Quiz 3 Neurology and Pulmonology Flashcards
Nervous System
Control system of body
Broken down into two major categories CNS and PNS
Central Nervous System - CNS
is located in
Brain and Spinal Cord
Peripheral Nervous System - PNS
is
Everything else: including spinal nerves and cranial nerves
Peripheral Nervous system breaks down into
Efferent Division (Motor)
&
Afferent Division (Sensory)
Efferent Division
aka Motor Division
Information traveling from Brain and Spinal Column to other parts of the body
Afferent Division
aka Sensory Division
carries information from other parts of the body to the brain and spinal cord
Afferent Division breaks into (unofficial categories)
Visceral - Internal organs sensing change in internal organ
&
Somatic - relays “something” about the environment ie table is smooth, clothes soft etc. to the brain
Efferent Division breaks into
Somatic Nervous System (SNS)
&
Autonomic Nervous System (ANS)
Somatic Nervous System (SNS)
controls
Motor Control of Skeletal Muscle
Voluntary/Involuntary - includes reflexes
Autonomic Nervous System - ANS
breaks into
Sympathetic Division - generally stimulatory (neurotransmitter at postganglionic synapse is NE - norepinephrine primary neurotransmitter for adreginic receptor sites A1 - Vasoconstriction, ß1 Increase heart rate and force of contraction, ß2 bronchodialation)
&
Parasympathetic Division - generally rest & relax, ie digestion, slows heart rate, peripherial vasodialation
(neurotransmitter at pre & postganglionic synapse is ACh- Aceytlcholine is primary neurotransmitter for muscarnic/nicotinic receptor sites)
Autonomic Nervous System is responsible for
All Motor control that is involuntary, everything but skeletal muscle
ie. Cardiac, Smooth, glandular secretions etc
Hirearchy of Nervous System
Nervous System
- CNS - Brain & Spinal Cord
-
PNS - Everything Else
-
Afferent - Sensory
- Somatic -
- Visceral -
-
Efferent - Motor
-
Somatic Nervous System - Voluntary
- Corticospinal Pathway (Pyramidal)
- Medial & Lateral Pathway (Extrapyramidal)
-
Autonomic Nervous System - Involuntary Actions
- Sympathetic Division -
- Parasympathetic Division -
-
Somatic Nervous System - Voluntary
-
Afferent - Sensory
Neuron
The functional unit of the nervous system
Dendrites
Where the neuron recieves the information
Synaptic Terminal
aka: Synaptic Knob, Bouton
Where information is sent out
Axon Hillock
All or nothing point of Neuron
If input is large enough to reach axon hillock, charge will procede down axon to Synaptic terminal
Synapse
Pre/Post Synaptic Neuron
Synaptic Cleft
Neurotransmitter
Synapse - Location where two neurons come together and share information
Presynaptic Neuron - sending of information via chemical neurotransmitter when elicited by action potential
Postsynaptic Neuron - dendrites recieve signal which excites/inhibits signal
Synaptic Cleft -gap between pre and post synaptic neurons
Neurotransmitter - specific chemical agent released by a presynaptic cell, on excitation, that crosses the synaptic gap to stimulate or inhibit the postsynaptic cell
Functional Classes of Neurons
- Sensory Neurons
- Motor Neurons
- Interneurons
Sensory Neurons
Deliver information from perriphery via sensory receptors to the CNS
- Composed of Afferent neuron fibers relaying:
- somatic - sensing a change in external environment
- visceral - sensing some change in internal organ
Motor Neurons
carry instructions from CNS to peripheral effectors
- Somatic - Skeletal Muscle movement
- Visceral - everything else - Cardiac Muscle - cardiac/smooth muscle; glandular,
Sympathetic VS Parasympathetic
- Oppose each other in autonomic function
Homeostasis could be described as a balance between Parasympathetic (rest and digest) & Sympathetic (Fight of Flight)
- Generally, the sympathetic nervous system releases a chemical called norepinephrine, which is excitatory to neurons, from its postsynaptic neurons.
- The parasympathetic nervous system releases a chemical called acetylcholine from its postsynaptic neurons.
- Originate from different locations at the base of the brain;
- sympathetic preganglionic fibers tend to be shorter
Interneurons
- Coordination of information between sensory and motor neurons
- Located primarily in brain, redirect information so appropriate response occurs
3 components of homeostasis and their parallels in nervous system
- Receptor - Sensory Neurons
- Control Center - Interneurons
- Effector - Motor Neurons
Neuroglia
aka: Glia Cells/Supportive Cells
Glue that holds Nervous System together
4 Types of Neroglia in CNS
- Apendymal Cells
- Astrocytes
- Oligodendricytes
- Micro Glia
2 Types of Neroglia in PNS
- Schwann Cells
- Satellite Cells
Apendymal Cells
- Belongs to CNS
- Forms lining of central canal and ventricles where CSF is found
Astrocytes
- Found in CNS
- surround capillaries responsible for blood-brain barrier
- regulate passage of “stuff” crossing into interstitial fluid between neurons
- regulate ion concentrations in interstitial fluid
Oligodendrocytes
- Blongs to CNS
- Forms Mylein Sheath that is rolled around axon; flattened out like a pancake squeezing out cytoplasm
- Membrane is primarily lipid that creates insulation
- Internodes are the myelin sheath between Nodes of Ranvier - the space between oligodendrocytes
Microglia
- Belong to CNS
- Engulf cell debris and waste products
Schwann Cells
- Belongs to PNS
- PNS version of Oligodendrocytes
- Myelin sheath that wraps peripherial axons
Satellite Cells
- Belongs to PNS
- PNS version of Astrocytes
- Surround cellbodies of neurons and regulate exchange with interstitial environment
Chemical Gradient
- Concentration Gradient based on the # of ions of a particular kind
- each chemical has its own gradient and will look to equalize it own concentration
Leak Channels
- Allow free movement of a particular ion in/out of a cell
- Usually specific to one type of ion
Electrical Gradient
- Exists alongside Chemical gradient
- Electrical gradient may move chemical in/out based on charge of ECF vs ICF environment
Current
- movement of charges to eliminate the potential difference
- ie fixing the electrical or chemical gradients
Cell membrane as it relates to Current
- Becomes a barrier that creates resistance by restricting the flow of current
Resistance
- how much the barrier restricts the flow of current
Electrochemical Gradient
Sum of all Electrical and Chemical factors that determine the direction of ion flow
For example:
- K+ wants to move out of the cell due to concentration gradient from Hi to Low; however because the presence of the Protein Anion and the overall negative charge inside the cell, the K+ is attracted, and wants to pass back into the cell.
- Na+ wants to move into the cell due to concentration gradient between ECF and ICF; and the electrical gradient which is negative inside cell and attractive to Na+
Polarized
meaning with charge
Depolarized
- adding positive charge
- Becoming less negative
- moving toward zero
- change in ion flow ⇒ becoming more more positive
Hyperpolarized
- When cell moves more negative towards resting potential
*
Significance of Na+K+ in maintaining
resting membrane potential
- Na+K+ Pump maintains the resting membrane potential across by pumping sodium out of the cell and potassium into cell against concentration gradients.
- Enables cells ability to depolarize and propogate an electrical impule to the synapse
Graded Potential
-
propogated in a graded and decremental fashion
- Propogated - Charge spreads outward in all directions
- Graded - Vary in size in relation to size of chemical input
- Decremental - decreases in size as it moves further from point of orgin
Action Potential
- Propogated changes in transmembrane potential
- once initiated it will affect the entire excitable membrane
- All or nothing, must meet threshold @ axon hillock to initiate Action Potential all the way to Synapse
- Not decremental or graded
Threshold
minimum stimulus required to form an action potential
Steps to the Formation of an Action Potential
- The presynaptic neuron sends neurotransmitters to postsynaptic neuron. (A chemical message)
- Once the threshold of excitation is reached (Axon Hillock) the neuron will fire an action potential.
- Na+ channels open and Na+ is forced into the cell by the concentration gradient and the
electrical gradient. depolarizing the neuron. - K+ channels open (@ -30mV) and K+ is forced out of the cell by the concentration gradient and the
electrical gradient. The neuron continues to depolarize. - The Na+ channels close at the peak of the action potential (+30mV). The neuron starts to repolarize. The K+ channels close, but they close slowly and K+ leaks out.
- The neurotransmitter is released to the postsynaptic neuron
- The resting potential(-70mV) is overshot and the neuron falls to a -90mV (hyperpolarized)
- The Na+/K+ pump then starts to pump 3Na+ ions out for every 2K+ ions it pumps in, some K+ leaks out synapse.
- The neuron returns to resting potential
Absolute Refractory Period
- period of time when neuron is unavailable to refire
- From time it leaves it’s resting potential -70mV, depolarizes yo +30mV and returns to -70mV
- Like Toilet - the time when toilet is flushed until it has minimum amt. of water necessary to flush again.
Relative Refractory Period
- Period of time after cell has depolarized and returned to initial resting potential; however cell is now in hyperpolarization phase and is not best suited for reconduction
- Analogous to being able to flush the toilet before it is optimal to do so.
Characteristics of Unmylenated Neurons
- Continuously Propogatate - local current depolarizes adjacent membrane
- Can’t travel backwards (True for all AP’s)
Myelinated Neuron
- Oligodendrocytes/Schwanns Cells that wrap around axon,
- Produces salutatory conduction/propogation as nerve impulse jumps from node to node along signal path
Two types of synapses
- Electrical - does not require chemical nerotransmitter
- Chemical - common in cardiac cells, requires use of nerotransmitter; *makes up majority of synapses
Ionotropic
- is a special kind of effect of a hormone on its target.
- The hormone activates or deactivates ionotropic receptors (ligand-gated ion channels).
- The effect can be either positive or negative, whether the effect is a depolarization or a hyperpolarization respectively.
Metabotropic
- effects some sort of metabolic activity inside the cell
- ie. second messengers are molecules that relay signals from receptors on the cell surface to target molecules inside the cell
Arrival at the synapse
- AP arrives at synaptic knob
- Voltage changes allow opening of Ca2+ voltage gated chanels entry of Ca2+ions
- Entry of Ca2+ ions allows vessicles containing nerotransmitters to fuse with membrane and excytosis of neurotransmetters into synaptic clef
- Neurotransmitter binds to ligand gated channel on post synaptic membrane, inhibitory/excititory transmission follows
- Neurotransmitter broken down or taken up into presynaptic membrane
Meninges
Description and purpose
are 3 layers of specialized membranes that Surround brain and spinal cord
Provides protection, stability, shock absorption to CNS Tissue
1 Physiologic difference between
cranial and spinal Meninges
Spinal Meninges contain adipose tissue in epidural space where local anesthia can be administered.
vs.
Cranial meninges have no epidural space.
Meninges Layers
Dura Matter - Outermost membrane just under bone, responsible
Subdural Space - Lymphatic fluid
Arachnoid matter -
Subarachnoid space - Blood Vessels and CSF
Pia Matter - Follows contours of the brain tissue; has blood vessels
Cerebral Cortex - Brain - Gray matter
Types of Cranial Bleeds
Epidural
Subdural
Subarachnoid
Interparenchymal
Spinal Cord
Relay between body and brain
Sends/receives messages to/from Brain
&
Sends/recieves messages from Periphery
Includes SPINAL & CRANIAL Nerves
Vertebrae
Cervical Spine C1-C7
Thoracic Spine T1-T12
Lumbar L1-L5
Sacral S1-S5
Coccyx 3-5 Fused
Spinal Cord stops around which vertebrae?
What structure continues from there?
L1 or L2
Cauda Equina - looks like horses tail extends from bottom of spinal cord
Spinal Nerves
31 Pairs of spinal nerves
Spinal Nerves #’s correspond to adjacent just lower vertebrae for everything T1 and below.
ie. Just below the T1 Vertebrae is the T1 Spinal Nerve
Cervical Spinal Nerves are ontop of corresponding vertebrae
ie Spinal nerve C7 is just ontop of C7
and
Just under the C7 Vertebrae is the C8 Spinal nerve
Spinal Nerve Layout
Central Canal - Contains CSF
Dorsal (posterior) Root Ganglia - carries sensory information
Ventral Root Ganglia (Anterior) - Carries motor information
Two ganglia join to form mixed (motor/sensory) for innervation of periphery
Main components of the brain
Cerebrum
Diencephaion
Mid-Brain
Pons
Medulla Oblongata
Cerebellum
Brain Germ Pg 382
Cerebrum
Outter Shell - kind of provides protection for basal functions located in mid-brain
Responsible for all higher order functions
ie: sensation, learning, thinking and memory, storage and retrival, speech
Corpus collosum
Bridge between L&R Hemispheres of Brain
Plasticity - ability of brain to compensate for left or right hemisphere damage; ability is better as you are younger
Diencephalon
kind of subdivision of cerebrum, buried in that portion of the brain
Comprised of: Epithalamus/Thalamus/Hypothalamus
integration of conscious and unconcious sensory information and motor commands
Hypothalamus is responsible for temperature regulation
Brain Stem and components
Brain Stem - responsible for basal functions
- Mid Brain - processing visual and auditory information; generates involuntary motor response; contains Reticular activating system (RAS) = has affect on level of conciousness ie. being hit in the face
- Pons - Rate and Depth of Respiration; functions as relay center; pontine pupils (pons pupils) - severely constricted pupils
- Medulla Oblongata - connects brain to spinal cord; contains the cardiac, respiratory, vomiting and vasomotor centers and deals with autonomic, involuntary functions, such as breathing, heart rate and blood pressure.
Cerebellum
Responsible for balance and gait
Ataxia - impairment in balance; controls positive muscles which aid in balance
Lobes of the brain
Identified by regions of skull that they are adjacent to
- Frontal - conscious thought; damage can result in mood changes, social differences, etc. The frontal lobes are the most uniquely human of all the brain structures.
- Parietal - integrating sensory information from various senses, and in the manipulation of objects
- Temporal - senses of smell and sound, as well as processing of complex stimuli like faces and scenes
- occipital -sense of sight; lesions can produce hallucinations
Primary Motor and Sensory Cortex
Motor Cortex sits in Anterior
Sensory Cortex is Posterior
Hands and Face have largest amount of sensory and motor function dedicated to them specifically.
Broca’s and Wernicke’s area
Speech and language areas sometimes affected in stoke deficits
Broca’s - Area linked to speech production
Wernicke’s - Area linked to understanding of written and spoken language
Cranial Nerves
Part of Peripherial Nervous System
12 pairs
Things that control the face, eyes, what you see, expressions, saliva, tears etc
Cranial Nerve #10
Vagus Nerve
Longest nerve in human body
Responsible for both sensory and motor function
Parasympathetic innervation stimulatory & inhibitory
innervates soft palate, esophagus, pharanx, cardiac muscle, smooth muscle,
Two major collections of skeletal muscle motor pathways
Corticospinal Pathway (Pyrimidal System) - Voluntary control over skeletal muscle
Medial & Lateral Motor Pathways(Extra-Pyrimidal System) - Involuntary/subconcious control ⇒ muscle tone ⇒ trunk and limbs
Nervous System/PNS/Efferent/
Extra Pyrimidal Syndrome
involuntary muscle movements or spasms that usually occur in the face and neck.
An individual may suffer from this syndrome as a result of a head injury or Parkinson’s disease, though the primary cause is an adverse reaction to antipsychotic drugs.
Some forms can be treated with Benedryl
Dystonia or dystonic reation is a disorder characterized by involuntary muscle contractions that cause slow repetitive movements or abnormal postures.
Dual Innervation
Sympathetic
&
Parasympathetic Divisions
Prevalent in Autonomic nervous system
Where both Sympathetic and Parasympathetic Nervous Systems bring nerves to the same peripheral organs
actions oppose each other but can be either stimulatory or inhibitory
ie digestive system - Stimulation is initiated by parasympathetic division vs decreased activitiy initiated by sympathetic
Cardiovascular system - Stimulation is initiated by Sympathetic division; decrease in activity initiated by parasympathetic division
What are the 5 basic fucntion of the respiratory system?
- Provides and extensive surface for gas exchange
- Move air to/from lungs
- Protection of respiratory surfaces from changes temperature and exposure to pathogens
- Production of Sound
- Facilitate olfactory
Anatomy of Respiratory System
see diagram
Anatomy of nasal and oral structures
See Diagram
Pharynx: consists of
- Nasopharynx
- Oropharynx
- Laryngopharynx
Chamber that is shared by respiratory and digestive tracts
Trachea
- main entrance to lungs
- C-shaped cartilage protects airway
- Trachealis muscle bridges the gap between free ends of C-shaped cartilages at the posterior border of the trachea, adjacent to the esophagus.
- Trachealis muscle is comprised of smooth muscle and can be relaxed via sympathetic stimulation(+air flow, +diameter, -resistance) in the event of food bolus with glucagon (ß2 agonist)
- When Trachealis Muscle contracts it plumps (gets fatter) reducing the diameter of the trachea
- Food Bolus - large food particle stuck in esophagus
- descends from larynx @ C6 to carina @ T5
Larynx
includes:
- epiglottis - blocks food from trachea
- thyroid cartilage
- cricothyroid cartilage
found between C4-C6
Seperates upper and lower airways
Hilus
Entrance to lung from bronchi
Where pleural membranes attach
Carina
base of trachea
Splits into Left & Right mainstem Bronchi
Right mainstem is wider and more anatomically straight down
Sits around T5
Left Bronchi is off to the side at an angle
Right lung has 3 lobes
Left lung has 2 lobes
Bronchi breaks into
- Primary Bronchi
- Secondary Bronchi
- The tertiary bronchi (also known as the segmental bronchi
- Bronchioles - first structures without cartilage terminate at alveoli
Bronchioles
- Bronchioles - first structures without cartilage or glands in their submucosa
- Wrapped in increasing amounts of smooth muscle as it descends respiratory tract
- Smooth muscle cells have ß2 receptors on them which when sympathetically stimulated cause relaxation = bronchodialation, more space
- Asthma - broncoconstriction and inflammation decreases airflow
Respiratory Mucosa
epithelium - lining of respiratory tract
and mucous membrane plus connective tissue
nutrients must be provided by diffusion - ie from basal lamina or lumen (or airway = O2)
**will not be asked- cells of respiratory tract are primarily pseudo stratified columnar epithelium
Lamina Propria
is a thin layer of loose connective tissue which lies beneath the epithelium and together with the epithelium constitutes the mucosa
contains smooth muscle cells which increase in number as it descends down respiratory tract
The lamina propria is also rich in immune cells known as lymphocytes
Goblet Cells
glands that secreet mucus onto surface of epithelium of respiratory tract where cilia sweep away contaminants/pathogens towards the throat for elimination of pathogens from respiratory tract
External/Internal Nares
External Nare is what you see
Internal Nares are highly vascular to warmand humidify the air entering respiratory system; blood vessesls dialate when they need to warm the air and contrict when unnecessary
Epistaxis potential due to vasculature; HTN can cause nosebleeds
Nares are seperated by septum
Lateral surfaces of the nares contain turninates which cause turbulance in air flow aiding in warming and removal of debris
Hard and soft pallate
Separates oropharnyx from nasal cavity & nasopharynx
Gillotic opening and structures
The opening between the vocal cords at the upper part of the larynx
- glottis is the vocal apparatus of the larynx
- flase vocal cords (vestibular folds) sit on eiter side of the vocal cords and glottic opening
- Vocal cords (vocal folds) - ligaments covered by folds of epithelium
- responsible for cough reflex hypersensitive to foreign matter; causes increase in intercranial pressure
Lungs
enclosed in pleural cavity
right has three lobes, left has two
primary/secondary/tertiary bronchi followed by
Bronchioles and alveoli - are part of respiratory system but not respiratory tract
Alveoli
Alveoli - plural; Alveolis - singular
the sac where bronchioles terminate and gas exchange takes place
alveolar membrane is the gas-exchange surface
Surfactant
- develops in last four weeks of fetal development
- air/water boundary which creates surface tension in aveoli and prevents lung from collapsing at end of expiration
- an increase in interstitial fluid can cause alveoli to collapse and not reopen preventing gas exchange
- responsible for lung compliance
ARDS
Acute Respiratory Distress Syndrome
attacks and destroys avaliability/production of surfactant
creates poor lung compliance
Emphysema and relationship to Compliance
Pt’s with Emphysema have increased lung compliance because the elastic tissue has been damaged, usually due to their being overstretched by chronic overinflation
there is no problem inflating the lungs there is extreme difficulty exhaling air. In this condition extra work is required to get air out of the lungs
ACE
Angiotensin Converting Enzyme
- enzyme that participates in the conversion of Angiotensin I into Angiotensin I, which is responsible for maintaining bloodvolume and blood pressure
- produced in the lungs
What is the reason the body needs O2?
Without oxygen the is no ATP
needed for
- Ventilation - getting air IN/OUT of Lungs
- Difussion - getting O2 into the blood and CO2 out of the lungs
- Perfusion - avaliability for blood supply to all tissues
Respiration
- External - exchange of O2/CO2 between environment and body fluid
- Internal - exchange between fluids(blood) and peripheral tissues (individular cells)
- cells ie cellular respiration
- glycolysis
- krebs cycle
- oxidative phosphorylation (requires O2)
- cells ie cellular respiration
***bottom line need O2 for oxidative phosphorylation and production of ATP ⇒ energy ⇒ life
Ventilation
- Pulmonary Ventilation -Air In/Out of Lungs
- Alveolar Ventilation -Air In/Out of the Alveoli
Respiration physiology requires understanding of 3 gas laws
- Boyle’s Law
- Dalton’s Law
- Henry’s Law
Boyle’s Law
P = 1/V
Pressure and volume are inversely related
The greater the volume the smaller the pressure; The smaller the volume the greater the pressure
Respiratory Cycle and Pressure gradients
Respiratory cycle = 1 Inhalation + 1 Expiration
- Lungs @ rest ie. P in lungs = P in Environment
-
Inhalation:
- Diaphram contracts, ribcage expands increasing volume decreasing pressure in lungs
- Creation of pressure gradient causes air to flow into lungs until equalized
- Exhalation:
- Diaphram relaxes, Ribcage contracts increasing pressure in lungs
- Creation of pressure gradient causes air to flow out of lungs until equalized
Compliance
How easily lungs expand and contract
ie how easily someone is bag or ventilate
Poor Compliance = Difficult to move air, increase in amount of force
Decreased compliance = inability to move the thoracic cage
Resistance
Problem with equiptment
ie. pt clenching on tube, vomit in BVM
indicates a mechanical problem not a compliance problem
Heavy Breathing creates
increases the size of the pressure gradient
allows more air in and out of lungs to provide more O2 to the body tissues
ie exercising
Hyperventilation is breathing faster than normal for sake of increasing O2 and decreasing CO2
Preoxygenation - no increase in rate, used to properly saturate O2 levels before intubation
Components of Respiratory Cycle
- Rate (f)- frequency
- Tidal Volume (VT) - Average volume of Inspiration (5-7ml/kg of avg body weight)
- Minute Volume (VE) - Amount of air in/out of lungs per minute
f x VT = VE
Example:
f = 12 Breaths per minute; VT = 500mL
12 x 500 = 6000mL = 6L of air/minute
Alveolar Ventilation
- Anatomic Dead Space (VD) = amount of inhaled air that does not come into contact with alveolar surface ie unable to participate in gas exchange
- Average Adult 150mL
- Aveolar Ventilation (VA) - amount of air able to participate in gas exchange
(VT - VD) f = VA
Example:
(500mL - 150mL) 12 = 4200mL =
- 2L of Alveolar ventilation
ie. an increase in Shallow respirations = decreased tidal volume = less exchanged air
Asthma patients have trouble getting rid of air
Normally 1 sec In / 2 Sec out; asthma 1 sec in/ 4-5 out
Lung Capacities
Chart
- TV = Tidal Volume: Normal air movement in/out of lungs in one breath
- ERV = Expiratory reserve volume: the maximal volume of air that can be exhaled from the end-expiratory position
- IRV = Inspiratory reserve volume: the maximal volume that can be inhaled from the end-inspiratory level important allows for increased air intake during exercise
- IC = Inspiratory capacity: the sum of IRV and Tidal volume
- IRV + ERV + TV = Vital Capacity VC
- RV = Residual volume: the volume of air remaining in the lungs after a maximal exhalation
- TLC = Total lung capacity: the volume in the lungs at maximal inflation
- Functional Residual Capacity: Important flight/critical care = Expiratory Reserve Volume + Residual volume (remaining air left in lungs) after maximum exhalation
- Minimum Volume - still has 30-120mL when collapsed
Dalton’s Law
each gas contributes to the total pressure based on the relative abundance (partial pressure) contributed by single gas
Atmosphere:
78% Nitrogen, 21% Oxygen, 1% Trace Elements
PN2 + O2 + PCO2 = 760 Hgmm
Henry’s Law
- At given temperature, the amount of a particular gas that is disolved in solution is directly proportional to the partial pressure of theat gas
The way I understand it:
- More gas molecules are soluble at a higher pressure ie CO2 is disolved when a can of soda is closed; when opened pressure decreases and CO2 equalizes to that of the partial pressure in environment
Gas Exchange in Alveoli
Partial pressures of O2 and CO2 in Blood returning from Body are:
- PCO2 = 45mmHg
- PO2 = 40mmHg
In Alveolar Partial Pressures of Inhaled Air are:
- PCO2 = 40mmHg
- PO2 = 100mmHg
***The PO2 is higher in alveoli and wants to move across to the blood; like wise the PCO2 is higher in blood and wants to move into alveoli to be exhaled by the lungs.
Gas exchange at cellular level
Partial pressures of O2 and CO2 in Blood ariving from lungs
- PCO2 = 40mmHg
- PO2 =100mmHg
Partial pressures of O2 and CO2 of blood leaving tissues
- PCO2 = 45mmHg
- PO2 = 40mmHg
***Because the arriving blood has higer concentration of O2 in than cell, it moves down concentration gradient into tissues; like wise the higher levels of CO2 in cell moves into blood to be transported back to lungs for exhalation
Sickle Cell
- Genetic blood disorder in which globin protein does not fold up correctly and cannot carry the maximum number of O2
- Is a medica
Hemoglobin
- carries oxygen from the respiratory organs to the rest of the body\
- Optimally can carry 4 O2 molecules
- carbaminohemoglobin is when CO2 is bound to the globin protein
Hb + O2 <-> HbO2
Hb = efficency of O2 transport
reversible action of Oxygen binding and releasing to Hemoglobin
**Oxygen can only travel in bloodstream bound to Hemeglobin or disolved (ie Henry’s Law)
Oxygen Disassociation Curve
is a Relationship of Partial Pressure of O2 and SpO2
- PO2 > 60 = SpO2 > 90%
- if PO2 < 60 = SpO2 drops rapidly
SpO2 = % Oxygen saturation = % of Heme Units that have bound O2
*100% only means that all avaliable Hemeoglobin is saturated, there may be more free O2 circulating in blood stream.
Conditions change dissociation points: Increases in temperature/pH shifts to right ie disassociates earlier, Decreases in pH and Temperature disassociates later
**Trend to give less O2 if Pulse Ox
CO2 Transport
3 Modes
- Bound to Heme ie Carbaminohaemoglobin
- Disolved
- converted to carbonic acid
H+ + CO3- <> H2CO3 <> H2O + CO2
- When CO2 leaves tissues one of its options is to combine with water and make carbonic acid where it can be: transported that way and be converted back upon arrival at alveoli, or converted to H ions
