Questions and Answers
What are the three primary functions of the gastrointestinal system?
Provide nutrients, secretion of digestive juices, absorption of nutrients
What occurs during the 4th week of gestation?
Which of the following conditions are considered congenital anomalies of the gastrointestinal system? (Select all that apply)
What is the primary function of the mouth and salivary glands in digestion?
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What is the approximate length of the small intestine?
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What component of the gastrointestinal system is responsible for moving food through the esophagus?
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The lower esophageal sphincter (LES) is located at the beginning of the esophagus.
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Which part of the stomach is known for temporary food storage?
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The duodenum is the first _____ cm of the small intestine.
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What type of muscle primarily composes the intestinal wall?
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What stimulates gastric secretions when thinking about food?
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Cholecystokinin is secreted by I cells in the jejunum.
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What are the functions of intestinal muscular activity? (Select all that apply)
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Study Notes
Gastrointestinal Functions
- Provides nutrients through propulsive and mixing movements.
- Involves secretion of digestive juices.
- Absorbs nutrients effectively.
Congenital Anomalies
- Start developing as early as the 4th week of gestation.
- Common issues include atresia, fistula, and stenosis.
- Esophageal atresia and tracheoesophageal fistula are prevalent forms.
Functional Anatomy of the GI Tract
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Mouth and Salivary Glands:
- Entry point for nutrients.
- Food is moistened and broken down by saliva.
Geriatric Considerations
- Aging leads to atrophy of bone tissue and acinar cells in salivary glands.
- Decreased saliva production and alkalinity contribute to halitosis and dental issues.
- Loss of teeth and reduced taste perception are common.
The Esophagus
- A collapsible tube approximately 25 cm long.
- Uses peristaltic waves to transport food.
- Contains mucous glands in the submucosa.
- Features a lower esophageal sphincter (LES) for regulation.
Stomach Anatomy
- Cardiac Region: Near the esophageal opening.
- Fundus: Temporary storage area, may fill with air.
- Antrum: Lacks rugae (folds).
- Pyloric Region: Smooth area leading to the small intestine.
Small Intestines
- Approximately 5-6 meters in length.
- Duodenum: First 22 cm, primarily involved in digestion.
- Jejunum: Next 2 meters, focuses on nutrient absorption.
- Ileum: Completes the small intestine, absorbs remaining nutrients.
Large Intestines
- About 1.5 meters long, frames the small intestine.
- Divided into transverse, descending, sigmoid colon, and rectum.
GI Motility Characteristics
- The intestinal wall consists of skeletal muscle at either end and smooth muscle in the middle.
- Muscular movements are controlled by the central nervous system (CNS) and modulated by hormones.
Neuronal Control of GI Tract
- Governed by the intrinsic nervous system.
- Parasympathetic (PNS) activity increases digestion via the vagus nerve.
- Sympathetic (SNS) activity decreases digestion, primarily from sacral segments.
Basic Anatomy of Autonomic Nervous System (ANS)
- Consists of preganglionic and postganglionic neurons.
- Preganglionic neuron is myelinated; postganglionic neuron is unmyelinated.
Electrical Activity of Gastrointestinal Smooth Muscle
- Slow waves are continuously present.
- Spike potentials result from neurotransmitters like acetylcholine (depolarization) and norepinephrine (hyperpolarization).
Hormonal Control in Digestion
- Vagus nerve impulses stimulate gastric secretions upon stimulus from food.
- Gastrin: Secreted by G cells to promote gastric activity.
- Cholecystokinin (from jejunum) and Secretin (from duodenum) regulate digestive processes.
- Gastric inhibitory peptide: Decreases stomach motility in response to fats.
Intestinal Muscle Contraction
- Muscular contractions are essential for digestion and nutrient absorption.
- Mixing: Keeps contents mixed via peristalsis or constrictive contractions.
- Propulsive Movement: Slow movement that helps push materials forward through the gastrointestinal system.
Movement of Nutrients During Chewing
- Controlled by multiple cranial nerves (CN V, VII, IX, X, XI, XII) for effective mastication.
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Description
Explore the functionalities of the gastrointestinal system, including nutrient provision, secretion of digestive juices, and absorption processes. This chapter also covers congenital anomalies such as atresia, fistula, and stenosis, highlighting their occurrence from early gestation.
