Human Physiology Exam III

Parillon Fall 2025

List the carbonic acid-bicarbonate buffer system.

H+ + HCO3- → H2CO3; hydrogen ion + bicarbonate ion → carbonic acid

List the protein buffer system.

Hb + H+ → Hb-H; hemoglobin + hydrogen ion → reduced hemoglobin

List the phosphate buffer system.

H+ + HPO4 2- → H2PO4-; hydrogen ion + monohydrogen phosphate → dihydrogen phosphate

In the carbonic acid-bicarbonate buffer system, what does the hydrogen ion bind to?

HCO3- bicarbonate ion

In the protein buffer system, what does the hydrogen ion bind to?

Hb hemoglobin

In the phosphate buffer system, what does the hydrogen ion bind to?

HPO4 2- monohydrogen phosphate

What is acidosis?

when blood pH drops below normal range because of high hydrogen ions and low bicarbonate ions

If a blood pH is below 7.35, is it acidosis or alkalosis?

acidosis

What can cause bicarbonate ion (HCO₃^-) loss in metabolic acidosis?

severe diarrhea, accumulation of another acid, and renal dysfunction

What is alkalosis?

when blood pH rises above normal range because of high bicarbonate ions

If a blood pH is above 7.45, is it acidosis or alkalosis?

alkalosis

What can cause bicarbonate ion (HCO₃^-) increase in metabolic alkalosis?

excess vomiting, endocrine disorders, and excessive intake of antacids

What can cause abnormally high P_CO2 levels in respiratory acidosis?

hypoventilation

What can cause abnormally low P_CO2 levels in respiratory alkalosis?

hyperventilation

What are the three basic tasks to produce urine?

glomerular filtration, tubular reabsorption, and tubular secretion

What are the four pressures that affect glomerular filtration?

glomerular capillary hydrostatic pressure, Bowman’s space hydrostatic pressure, plasma colloid osmotic pressure, and Bowman’s space colloid osmotic pressure

How is glomerular filtration rate regulated?

autoregulation, neural regulation, and hormonal regulation

What is the average glomerular filtration rate?

180 L/day

What are the two routes of reabsorption?

paracellular (between cells) and transcellular (through cells)

True or False: Reabsorption moves into the capillary network.

True

What is reabsorption in the urinary system?

Much of the solutes and water are taken back into the bloodstream

Where is intracellular fluid located?

within the cells

Where is extracellular fluid located?

surrounding the cells

What does carbonic anhydrase do?

converts carbon dioxide to bicarbonate in red blood cells

List the movement of ions across a nephron.

renal corpuscle (Bowman’s capsule and glomerulus), proximal tube, loop of Henle, distal tube, collecting duct

What is ventilation?

breathing; inhalation and exhalation

What does the respiratory epithelium aid in?

removing dust and debris

What is the respiratory epithelium made of?

cilia, mucus, and mucociliary escalator

List the movement of air.

nose, pharynx, larynx, trachea, bronchi, lungs

What happens in Type I alveolar cells?

main site of gas exchange

What do Type II alveolar cells do?

secrete surfactant

What is the transport mechanism at the alveoli?

diffusion

What is the transport mechanism at the glomerular capillary?

filtration

What is the alveolar pressure at rest?

760 mmHg

What is the intrapleural pressure at rest?

756 mmHg

What is the alveolar pressure during inspiration?

758 mmHg

What is the intrapleural pressure during inspiration?

754 mmHg

What is the alveolar pressure during expiration?

762 mmHg

What is the intrapleural pressure during expiration?

756 mmHg

What are the 3 factors that affect ventilation?

surface tension of alveolar fluid, compliance of lungs, airway resistance

How is surface tension of alveolar fluid reduced?

surfactant

What is lung compliance?

how much effort is required to stretch the lungs and chest wall

What is airway resistance?

airway through the lungs encounters resistance caused by friction

Dilation _______ (increases/decreases) resistance.

decreases

Constriction _______ (increases/decreases) resistance.

increases

What is the equation for airflow?

flow = change in pressure/resistance

What is tidal volume?

a normal, passive breath; 500 mL

During gas exchange, what is the atmospheric air pressure?

PO2 = 159 mmHg, PCO2 = 0.3 mmHg

During gas exchange, what is the alveolar air pressure?

PO2 = 105 mmHg, PCO2 = 40 mmHg

What are the 4 factors affecting oxygen affinity to hemoglobin?

pH, partial pressure of carbon dioxide, temperature, BPG

During a reverse chloride shift, is CO₂ high or low?

low

During a chloride shift, is CO₂ high or low?

high

What is the role of carbonic anhydrase in the lungs?

converts bicarbonate to CO2

What are the respiratory centers in the pons?

pneumotaxic and apneustic area

What are the respiratory centers in the medulla oblongata?

ventral and dorsal respiratory group

What does the pneumotaxic area do?

inhibits DRG

What does the apneustic area do?

prolongs inspiration

What does the dorsal respiratory group (DRG) do?

quiet breathing

What does the ventral respiratory group (VRG) do?

generates rhythm and contains Pre-Botzinger

As pH _________ (increases/decreases), the affinity of hemoglobin for O₂ decreases.

decreases

As PCO2 _________ (increases/decreases), the affinity of hemoglobin for O₂ decreases.

increases

As temperature _________ (increases/decreases), the affinity of hemoglobin for O₂ decreases.

increases

As BPG _________ (increases/decreases), the affinity of hemoglobin for O₂ decreases.

increases

List the physiological movement of the respiratory system.

ventilation, pulmonary gas exchange, transport of O2 and CO2 by the blood, systemic gas exchange, cellular respiration

True or False: Ventlation involves inhalation and exhalation.

True

During inspiration, does thoracic cavity volume increase or decrease?

increase

During expiration, does thoracic cavity volume increase or decrease?

decrease

Which is higher: the partial pressure of oxygen in lung tissue vs the partial pressure of oxygen in alveoli.

partial pressure of oxygen in alveoli

Which is higher: the partial pressure of CO₂ in lung tissue vs the partial pressure of CO₂ in alveoli.

partial pressure of CO2 in lung tissue

What is hypoxia?

a deficiency of O2 at the tissue level

What are the 4 types of hypoxia?

hypoxic, anemic, ischemic, histotoxic

What is hypoxic hypoxia?

caused by low oxygen pressure in arterial blood as a result of high altitude, airway obstruction, or fluid in the lungs

What is anemic hypoxia?

too little functioning hemoglobin is present in the blood, which reduces O2 transport to tissue cells

What is ischemic hypoxia?

blood flow to a tissue is so reduced that too little O2 is delivered to it

What is histotoxic hypoxia?

blood delivers adequate O2 to tissues, but the tissues are unable to use it properly because of the action of a toxic agent (ex. cyanide)

Can Ca³⁺ power skeletal muscle contractions?

no

Is Ca³⁺ an electrolyte?

no, it’s not stable in water

Which receptors sense changes in osmolarity?

osmoreceptors in the hypothalamus

List the pathway if blood pressure falls, decreasing the glomerular filtration rate.

blood pressure falls, GFR decreases, JGA detects, RAA and aldosterone activate, blood pressure rises, GFR returns to normal

Which reflex occurs at the bladder?

micturition/urinating

Which type of receptor senses high bladder volume?

stretch receptors

AQP2 (Aquaporin 2) mutation leads to nephrogenic diabetes insipidus with polyuria, polydipsia, and hypernatremia. This mutation (T125M) retains AQP2 in the endoplasmic reticulum. Is ADH able to exert its resulting function well with this mutation? Why or why not.

no because the misfolded protein is retained in the endoplasmic reticulum and can’t be trafficked to the cell membrane to facilitate water reabsorption

Define The Law of Laplace.

If tension is the same, pressure is different because the alveoli are different sizes. If pressure is the same, tension is different which means air can’t flow from small, to large alveolus.

How may volumes of the lung can be captured and what are they?

4; inspiratory reserve, tidal, expiratory reserve, residual

What transport mechanism drives movement from higher partial pressures to lower partial pressures?

expiration

What is most O₂ bound to for transport and what is most of CO₂ transported as?

Most of the O2 is bound to red blood cells for transport. Most of the CO2 is transported as deoxygenated blood.