Week 1 - CO Poisoning, O2 transport Flashcards
Oxygen Transport
Narcolepsy
Rare, long-term brain condition that results in sleep at inappropriate times (suddenly, all day drowsiness, cataplexy, sleep paralysis are all manifestations)
May be caused by a lack of the brain chemical hypocretin (orexin)
Sleep apnoea - what are the two types?
pauses in breathing / periods of shallow breathing during sleep, which can be caused by a blockage (OSA) or lack of effort to breath (CSA). Being overweight is a risk factor.
Insomnia
A broad term for many types of trouble sleeping including inability to fall asleep or stay asleep during the night. It is often caused by psychological/mental health issues such as anxiety and depression or environmental factors
Glasgow Coma Scale - definition
test to determine the level on consciousness following a traumatic brain injury
E - Eye response
V - Verbal response
M - Motor response
Glasgow Come Scale - ratings
E - Eye response (4-NT)
Spontaneous, sound, pressure, none, NT
V - Verbal response (5-NT)
Orientated, confused, non-coherent words, sounds, none, NT
M - Motor response (6-NT)
obeys command, localising to pressure, normal flexion, abnormal flexion, extension, none, NT
Severe: GCS 8 or less
Moderate: GCS 9-12
Mild: GCS 13-15
AVPU scale - definition and ratings
AVPU scale - test to determine level of consciousness (simplified version of the GCS)
Alert - awake, open eyes, respond to voice, bodily control
Verbal - Some sort of response when you speak to them (whether eyes, sounds, motor response)
Pain response - Response upon mild pain stimulus (trapezoid pinch, finger pinch, above eye pinch)
Unresponsive - No eye, voice or motor response to either verbal or pain queues
Normal temperature range
Approx 36-38 C
Normal pulse range
Approx 60-100
Normal respiration rate
Approx 12-20
Normal blood pressure
120/80
Normal O2 saturation
between 80-100 mmHg or 95-100% pulse ox
How to assess circulation in a patient - 4 ways
Bumucosa cyanosis - blue skin on lips, tongue, mucous membranes implying lack of oxygen in blood
Peripheral cyanosis - Blue skin in hand, feet, limbs
Capillary refill - End of finger should refill in 3 seconds after being squeezed
Distal pulse - pulse at wrists and ankles
How is oxygen transported?
Two methods
Mostly (97%) in haemoglobin and the remainder in plasma
How is CO2 transported?
Four different ways
- In plasma as a gas (a few %)
- Mix with water in blood plasma to form H+ ions and bicarbonate (a few more %)
- Mix with water in red blood cells to form H+ ions and bicarbonate (carbonic anhydrase on RBC membrane makes the reaction more rapid) (approx 70%)
- Transporter protein trades the bicarbonate with chloride and H+ is picked up by haemoglobin - CO2 binds with haemoglobin - carbaminohaemoglobin (HbCO2)
Bicarbonate in blood
Bicarbonate is important buffer within plasma - an important ‘blood gas’, low bicarbonate would indicate another issue
How does carbon monoxide poisoning work?
After carbon monoxide is breathed in, it enters your bloodstream and mixes with haemoglobin (the part of red blood cells that carry oxygen around your body) to form carboxyhaemoglobin.
Shifts curve so far left that it can’t release oxygen
Affects bodies ability to make ATP
Describe oxygen dissociation curve
The shape of the curve is SIGMOID, determined by the nature of positive cooperativity (i.e. When one oxygen attaches to haemoglobin, the affinity for oxygen increases until the haemoglobin reaches 100% saturation - 4 oxygen molecules)
Partial pressure
In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas if it alone occupied the entire volume of the original mixture at the same temperature
Dalton’s Law
Total Pressure = Sum of all partial pressures
Henry’s Law
Mass of dissolved gas (at given volume, equilibrium) is proportional to the partial pressure of the gas
“…when a gaseous mixture (e.g., the atmosphere) is in contact with a solution, the amount of any gas in that mixture that dissolves in the solution is in direct proportion to the partial pressure of that gas”
I.e. When there is more oxygen present, more oxygen moves into the bloodstream
Carboxyhaemoglobin
haemoglobin and carbon monoxide
Oxyhaemoglobin
oxygenated haemoglobin (deoxy is de-oxygenated haemoglobin)
Methaemoglobin
iron molecules in the ferric state (Fe3+) rather than the ferrous state (Fe2+) which means it cannot bind to oxygen.
When the oxygen dissociation curve moves to the left or the right, what does this mean?
Left for lungs - Left shift indicates higher affinity for oxygen to encourage binding to haemoglobin in the lungs
Right for muscles - Indicates lower affinity of haemoglobin for oxygen, due to bodies need for more oxygen (such as in working muscles)
Factors that determine shift include:
- TEMP - when temperature INCREASES, shifts right to encourage further oxygen in tissues
- 2-3 DPG
- H+ IONS
- CO2 - increased presence of CO2 shifts right, as it means muscles are creating energy which requires oxygen (and CO2 is a bioproduct that needs to be carried away)
Give an overview of glycolysis: input, products, where it takes place
Glucose (6C) from food is broken down into two pyruvate (3C), as it is a simpler format to extract energy
Input: Glucose (6c)
Output: 2 pyruvate (3c) + 2ATP (net) + 2NADH
Where: cytoplasm / cytosol
Give an overview of the Krebs Cycle, describing input/s, key intermediate stages and products and where it takes place
Input: Acetyl CoA
Citrate (6c), oxaloacetate (4c)
Output: Per cycle - 3x NADH, 1x FADH, 1x ATP, 2 CO2 as waste
Where: mitochondria - outer membrane
Intermediate step between glycolysis and Krebs cycle
Pyruvate is transformed into Acetyl CoA, which then begins the citric acid cycle.
Give an overview of the electron transport chain/ oxidative phosphorylation, describing input/s, key intermediate stages, products and where it takes place
All of the electrons removed from the processes so far are carried by NADH and FADH to start the electron transport chain. Simply, redox reactions occur as electrons are transferred from their donors (NADH/FADH) to the acceptors (Oxygen). This process fuels ATP synthase, which is the main producer of the ATP required for cell processes
Input: NADH, FADH, electrons, oxygen as transporter
Output: 34/36 ATP, H2O as waste
Where: mitochondria - inner membrane
What happens when oxygen is not present? (describe anaerobic respiration)
Anaerobic respiration occurs when oxygen is not present (for example, when athletes need energy quickly).
Glycolysis still occurs - glucose to pyruvate
Pyruvate then turned into lactic acid
OUTPUT: NAD+
The biproduct (waste) of this process is lactic acid rather than CO2 and H2O
How has respiration been impaired by CO? (two ways)
Binding with haemoglobin to restrict oxygen uptake
Binding with cytochrome c oxidase which impacts ability to transport electrons
What is the central nervous system?
brain and spinal cord - CONTROL CENTER
What is the peripheral nervous system?
cranial / spinal nerves - COMMUNICATION LINES
What is the somatic nervous system?
Controls VOLUNTARY muscles and transmits sensory information to CNS
What is the autonomic nervous system?
Controls INVOLUNTARY body functions
What are the parasympathetic and sympathetic nervous systems?
Parasympathetic - CALMS body to conserve/maintain energy
Sympathetic - AROUSES body to expend energy
Cells types in nervous system
Neurons - send signals
Glial cells - provide support, digestion, insulation in CNS and PNS
PNS - Schwann and satellite cells
CNS - astrocytes, microglia, oligodendroglia
Resting potential
difference in voltage between the inside and outside of the neuron
Action potential
occurs when a neuron sends information down an axon, away from the cell body.
Sodium pump
sodium and potassium both need to move across the nerve cell membrane through active transport. Unequal distribution inside and outside generate the electrical impulses required to send messages
Introduction / consent
Obtaining consent from patients, discussing confidentiality
- Who you are - name and role
- What is the purpose - our learning
- How long will it take - outline amount of time it will take to gather information
- What will happen to the information / who will you share it with - passing any details on to doctor / medical team
- What if they say no - if you don’t want to talk, won’t affect your care
Initiating consultation (consent above)
- Introduction: Role as medical student - to learn, to listen, to understand, as conduit to doctor (need to make it clear that you will share any information shared with doctor)
- Establish purpose
- Consent
- Establish rapport
- Establish comfort
Describe respiratory system gross anatomy
Nasal / oral cavity Pharynx Larynx Trachea Right / left Bronchus Right - three bronci left - two bronchi Bronchioles Alveolus
Describe alveolus structure and function
Terminal end of the lung capillaries, where gas exchange occurs
Macrophages
Pneumocytes -
Type 1: gas exchange, squamous (flat) / thin
Type 2: secretion of surfactant, cuboidal
Pulmonary surfactant:
is a mixture of lipids and proteins which is secreted into the alveolar space by epithelial type II cells. The main function ofsurfactantis to lower the surface tension at the air/liquid interface within thealveoliof thelung
Gibb’s reflective cycle
Description, feelings, evaluation, analysis, conclusion, action plan
Differences between left and right lung
Left - smaller to make room for heart, 2 lobes
Right - longer and more upright, 3 lobes
Functional residual capacity of the lungs
Maximum expiration (breathe out) + residual volume (what’s left)
Cellular respiration
process of converting biochemical energy to ATP
Hamburger shift
Exchange of bicarbonate ions and chloride ions across membranes of RBCs
Haldane effect
Left for lungs, haem has high affinity to pick up oxygen
Bohr effect
Right for muscle, haem has low affinity for oxygen to drop off oxygen in tissues
Carbaminohaemoglobin
Carbon dioxide binds with oxygen
Three examples of exclusion criteria for anatomy body donors
Obesity
Post-mortem examination
Some infectious diseases - hepatitis, HIV/AIDS
Describe key points from Human tissue act of 2004
Permits with consent donation of whole bodies for anatomical examination following certified/registered death
Must be licensed to examine the body, removal of body parts / organs, storage
Describe the Calgary Cambridge model of communication
Initiate, gather information, physical examination, explanation / planning, close the session (all supported by structure and relationship building)
What is consent? Three factors
Consent means a voluntary, uncoerced decision, made by a competent person on the basis of adequate information and deliberation, to accept some proposed course of action
INFORMED
COMPETENT
VOLUNTARY
Oxygen cascade
pO2 drops at every step from atmospheric gas to mitochondria (from about 21kPa to 3kPa)
Conducting zone of the respiratory system
Trachea, bronchi, bronchioles, terminal bronchioles
Transitional and respiratory zones of the respiratory system
Respiratory bronchioles, alveolar ducts, alveolar sacs
What determines oxygen delivery? (two elements)
Cardiac output x oxygen content
Where is oxygen stored? (three locations and approximate amounts)
Lungs - 450ml
Blood - 850ml
Dissolved and in tissues - 250ml
What is a clinical skill?
Any discrete and observable act within the overall process of patient care
Describe the parts of a neuron
Soma with a cell body and dendrites
Long axon (nerve fiber) covered in myelin separated by nodes of ranvier
Ends with terminal boutons
What are the 4 basic types of a neuron?
Bipolar
Unipolar
Multipolar
Pyramidal
What are the functions / characteristics of a neuron? (3 processes)
Receive, process and generate signals
–Action potentials
–Chemical neurotransmission (synapses)
–Electrical neurotransmission (gap junctions)
THEY DO NOT PROLIFERATE (exception: neural stem cells)
What is the basic process of a synapse?
Nerve impulse triggers release of neurotransmitters into synaptic gap
Channel opens and nerve impulse sent
(without neurotransmitter, channel closed, no signal sent)
Describe the three types of glial cells in the CNS
Astrocyte - clean up, transport, stability, digestion, regulation
Microglia - digestion
Oligodendroglia - insulation
Describe the two types of glial cells in the PNS
Satelitte cells - support
Schwann cells - insultation
What are the meniges of the CNS? (6 layers)
Skin, periosteum, bone, dura mater, arachnoid, pia mater
What are the functions of CSF? (four)
Buoyancy
Protection
Chemical stability
Prevention of brain ischaemia (restriction of blood vessels to brain)
What are the lobes of the brain? (six)
Frontal Parietal Occipital Temporal Brain stem Cerebellum
What are the three part of the brain stem?
Midbrain
Pons
Medulla
What are the regions of the spinal cord? 4 with corresponding vertebrae & post-spine region
Cervical (C1-8) Thoracic (T1-12) Lumbar (L1-5) Sacral (S1-5) Conus / Cauda equina
Regions for dermatomes (5)
Trigeminal Cervical Thoracic Lumbar Sacral
Only make sense if person is on all fours
Define eteroceptors, proprioceptors, enteroceptors
Exteroceptors- respond to stimuli outside the body
Special senses (e.g. photoreceptors, olfactory
neurones, cochlear hair cells) and body surface (e.g.
mechanoreceptors, chemoreceptors….)
Proprioceptors- Stimuli from muscles tendons and joints.
Enteroceptors (visceroceptors) - Internal surfaces such as walls of viscera, blood vessels.
What are mechanoreceptors?
Type of exteroceptor subdivided by sensation (vibration, temperature, touch for example)
What is the CNS blood supply?
Arteries - carotid, vertebral (circle of Willis, Cerebral arteries)
Veins - venous sinuses, jugular veins
Describe the circle of willis
Can be seen from inferior view of brain
Brings together the Internal carotid artery, middle cerebral artery and the basilar artery
What is the McWhinney model?
Patient centred approach
Patient presents problem, gather information, parallel search of two distinct frameworks (DISEASE / DOCTOR and ILLNESS / PATIENT), which are then integrated and used collaboratively
What is the vital capacity of the lungs ?
Inspiratory reserve volume + Tidal volume + expiratory reserve volume
What is the functional residual capacity of the lungs?
Expiratory reserve volume + residual volume
What is your normal breathing at rest called?
Tidal volume
What’s the difference between gap junction and synapse
A gap junction is called an electrical synapse in neurons and nerves. So an electric synapse is a specific type of gap junction, namely the electrically conductive link between two neighboring neurons.
A chemical synapse is a biological junction through which neurons’ signals can be exchanged. A chemical synapse is not a gap junction, because of the 20 to 40 nanometer distance that separates the cells.
