Chapter 22

external respiration

where oxygen and carbon dioxide exchange between the lungs and the blood

internal respiration

where oxygen and carbon dioxide exchange between systemic blood vessels and tissue.

site of gas exchange

alveoli

nasal cavity

gas exchange for conducting portion

pseudostratified ciliated columnar epithelium

line respiratory epithelium, contains goblet cells and cilia to help remove mucus and debris from nasal cavity

cuboidal epithelial cells

compose lower respiratory epithelium

simple squamous

compose thin walls of alveoli

smooth muscle

surround bronchioles

right bronchi

has a larger diameter and steeper incline

act of swallowing

causes the pharynx and larynx to lift upward, allowing the pharynx to expand and the epiglottis of the larynx to swing downward, closing the opening to the trachea. These movements produce a larger area for food to pass through, while preventing food and beverages from entering the trachea.

hyaline cartilage

found in C-shapes surrounding trachea

C-shapes

pieces of hyaline cartilage that are connected by dense connective tissue, rings of cartilage provide structural support and prevent the trachea from collapsing.

fibroelastic membrane

allows trachea to stretch and expand during inhalation and exhalation

esophagus

borders trahcea posteriorly

bronchiole

branches from the tertiary bronchi. about 1 mm in diameter, further branch until they become the tiny terminal bronchioles, which lead to the structures of gas exchange. There are more than 1000 terminal bronchioles in each lung. The muscular walls of do not contain cartilage like those of the bronchi. This muscular wall can change the size of the tubing to increase or decrease airflow through the tube, controlled by autonomic nervous system

sympathetic stimulation

causes bronchodilation

parasympathetic stimulation

causes bronchoconstriction

alveoli

made of simple squamous which is optimal for gas exchange; Thinness (just ~0.5 micrometers across the alveolar-capillary barrier) means oxygen and carbon dioxide can diffuse quickly between air in the alveolus and red blood cells in the capillaries.

alveolar duct

tube composed of smooth muscle and connective tissue which opens into cluster of alveoli

alveolus

one of the many small, grape-like sacs that are attached to the alveolar ducts

alveolar sac

a cluster of many individual alveoli that are responsible for gas exchange

alveolar pores

connects alveoli to their neighbours, help maintain equal air pressure throughout the alveoli and lung

alveolar wall consists of

type I alveolar cells, type II alveolar cells, and alveolar macrophages

type I alveolar cell

a squamous epithelial cell of the alveoli, which constitute up to 97 percent of the alveolar surface area. These cells are about 25 nm thick and are highly permeable to gases

type II alveolar cell

interspersed among the type I cells and secretes pulmonary surfactant

pulmonary surfactant

a substance composed of phospholipids and proteins that reduces the surface tension of the alveoli, critical for inflation to occur as it reduces surface tension of alveoli

alveolar macrophage

a phagocytic cell of the immune system that removes debris and pathogens that have reached the alveoli

simple diffusion

respiratory membrane allows gases to cross by this process, allowing oxygen to be picked up by the blood for transport and CO2 to be released into the air of the alveoli

bronchial asthma tissue

include thickened mucosa, increased mucus-producing goblet cells and eosinophil infiltrates; airway is narrowed/constricted, mucus production is excessive, epithelial cells are damaged/shredding, smooth muscle is hypertrophied, thickened and contracted, basement membrane is thickened, many inflammatory cells such as eosinophils and mast cells

normal lung tissue

airway is wide/open, mucus production is low/normal, epithelial cells are intact, smooth muscle is thin and relaxed, basement membrane is thin and few inflammatory cells

cardiac notch

an indentation on the surface of the left lung, and it allows space for the heart

left lung

has smaller capacity for air volume compared to the right lung. This is because the heart is situated on the left side of the chest, taking up space that would otherwise be occupied by lung tissue; has two lobes: superior and inferior

right lung

3 lobes (superior, middle, inferior)

quiet breathing

also known as eupnea, is a mode of breathing that occurs at rest and does not require the cognitive thought of the individual. the diaphragm and external intercostals must contract

diaphragm and external intercostal muscles

used for quiet breathing

deep breath

called diaphragmatic breathing, requires the diaphragm to contract. As the diaphragm relaxes, air passively leaves the lungs

shallow breath

called costal breathing, requires contraction of the intercostal muscles. As the intercostal muscles relax, air passively leaves the lungs.

forced breathing

also known as hyperpnea, is a mode of breathing that can occur during exercise or actions that require the active manipulation of breathing, such as singing. inspiration and expiration both occur due to muscle contractions. In addition to the contraction of the diaphragm and intercostal muscles, other accessory muscles must also contract. During forced inspiration, muscles of the neck, including the scalenes, contract and lift the thoracic wall, increasing lung volume. During forced expiration, accessory muscles of the abdomen, including the obliques, contract, forcing abdominal organs upward against the diaphragm. This helps to push the diaphragm further into the thorax, pushing more air out. In addition, accessory muscles (primarily the internal intercostals) help to compress the rib cage, which also reduces the volume of the thoracic cavity

muscles in forced breathing

diaphragm, intercostal muscle, muscle of the neck including scalenes, obliques

pleura

a serous membrane that surrounds the lung, create a division between major organs that prevents inferference due to movement of organs while preventing spread of infection

mediastinum

separates right and left pleurae

visceral pleura

layer that is superficial to lungs and extends into and lines lung fissures

parietal pleura

outer layer that connects to the thoracic wall, the mediastinum, and the diaphragm.

hilium

where visceral and parietal pleurae connect to each other

pleural cavity

the space between the visceral and parietal layers. The pleurae perform two major functions: They produce pleural fluid and create cavities that separate the major organ

pleural fluid

secreted by mesothelial cells from both pleural layers and acts to lubricate their surfaces. This lubrication reduces friction between the two layers to prevent trauma during breathing, and creates surface tension that helps maintain the position of the lungs against the thoracic wall

pulmonary ventilation

(breathing) is movement of air into and out of lungs. The major mechanisms that drive it are atmospheric pressure (Patm); the air pressure within the alveoli, called intra-alveolar pressure (Palv); and the pressure within the pleural cavity, called intrapleural pressure (Pip).

boyle's law

In a gas, pressure increases as volume decreases; inverse relationship; describes the relationship between volume and pressure in a gas at a constant temperature

boyle's law and breathing

the ability to breathe—to have air enter the lungs during inspiration and air leave the lungs during expiration—is dependent on the air pressure of the atmosphere and the air pressure within the lungs

respiratory volume

term used for various volumes of air moved by or associated with lungs at a given point in respiratory cycle. Four major types: tidal, residual, inspiratory reserve, and expiratory reserve. dependent on a variety of factors and measuring the different types of respiratory volumes can provide important clues about a person's respiratory health

tidal volume

amount of air that normally enters the lungs during quiet breathing which is about 500 mL

expiratory reserve volume

amount of air you can forcefully exhale past a normal tidal expiration, up to 1200 milliters for men

inspiratory reserve volume

is produced by a deep inhalation, past a tidal inspiration

residual volume

the air left in the lungs if you exhale as much air as possible. makes breathing easier by preventing alveoli from collapsing

respiratory capacity

the combination of two or more selected volumes which further describes the amount of air in the lungs during a given time

total lung capacity

sum of all of the lung volumes (TV, ERV, IRV, and RV), which represents the total amount of air a person can hold in the lungs after a forceful inhalation

vital capacity

amount of air a person can move into or out of his or her lungs and is the sum of all of the volumes except residual volume (TV, ERV, IRV)

inspiratory capacity

the maximum amount of air that can be inhaled past a normal tidal expiration, is the sum of the tidal volume and inspiratory reserve volume

functional residual capacity

is the amount of air that remains in the lung after a normal tidal expiration; it is the sum of expiratory reserve volume and residual volume

atelectasis

collapsed lung, due to plugged bronchioles -> collapse of alveoli, wound that admits air into pleural cavity (pneumothorax), thoracentesis

dorsal respiratory group

portion of medulla oblongata, involved in maintaining a constant breathing rhythm by stimulating the diaphragm and intercostal muscles to contract, resulting in inspiration. When activity in the DRG ceases, it no longer stimulates the diaphragm and intercostals to contract, allowing them to relax, resulting in expiration

ventral respiratory group

portion of medulla oblongata, involved in forced breathing, as the neurons in the VRG stimulate the accessory muscles involved in forced breathing to contract, resulting in forced inspiration. The VRG also stimulates the accessory muscles involved in forced expiration to contract

central chemoreceptor

one of the specialized receptors that are located in the brain and brainstem

peripheral chemoreceptor

one of the specialized receptors located in the carotid arteries and aortic arch

chemoreceptors

detect changes in the chemical composition of blood and cerebrospinal fluid (CSF), specifically focusing on levels of carbon dioxide (CO2), hydrogen ions (H+), and oxygen (O2); stimulated by concentration changes such as CO@ and H ions

effect on pH

increased CO2 lead to increased levels of hydrogen ions, decreasing pH

effect on rate of breathing

increase in hydrogen ions in the brain triggers the central chemoreceptors to stimulate the respiratory centers to initiate contraction of the diaphragm and intercostal muscles. As a result, the rate and depth of respiration increase, allowing more carbon dioxide to be expelled, which brings more air into and out of the lungs promoting a reduction in the blood levels of carbon dioxide, and therefore hydrogen ions, in the blood

low levels of CO2 in blood

cause low levels of hydrogen ions in the brain, leading to a decrease in the rate and depth of pulmonary ventilation, producing shallow, slow breathing.

pulmonary embolism

pulmonary vessels blocked by blood clots, fat , or air bubbles

pulmonary blood pressure

low, 30 mm Hg or less

hyperpnea

normal response, is an increased depth and rate of ventilation to meet an increase in oxygen demand as might be seen in exercise or disease, particularly diseases that target the respiratory or digestive tracts. This does not significantly alter blood oxygen or carbon dioxide levels, but merely increases the depth and rate of ventilation to meet the demand of the cells

hyperventilation

an increased ventilation rate that is independent of the cellular oxygen needs and leads to abnormally low blood carbon dioxide levels and high (alkaline) blood pH.

examples of hyperpnea

intense exercise, high altitude, in fever or infection, pregnancy.

examples of hyperventilation

panic attack or anxiety, pain or emotional distress, over breathing before free diving, breathing too fast while at rest

additional parts needed for oxygen transport

Alveoli, lungs, red blood cells, heart and vessels, partial pressure gradients, regulatory molecules.

air flow

Larynx -> trachea -> primary main bronchi -> secondary lobar bronchi -> tertiary segmental bronchi -> bronchioles -> terminal bronchioles -> respiratory bronchioles -> alveolar ducts -> alveolar sacs -> alveoli