Human Respiratory System, Mechanism of Breathing, Exchange & Transport of Gases

Flashcards covering human respiration, respiratory anatomy, mechanics of breathing, gas exchange mechanisms, and oxygen/carbon dioxide transport pathways.

What is the definition of respiration according to the lecture notes?

Respiration is the oxidation of nutrients to release energy for biological work.

What is breathing as defined in human physiology?

Breathing is the exchange of oxygen from the atmosphere with carbon dioxide produced by the cells.

What chemical equation represents aerobic respiration?

The chemical equation is $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + 36\,\text{ATP (Energy)}$.

How do external respiration and internal respiration differ in their location of gas exchange?

External respiration (ventilation) is the exchange of oxygen and carbon dioxide at the alveoli, whereas internal respiration (cellular respiration) is the exchange of oxygen and carbon dioxide at the cellular level.

What are the primary process steps and ATP yield of anaerobic respiration?

Anaerobic respiration begins with Glycolysis (where one glucose molecule is partially broken down into two pyruvate molecules to yield $2\,\text{ATP}$) and is completed via fermentation, yielding by-products like lactic acid or ethanol without oxygen.

What are the chemical equations for lactic acid fermentation and alcoholic fermentation?

Lactic acid fermentation: $C_6H_{12}O_6 \rightarrow 2C_3H_6O_3 + 2\,\text{ATP}$; Alcoholic fermentation: $C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2 + 2\,\text{ATP}$.

Identify the parts of the human respiratory system labeled in this anatomical diagram.

The diagram illustrates the external nostrils, nasal cavity, pharynx, larynx, epiglottis, trachea, primary bronchus, pleural cavity, left lung, right lung, and diaphragm.

What are the three functional parts of the nasal chamber and their respective roles?

1. Vestibular Part: Has hair and sebaceous glands to filter dust and microorganisms. 2. Respiratory Part: Warms and moistens inhaled air (conditioning of air). 3. Olfactory Part: Lined by olfactory epithelium and involved in the sense of smell.

What is the function of the pharynx in the respiratory system?

The pharynx is a common passage for air and food that connects the nasal cavity to the larynx.

What is the larynx, and how is food prevented from entering it?

The larynx (Voice Box or Sound Box) contains vocal cords for sound production and is surrounded by nine cartilages; the epiglottis, a thin elastic cartilage, prevents food from entering the windpipe.

What structural feature supports the trachea, and how far does it extend?

The trachea (windpipe) is supported by C-shaped hyaline cartilage rings and extends up to the mid-thoracic cavity to carry air to the bronchi.

How does the branching sequence progress from the trachea to the alveoli?

The trachea divides into primary bronchi, which enter the left and right lungs and divide into secondary and tertiary bronchi; tertiary bronchi divide into smaller branches to form bronchioles, which lead to the alveoli.

Why are alveoli considered the structural and functional units of the lungs?

Alveoli are tiny, thin-walled air sacs surrounded by blood capillaries that serve as the main sites of gas exchange.

How do the right and left lungs differ in lobe number, and why?

The right lung has $3\,\text{lobes}$, while the left lung has $2\,\text{lobes}$ to accommodate the heart.

Compare the movements of the diaphragm, rib cage, and chest cavity during inspiration versus expiration.

During inspiration, the diaphragm contracts and moves downwards, the rib cage moves upward and outward, and chest cavity volume expands; during expiration, the diaphragm relaxes and moves upwards, the rib cage moves downward and inward, and chest cavity volume decreases.

What three anatomical layers form the diffusion membrane through which gases pass during exchange in the lungs?

1. Squamous epithelium of the alveoli, 2. Basement membrane, and 3. Endothelium of blood capillaries.

How does the solubility of $CO_2$ compare to that of $O_2$ across the respiratory membrane?

The solubility of $CO_2$ is $20-25\,\text{times}$ higher than that of $O_2$.

What process of gas exchange is illustrated in this diagram showing partial pressures across the alveoli, blood capillaries, and tissues?

Gas exchange occurs by simple diffusion driven by partial pressure gradients ($PO_2$ and $PCO_2$) between alveolar air ($PO_2 = 104\,\text{mmHg}$, $PCO_2 = 40\,\text{mmHg}$), systemic blood, and body tissues.

What two forms transport oxygen in the blood, and in what percentages?

1. Dissolved in Plasma ($3\%$), and 2. Bound to hemoglobin as Oxyhemoglobin ($HbO_2$) ($97\%$).

How many oxygen molecules can a single hemoglobin molecule carry?

One hemoglobin molecule can carry four oxygen molecules.

Which physiological conditions in the alveoli favor the formation of oxyhemoglobin?

High $PO_2$, Low $PCO_2$, Low $H^+$ concentration, and Low Temperature.

Which physiological conditions in tissues favor the dissociation of oxygen from oxyhemoglobin?

Low $PO_2$, High $PCO_2$, High $H^+$ concentration, and High Temperature.

How much oxygen is delivered to tissues by $100\,\text{mL}$ of oxygenated blood, and how much carbon dioxide is carried from tissues by $100\,\text{mL}$ of deoxygenated blood?

Every $100\,\text{mL}$ of oxygenated blood delivers approximately $5\,\text{mL}$ of oxygen to tissues, and every $100\,\text{mL}$ of deoxygenated blood carries approximately $4\,\text{mL}$ of carbon dioxide from tissues.

What shape is the oxygen-hemoglobin dissociation curve, and what relationship does it describe?

It is a sigmoid curve representing the percentage saturation of hemoglobin ($Hb$) with $O_2$ plotted against the partial pressure of oxygen ($PO_2$).

What are the three modes of carbon dioxide transport in blood and their relative percentages?

1. Dissolved in Plasma as Carbonic Acid ($7\%$), 2. As Carbaminohemoglobin ($HbCO_2$) ($20-25\%$), and 3. As Bicarbonate Ions ($HCO_3^-$) ($70\%$).

What role does carbonic anhydrase play in carbon dioxide transport in red blood cells?

Carbonic anhydrase catalyzes the reaction of $CO_2$ with $H_2O$ inside RBCs to form carbonic acid ($H_2CO_3$), which dissociates into bicarbonate ions ($HCO_3^-$) and hydrogen ions ($H^+$).

What cellular process of $CO_2$ transport and ion exchange between systemic and pulmonary capillaries is shown in this diagram?

The diagram illustrates the uptake of $CO_2$ in systemic capillaries forming $HCO_3^-$ (with chloride shift $Cl^-$) and its reverse conversion in pulmonary capillaries to release $CO_2$ into the alveolus.