Anatomy & Physiology

Conducting Zone

This functional division of the respiratory system is a rigid zone with a lot of cartilage, it has big open spaces that are passages for airflow, it warms and humidifies air, and no gas exchange takes place within it. It includes the nose through the terminal bronchioles.

Respiratory Zone

This functional division of the respiratory system includes all the parts involved in gas exchange, it includes the respiratory bronchioles, alveolar ducts, and alveoli.

Upper Respiratory Tract

This structural division of the respiratory system includes organs in the head and neck (from the nose to the larynx)

Lower Respiratory Tract

This structural division of the respiratory system includes organs in the thorax (the trachea to the lungs)

Pharynx

This is part of the conducting zone, and it is a muscular funnel behind the mouth/nose that is a passageway for air food, and liquid.

Nasopharynx

This is the most superior part of the pharynx, it is only for air, and it is lined with pseudostratified columnar epithelium that help with protection.

Oropharynx

This is the middle part of the pharynx, and it is a passage for food, liquid, and air. It is made of stratified squamous epithelium to withstand the friction of everything passing through it

Laryngopharynx

this is the most inferior part of your pharynx, and it is a passage for food, liquid, and air. It is superior to the esophagus, and it is made of stratified squamous epithelium.

Larynx

This is also called the voice box, it is a cartilaginous chamber below the pharynx and anterior to the esophaus. Its primary function is to direct air to the trachea and food/liquid to the esophagus. It has the secondary function of producing sound

Epiglottis

This is the flap of cartilage that guards the opening of the larynx, it keeps food/drink from entering the trachea

Trachea

This is a rigid tube supported by rings of hyaline cartilage, and it is a passageway for air. It is lined with psuedostratified columnar epithelium, which make up the mucociliary escalator.

Mucociliary Escalator

This is made of pseudostratified columnar epithelium in the trachea, and it helps remove debris/inhaled particles. Goblet cells produce mucus, trapping debris, then cilia move the mucus up towards the pharynx, allowing it to be swallowed. It continues through the bronchi

Goblet Cells

These are cells usually found in pseudostratified columnar epithelium that release a protective layer of mucus

Cilia

These are hair like extensions of the lumen side of epithelial tissue that move in a wave motion.

Right Lung

This lung has three lobes and is shorter than the other

Left Lung

This lung has two lobes and is tall and narrow, it also has the cardiac impression/notch in it

Main Bronchi

These are the first divisions of the trachea, they are also called primary bronchi

Lobar Bronchi

These are divisions of the main/primary bronchi, they are also called secondary bronchi

Segmental Bronchi

these are divisions of lobar/secondary bronchi, they are also called tertiary bronchi. Bronchioles branch off from here.

Clara Cells

These are cells in terminal and respiratory bronchioles that secrete a protective lining and act as stem cells for cell regeneration

Terminal Bronchioles

These are bronchioles with a thick layer of smooth muscle, and they each branch into two or more respiratory bronchioles

Respiratory Bronchioles

these are the beginning of the respiratory zone, and they have a thin layer of smooth muscle. They branch into alveolar ducts and alveoli.

Alveoli

These are sites of gas exchange with capillaries.

Type I Alveolar Cells

These are the squamous epithelial cells lining alveoli, they are only a single layer in order to provide easy gas exchange and they make up 95% of cells in the lining.

Type II Alveolar Cells

These are the cuboidal epithelial cells in alveoli lining, they secrete fluid with surfactant, which increases pulmonary compliance allowing the lungs to expand easier, they are also called “great alveolar cells” and they make up 5% of cells in the lining.

Type III Alveolar Cells

These are macrophages in the alveoli, they are also called dust cells and they function to travel through alveoli, phagocytizing inhaled particles.

Respiratory Membrane

This is the barrier between air in the alveoli and blood, and it is made of alveolar epithelium, the shared basement membrane, and endothelial cells of the capillaries.

Pulmonary Ventilation

This is another term for breathing, which is a repetitive cycle of inspiration and expiration.

Atmospheric Pressure

760 mmHg, 1 atm at sea level (gets lower at higher elevations)

Intrapulmonary Pressure

This is the pressure within the lungs, during expiration it is higher than atmospheric pressure and during inspiration it is lower than atmospheric pressure

Boyle’s Law

At constant temperature, the pressure of gas is inversely proportional to its volume

Diaphragm

This muscle is the prime mover of respiration, when it contracts it flattens and increases the volume of the lungs and taking in air. When it relaxes it bows upward, expelling air by decreasing the volume of the lungs.

Intercostal Muscles

These muscles are synergists to the diaphragm, and they sit between the ribs. They enlarge/contract the thoracic cavity, creating or eliminating space for the lungs to expand or contract

Bronchodilation

This is stimulated by epinephrine and sympathetic innervation, and it is when bronchioles expand their diameter in order to create less resistance to air.

Bronchoconstriction

This is stimulated by histamine, cold air, irritants, or parasympathetic innervation. It is when the smooth muscle in the bronchioles contracts and reduces its diameter, increasing resistance to airflow.

Pulmonary Compliance

This is the ease with which the lungs can expand. It decreases with lung diseases that cause scar tissue, and surfactant from great alveolar cells increases it.

Dalton’s Law

This law states that a gases partial pressure is equal to that gases partial volume * the total pressure

Oxygen is 20.9% of the atm, its partial pressure is:

0.209 × 760 mmHg = 159 mmHg

and it would be expressed as PO₂

Loading

This is the movement of gas into the blood

Unloading

This is the movement of gas out of the blood

104 mmHg

PO₂ in the alveoli =

40 mmHg

PO₂ in the capillaries of the lungs =

46 mmHg

PCO₂ in the capillaries in the lungs

40 mmHg

PCO₂ in the alveoli

CO₂

___ is 20x more soluble than O₂, allowing it to diffuse across the respiratory membrane easier

Factors that Affect Alveolar Gas Exchange

1. Pressure gradients of gases

2. Solubility of gases

3. Membrane thickness

4. Membrane surface

5. Ventilation-perfusion coupling

Ventilation-Perfusion Coupling

This is the matching of air flow and blood flow. If there is high air flow in some areas, then blood flow to those areas will increase. If there is low air flow in other areas, then blood flow will decrease there.

Oxygen Transport

98.5% is carried on hemoglobin

1.5% is dissolved in blood plasma

Carbon Dioxide Transport

90% is transported as bicarbonate (HCO₃^-)

5% is carried on proteins (mostly hemoglobin)

5% is dissolved in blood plasma

Carbamino Compounds

This is the term for carbons bound to proteins, the most common of which is hemoglobin.

46 mmHg

PCO₂ in tissues

40 mmHg

PCO₂ in arterial blood

Carbonic Anhydrase

These are the enzymes found in RBC’s that catalyze the reaction to make hydrogen ions and bicarbonate:

CO₂ + H₂O → H₂CO₃ → H⁺ + HCO₃^-

Carbon Dioxide Loading

1. CO₂ reacts with H₂O to make HCO₃^- and H⁺

2. antiport pumps pump HCO₃^- out of RBC and exchange for Cl^- ions

3. H⁺ ions bind to hemoglobin in RBC

Chloride Shift

This is where chloride ions are exchanged for bicarbonate during carbon dioxide loading in RBC’s

95 mmHg

PO₂ in blood

40 mmHg

PO₂ in systemic tissues

Oxygen Unloading

1. H⁺ binds to hemoglobin

2. Reduced Hb affinity for O₂ causes release

3. Diffusion into tissues

Alveolar CO2 Exchange

1. Bicarbonate moves back into the erythrocyte and chloride moves out

2. bicarbonate recombines with hydrogen ions to form CO₂ and H₂O

3. CO₂ diffuses out of the erythrocyte into blood plasma, than out into an alveolus because of partial pressure

Haldane Effect

This effect is where CO₂ binds more readily to deoxyhemoglobin (HHb), because of the exposed iron atom.

Ambient PO2

Active tissues have a lower PO₂ because more O₂ is unloaded from hemoglobin since more oxygen is needed.

Ambient pH

Active tissues have a higher PCO₂, more CO₂ raises H⁺ concentrations in blood (lower pH), more H⁺ ions cause dissociation of O₂ from Hb

Bohr Effect

This effect describes how H⁺ ions cause the dissociation of O₂ from hemoglobin

Chemoreceptors

These are what measure blood chemistry in the carotid and aortic bodies. They monitor PO₂, CO₂, and pH

Acidosis

This is a condition where blood pH is under 7.35

Alkalosis

This is a condition where blood pH is over 7.45 pH

Hypoventilation

This causes acidosis because of the insufficient release of CO₂, and it shifts the carbonic acid reaction right

Hyperventilation

This causes alkalosis because of a release of excess CO₂, and it shifts the carbonic acid reaction left.

Digestive System

This is an organ system that processes foods, extracts nutrients, and eliminates residue

Functions: ingestion, secretion, mixing and movement, digestion, absorption, excretion

Mechanical Digestion

This is the physical breakdown of food into smaller particles (chewing, churning). It exposes more surface area of food for digestive enzymes

Chemical Digestion

This process is hydrolysis reactions that break macromolecules into their monomers, and it is carried out by digestive enzymes.

Polysaccharides → monosaccharides

Proteins → amino acids

Fats → monoglycerides and fatty acids

Nucleic acids → nucleotides

Digestive Tract

This is also called the alimentary canal, and it is a tube going from the mouth to the anus. It includes the GI tract, but the GI tract is not all of this

GI Tract

This is just the stomach and the intestines, it is part of the digestive tract

Mucosa

This is the layer of the alimentary canal that lines the lumen, it is made of an epithelium layer, the lamina propria, and the muscularis mucosae

Lamina Propria

This is a layer of the mucosal layer of the alimentary canal, and it is the loose connective tissue between the epithelium and the muscularis mucosae

Muscularis Mucosae

This is the smooth muscle part of the mucosal layer of the alimentary canal that creates ridges to increase surface area

Submucosa

This is the second deepest layer of the alimentary canal, and it is a thick layer of loose connective tissue. It also includes nervous tissue that regulates digestive secretions

Submucosal Plexus

This is the nervous tissue of the submucosa that regulates digestive secretion. It is half of the enteric nervous system.

Muscularis Externa

This is the third deepest layer of the alimentary canal, and it is a thick layer of smooth muscle that propels food/waste through the alimentary canal. It includes nervous tissue that regulates digestive secretions and motility

Myenteric Plexus

This is the nervous tissue in the muscularis externa, it regulates digestive secretions and motility. It is half of the entering nervous system

Enteric Nervous System

Myenteric Plexus + Submucosal Plexus =

Serosa

This is the outermost layer of the alimentary canal, and it is a layer of loose connective tissue that helps ancho different organs of the digestive system

Short Reflexes

These are reflexes in the nervous system that are signaled completely within the GI tract by the enteric nervous system (local control)

Long Reflexes

These reflexes happen when receptors in the GI tract send signals to the CNS, which then send signals back to an effector. Most of these signals are carried via the vagus nerve and multiple sympathetic neurons.

Cephalic Phase

This phase of stomach regulation occurs before food enters the stomach, and it is stimulated by smell, tase, or the thought of food which leads to gastric secretions

Gastric Phase

This phase of stomach regulation is initiated by the presence of food in the stomach, and the greatest volume of stomach secretions are seen during this phase

Intestinal Phase

This phase of stomach regulation is initiated by the presence of chyme in the small intestine, and it stimulates intestinal secretions along with inhibiting gastric secretions.

Mouth

This structure houses the oral (buccal) cavity, and it functions in ingestion, mastication, and chemical digestion via saliva. It is lined with stratified squamous epithelium

Bolus

This is the chewed, saliva-enhanced food that is swallowed.

Saliva

This is released from salivary glands, and it includes salivary amylase, lingual lipase, lysosome (bacterial enzyme), and immunoglobulin A (antibacterial antibody)

Esophagus

This structure is a muscular tube that leads from the pharynx to the stomach.

Peristalsis

This is the wave of muscular contractions that moves food towards the stomach in the esophagus

Upper Esophageal Sphincter

This is the constriction point between the pharynx and esophagus, it remains closed unless swallowing

Lower esophageal Sphincter

This is the border between the esophagus and stomach, it prevents stomach contents from regurgitating into the esophagus. Heartburn occurs when this fails.

Stomach

This is a muscular sac in the upper left abdominal cavity and inferior to the diaphragm. Its primary purposes are food storage and digestion. It is highly acidic (1.5-3.5 pH). It produces chyme.

Chyme

This is the soupy/pasty mixture of semi-digested food in the stomach

Pyloric Sphincter

This is what regulates the passage of chyme into the small intestine

Gastric Rugae

These are longitudinal wrinkles in the mucosal layer of the stomach that occur when it is empty. When the stomach is full, the mucosa layer is flat.

Gastric Pits

These are depressions in the gastric mucosa where glands open in the bottom of.

Mucus Cells

This type of stomach gland cell secretes mucus

Regenerative/Stem Cells

This type of stomach gland cell divides rapidly to generate new cells