Respiratory System Flashcards
internal respiration meaning
use of O2 and production of CO2 by cells
external respiration definition
movement of gases between environment and cells
what gradient determines air flow?
a pressure gradient (from high to low)
what conditions are needed for air to flow into the lungs?
- low pressure inside the lungs = higher volume
what is bulk flow?
movement of fluid as a result of pressure gradient
what factors led to an increase in O2 needs
- larger size
- endothermy
- habituation of new environments
- large nervous system
what are unique features of gills?
- highly vascularised
- large SA
- thin membranes
- operculum
- countercurrent exchange -> swimming moves water through gills
amphibian respiratory features
- combination of skin, gills and lungs
- use buccal cavity to draw in air and squeeze it down mouth
- intermttent breathers
reptile breathing
- emergence of inspiratory/expiratory
- reduce internal air pressure and suck air into lungs using muscular pumps
bird respiratory
- need a higher metabolic rate due to more O2 required for flying
- change air pressure in air sacs
- air sacs flow onto lungs
- counter current flow in lungs
- high haemoglobin affinity
mammal features
- high SA
- upper and lower resp tract
- diaphragm + inter-coastal muscle for pressure gradient
- pleural sac around lungs for inflation
what’s included in upper resp tract
- oral and nasal cavity, pharynx and larynx
what’s included in lower resp tract
- trachea, bronchi, bronchioles, alveoli
features of upper resp tract
- goblet cells and cilia
- cartilage rings in trachea and bronchi
- smooth muscle and no cartilage n bronchioles
features of lower tract
- large SA
- thin walls
- no goblet cells
- absent cilia (may be sparse)
- no cartilage
- alveolar sac -> clusters of alveoli
features of alveoli
- single thin epithelial layer
- surfactant secreting type II alveolar cells
- macrophages
features of bronchioles
- smooth muscle walls
features of bronchi
- cartilage rings
- ciliated
- epithelium
- goblet cells
features of trachea
- cartilage rings
- ciliated epithelium
- goblet cells
nasal cavity
- ciliated epithelium
- goblet cells (mucus)
- hair
how is O2 transported in blood
- gas transport proteins
- matalloproteins -> carry metal ions which reversibly bind to O2 and increase O2 carrying capacity by 50X
- HEMOGLOBIN in vertebrates is the protein
- contained within red blood cells
How is homeostasis related?
- blood gas levels are regulated variable
- chemoreceptors are sensors
- medulla = control centre
- effectors = heart, lungs/resp muscles
what is partial pressure
- fraction of air made up by a particular gas
- pp of individual gas = total pressure of gas x % of individual gas (only at sea level where water = 0%)
definition of diffusion of gases
movement of gas mols from region of high pp to low pp
what is the diffusion coefficient
- measure of permeability of a particular membrane to a particular gas
- constant for each gas
- dependent on solubility and molecular weight
- more soluble = large coefficient
- smaller molecule = diffuse faster = larger co.
- e.g. CO2 more soluble than O2, so at any pressure CO2 dissolves faster in water and crosses membrane faster
what is diffusion rate proportional to?
- surface area
- diffusion coefficient
- magnitude of the pp gradient
what is diffusion rate inversely proportional to?
membrane thickness
What is Fick’s law?
V = A x D x ChangeP/T
- diffusion rate = V
- Membrane SA = A
- diffusion coefficient = D
- PP gradient = P = P1 – P2
- membrane thickness = T
What is the pressure gradient
- difference in pressure between two areas
- ## the only factor that can change in the short term
what is bulk flow
- all air movement due to pressure gradient
- flow (Q) is proprotional to pressure gradient
- flow inversely proportional to resistance (r)
- Q = changeP/R
how is a pressure gradient generated?
- change in lung volume due to muscles
- small volume = high pressure due to molecules bouncng off each other and walls
- large volume = more space = less contact
what determines resistance
- radius
- flow pattern
- fluid viscosity
- length
why does radius have such a large impact on flow
- resistance to the fourth power of r
why is resistance lower in bronchioles than trachea
- so many that their total cross sectional area reduces resistance
Flow patterns and impact
- turbulent = slower flow
- transitional = in between, still bouncing
- laminar = straight through flow, no bouncing
*highest turbulence in trachea
Special properties of flow
- pressure gradient is variable (resp muscles)
- bronchioles are collapsible
- bronchiolar radius can be actively regulated (smooth muscle rings)
how s bronchiolar resstance altered passively
- each breath causes changes in thoracic pressure
- this lead to changes in pressure of bronchioles leading to changing radius passively
how is bronchiolar resistance altered actively
- smooth muscle contracts or relaxes
- causes longer term variation to resistance
- under intrinsic and extrinsic control
local control of smooth muscle
- chemical mediators (CO2) cause dilation
- histamine produces strong bronchoconstruction and mucus -> paracrine hormone = rapid constriction
extrinsic control of smooth muscle
- autonomic nervous system and hormones
- parasympathetic nerve system causes contraction input
- sympathetic reacts to adrenaline to cause relaxation
