11806481
Description
Flashcards by J yadonknow, updated more than 1 year ago
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Created by J yadonknow
almost 7 years ago
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| Question | Answer |
| What do guard cells control? | Air and water movement |
| What do they open in response to? | Open in direct response to K+ influx and turgor pressure |
| What type of signalling is involved? | localised single cell signalling |
| What regulatory system do mammals have? What does it maintain? | A neural network which controls and regulates breathing Homeostasis |
| Name the components of this regulatory system and their role | Brain stem - central controller Respiratory muscles - effector Receptors - sensor |
| What are sensors? | Specialised nerve endings |
| What type of sensors are relevant to this system? | Mechanical loading sensors and chemoreceptors |
| What is the role of sensors? | Relay information back to the brainstem |
| What does this result in? | An increase/decrease in minute ventilation pattern, so there's enough O2 influx and CO2 removal to meet metabolic needs |
| Where do breathing patterns arise? | In the medulla |
| What happens to the breathing pattern when you damage the connection between the medulla and the pons? | Pattern of breathing becomes more erratic as inspiratory phase slows down and expiratory phase accelerates |
| What does this show? | That the Pons is responsible for modulating the pattern and rhythm of tidal breathing |
| How does the pons do this? | By driving contraction/relaxation of respiratory muscles in a regular rhythmic way |
| What sort of damage disables conscious control of breathing? | Damage between the brain stem and the cerebral cortex |
| What is the medulla respiratory centre? | A rhythm/pattern generator |
| How do nerves fire here? | Action potentials are fired spontaneously |
| What is the Pre-Bötzinger Complex? | A complex showing the regular burst activity of nerve firing during inspiration |
| What type of firing is this and what does it cause? | Regular rhythmical firing that triggers contraction of the diaphragm |
| What sort of complex shows the nerve firing of action potentials during pre-inspiration/expiration? | A Retrotrapezoid nucleus/ parafacial respiratory group |
| How do these two complexes work together? | When one complex is silent, the other is firing action potentials, so there's 2 oscillations generating an on/off breathing pattern |
| Summarise the involvement of nerves firing in inspiration (4) | Firing of action potentials generates contraction Causes an increase in the volume of the thorax Causes changes in pressure and ventilation Causes air to move into the lungs |
| Draw a diagram showing how the controller, sensor and effectors are all interlinked | Cortex Limbic system (emotion) Hypothalamus (temperature) Pneumotaxic centre Apneustic centre Sensory receptors voluntary control Medullary Respiratory Centre Spinal cord Respiratory muscles, diaphragm, intercostals |
| Describe in detail the process by which a regular breathing pattern is generated | M.R.C generates electrical activity which is relayed down the spinal cord, to the diaphragm and intercostal muscles PONS modulates rhythm + pattern of breathing Limbic system and Hypothalamus can modify breathing pattern These higher centres of the brain relay information via the pons to modulate and adjust the rhythm and patterns of breathing |
| Name 2 lung receptors | Stretch receptors Mechanical receptors |
| How do stretch receptors affect ventilation? | Fire when lung is inflated, don't desensitise if inflation is maintained Prevent over-inflation by modulating inspiration in Tidal Volume Important in establishing normal breathing patterns, infant's first breath etc. |
| What receptors detect changes in the pulmonary system? | Juxta-Pulmonary (J) Receptors |
| What happens when these receptors are stimulated? | Stimulation leads to shorter shallower breaths |
| What receptors detect position/length? | Proprioreceptors |
| What are these receptors sensitive to and what is their function? | Load and length of the muscle Terminates respiratory phase |
| Name a pain receptor | Nociceptors |
| What do chemoreceptors detect? | Changes in blood chemistry in systemic arteriole blood |
| How are the chemicals in blood detected? | CO2 production is estimated from PCO2 O2 production is estimated from PO2 H+ production is estimated from pH |
| Which chemoreceptors are responsible for chemical detection in the brain? | Central chemoreceptors peripheral chemoreceptors |
| Where is the central chemoreceptor located | In the brainstem near the ventrolateral surface of the medulla |
| How do CCRs detect changes in blood chemistry? | Bathed in CSF and sensitive to changes in pH of CSF (index of PCO2) |
| How do changes in pH occur in CSF? | Charged particles can't cross the BBB CO2 can freely Reacts with H2O and dissociates into its ions |
| How is ventilation triggered by an increase in H+ in the CSF? | H+ increase stimulates chemoreceptors to increase their firing Increases ventilation |
| What is characteristic of these CCRs? | Has a relatively slow response time Indirectly sensitive relatively insensitive to Po2 changes |
| Where are the peripheral chemoreceptors located? | Near the carotid and aortic arteries |
| Draw a diagram showing the neural connection between the brain and the heart | Brainstem respiratory area Carotid sinus nerve Carotid bodies Vagus nerve Aortic bodies |
| Where are PCR nerve endings located? | Nerve endings located in areas of high blood flow |
| What are PCRs sensitive to? | sensitive to changes in blood chemistry Drop in O2% increases action firing |
| What is characteristic of PCRs? | Rapid response Directly sensitive (can detect oscillations in breathing) Hypoxia, hypercapnia and H+ increase all have the same effect |
| Draw a shitty graph showing what happens when chmoreceptors detect an increase in CO2 partial pressure | Increase in PCO2 in inspired air 1 litre Start End |
| Draw another shitty graph showing the relationship between minute ventilation and arterial PO2 in response to hypoxia/hypercapnia | high pco2 line normal pco2 line |
| How are pCO2 and pO2 interrelated? | An increase in pCO2 and decrease in PO2 act synergistically |
| What is the main drive to breathe? | An increase in pCO2 |
| What is typical of organisms that can hold their breath for a long time? | High myoglobin content in muscles High RBC count/Hb concentration |
| Describe the cause and effects of the Diving reflex in mammals (5) | Triggered by cold water to the face Reduced heart rate increased peripheral vasoconstriction Latate accumulation in muscle Energy conservation (Delayed increase in pCO2) |
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