Anatomy Test 3 Outline Question Set 5

Digestive System Overview

• The hard palate forms the boundary between the oral and nasal cavities.
• The enteric nervous system controls local reflexes regulating digestive tract functions.
• Intraperitoneal organs are completely covered by visceral peritoneum.
• The submucosa layer of the digestive tract contains blood vessels, nerves, and lymphatics.
• Enteric sensory neurons detect changes in the digestive tract's chemical environment.

Oral Cavity and Salivary Glands

• The labial frenulum connects the upper lip to the gingiva.
• The serous component of saliva contains amylase for carbohydrate digestion.
• Saliva contains bicarbonate and lysozyme for protection.
• The sublingual salivary gland produces the thickest mucous secretion.
• The buccinator muscle aids in chewing and pushing food against the teeth.

Teeth and Mastication

• Canines tear food.
• The masseter and temporalis muscles close and elevate the jaw during mastication.
• Enamel is the highly calcified outer layer of the tooth crown.
• The mastication reflex is integrated within the medulla oblongata.
• The pulp cavity of a tooth contains nerves and blood vessels.

Pharynx and Swallowing

• The pharyngeal constrictors push food into the esophagus.
• The epiglottis covers the larynx during swallowing to prevent food entry.
• The nasopharynx only transports air.

Esophagus and Peristalsis

• The esophageal hiatus is the passage through the diaphragm for the esophagus.
• The lower third of the esophagus contains only smooth muscle.
• Peristalsis in the esophagus begins with a wave of relaxation followed by contraction.

Stomach Anatomy and Digestion

• The stomach's muscularis layer has an additional oblique layer.
• Parietal cells in the stomach produce hydrochloric acid.
• Pepsinogen is activated by hydrochloric acid to form pepsin.
• Gastrin stimulates hydrochloric acid secretion.

Small Intestine Functions and Structure

• Most digestion and absorption occur in the duodenum and jejunum.
• Villi and microvilli increase surface area for absorption in the small intestine.
• Brunner's glands in the duodenum secrete bicarbonate-rich mucus.
• Fats are absorbed into lacteals within the villi.
• The ileum is the terminal portion of the small intestine.

Accessory Organs: Liver, Gallbladder, Pancreas

• Bile emulsifies fats.
• Pancreatic juice neutralizes stomach acid with bicarbonate ions.
• Cholecystokinin (CCK) stimulates bile release from the gallbladder.
• The primary liver function is to produce and secrete bile.
• Hepatocytes in the liver produce bile.

Large Intestine and Absorption

• The primary function of the large intestine is to absorb water and electrolytes.
• The cecum is the first section of the large intestine.
• Bacteria in the colon produce vitamin K.
• Mass movements in the large intestine are often triggered by eating.
• The ileocecal valve regulates the passage of feces from the ileum to the cecum.

Defecation and Rectal Function

• The defecation reflex is initiated by distension of the rectum.
• The internal anal sphincter is controlled by involuntary smooth muscle.
• The external anal sphincter controls voluntary defecation.
• The rectum stores waste before defecation.
• Peristalsis in the rectum triggers the defecation reflex.

Carbohydrate, Protein, and Lipid Digestion

• Amylase begins carbohydrate digestion in the mouth.
• Pepsin is essential for protein digestion in the stomach.
• The pancreas produces lipase to digest fats in the small intestine.
• Trypsin and chymotrypsin break down proteins into amino acids in the small intestine.
• Lactase deficiency causes lactose intolerance.

Absorption of Nutrients

• Monosaccharides are absorbed by active transport.
• Amino acids are transported by active transport mechanisms.
• Triglycerides are absorbed as chylomicrons into the bloodstream.
• Fat-soluble vitamins are absorbed through lymphatic vessels with lipids.
• The small intestine is the primary site of nutrient absorption.

Metabolism and Cellular Respiration

• Glycolysis occurs in the cytoplasm.
• The end products of aerobic respiration are carbon dioxide, water, and ATP.
• Beta-oxidation breaks down fatty acids into acetyl-CoA.
• Lactic acid is formed from pyruvate in the absence of oxygen.
• Gluconeogenesis is the formation of glucose from non-carbohydrate sources.

Energy Balance and Nutrient Use

• Carbohydrates primarily provide quick energy through ATP production.
• Excess glucose is stored as glycogen.
• Essential amino acids must be obtained from the diet.
• Lipids build cell membranes and provide long-term energy storage.
• During prolonged exercise, the body uses energy from lipids and glycogen stores.

Hormonal Regulation of Metabolism

• Insulin lowers blood glucose by promoting glucose uptake in cells.
• Glucagon stimulates glycogen breakdown to increase blood glucose.
• Epinephrine increases glucose availability for energy.
• Cortisol stimulates gluconeogenesis to increase blood glucose.
• During fasting, glucagon maintains blood glucose levels.

Thermoregulation and Heat Production

• The hypothalamus is the thermoregulation center.
• Conduction is heat loss through direct contact.
• Evaporation is the mechanism for cooling the body through sweating.
• Shivering increases body temperature by increasing cellular respiration in muscles.
• The body conserves heat by vasoconstriction in cold temperatures.

Vitamin and Mineral Absorption

• Vitamin C is important for collagen synthesis and immune function.
• Vitamin B12 deficiency can lead to anemia.
• Vitamin D is essential for calcium absorption in the intestines.
• Iron is crucial for hemoglobin synthesis and oxygen transport.

Vitamin K

• Vitamin K is essential for blood clotting.

Macronutrient Functions and Energy Balance

• Carbohydrates are the primary dietary source of energy for cellular processes.
• The body primarily stores long-term energy reserves as triglycerides in adipose tissue.
• Proteins are crucial for building and repairing body tissues.
• Lipids are essential for forming cell membranes and providing insulation.
• During prolonged fasting, the body primarily relies on lipolysis of stored fat for energy.

Absorptive and Postabsorptive States

• The absorptive state is characterized by the body storing excess nutrients as glycogen and fat.
• Liver glycogen is the body's main source of glucose during the postabsorptive state.
• Gluconeogenesis, the process of producing glucose from non-carbohydrate sources, mainly occurs in the liver.
• Glucagon is the primary hormone active in mobilizing stored nutrients during the postabsorptive state.