The Respiratory System

Chapter 22: The Respiratory System

• The major function of the respiratory system is gas exchange, supplying oxygen to the blood and removing carbon dioxide.
• Respiration involves pulmonary ventilation (breathing), external respiration (gas exchange between lungs and blood), transport of respiratory gases, and internal respiration (gas exchange between blood and tissues).

Respiratory Zone

• Structures include the bronchioles, alveolar ducts, and alveoli, and they are essential for gas exchange.

Functions of the Nose

• The nose filters, warms, and moistens air, detects odors, and serves as a resonating chamber for speech.

Pharynx

• The pharynx is a passageway for air and food, also facilitates exposure of immune system to inhaled antigens.

Larynx

• The larynx functions in voice production and provides an open airway.

Nine Cartilages of the Larynx

• The nine cartilages include the epiglottis, thyroid cartilage, cricoid cartilage, arytenoid cartilages (2), corniculate cartilages (2), and cuneiform cartilages (2).

Carina

• The carina is a ridge at the bifurcation of the trachea into the main bronchi.

Surfactant Secreting Cells

• Type II alveolar cells (pneumocytes) secrete surfactant.

Infant Respiratory Distress Syndrome (IRDS)

• IRDS is caused by a lack of surfactant in premature infants, leading to alveolar collapse.

Nutrient Supply to the Lungs

• The bronchial circulation supplies nutrients to the lungs; pulmonary circulation is for gas exchange.

Pneumothorax

• Pneumothorax is the presence of air in the pleural cavity, leading to lung collapse.

Serous Fluid in Pleural Pleurae

• The serous fluid reduces friction between the lungs and chest wall during breathing.

Gas Laws

• Boyle’s Law: Pressure and volume are inversely related (P1V1 = P2V2).
• Dalton’s Law: The total pressure exerted by a mixture of gases is the sum of the partial pressures of each gas.
• Henry’s Law: The amount of gas that dissolves in a liquid is directly proportional to the partial pressure of the gas.

Bohr Effect

• The Bohr effect is the decrease in hemoglobin's affinity for oxygen when pH decreases or carbon dioxide increases.

Stimulus for Breathing

• The most powerful stimulus for breathing in a healthy individual is an increase in carbon dioxide levels (hypercapnia).

Pressure and Volume Changes During Breathing

• During inspiration, lung volume increases and pressure decreases; during expiration, lung volume decreases and pressure increases.

Hering-Breuer Reflex

• The Hering-Breuer reflex is a protective mechanism that prevents overinflation of the lungs.

Tidal Volume

• Tidal volume is the volume of air inhaled or exhaled during normal breathing (approximately 500 ml).

Ciliated Mucous Epithelium

• The ciliated mucous epithelium in the nose traps inhaled particles and moves them toward the pharynx to be swallowed.

Exchangeable Air Volume

• Vital capacity represents the total volume of exchangeable air.

Hypoxia Types

• Hypoxia can be hypoxic, anemic, ischemic, or histotoxic.

Hemoglobin Saturation with O2

• Increased Po2, decreased Pco2, decreased acidity, decreased temperature, and decreased BPG increase hemoglobin saturation with O2.

Carbon Dioxide Transport

• Carbon dioxide is transported in the blood as bicarbonate ions, bound to hemoglobin, and dissolved in plasma.

Carbonic Anhydrase

• Carbonic anhydrase is an enzyme that catalyzes the reaction between carbon dioxide and water to form carbonic acid.

Hypercapnia

• Hypercapnia, or increased carbon dioxide levels, results in respiratory acidosis.

Influence of pCO2 on Phrenic Nerve

• Increased pCO2 levels increase the activity of the phrenic nerve, stimulating breathing.

Uvula

• The uvula is a fleshy extension at the back of the soft palate.

Chapter 23: The Digestive System

GI Tract Histology

• The general histology of the GI tract includes four layers: mucosa, submucosa, muscularis externa, and serosa (or adventitia).

Saliva Composition

• Saliva consists of water, electrolytes, mucus, enzymes (amylase, lysozyme), and antibodies.

Saliva Functions

• Saliva cleanses the mouth, dissolves food chemicals, moistens food, and begins the chemical breakdown of starch.

Deglutition Phases

• Deglutition (swallowing) involves the buccal (voluntary), pharyngeal (involuntary), and esophageal (involuntary) phases.

Esophagus Epithelium

• The esophagus has a stratified squamous epithelium.

Peristalsis and Segmentation

• Peristalsis involves wave-like contractions that propel food forward, while segmentation mixes food with digestive juices.

Stomach Anatomy

• The stomach is divided into the cardia, fundus, body, and pylorus.

Gastric Gland Secretions

• Gastric glands secrete hydrochloric acid (HCl), pepsinogen, mucus, intrinsic factor, and hormones (e.g., gastrin).

Gastric Juice Secretion

• Gastric juice secretion occurs in three phases: cephalic (before food enters), gastric (when food enters the stomach), and intestinal (as food enters the small intestine).

Liver Functions

• The liver produces bile, detoxifies blood, metabolizes nutrients, and stores vitamins and minerals.

Pancreatic Enzymes

• Pancreatic enzymes include amylase, lipase, protease, and nuclease.

Pancreatic Secretion

• Pancreatic secretion is regulated by hormones (secretin, cholecystokinin) and the parasympathetic nervous system.

Hepatic Portal Circulation

• The hepatic portal circulation carries nutrient-rich blood from the GI tract to the liver.

Hepatopancreatic Ampulla

• The hepatopancreatic ampulla (Ampulla of Vater) is where the common bile duct and pancreatic duct empty into the duodenum.

Bile

• Bile is a fluid produced by the liver that emulsifies fats.

Bile Production

• Hepatocytes make bile; bile emulsifies fats, aiding in their digestion and absorption.

Small Intestine

• The small intestine consists of the duodenum, jejunum, and ileum.

Plicae Circularis

• Plicae circulares are circular folds in the small intestine that increase surface area for absorption.

Enterokinase

• Enterokinase (enteropeptidase) is an enzyme that activates trypsinogen into trypsin.

Nutrient Absorption

• Nutrients are absorbed through active and passive transport mechanisms.

Water Absorption

• The majority of water is absorbed in the small intestine.

Protein Digestion Start

• Protein digestion begins in the stomach.

Gastric Secretion Stimulant

• Gastrin stimulates gastric secretion.

Carbohydrate Digestive Enzyme

• Amylase digests carbohydrates.

Chyme

• Chyme is the mixture of partially digested food and gastric secretions in the stomach.

Protein Denaturation

• Proteins are denatured in the stomach by hydrochloric acid (HCl).

Bicarbonate Release Trigger

• The release of bicarbonate-rich pancreatic juice is triggered by secretin.

Anal Sphincter Control

• The internal anal sphincter is involuntary, while the external anal sphincter is voluntary.

Chapter 24: Metabolism

Cellular Respiration

• The primary function of cellular respiration is to produce ATP (energy) by breaking down glucose and other organic molecules.

Cholesterol in Membrane Fluidity

• Cholesterol maintains membrane fluidity by preventing it from becoming too rigid at low temperatures and too fluid at high temperatures.

Gluconeogenesis

• Gluconeogenesis is the synthesis of glucose from non-carbohydrate sources like amino acids and glycerol.

Glycogenolysis

• Glycogenolysis is the breakdown of glycogen to glucose.

Digestion Hormones

• During the absorptive phase, insulin is the primary hormone; during the post-absorptive phase, glucagon, epinephrine, growth hormone, and cortisol are dominant.