Gas Exchange and Respiratory Anatomy

Questions and Answers

What occurs in the lungs when CL- moves out of the RBCs?

Oxygen is released from hemoglobin.

Bicarbonate ions re-enter RBCs.

Oxygen is absorbed into the blood.

Carbon dioxide and water are formed. (correct)

What type of salivary glands produce saliva that is rich in enzymes?

Muscous glands

Mixed glands

Parotid glands (correct)

Sublingual glands

Which of the following best describes obstructed lungs?

Can not expand even with forceful inhalation.

Easy to expand but hard to exhale. (correct)

Difficult to breathe in but easy to breathe out.

Easily exhaled with normal effort.

Which phase of swallowing is primarily voluntary?

Oral phase Signup and view all the answers

Which component of saliva is primarily involved in breaking down carbohydrates?

Alpha-amylase Signup and view all the answers

What initiates the salivatory reflex?

Stimulation in the oral cavity Signup and view all the answers

Which of the following correctly describes the composition of saliva?

99% water and 1% organic and inorganic waste Signup and view all the answers

What effect do sympathetic fibers have on saliva production?

Inhibit secretion of saliva leading to thick saliva. Signup and view all the answers

Which type of cells in the gastric mucosa are primarily responsible for the secretion of hydrochloric acid?

Parietal cells Signup and view all the answers

What role does intrinsic factor play in the stomach?

Facilitates absorption of vitamin B12 Signup and view all the answers

Which enzyme is critical for lipid digestion in infants?

Gastric lipase Signup and view all the answers

What triggers the cephalic phase of gastric secretion?

The sight or smell of food Signup and view all the answers

What is the normal daily production of gastric juice?

1.5-2 L Signup and view all the answers

Which hormone is produced by G-cells, and what is its primary function?

Gastrin; stimulates gastric acid production Signup and view all the answers

During which phase of gastric secretion is the secretion primarily increased by distension of the stomach?

Gastric phase Signup and view all the answers

What is the optimal pH range for the action of enzymes in gastric juice?

1.5-2.5 Signup and view all the answers

What is the primary role of secretin in the digestive process?

Promoting pancreatic secretion of bicarbonate Signup and view all the answers

Which hormone is responsible for inhibiting stomach contraction?

Cholecystokinin (CKK) Signup and view all the answers

What is the primary stimulus for peristalsis in the gastrointestinal tract?

Mechanical distention Signup and view all the answers

What physiological event does motilin trigger during fasting?

Cyclic increase in gastrointestinal motility Signup and view all the answers

What effect does sympathetic nervous system stimulation have on peristalsis?

Slows peristalsis Signup and view all the answers

Which of the following describes the primary function of segmentation in the alimentary tract?

Mixing and churning contents Signup and view all the answers

During active absorption in the gut, what happens to blood flow?

Increases eight-fold Signup and view all the answers

What is the primary source of blood supply to the intestines?

Celiac and mesenteric arteries Signup and view all the answers

Which of the following correctly describes the function of secretin in the gastrointestinal system?

Inhibits gastric acid secretion Signup and view all the answers

What is the primary role of the myenteric plexus within the enteric nervous system?

Regulate gastrointestinal movements Signup and view all the answers

Which part of the gastrointestinal tract has the highest frequency of rhythmic contractions?

Duodenum Signup and view all the answers

How do spike potentials in gastrointestinal smooth muscle typically occur?

When resting membrane potential exceeds -40 mV Signup and view all the answers

What neurotransmitter is primarily involved in inhibiting the smooth muscle of the gastrointestinal tract?

Norepinephrine (NE) Signup and view all the answers

Which structure is primarily responsible for the rate and depth of breathing regulation?

Pneumotach center Signup and view all the answers

Which of the following best describes tonic contractions in the gastrointestinal system?

Are continuous and last several minutes to hours Signup and view all the answers

Which component of the respiratory system is considered the anatomical dead space?

Conducting portion Signup and view all the answers

What role do interstitial cells of Cajal play in gastrointestinal motility?

Serve as electrical pacemakers for smooth muscle cells Signup and view all the answers

Which of the following factors can cause depolarization of the gastrointestinal smooth muscle membrane?

Stretch of muscle and stimulation by acetylcholine Signup and view all the answers

What primarily causes bronchiolar constriction?

Histamine release Signup and view all the answers

What effect does the Haldane effect have on oxygen and carbon dioxide transport in the blood?

Decreases carbon dioxide binding affinity in the presence of oxygen Signup and view all the answers

What is the function of the submucosal plexus within the enteric nervous system?

Control GI secretion and local blood flow Signup and view all the answers

What initiates the Hering-breuer inflation reflex?

Sensory stretch receptors in the bronchi and bronchioles Signup and view all the answers

Which reflex involves the gastrointestinal tract sending signals to the central nervous system and back?

Pain reflex Signup and view all the answers

What is the primary effect of parasympathetic innervation on the gastrointestinal tract?

Enhance digestion and absorption Signup and view all the answers

Which factor primarily decreases lung compliance?

Pathological anatomical changes Signup and view all the answers

Which law relates the partial pressures of gases in a mixture?

Dalton's law Signup and view all the answers

Which hormone is secreted by G cells and stimulates gastric motility?

Gastrin Signup and view all the answers

What distinguishes spike potentials from slow waves in gastrointestinal smooth muscle?

Slow waves are periodic, while spike potentials are true action potentials Signup and view all the answers

What characterizes Cheyne-Stokes breathing?

Alternation of deep breaths with periods of apnea Signup and view all the answers

Which type of muscle is predominantly responsible for airway resistance in the respiratory system?

Smooth muscle Signup and view all the answers

What is the role of septal cells in the alveoli?

To produce surfactant Signup and view all the answers

Which condition increases the release of erythropoietin?

Reduced atmospheric oxygen levels Signup and view all the answers

How is carbon dioxide primarily transported in the blood?

As bicarbonate ions (HCO3) primarily Signup and view all the answers

What is the immediate effect of increased thoracic cavity size during inhalation?

Decreased alveolar pressure Signup and view all the answers

Which condition describes an inability of the alveoli to exchange gases effectively?

Physiological dead space Signup and view all the answers

Which hormone stimulates the production of red blood cells in response to decreased oxygen levels?

Erythropoietin Signup and view all the answers

Study Notes

Gas Exchange and Respiratory System

Bronchi and Bronchioles: Bronchi have less cartilage, increasing movement; bronchioles contain almost entirely smooth muscle, contributing to obstructive diseases.
Muscle Involvement: External intercostals are essential for breathing, assisted by sternocleidomastoid, anterior serrati, and scaleni for inhalation; internal intercostals primarily aid in expiration.
Respiratory Centers:
- Dorsal respiratory group (DRG) in medulla regulates inspiration and breathing rhythm.
- Ventral respiratory group (VRG) is inactive during quiet respiration; DRG innervates VRG.
- Pneumotach center in the pons modifies the rate and depth of breathing.
- Apneustic center prolongs inspiration.
Inflation Reflex: Hering-Breuer reflex involves stretch receptors in bronchi, inhibiting inspiratory signals via the vagus nerve when tidal volume exceeds three times normal.
Chemical Control: Ventral medulla chemoreceptors respond to increases in CO2 and H+, influencing respiration indirectly through CO2 crossing the blood-brain barrier.
Acclimatization: Reduced sensitivity of the respiratory center increases alveolar ventilation in adaptation to chronic changes.
Nerve Influence:
- Parasympathetic system uses acetylcholine (Ach) for constriction, also affected by smoking.
- Sympathetic stimulation results in bronchodilation through norepinephrine and adrenal secretions.
Types of Respiration:
- External respiration: exchange of gases in the respiratory system.
- Internal respiration: gas exchange between alveoli and bloodstream.
- Cellular respiration: oxygen use by cells for ATP production.

Alveoli and Surfactant

Alveolar Structure: Alveolar sacs are the site of gas exchange, surrounded by capillaries; gas exchange occurs across the alveolar epithelial layer.
Surfactant Function: Produced by septal cells, surfactant reduces surface tension, preventing alveolar collapse according to La Place's law (smaller alveoli have higher surface tension).
Alveolar Macrophages: Important for phagocytizing particles and pathogens, particularly those smaller than 2.5 micrometers.

Pleural Mechanics

Pleura Layers: Parietal pleura lines thoracic wall; visceral pleura covers lung surface.
Intrapleural Pressure: Maintains lung expansion by ensuring intrapulmonary pressure is higher than intrapleural pressure.

Ventilation Dynamics

Breathing Mechanics:
- Inhalation occurs when atmospheric pressure exceeds alveolar pressure (ideal difference is about -1 mm Hg for quiet breathing).
- Exhalation is when alveolar pressure exceeds atmospheric pressure.
Breathing Terms:
- Eupnea: normal quiet breathing.
- Hyperpnea: increased ventilatory effort.
- Apnea: cessation of breathing.
- Cheyne-Stokes: alternating cycles of deep and shallow breathing.

Respiratory Volume and Capacity

Key Measurements:
- Respiratory rate: breaths per minute.
- Tidal volume: volume of air per breath.
- Minute ventilation: breaths/minute x tidal volume.
- Alveolar ventilation: air available for gas exchange factoring in dead space.
Factors Affecting Lung Volumes:
- Airflow resistance mainly from smooth muscle.
- Compliance influenced by surfactant, decreasing as lungs expand.
- Changes in lung elasticity can signal pathologies like emphysema.

Gas Transport and Hemoglobin

Gas Laws:
- Dalton's law: total pressure is the sum of partial pressures of individual gases.
- Henry's law: ratio of gas concentration in liquid phase is proportional to partial pressure.
Oxygen Transportation: 97% of oxygen in the blood is bound to hemoglobin; fetal hemoglobin binds oxygen more effectively than maternal hemoglobin.
Carbon Dioxide Transport: Transported as free CO2 (7%), bicarbonate (70%), and carbaminohemoglobin (23%); Haldane effect indicates increased O2 binding reduces CO2 binding affinity.

Erythropoiesis and Hormonal Regulation

Erythropoietin Production: Increased in response to low oxygen levels (anemia) and high blood pH; renal failure diminishes production.
Chloride Shift: HCO3- moves from RBC to plasma, while Cl- enters RBCs. In the lungs, the process is reversed, facilitating CO2 release.

Digestive Functions and Salivation

Oral Cavity Functions: Includes sensory reception, mechanical processing, partial chemical digestion, and protection via saliva.
Salivary Glands Types:
- Parotid: serous, enzyme-rich saliva.
- Sublingual: mucous, viscous saliva.
- Submandibular: mixed saliva production.

Gastric Functions

Gastric Juice Composition: 99.5% water; key components include HCl for pH regulation and enzyme activation.
Gastric Secretion Phases: Cephalic (30%), Gastric (60%), Intestinal (10%); these phases are triggered by sensory stimuli and food presence in the stomach.
GI Tract Motor Functions: Controlled by smooth muscle through coordinated contractions driven by slow waves and spike potentials, influenced by various neurohormonal factors.

Enteric Nervous System

Control Mechanisms: Consists of myenteric and submucosal plexuses, governing GI motility, secretion, and blood flow independently of CNS inputs.
Autonomic Influence: Parasympathetic promotes secretion; sympathetic inhibits motility and secretions through norepinephrine.

Reflexes and Hormonal Influences

Gastrointestinal Reflexes: Including gastrocolic, enterogastric, and colonoileal reflexes aiding in digestion and movement control.
Hormones Affecting Digestion:
- Gastrin: promotes acid secretion in response to food intake.
- Secretin: regulates intestine acidity and promotes pancreatic bicarbonate secretion.
- Cholecystokinin (CCK): stimulates bile release and modulates gastric activity.

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Description

This quiz covers the essential aspects of gas exchange, focusing on the anatomy of the airways, including bronchi and bronchioles. It examines the role of smooth muscles and the associated respiratory centers that regulate breathing. Test your knowledge on these crucial respiratory functions and structures.