-
Internal make up of a cell
- Water
- Proteins
- Lipids
- Ions
- Carbohydrates
-
External matrix of cell
- Lipid layer
- Structural quality
- Primarily phospholipid, cholesterol, glycolipid
- Permeable to fat soluble substances (O2, CO2)
- Impermeable to water and water soluble substances
-
Cell Membrane Proteins
- Functional qualities of the cell membrane
- Change the structure, change the function
- Mainly glycoproteins
- Fuctions: recognition and binding units pores or transport units, cell surface markers, cell adhesion catalysts
-
Cell membrane carbohydrates
- usually attached to outer surface
- Functions: negative charge, attachment or adhesions, receptors, immune reactions
-
Cell communications:
Synaptic
Pancreatic
Endocrine
Autocrine
- Synaptic - a long arm to excrete the chemical signal, and the target cell accepts the chemical through a receptor
- Pancreatic - cell excretes signals into the extracellular space, and the receptor on the other cell accepts the signal
- Endocrine (hormonal) - chemical signal is excreted into the blood stream and then released and picked up by another cell's receptors.
- Autocrine - a cell makes its own signaling chemicals, excretes it, and then picks them up again via receptor
-
-
Hypertrophy
Increase in size
-
Hyperplasia
Increase in population
-
Metaplasia
transformation into another cell
-
Dysplasia
Abnormal size or organization
-
-
Cell Injury
Causes: Physical agents, Chemical agents, Biological agents, and nutritional imbalances.
MEchanisms of Injuries: free radical formation, hypoxia and ATP depletion, disruption of intracellular calcium
-
Apoptosis
- Programmed sequence of events leads to elimination of cells without releasing harmful substances to surrounding area. Cell suicide.
- Apoptosis gone wrong - Alzheimer, huntington, parkinson
-
Autocrine Cell Injury
- Hormone is released from and affects the same cell. Ie insulin like
- growth factors secreted in a muscle cell has growth - promoting actions
- on the cell
-
Ion
Acid
Base/Alkali
- Ion - negative
- Acid - liberates hydrogen ions in solution
- Base/Alkali - accepts hydrogen ions in solution
-
Normal body values for pH
- Arterial blood ~ 7.35-7.45
- Venous blood ~ 7.35
- Interstitial ~ 7.35
- ICF ~ 6.0-7.35
-
Buffer systems to fix pH changes
- 1. Protein buffer system
- instantaneously
- amino acids have at least one carboxyl (COOH) which releases an H+, and amino group (NH2) which accepts H+
- 2. Carbonic acid-bicarbonate buffer system
- Carbonic acid acts as a weak acid (releases H+)
- Bicarbonate acts as a weak base (holds the H+)
- CO2 + H20 <---> H2CO3 <---> H+ + HCO3-
- 3. Phosphate buffer system
- usually intracellular
- works to buffer acid in urine
- H2PO4- (dihydrogen phosphate) : weak acid that can buffer a strong base
- HPO42- : acts like a weak base by buffering the H+ released by a strong acid
-
Respiratory Regulation
- CO2 blown off directly
- compensates by rate and volume
- 1-2 times more potent
- happens within minutes
- Increase in H+ in the blood stimulates peripheral chemoreceptors
- stimulates the respiratory center
- increases alveolar ventilation
- causes an increase in CO2 elimination
- decrease in PcCO2
- maintaining pH
-
Decreased pH =
- decreased ventilation
- increase PaCO2
- Increase H2CO3
-
Increased pH =
- Increased Ventilation
- Decrease PaCO2
- Decrease H2CO3
-
Renal Conotrol
- Excretion of H+ in urine is the only way to eliminate hyge excess
- Metabolic reactions produce 1 mEq/L of nonvolatile acid for every kg of weight
- Kidneys synthesize new bicarbonate and save filtered bicarbonate
- RF can cause death rapidly due to its role in pH balance
-
Normal pH, PCO2, PO2, HCO3 values
- pH 7.35-7.45
- PCO2 35-45 mmHg
- PO2 80-100 mmHg
- HCO3 22-28 mEq/L
-
Metabolic/Respiratory Acidosis
- Acidosis : pH <7.35
- Metabolic: HC03- <28 mEq/L
- Respiratory: PCO2 > 45 mmHg
-
Metabolic/Respiratory Alkalosis
- Alkalosis : pH >7.45
- Metabolic: >28 mEq/L
- Respiratory: PCO2 <35 mmHg
-
Respiratory Acidosis
- elevation of PCO2 of blood
- from lack of CO2 removal, ie. emphysema, pulmonary edema, brainstem injury
- Tx: ventilation therapy to increase CO2 exhalation
-
Respiratory Alkalosis
- Arterial blood PCO2 is too low, ie Hyperventilation from HAPE, disease, stroke, anxiety, aspirin overdose
- Renal comensation involves a decrease in H+ excretion, and an increased reabsorption of bicarbonate
-
Metabolic Acidosis
- Blood bicarbonate ion concentration too low, ie. ion loss via diarrhea or RF, acid accumulates
- Respiratory compensation by hyperventilation
- Tx : ventilation, correct the cause
-
Metabolic Alkalosis
- Blood bicarbonate levels are too high
- Non-respiratory loss of acid; ie vomiting, gastric suctioning, diuretics, dehydration, ++ alkaline drugs
- Respiratory compensation is hypoventilation
- Tx: fluid and electrolyte therapy
-
Gas Exchange
- Capillary beds are wrapped around the alveoli for O2 / CO2 exchange.
- 2 types of cells on the alveolar:
- Type 1 cells -gas exchange
- Type 2 cells - synthesizes surfactant
-
Oxyhemoglobin
- Oxyhemoglobin contains 98.5% chermically combined oxygen and hemoglobin
- Only 1.5% transported dissoved in blood
- Only dissolved O2 can diffuse into tissues
-
Hemoglobin
Hb affinity for 02
- Four polyphyrin rings, each with an oxygen binding site
- Major determinant of hemoglobin saturation in the partial pressure of oxygen in the blood
- Blood is almost fully saturated at p02 of 60 mm
- Hb affinity for 02
- oixygen concentration
- acidity
- carbon dioxide
- temperature
- cellular metabolism (2,3 DPB or 2,3 BPG)
- As acidity increases, O2 affinity for Hb decreases. H+ binds to Hb and alters the structure, leaving O2 behind for tissues
-
Left Shift long list
- decrease in temperature
- decrease in 2.3 DPG
- decrease in pCO2
- increase in pCO
- increase in pH (alkalosis)
- high 02 affinity
- haemoglobin - fetal
-
Right Shift long last
- increase temperature
- increase in 2,3 DPG
- increase pCO2
- decrease PCO
- decrease pH (acidosis)
- low 02 affinity
- adult haemoglobin
-
Left/Right shift, short list
-
CO2 transport
- 8% dissolved
- 80% bicarbonate ions
- 10-12 % carbamino compounds
-
Hypoxia
- inadequate oxygen
- Hypoxic hypoxia - decrease oxygen in the environment
- Anemic hypoxia - impaired oxygen transport
- Histotoxic Hypoxia - cell use of oxygen impaired
- Hypoxemia - decreased oxygen in the blood
-
Ventilation/Perfusion
For gas exchange to occur, ventilation must be matched closely to perfusion
- V=Q : normal
- V>Q : dead space; normal ventilation with no perfusion
- V<Q : shunt; normal perfusion with no ventilation. usually pathologic
V=Q=0 : silent unit, no ventilation no perfusion
- PCO2 increases and PO2 decreases with no ventilation
- Decreased tissue PO2 around under-ventilated alveol constricts their arteries and diverts blood to better ventilated alveoli
- The unoxygenated blood mixes with the oxygenated blood, thus lowering the average oxygen saturation post capillaries
-
-
Osmole
One mole of solute particles
-
Osmolality
Concentration of solute in osmoles/kg (solvent - mass)
-
Osmolarity
Concentration of solute in osmole/litre (solution - volume)
-
Milliequivalent
Grams of solute in one ml of solution
-
Fluid Compartments
- ICF : intracellular
- 40% TBW
- ECF : Extracellular
- 1/3 intravascular
- 2/3 interstitial
- 20% TBW
-
Intracellular (ICF) <---> Interstitial
Diffusion
-
Intravascular <---> Interstitial
- Primarily by hydrostatic pressure
- lesser extent by diffusion
-
Osmosis
Movement of water from an area of high water concentration to low water concentration (down its concentration).
-
Hydrostatic Pressure
Pressure exerted by the movement or mass of water.
-
Isotonic
Solution on opposite sides of a membrane are equal in concentration.
Inside and outside of the cell are equal pressure.
-
Hypertonic
Concentration of a given solute is greater on one side of a membrane than the other.
-
Hypotonic
Concentration of a given solute is less on one side of a membrane than the other.
-
Functions of Blood
Transport: respiratory gases, nutrients, resgulatory substances, waste products
Thermoregulation: temperature
-
Components of Blood
- RBC 45%
- Electrolytes, enzymes, fats, proteins, carbohydrates
- WBC and Platelets 1%
- Monocyte, neutrophyil, basophil, eosinophil, lymphocyte, platelets
Plasma 54%
RBC = Hematocrit = percentage of blood occupied by red blood cells
-
Lymphatic System
- responsible for removal of interstitial fluid from tissues
- absorbs and transports fatty acids from circulation
- transports WBC to and from lymph to bones
- Areas drained by:
- right lymphatic - head and right chest/arm
- thoracic ducts - left chest/arm and lower body
-
Dehydration Causes and Thirst Stimulation
Loss of total body water
Isotonic - H20, Na+ lost in equal proportions; bleeding, diarrhea
Hyponatremic - increased loss of sodium; sweating, diuretics
Hypernatremic - decreased loss of sodium; increased salt intake
Thirst is stimulated by dry mucous membranes, dehydration of osmoreceptors, angiotensin II, and sympathetic nervous system (baroreceptor stimulation).
-
ADH
Stimulated by high osmotic pressure in the blood (high concentration of solutes, but low water).
- Osmoreceptors ->
- Synthesizesd + ADH ->
- Into bloodstream ->
- Kidneys retain H20 ->
- decrease urine; arterioles constrict ->
- increase in BP ->
- Decreased blood osmotic inhibits hypothalamic osmoreceptors ->
- inhibition of osmoreceptors reduce or stops ADH secretions
-
Renin-Angiotensin-Aldosterone
R-A : Stimulated by a decrease in glomerular filtration rate (GFR)
- A : stimulated by angiotensin II or increase in serum K+
- :Stimulates increase in Na+ reabsorption and water reabsorption in the distal convoluted tubule
-
Renin-Angiotensin Aldosterone Steps
- -Dehydration, Na+ deficiency
- -Decrease in blood volume
- -Decrease in blood pressure
- -Increased renin (from juxtaglomerular cells of the kidneys)
- -Angiotensin is released from the liver
- -Increased Angiotensin I goes to the lungs
- -Angiotensin Converting Enzyme (ACE) from the lungs converts Angiotensin I to Angiotensin II
- -Vasoconstriction of arterioles
- -Increased Aldosterone (via adrenal cortex)
- -Kidneys increase Na+ and H2O reabsorption
- increased blood volume
- -blood pressure increases until it returns to normal
-
Nervous System Function
- 1- Higher (cortical) brain: information, conscious control
- 2- Lower brain: vegetative body process
- 3- Spinal cord: reflexes
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Major divisions of the brain
- Brainstem: midbrain, pons, medulla oblongata
- Cerebellum:
- Diencephalon: thalamus, hypothalamus
- Cerebrum: sensory, motor, associative areas; basal ganglia, limbic system
-
Meninges
- Dura Mater
- Arachnoid Mater
- Pia Mater
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Brain Stem
- transitions between spinal cord and brain
- vegetative functions
-
Brain Stem: Midbrain
- involuntary motor reflexes to sudden auditory and visual stimulus
- motor nuclei for cranial nerves II, IV
- reticular activating system (RAS): consciousness
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Brain Stem: Pons
- involuntary control of pace and depth of respiration
- sensory and motor nuclei of cranial nerves (V-VIII)
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Brain Stem: Medulla Oblongata
- physically connects brain and spinal cord
- relay station for ascending and descending tracts
- cardiovascular centre (heart rate, vasomotor centre)
- respiratory rhythmicity
-
Diencephalon: Thalamus
- Relay point for ascending sensory information that will reach conscious awareness
- Filters sensory information
- Relay information from cerebellum and basal ganglia to primary motor area of cortex
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Diencephalon: Hypothalamus
- ANS Control
- produces hormones (ADH, oxytocin)
- Emotional and behavioural patterns
- Eating and drinking regulation
- Maintains body temperature
- Circadian rhythms
-
Cerebellum
- Inferior and posterior aspects of cranial cavity
- 1/10 brain mass, half the neurons
- rapid adjustments in muscle tone and position to maintain balance and equilibrium
- fine tunes voluntary and involuntary movements
-
Cerebrum: Cerebral cortex
- gray matter layer on cerebral surface
- outer layer of the brain
- responsible for consciousness
- impulse distribution to cerebrum
- cerebrum contours
- 1. Sensory: primary - auditory, visual, etc. secondary - adjacent
- 2. Motor: mostly anterior, Broca's speech, motor, etc
- 3. Associative: motor and sensory areas connected by tracts
-
Basal Ganglia
- Nuclei deep in hemispheres
- Receive input from cortex and output back to motor parts of cortex
- Regulates initiation and termination of movement, some cognitive functions
- Associated with several psychiatric disorders
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Limbic System
- Ring of structures on inner border of cerebrum
- Emotional part of the brain
- Hippocamups has a role in memory
-
Cranial Nerves
- Olfactory - smell
- Optic - vision
- Occumomotor - eye movement, pupils
- Trochlear - eye movement
- Trigeminal - chewing
- Abducens - lateral eye movement
- Facial - facial expressions
- Vestibulocechlear - hearing, equilibrium
- Glossopharyngeal - swallowing, throat
- Vagus - autonomic function, heart
- Spinal Accessory - shoulder movement, head rotation
- Hypoglossal - tongue movement
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Neuron Structure
- Dendrites - extensions to receive incoming impulses
- Cell body - controls metabolism of cell
- Axon - contains fibre that carries outgoing impulses to end organ fibres (skeletal and smooth muscle; central nervous system)
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Electrical Nerve Transmission
Activation of sodium channel to open by means of a voltage stimulus across the membrane. The activation is transferred between nerve cells
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Chemical Nerve Transmission
activation of cell membrane by chemical irritant/mediator (neurotransmitter)
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Neurotransmitters: Acetyl Choline
ACh released into synapse, timed by acetylcholinesterase. Choline is taken back via presynaptic membrane for resynthesis.
Presynaptic receptors provide a negative feedback loop, monitoring the total amount of ACh.
- PNS: activates muscles, ANS major transmitter
- ACh binds to ACh receptors, which opens the Na+ channels in the cell membrane.
CNS: ACh with associated neurons forms a system, called the cholinergic system; anti-excitatory actions.
- 2 major types or ACh receptors:
- Nicotinic receptors, Muscarinic receptors.
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Neurotransmitters: Amines
Dopamine, norepinephrine, epinephrine, serotonin, histamine.
Involved in limbic system, hypothalamus, basal ganglia.
- NE is released at SNS post ganglionic nerve endings.
- DA, NE, and seotonin regulating thought processes and moods. Antipsychotic and mood-altering drugs change their activities.
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Neurotransmitters: Amino Acids
- Excitatory: Glutamate, Asparate (NMDA)
- Glutamate - widely spread through the brain, considered the primary excitatory neurotransmitter. Involved in memory, and considered neurotoxin when found in excess amounts within the synapse.
- NMDA - will not open unless the binding is paired with a cotransmitter and concurrent depolarization of the membrane. Ligand-gated calcium ion channel, blocked by Mg ion when postsynaptic membrane is polarizerd. Responsible for long-term changes in the synapse, and may be related to long term memroy.
- Drugs that interfere with NMDA receptors block memory; activating drugs produce hallucination and nightmares.
- Inhibitory: Glycine, y-Aminobutyric acid (GABA)
- GABA - formed by decarboxylation (CO2 removal) of glutamate, changing it from an excitatory to an inhibitory substance. GABAA is a classic ligand-gated CL- channel that produces an IPSP (inhibitory postsynaptic potential) when activated and GABAB is a metabotropic receptor that also produces IPSP and is linked to cytoplasmic signaling cascades within the cell.
Barbituates and benzodiazepines exert their depressive effects by increasing GABA activity.
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Neurotransmitter: Polypeptides
Vasopressin, oxytocin, growth hormone; corticotropin, and thyrotropin releasing hormones; glucagon, angiotensin II, endorphins.
Functions as primary neurotransmitter in the synapse, more often released with other polypeptides. Released in very small quantities.
Neuropeptides have long-lasting effects on post synaptic cell, mediating changes in receptor number orr structure and altering the response of intracellular signalling pathways.
Ex - transmission and perception of pain: substance P, endorphins, and enkphalins
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Neurotransmitter: Purines
- Adenosine triphosphate (ATP), adenosine.
- Neurotransmitters in various brain regions.
- Adenosine:
- -Continuously released by most neurons and modulates neurotransmission by blocking neurotransmitter release.
- -May prevent seizure activity, but the main ATP role is elucidated.
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Neurotransmitters: Gases
Nitric oxide, Carbon monoxide
- -Diffuse through cell membrane, doesn't need synaptic receptors
- -Binds and stimulate guanylyl cyclase, an enzyme that produces cGMP (cyclic guanosine monophosphate) a second messenger in the cell. Or alter the activity or ion pumps, metabolic enzymes and DNA transcription factors.
- -NO can be synthesized in postsynaptic neuron and diffuse locally to affect presynaptic neurons
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Agonist
Anything that enhances a transmitters effects
-
Antagonist
Anything that reduces the action of a transmitter
-
Autonomic Nervous System
- Components in both CNS and PNS
- 2 neuron system: preganglionic neurons (myelinated); postganglionic (unmyelinated). No two sympathetic responses are ever the same.
Sympathetic: arise out of the spinal cord, T1 - L2. Thoracolumbar division, some preganglionic fibres go straight to adrenal medulla.
Parasympathetic: arise from cranial nerves III, VII, IX, X and sacrum.
Spinal Cord - Preganglionic Neuron (myelinated) ACh - Postganglionic Neuron (unmyelinated) - effectors.
Spinal - Somatic Motor Neuron (myelinated) - ACh - effectors
-
Adrenergic Receptors:
- Alpha 1 - primarily vasoconstriction in a larger blood vessel
- Alpha 2 - vasodilation in some smalle (skeletal) blood
- vessels
- Beta 1 - vascular smooth muscle
- Beta 2 - extravascular smooth muscle
- Beta 3 - appear to play a role in lipolysis
-
Cholinergic Receptors
Muscarinic and Nicotinic
-
Autonomic Nervous System:
Sympathetic Nervous System
- ACh to Adrenal medulla - Epi - Various Organs
- ACh to Ganglion - NE - Various Organs
- ACh to Ganglion - ACh - Sweat Glands
-
Autonomic Nervous System:
Parasympathetic Nervous System
ACh to Ganglion - ACh - Various Organs
-
Adrenergic Proteins in Postsynaptic plasma membranes activated by neurotransmitter norepinephrine and hormone (nor/epi)
- Alpha 1 - Smooth muscle fibers (excitation -> contraction = constriction and pupil dilation)
- Alpha 2 - Pancreatic Islets secrete insulin (B cells) (decrease insulin secretion)
- Beta 1 - Cardiac muscle cells (excitation = increase rate/force)
- Beta 2 - Smooth muscles in A/W walls (inhibition -> relaxation, dilates A/W, vasodilation, etc.)
-
Physical Barriers (skin and mucous membranes)
- closely packed iceratinized epithelial cells
- mucous membranes
- gastric juices
- perspiration and lysozymes
- hair
- tears and salvia
- urine, defecation, vomiting, vaginal secretions
-
Internal Defences
- Antimicrobial proteins
- Phagocytes and natural killers
- Inflammation
- Fever
-
Signs of Inflammation
- Rubor (redness)
- Tumor (swelling) colour (heat)
- Dolor (pain)
- Functio laesa (decrease function)
-
Immediate local response
- local damage to tissues cause local response
- release of chemical mediators
- vasodilation and increased vessel permeability
- clotting factors leak into area, also to trap microbes
-
Inflammatory Chemical Mediators
- Histamine:
- -Performed in mast cell, released with antigen exposure
- -Important to asthma; smooth muscle contraction, vascular permeability, edema, irritant receptors
- -Antihistamines not effective in asthma
- Leukotrienes:
- -Synthesized in and released from mast cells and basophils
- -Direct bronchoconstrictor effector on smooth muscle
- -Increased vascular permeability
- Prostaglandins:
- -Released from damaged cells and mast cells
- -Direct bronchoconstrictor effect on smoth muscle
- -Increased vascular permeability
- -Both leukotrienes and prostaglandins come from same chemical precursor
-
Hemodynamic Response (stages) to inflammation
- 1 to 24 hours, sustained increased vessel permeability
- Monocytes infiltrate area within an hour via emigration
- Granulocytes take longer (basophils, neutrophils, and eosinophils)
-
Phagocytes
- Types of white blood cells
- Neutrophils and macrophages
- Neutrophils and monocytes migrate to the injury site
- Monocytes become wandering or fixed macrophages
-
Phagocytosis:
- Chemotaxis
- Adherance
- Injection
- Digestion
- Killing
- Emigration - cell leaves the blood stream
- Chemotaxis - cell starts to wrap around the injury
- Phagocytosis - cell completely wraps around injury
-
COPD
- group of diseases with all the same characgtristics
- leading cause of M+M
- chronic bronchitis, emphysema, asthma, cystic fibrosis
-
Cystic Fibrosis
- hereditary disorder of the exocrine glands and the epithelial lining of the respiratory, GI and reproduction tracts
- results in abnormal and viscous secretions by exocrine glands
- high electrolyte concentration in sweat
- Patho: abnormal, viscous secretions; GI tract: malabsorption, malnutrition; Respiratory: mucous secreted from bronchial glands, obstructs small A/W (bronchi, bronchioles) physical damage to epithelial surfaces
- Clinical: failure to thrive, chronic infection, alveolar damage, chronic A/Q obstruction (V/Q mismatch) pulmonary hypertension (cor pulmonale)
-
Restrictive Diseases
- chronic diffuse infiltrative diseases of the lungs
- 150 diseases sharing clinical features
- decreased lung volumes with normal expiratory flows
- usually a reduction in fuddusing capacity
- usually chronic
- Ie. Pulmonary fibrosis
-
Pulmonary Fibrosis
- inflammation and scarring of alveolar tissue
- idiopathic or secondary
- Interstitial diseases (known etiology - silicosis, asbestosis, coal miners pneumoconiosis, farmers lungs, drug or radiation induced)
- Patho: functionally smaller lungs, decreased lung complication/lung volume, V/Q mismatch, pulmonary hypertension, impaired diffusion
-
Pulmonary Embolus
- occlusion of pulmonary arter or one of its branches by matter carried in blood (fat, air, embolus, amniotic fluid)
- often misdiagnosed
- contributing factors: abnormal vessel walls, stagnation, increased coagulability
- Patho: most ventilation locations, hemorrhage with congestive atelectasis +/- pleural effusion. pathologic increas in dead space ventilation
- Clinical: dyspnea, pleuritic chest pain, hemoptsis, pleural effusion, pleural friction rub
-
ARDS
- acute respiratory failure
- shock lung or non-cardiogenic pulmonary edema
- lung injury characterized by breakdown of normal barrier between pulmonary capillaries and interstitial space/alveoli
- Etiology includes aspiration, gas inhalation, pneumo sepsis, shock, trauma, drugs, neurogenic
- Pathogenesis: underlying causes result in a variety of cells and mediator involvement: pulmonary capillary endothelial cells (interstitial edema); alveolar epithelial cells (alveolar edema/collapse), shunting, V/Q mismatch, decreased pulmonary compliance
- Clinical: dyspnea, wet crackles, >50% mortality, pulmonary edema, no response to normal therapy.
-
Pneumoniua
- acute inflammation of gas exchange units of lungs
- variety of microorganisms (viral, bacteria, aspiration)
- hospital or community acquired
- immune status of the host
- Patho: reaches distal area, intense inflammatory reaction occurs, worse case (consolidation, necrotizing pneumonia, destroys lung tissue, scar formation, decreased lung function)
- Clinical: generalized malaise, fever, cough, dyspnea, areas of consolidation, crackles
-
Pleura Disorders
Pleurisy (pleuritis) - inflammation of the pleura, characteristic pain pattern
Pleural Effusion - fluid build up in the pleural space
Pleural Pain - abrupt onset, usually unilateral and localized, made worse by inspiration and movement, tidal volume reduced
Atelectasis - alveolar collapse, resulting in incomplete lung expansion. Caused by increased alveolar recoil due to surfactant loss, lung compression, airway obstruction
-
Myasthenia Gravis
- -Disease of the neuromuscular end plate
- autoimmune disorder where antibodies to cholinergic receptors are produced
- -Slow onset, muscle weakness and fatigue, from ocular to facial to throat
- Dx: usually by history, cholinesterase inhibitor to confirm diagnosis
- Tx: maintained with cholinesterase inhibitors therapy neostigmine, pyridostigmine, ambenonium. Immunosupressives, intubation, ventilation
- Myasthenia crisis: stressor origin, exacerbates disease process, respiratory involvement
-
Guillaine Barre Syndrome
- Acute inflammatory polyneuritis of unknown cause affecting primarily peripheral motor and sensory neurons
- viral or traumatic
- involves segmental loss of myelin sheath (delayed hypersensitivity reaction again myelin sheath)
- Sensory abnormalities progressing to paralysis
- Usually self limiting and effects reverse with time
- Tx: symptomatic, usually needs ventilatory support, monitoring respiratory reserve volumes
-
Tuberculosis
- Bacterial infection transmitted by airborn dust (myobacterium tb)
- Stage 1 - bacterium inhaled into lungs, inflammatory response, may be contained at this point
- Stage 2 - bacteria multiply rapidly, from tubercles, may spread to other organs
- Stage 3 - two to three weeks, infection contained but granulomas form, tissue destruction, can lay dormant for years
- Stage 4 - tubercle erodes, releases bacteria to reinfect
- Clinical: productive cough, fever, weight loss, hemoptysis, chest pain, fatigue, night sweats
-
Obstructive Diseases
- Disease process resulting in reduced air flow and ventilation
- V/Q mismatch and pathologic shunt (oxygenated and deoxygenated blood mixed)
-
Asthma
Characterized by hyper-responsiveness of the airways - bronchospasm/constriction, increased mucous secretion, injury to mucosal lining, inflammation of the airway.
- Catagories: Catagories are often misleading and inaccurate.
- Allergic/Extrinsic (result of antigen-antibody reaction on mast cells of the respiratory tract. Childhood).
- Idiopathic/Intrinsic (implies its a result of imbalance of autonomic nervous system, generally no antibodies formed).
Early phase: occurs within minutes, bronchospasm, mucosal edema, generally inhibited or reversed by bronchodilators (B2 agonists)
Late phase: 4-8 hours later, can last longer, might be associated with an early phase, invasion of inflammatory cells into damaged tissue (basophils, eosinophils, neutrophils), produced epithelial injury and edema.
Common provocative stimuli: exposure to allergen, inhaled irritants, respiratory tract infection, exercise, cold air, humid air.
- Patho:
- -epithelial damage,
- -hypertrophy and hyperplasia of smooth muscle layer
- -thickening of epithelial basement membrane
- -enlargement of mucous secreting apparatus -edema/infiltrates or eosinophils in bronchial wall
- inflammation
- -narrowing of the airways (smooth muscle contractions, mucosal/submucosal edema)
- -increased airway resistance (espec. expiration)
- -non-uniform distribution of disease process (A/W resistance variable, ventilation variable, V/Q mismatch)
Clinical: usually childhood asthma, wheezing/dyspnea with symptom free intervals, cough, dyspnea, wheezing chest tightness.
-
Allergic Response
- Allergen
- Mast cells (release histamine, leukotrienes, prostaglandins)
- Infiltration of Inflammatory cells (cytokines, interleukins, other inflammatory mediators)
- Airway Inflammation including
- -edema
- -impaired mucociliary function
- -epithelial injury
- -airflow limitation
- -bronchospasm
- -increased A/W responsiveness
-
Status asthmaticus
Doesn't respond to conventional therapy. Severe hypoxemia, lacticacidosis, respiratory failure
-
Chronic Bronchitis
- -Hypersecretions of mucous and a chronic productive cough for at least 3 months of the year for at least two years
- -Increased incidence in smoking and air pollution exposure
- Patho:
- -Influx of inflammatory cells into airway wall
- -Increased size and number of mucous secreting cells
- -Decreased ciliary function
- -Altered mucous composition (tick and tenacious)
- Consequences
- -A/W inflammation leads to a thickened wall (decreased lumen size, increased A/W resistance), mucous alterations, chronic productive cause, bronchospasm, progression (affects large bronchi till all a/w are involved. narrows and closes, V/Q mismatch)
- -Blue bloater: extreme presentation of disease.
- -Fat, obese, build up of fluids due to heart disease
- -Blue - chronic hypoxemia, polycythemia
- -Elderly blue bloater are rare due to presence of cor pulmonale
-
Emphysema
- -Disease resulting in the destruction of alveolar walls distal to the terminal bronchioles
- -Obstruction from changes in lung tissue and not inflammation
- -Major mechanism of impaired airflow in the loss of elastic recoil.
- Patho:
- -breakdown of elastin in alveolar walls
- -leads to destruction of alveolar walls
- -decrease elastic recoil (hyperinflation, decreased diffusion)
- -Enlargement of air spaces (bullae) and air spaces adjacent to pleura (blebs - incrased air trapping)
- -V/Q mismatch
- Clinicals:
- -Dyspnea and SOB OE (chronic hypoxia with minimal reserve)
- -Barrel chested (air trapping, flat costal angle)
- -Chronical accessory muscle use leads to hypertrophy
- -Muscle wasting and weight loss
- -Clubbing
- -Pursed lipped breathing
- Pink Puffer
- -extreme presentation
- -pink - not initially hypoxic (oxygen levels maintained by increased respiratory rate)
- -puffing - pursed lipped breathing (attempt to build and maintain reserve volume)
-
CO2 Retention
- small number of patients
- chronic increased levels of CO2 alters the stimulation of chemoreceptors
- switch from an increase of CO2 to decrease of O2 levels as prime stimulus
- potential that oxygen therapy could reduce ventilatory drive
- no hypoxic patient should have oxygen withheld
-
Pulmonary Hypertension
- decrease PO2
- increase pulmonary vasoconstriction
- increase right ventricular workload
- right ventricular failure
-
Blood flow through the hearts
- inferior/suprerior vena cava
- right atrium
- tricuspid valve
- right ventricle
- pulmonary valve
- pulmonary trunk
- left pulmonary arteries
- lungs
- left pulmonary veins
- left atrium
- mitral valve
- left ventricle
- aorta
- body
-
Left Coronary Artery
- Left Anterior Descending (lt ventricle and septum)
- Circumflex (lt atrium, posterior and lateral left ventricle)
- Mainly anterior and left ventricle
-
Right Coronary Artery
- Supplies right and posterior and inferior left ventricle
- SA, AV node
-
Pacemaker Cells
- Specialized excitatory and conductive muscle
- Same general structure as musclecells but with fever contractile fibres
-
Automaticity
Ability of cells or groups of cells to generate their own impulses
-
Rhythmicity
Impulses tend to fire rhythmically from focus'
-
Conductivity
Cells ability to transmit impulses to adjacent
-
Electrical Isolation
Fibrous connective tissue rings support the AV valves
-
Resting Cell Membrane Potential
- Electrical potential difference accross the membrane at rest
- Dependant upon sodium/potassium pump, voltage dependant channels, protein molecules
- Cardiac cells ~-85mV
-
Threshold Potential
Change in cell membrane electrical potential difference that will result in a dramatic change in cell membrane permeability
-
Action Potential
Change in cell membrane electrical potential difference that will stimulate a response
-
Cardiac Action Potential Phases
- Phase 0 - rapid depolarization (Na+ in via fast channels)
- Phase 1 - early rapid repolarization (Na+ close, K+ out)
- Phase 2 - plateau phase ( Ca+ moves into cell, K+ out)
- Phase 3 - Terminal rapid repolarization (Ca+ stops, K+ out)
- Phase 4 - resting membrane potential difference (Na+/K+ returns to original levels)
-
Absolute Refractory Period
- Time when cells cannot respond to another impulse
- Onset of QRS to peak of T wave
- Phase 0 to halfway through phase 3
-
Relative Refractory Period
- Time during which cells could be depolarized if the impulse were strong enough
- Peak of T wave to end of T wave
- Halfway through phase 3 to early phase 4
-
Causes of Dysrhythmias
- Enhanced Automaticity
- Re-entry
- Escape Beats
- Conduction Disturbances
-
Tachydysrhythmias
- generally re-entry phenomenon
- rate problem
- -inadequate time for ventricles to fill
- -inadequate time for the coronary perfusion
- -increased myocardial workload
- Includes: SVT/PSVT, A-Fib, A-Flutter, V-Tach,
-
SVT/PSVT
- Generally caused by re-entry phenomenon close to the normal conduction pathways in the atria
- pre-excitation syndrome
-
Atrial Fibrillation
- Multiple re-entry phenomenon through out the atria
- lots of cuases
- rate problem for the first 24 hours, then evolves into embolus formation, and an embolic stroke
-
Atrial Flutter
- Re-entry outside the normal conduction pathways in the atria (strong enough to take over)
- Variety of causes, usually paroxysmal onset
-
Ventricular Tachycardia
- Re-entry outside the normal conduction pathways in the ventricles
- Rarely occurs in patients that do not have some level of heart disease
- May actually result in AV dissociation
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