa when highly acidic food enters the small intestine.

Secretin

Pancreatic Digestive Enzymes Functions of the Stimuli ______ and ______ - Stimulate the acinar cells of the pancreas to produce large quantities of digestive enzymes but relatively small quantities of water and electrolytes. - Without sufficient water, most enzymes remain stored in the acini and ducts until more fluid secretion occurs to wash them into the duodenum.

Acetylcholine, CCK

Pancreatic Digestive Enzymes Functions of the Stimuli ______ - Stimulates the secretion of large quantities of water solution of sodium bicarbonate by the pancreatic ductal epithelium.

Secretin

PHASES OF PANCREATIC SECRETION:

Cephalic Phase Gastric Phase Intestinal Phase

PHASES OF PANCREATIC SECRETION: ______ Phase - Nervous signals from the brain cause acetylcholine release by vagal nerve endings in the pancreas, leading to moderate enzyme secretion into the pancreatic acini (about ______% of total enzyme secretion after a meal). However, little secretion flows into the intestine due to small amounts of water and electrolytes.

Cephalic, 20

PHASES OF PANCREATIC SECRETION: ______ Phase - Nervous stimulation continues, accounting for another ______% to ______% of enzyme secretion after a meal. Again, only small amounts reach the duodenum due to lack of significant fluid secretion.

Gastric, 5, 10

PHASES OF PANCREATIC SECRETION: ______ Phase - Secretin Stimulates Bicarbonate Secretion After chyme enters the small intestine, pancreatic secretion increases, mainly due to secretin. Secretin, released when acidic chyme (pH < ______-______) enters the duodenum, stimulates the pancreas to secrete large quantities of fluid with ______ HCO3− concentration (up to 145 mEq/L) and ______ Cl− concentration.

Intestinal, 4.5, 5.0, high, low

Bile is secreted in two stages by the ______ The initial portion is secreted by the principal functional cells of the liver, the ______. This initial secretion contains large amounts of ______, ______, and other organic constituents. It is secreted into ______ that originate between the ______ cells Next, the bile flows in the canaliculi toward the ______, where the canaliculi empty into terminal bile ducts and then into progressively larger ducts, finally reaching the ______ and ______. From these ducts the bile either empties directly into the duodenum or is diverted for minutes up to several hours through the cystic duct into the ______.

liver hepatocytes, bile acids, cholesterol, minute bile canaliculi, hepatic interlobular septa, hepatic duct, common bile duct, gallbladder

The ______ Stores and Concentrates Bile

Gallbladder

Bile is stored in the ______ until needed in the duodenum.

gallbladder

The gallbladder can hold ______-______ ml but can store up to ______ by concentrating bile through absorption of water, sodium, chloride, and other small electrolytes.

30, 60, 450 ml

Composition of Bile - Bile contains ______, ______, ______, ______, and ______.

bile salts, cholesterol, lecithin, bilirubin, electrolytes

Composition of Bile - ______ are the most abundant, accounting for about half of the total solutes.

Bile salts

Composition of Bile - During concentration in the gallbladder, ______ and ______ are reabsorbed, making ______, ______, and ______ highly concentrated.

water, electrolytes, bile salts, cholesterol, lecithin

______ Stimulates Gallbladder Emptying

Cholecystokinin

______ is the primary stimulus for gallbladder contractions, released in response to fatty foods in the duodenum. ______ also increases pancreatic enzyme secretion. Gallbladder emptying requires ______ and relaxation of the ______.

Cholecystokinin (CCK), CCK, rhythmic contractions, sphincter of Oddi

Function of Bile Salts in Fat Digestion and Absorption Bile salts ______ fat particles, aiding in their digestion by lipase enzymes. They also form ______ with fatty acids, monoglycerides, cholesterol, and other lipids, facilitating their absorption into the blood. Without bile salts, up to ______% of ingested fats are lost in feces.

emulsify, micelles, 40

Enterohepatic Circulation of Bile Salts Bile salts are reabsorbed in the ______ and returned to the liver via the ______, where they are reused in ______.

ileum, portal circulation, bile secretion

Role of Secretin in Controlling Bile Secretion Secretin stimulates the secretion of a watery solution of ______ and ______ from the ______ cells lining the bile ducts, increasing the total quantity of ______ and helping ______ stomach acid in the duodenum.

Na+, HCO3−, epithelial, bile, neutralize

Liver Secretion of Cholesterol and Gallstone Formation Cholesterol is secreted in ______ and can lead to gallstone formation if it becomes excessively ______. This can occur when there is an imbalance in the substances that keep cholesterol dissolved in bile.

bile, concentrated

Secretion of the Small Intestine Secretion of Mucus by Brunner’s Gland in the Duodenum - Brunner's glands are located in the first few centimeters of the ______, between the ______ of the ______ and the ______ of ______.

duodenum, pylorus, stomach, papilla, Vater

Secretion of the Small Intestine Secretion of Mucus by Brunner’s Gland in the Duodenum - These glands secrete large amounts of ______ to protect the duodenal wall from acidic gastric juice. The mucus contains ______, which helps neutralize stomach acid.

alkaline mucus, HCO3−

Secretion of the Small Intestine Secretion of Mucus by Brunner’s Gland in the Duodenum Stimuli for Secretion 1. ______ or ______ stimuli on the duodenal mucosa. 2. ______, which increases secretion along with ______. 3. ______ hormones, especially ______.

Tactile, irritating, Vagal stimulation, stomach secretion, Gastrointestinal, secretin

Secretion of the Small Intestine Secretion of Mucus by Brunner’s Gland in the Duodenum Inhibition - ______ stimulation inhibits Brunner's glands, potentially leading to ______ in excitable individuals.

Sympathetic, peptic ulcers

Secretion of the Small Intestine Secretion of Intestinal Digestive Juices by the Crypts of Lieberkühn - Crypts of Lieberkühn are small ______ located over the entire surface of the small intestine, between the ______.

pits, intestinal villi

Secretion of the Small Intestine Secretion of Intestinal Digestive Juices by the Crypts of Lieberkühn - ______ cells secrete mucus to lubricate and protect the intestinal surfaces.

Goblet

Secretion of the Small Intestine Secretion of Intestinal Digestive Juices by the Crypts of Lieberkühn - ______ secrete large quantities of water and electrolytes in the crypts and reabsorb them along with digestion products over the villi.

Enterocytes

Secretion of the Small Intestine Secretion of Intestinal Digestive Juices by the Crypts of Lieberkühn - Enterocytes secrete about ______ ml/day of slightly alkaline extracellular fluid (pH ______ to ______), which is rapidly reabsorbed by the ______.

1800, 7.5, 8.0, villi

Secretion of the Small Intestine Secretion of Intestinal Digestive Juices by the Crypts of Lieberkühn Function - The fluid from the crypts provides a watery vehicle for absorption of substances from ______.

chyme

Secretion of the Small Intestine Digestive Enzymes in the Small Intestinal Secretion - Small intestine secretions have almost no enzymes without ______. ______ in the mucosa, especially those covering the villi, contain digestive enzymes that digest specific food substances during absorption.

cellular debris, Enterocytes

Secretion of the Small Intestine Digestive Enzymes in the Small Intestinal Secretion Types of Enzymes - ______: Split small peptides into amino acids. - ______: Sucrase, maltase, isomaltase, and lactase split disaccharides into monosaccharides. - ______: Splits neutral fats into glycerol and fatty acids.

Peptidases Disaccharidases Intestinal Lipase

Secretion of Mucus by the Large Intestine Mucus Secretion - ______ cells secrete almost no digestive enzymes, only mucus. This mucus contains moderate amounts of ______ from a few non-mucus-secreting epithelial cells.

Epithelial, HCO3−

Secretion of Mucus by the Large Intestine Regulation - Mucus secretion is mainly regulated by direct ______ stimulation of the epithelial cells and local nervous reflexes.

tactile

Secretion of Mucus by the Large Intestine Extreme Stimulation - Emotional disturbances can cause extreme ______ stimulation, leading to excessive mucus secretion and frequent bowel movements with little or no fecal material.

parasympathetic

Functions of Mucus:

· Protects the intestinal wall from excoriation. · Provides an adherent medium for holding fecal matter together. · Protects against bacterial activity in the feces. · The alkaline mucus (pH 8.0) prevents acids in the feces from attacking the intestinal wall.

______, ______, ______: The primary foods necessary for the body (excluding vitamins and minerals)

CARBOHYDRATES, FATS, PROTEINS

______: The process that breaks these macromolecules into smaller compounds for absorption

DIGESTION

______ - Large polysaccharides and disaccharides made of monosaccharides

Carbohydrates

Carbohydrates - Hydrolysis Process: Reverse of ______; enzymes split ______ using ______ - Key Enzymes ______ (______), ______, ______, ______, ______

condensation, monosaccharides, water (H₂O) Salivary amylase, ptyalin, pancreatic amylase, maltase, sucrase, lactase

______ - Mainly triglycerides (three fatty acids + glycerol)

Fats

Fats - Hydrolysis Process: Reverse of ______; enzymes split ______ from ______ - Key Enzyme: ______

condensation, fatty acids, glycerol Pancreatic lipase

______ - Long chains of amino acids linked by peptide bonds

PROTEINS

PROTEINS - Hydrolysis Process: Proteolytic enzymes return ______ and ______ from ______ to split ______. - Key Enzyme: ______, ______, ______, ______

H+, OH−, water, amino acids Pepsin, trypsin, chymotrypsin, carboxypolypeptidase

Carbohydrates Major Sources: ______ (cane sugar), ______ (milk), ______ (from potatoes and grains) ______: Indigestible in humans

Sucrose, lactose, starches Cellulose

Fats - Mainly neutral fats (______) from ______ sources

triglycerides, animal

PROTEINS - ______ proteins are long chains of amino acids.

Dietary

Carbohydrate Digestion 1. MOUTH digestive enzyme ______ (an ______) secreted mainly by the ______ glands hydrolyzes starch into the disaccharide maltose and other small polymers of glucose food remains in the mouth only a short time, so probably not more than ______% of all the starches become hydrolyzed by the time the food is swallowed.

ptyalin, α-amylase, parotid, 5

Carbohydrate Digestion 2. STOMACH Limited digestion due to ______ Starch digestion can continue in the stomach for up to an ______ before mixing with ______. The activity of ______ is inhibited by stomach acid, as it becomes inactive when the pH drops below ______.

acidity, hour, gastric secretions, salivary amylase, 4.0

Carbohydrate Digestion 3. SMALL INTESTINE Digestion by ______ is almost identical in its function to the α- amylase of saliva but is several times as ______. ______ to ______ minutes after the chyme empties from the stomach into the duodenum and mixes with pancreatic juice, all the carbohydrates will have become ______. ______ completes digestion to ______ and small ______ polymers before passing beyond the duodenum or upper jejunum.

pancreatic amylase, powerful, 15, 30, digested, Pancreatic amylase, maltose, glucose

SPECIFIC DIGESTION STEPS: Carbohydrate Digestion

1. MOUTH 2. STOMACH 3. SMALL INTESTINE

Protein Digestion 1. STOMACH ______ initiates protein digestion (______-______%)

Pepsin, 10, 20

Protein Digestion 1. STOMACH ______ - An important peptic enzyme in the stomach is most active at a pH of ______ to ______ and inactive at a pH above ______. ______ - released by ______ glands from ______ cells at a pH of about ______. Once mixed with stomach contents, the pH rises to ______ to ______, which is ideal for ______. - ______, ______, and ______ by splitting peptide bonds between amino acids.

Pepsin, 2.0, 3.0, 5.0 Hydrochloric acid, gastric, parietal, 0.8, 2.0, 3.0, pepsin, proteoses, peptones, polypeptides

Protein Digestion 2. SMALL INTESTINE duodenum and jejunum: pancreatic enzymes - ______, ______, ______, ______ break down proteins into smaller - ______ - ______ - ______

trypsin, chymotrypsin, carboxypolypeptidase, elastase polypeptides dipeptides tripeptides

Protein Digestion 2. SMALL INTESTINE Final digestion happens in the intestinal lining: ______ on the ______ (cells lining the intestinal villi) break these down into ______, which are then absorbed into the bloodstream.

peptidases, enterocytes, amino acids

SPECIFIC DIGESTION STEPS: Protein Digestion

1. STOMACH 2. SMALL INTESTINE

Fat Digestion 1. STOMACH ______ digestion (~______%)

Minimal, 10

Fat Digestion 2. SMALL INTESTINE - Emulsification by ______ and ______ increases ______. - ______ hydrolyzes triglycerides into ______ and ______.

bile salts, lecithin, surface area, Pancreatic lipase, fatty acids, monoglycerides

SPECIFIC DIGESTION STEPS: Fat Digestion

1. STOMACH 2. SMALL INTESTINE

______, ______, ______: Absorbed into the portal blood through intestinal villi.

Monosaccharides, Amino Acids, Fatty Acids

______ are formed when bile salts and phospholipids, which are amphipathic molecules, surround the lipids, forming a hydrophilic outer layer and a hydrophobic core.

Micelles

The ______ carry the lipids through the watery environment to the surface of intestinal cells, where they are absorbed.

micelles

Gastrointestinal Absorption The small intestine absorbs approximately ______-______ liters of fluid daily (______L ingested + ______L secreted).

8, 9, 1.5, 7

Gastrointestinal Absorption Limited absorption occurs in the stomach due to lack of ______ and ______ junctions.

villi, tight

Gastrointestinal Absorption - ______ liters of fluid enter the small intestine daily - The small intestine absorbs about ______ liters - the remainder passes into the ______, where most of the rest of it is also absorbed • Only ______ mL/d of water is excreted in the feces.

9, 8, large intestine, 100

ANATOMICAL BASIS OF ABSORPTION Total absorptive area of small intestine is about ______ (the size of a tennis court).

250 m²

ANATOMICAL BASIS OF ABSORPTION ______ - Increase surface area by 3x valvulae conniventes, extend circularly most of the way around the intestine and are well developed in the duodenum and jejunum, where they often protrude up to 8 millimeters into the lumen.

Folds of Kerckring

ANATOMICAL BASIS OF ABSORPTION ______ - Microscopic projections that enhance surface area by 10x, project about 1 millimeter from the surface of the mucosa

Villi

ANATOMICAL BASIS OF ABSORPTION ______ (______) - Further increase surface area by 20x

Microvilli, Brush Border

Sodium Secretion and Intake - About ______-______ grams of sodium are secreted into the intestines daily. - An average person also consumes ______-______ grams of sodium each day. - To prevent sodium loss through feces, ______-______ grams of sodium must be reabsorbed daily.

20, 30, 5, 8, 25, 35

Sodium Absorption Sodium is actively transported from the intestinal cells into the surrounding spaces, powered by ______ enzymes. This ______ the sodium concentration inside the cells, allowing sodium to flow in from the intestinal contents (______). Sodium absorption is aided by transport proteins such as: ______ ______ ______

ATPase, lowers, chyme SGLT1 (sodium-glucose transporter) sodium-amino acid co-transporters sodium-hydrogen exchanger

Water Absorption Sodium absorption creates an ______, causing water to follow through both the cells (______ pathway) and between them (______ pathway), eventually entering the bloodstream.

osmotic gradient, transcellular, paracellular

Aldosterone’s Role When dehydrated, the ______ glands secrete aldosterone, which boosts ______. This, in turn, enhances water and chloride ion absorption, especially in the colon, reducing water and sodium loss through feces.

adrenal, sodium absorption

Chloride Absorption - In the small intestine, chloride ions follow sodium due to the electrical gradient created by ______. -In the ______ and ______, chloride is absorbed through a ______.

sodium absorption, ileum, large intestine, chloride-bicarbonate exchanger

Bicarbonate Reabsorption In the upper small intestine, ______ are reabsorbed indirectly by combining with ______ to form water and carbon dioxide, which is ______.

bicarbonate ions (HCO3-), hydrogen ions (H+), exhaled

Bicarbonate Secretion in the Colon In the ileum and large intestine, bicarbonate is secreted in exchange for ______, helping neutralize acids produced by ______.

chloride absorption, gut bacteria

ABSORPTION IN THE SMALL INTESTINE Isosmotic Absorption of Water - Water is transported through the intestinal membrane entirely by ______. - It follows osmotic gradients, moving from areas of ______ solute concentration to ______ concentrations.

diffusion, lower, higher

EXTREME FLUID LOSS IN ______ Toxin overstimulates secretion, leading to a massive loss of fluids—up to ______ liters/day. Effect: Causes rapid ______, which can be fatal within days. Treatment: Immediate ______ with sodium chloride solution is essential to save lives.

CHOLERA, 10, dehydration, rehydration

ACTIVE ABSORPTION OF ESSENTIAL IONS ______ - Actively absorbed in the duodenum. - Controlled by Parathyroid Hormone (PTH) and Vitamin D.

Calcium

ACTIVE ABSORPTION OF ESSENTIAL IONS ______ - Actively absorbed, regulated to meet the body’s needs for hemoglobin production.

Iron

ACTIVE ABSORPTION OF ESSENTIAL IONS Other Ions (______, ______, ______): - ______ ions are easily absorbed. - ______ ions like calcium are absorbed in smaller amounts, as the body requires only small daily quantities.

Potassium, Magnesium, Phosphate, Monovalent, Bivalent

CARBOHYDRATE ABSORPTION Monosaccharides - 80% of absorbed carbohydrates are ______ (mainly from starch digestion). - ______ and ______ make up the remaining 20%.

glucose, Galactose, fructose

CARBOHYDRATE ABSORPTION Glucose Transport - Glucose absorption relies on ______. - Sodium pulls glucose into cells, facilitated by ______.

Sodium Co-Transport (SGLT1), GLUT2

CARBOHYDRATE ABSORPTION Fructose Absorption - ______ diffusion using ______ and ______, not dependent on ______.

Facilitated, GLUT5, GLUT2, sodium

ABSORPTION IN THE LARGE INTESTINE Water & Electrolytes: - Most water and electrolytes are absorbed in the proximal ______. - Sodium absorption creates an ______, promoting water absorption

colon, osmotic gradient

ABSORPTION IN THE LARGE INTESTINE Large Intestine Capacity: - Can absorb ______-______ liters of fluid per day. - Excess fluid causes diarrhea, often due to bacterial toxins like ______.

5, 8, cholera

ABSORPTION IN THE LARGE INTESTINE Feces Composition: - ______% water, ______% solid matter (dead bacteria, fats, proteins, undigested material).

75, 25

PROTEIN ABSORPTION - Absorbed as ______, ______, and ______. - Uses ______ (like glucose) for efficient absorption

dipeptides, tripeptides, amino acids, sodium co-transport

FAT ABSORPTION - ______ and ______ are absorbed via ______. - ______% of fats are absorbed with the help of micelles. - ______ fatty acids are absorbed directly into the blood, while ______ fats are processed into chylomicrons and transported via the lymphatic system

Monoglycerides, free fatty acids, bile micelles, 97, Short-chain, long-chain

______ is a mechanism the upper gastrointestinal tract uses to expel its contents when irritated, overdistended, or overexcited, particularly due to excessive stretching or irritation of the duodenum.

Vomiting

______ is a condition in which the lower esophageal sphincter fails to relax during swallowing. As a result, food swallowed into the esophagus fails to ______ from the esophagus into the stomach.

Achalasia, pass

The term ______ refers to difficulty or discomfort in swallowing.

dysphagia

______ is the most common cause of dysphagia.

Acid reflux disease

______ is an inflammation of the stomach's gastric mucosa, common in middle to late adulthood. It can range from mild and superficial to severe, potentially causing deep damage and mucosal atrophy.

Gastritis

______ gastritis - can lead to ulceration from the stomach's own secretions.

Acute

______ gastritis - can lead to achlorhydria (lack of stomach acid)

Chronic

A ______ is an open sores in the lining of the stomach or intestines, mainly caused by stomach acid or digestive fluids.

peptic ulcer

Peptic Ulcer These ulcers usually form near the stomach's exit (______), along the stomach's ______ curve, or in the lower ______ where stomach acid can flow back up.

pylorus, inner, esophagus

______ - Is the inflammation of the pancreas, occurring as either acute or chronic.

PANCREATITIS

______ - This is a sudden inflammation of the pancreas - Most commonly caused by excessive alcohol consumption or blockage of the pancreatic duct by a gallstone.

ACUTE PANCREATITIS

______ - Is a long-term inflammation of the pancreas, often caused by repeated episodes of acute pancreatitis - Other factors like smoking, high triglycerides, and autoimmune conditions can contribute. - It can lead to permanent damage and loss of pancreatic function.

CHRONIC PANCREATITIS

______ is the slow movement of feces through the large intestine, often due to excess fluid absorption or inadequate fluid intake.

Constipation

______ (______) - is a severe form of constipation where bowel movements are infrequent, leading to massive fecal accumulation and colon enlargement.

Megacolon, Hirschsprung's Disease

______ is the rapid movement of fecal matter through the large intestine.

Diarrhea

Diarrhea is the rapid movement of fecal matter through the large intestine, caused by: ______ - Inflammation from viral or bacterial infections that irritates the intestinal lining, increasing secretion and motility to expel the infection.

Enteritis

Diarrhea is the rapid movement of fecal matter through the large intestine, caused by: ______ - Triggered by stress or nervous tension, resulting from increased parasympathetic activity that heightens motility and mucus secretion in the colon.

Psychogenic Diarrhea

Diarrhea is the rapid movement of fecal matter through the large intestine, caused by: ______ - is a condition characterized by inflammation and ulceration of the large intestine's walls, leading to increased motility and frequent diarrhea.

Ulcerative Colitis