biology chapter 6 mcat

nares, pharynx, lARYNX, TRACHEA, bronchi, bronchioles

air path to the lungs

nares

nostrils, draws in air

pharynx

where air is warmed and humidified. It's a muscular, cone-shaped tube lined with moist tissue, extending from the skull base to the cricoid cartilage.

vibrissae

nose hairs, Their function is to filter out large particles and potential pathogens from inhaled air before they reach the lower airways. 

larynx

a cartilaginous structure located at the top of the trachea (windpipe) in the neck, crucial for protecting the lower respiratory tract and producing sound through its vocal cords. 

trachea

the tube that connects the larynx (voice box) to the bronchi and serves as a passageway for air to move between the upper respiratory tract and the lungs, facilitating breathing. It is composed of cartilaginous rings that prevent collapse and is lined with mucosa and cilia for filtering and warming air.

bronchi

the two large tubes that branch off from the trachea (windpipe) and carry air into the left and right lungs. 

bronchioles

small branches of the bronchi (which are tubes that branch off the trachea). They are essentially a continuation of the airway system into the lungs. Think of them as similar to how arteries branch into arterioles in the circulatory system

alveoli

small sacs that interface with the pulmonary capillaries allows gases to diffuse across a once cell thick membrane

surfactant

in the alveoli, reduced surface tension at the liquid gas interface preventing collapse

pleura

cover the lungs and chest wall

visceral pleura

pleura that lies adjacent to the lungs themselves

parietal pleura

pleura that lies on the chest wall

intrapleural space

lies between the two layers of the pleura and contains a thin layer of fluid that lubricates between the two pleural spaces

diaphragm

thin skeletal muscle that helps create the pressure differential required for breathing

external intercostal muscles

work with the diaphragm to expand the thoracic cavity, increasing the volume of the intrapleural space. This decreases the intrapleural space

inhalation

an active process

negative pressure breathing

the body's natural mechanism for inhaling air into the lungs, relying on a pressure differential created by muscle contractions that expand the thoracic cavity, leading to lower pressure inside the lungs compared to the atmosphere. When the diaphragm contracts and flattens, and the external intercostal muscles lift the rib cage, the volume of the thoracic cavity increases, which, according to Boyle's Law (inverse relationship between pressure and volume), decreases the pressure within the lungs (intrapulmonary pressure) below atmospheric pressure, causing air to flow in.

exhalation

may be passive or active process

spirometer

can be used to measure lung capacities and volumes

total lung capacity (TLC)

the maximum volume of air in the lungs when one inhales completely

Residual volume (RV)

the volume of air remaining in the lungs when one exhales completely

Vital capacity (VC)

the difference between the minimum and maximum volume of air in the lungs

tidal volume (TV)

the volume of air inhaled or exhaled in a normal breath

expiratory reserve volume (ERV)

the volume of additional air that can be forcibly exhaled after a normal exhalation

Inspiratory reserve volume (IRV)

the volume of additional air that can be forcibly inhaled after a normal inhalation

ventilation center

regulates ventilation, and collection of neurons in the medulla oblongata

chemoreceptors

respond to carbon dioxide concentrations, increasing the RR when there is a high rate of co2 in the blood

increase

chemoreceptors — rr when co2 levels are high in the blood

simple diffusion

lungs perform gas exchange with the blood through —- —- across concentration gradients

pulmonary arteries

deoxygenated blood with high co2 concentrations in brought to the blood through the —-

pulmonary veins

oxygenated blood with low co2 concentrations leaves the lungs via the —

lysozyme

in the nasal cavity, attacks peptidoglycan cell walls of gram positive bacteria along with saliva

macrophages

can engulf and ingest pathogens and signal to the rest of the immune system that there is an invader

mast cells

have antibodies on their surface that when triggered can promote the release of inflammatory chemicals, often involved in allergic reactions as well

bicarbonate buffer system

the respiratory system is involved in pH control through the — — —-

decreases

when blood ph —- rr increases to compensate by blowing off co2. this causes the left shift in the buffer equation reducing hydrogen ion concentration

increases

when blood ph —- rr decreases to compensate by trapping co2. this causes the right shift in the buffer equation increasing hydrogen ion concentration

bicarbonate buffer system

CO2 + H2O ⇌ H2CO3 ⇌ HCO3- + H+.