[CAS BI 315] - Midterm Exam Guide - Everything you need to know! (252 pages long)

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CAS BI 315
MIDTERM EXAM
STUDY GUIDE
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Respiratory Overview
Respiratory System
!Any structure in an animal that promotes the exchange of O2/CO2 with the environment
!Respiratory surface: surface across which the gases are actually moved
o!Very high surface area, very vascular
o!Alveoli
!Inspiration – the movement of air from the external environment through the airways
!Expiration – movement in the opposite direction
!During the resp cycle, the right ventricle pumps blood through the pulmonary system and into the capillaries
surrounding each alveolus
Anatomy
Pathway
!Air comes in through the nose or mouth into the pharynx
o!Pharynx branches into esophagus and larynx
o!Pharynx goes behind trachea and sometimes the esophagus needs room to expand when we swallow
food
!Larynx – part of the airways
o!Houses vocal cords
o!Vibrations of air pat the vocal cords causes them to vibrate, producing sounds
o!Opens into the trachea
!Trachea
o!Surrounded by cartilage in the front, but not in the back
o!Air-flow through trachea
!Epithelial cells on the surface have cilia, which beat in unison in one direction (upwards)
o!Air moves down, mucus moves up
!Mucus layer encompasses the cilia and is relatively thick and viscous
!As cilia beat up, they bring mucus with it (mucus escalator)
!Also brings pollutants that were ingested back up with mucus
!Mucus moves back up to the pharynx, where it is swallowed
!Keeps lungs clear of particulate matter and bacteria/dust
!Cystic fibrosis – mucous layer becomes thick and dehydrated, obstructing airways
o!Bifurcates and becomes 2 bronchi
!Ciliated, and make mucus
!Leads to thousands of bronchioles, which collect into alveoli on respiratory surface
o!Figure 13.3: Bronchioles
!Bronchioles are variable resistors
!Covered by rings of smooth muscle
!Bronchioles can open and close to give more air to some parts of the lungs, and less air
to others (can stop pathogenic air from going to the alveoli which is important bc if you
get an infection in the alveoli, alveoli will be taken out of air exchange process)
!Bronchioles contract to protect alveoli, but in people with asthma, bronchioles contract more
than they should so they take medication to keep bronchioles dilated
!Diaphragm – skeletal muscle found below lungs
!Thoracic cavity
!Alveoli
o!Air comes in and perforates alveolar ducts, at the same time moves CO2 in the other direction
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o!Alveoli are very thin cells with very little cytoplasma because their only job is to be thin to allow gas
to enter cell
o!Alveolar walls contain capillaries
o!Type 1 Alveoli: epithelial cells filled with hemoglobin and O2 by simple diffusion
o!Type 2 Alveoli: thicker cells, not involved with air exchange, that produce surfactant
!Filled with structures made up of lipids, which get secreted into alveolar air and coat Type 1
cells
!Cells are surrounded by fluid
!Structures inside alveoli (type 2) are called surfactants
!Amphipathic
!Decreases surface tension in alveoli
!Physically separating water molecules with surfactants
!Fetuses do not need surfactant bc they aren’t using their lungs
o!Around week 30, babies begin to produce surfactant to prepare for when they
begin to breathe
o!Babies born preterm may not have surfactant and will have a difficult time
breathing (respiratory distress syndrome)
!Increase cortisol levels to increase production of surfactant in baby
(glucocorticoid therapy or postnatal surfactant administration)
o!Cortisol acts on receptors in Type 2 cells, inducing cells
o!Fetal adrenal glands don’t produce cortisol until later in pregnancy
!Lungs
o!Covered by double membrane of fluid-filled tissue, “pleura”
o!Parietal pleura – attached to thoracic wall
o!Visceral pleura – attached to lungs
o!Interpleural fluid lubricates pleural surfaces during breathing
!
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