205 L8 Flashcards
Dive physiology
What are the peripherial chemoreceptors?
Carotid and aortic bodies
What do peripheral chemoreceptors sense?
Partial pressure of oxygen and carbon dioxide in your blood, along with the pH in your blood.
If there is less oxygen the receptors start firing off
Afferent information from the peripheral chemoreceptors.
Information from the carotid body is sent via the —— —– nerve to the ———- nerve to the ——- in the brain.
Information from the aortic body joins the —– nerve and goes to the —– in the brain.
Information from the carotid body is sent via the carotid sinus nerve to the glossopharyngeal nerve to the NTS in the brain.
Information from the aortic body joins the vagus nerve and goes to the NTS in the brain.
What stimulates the carotid bodies in the respiratory and cardiovascular response?
Respiratory response respiratory rate tidal volume airway resistance airway secretions respiratory muscles
Cardiovascular response arterial pressure heart rate contractility cardiac output vascular resistance
Stimulation of carotid bodies leads to an ——– in respiration (respiratory rate and tidal volume). Cardiovascular response = ——– arterial pressure, heart rate and contractility
Stimulation of carotid bodies leads to an increase in respiration (respiratory rate and tidal volume). Cardiovascular response = increased arterial pressure, heart rate and contractility
Carotid body response
The carotid bodies sit at the base of the —— and monitor —- —— and the amount of ——– in the blood going to the ——-. When it senses the —– is receiving less ——– it gets activated as a reflex arc, you increase ———- to try and get more ——— in, if its not enough you also increase ———- drive to your kidney and peripheral ———-, so those arteries ———- to ——– total peripheral resistance (TPR), which ——– mean arterial pressure and redirects blood flow going to the ——–.
So the carotid bodies are trying to ——- the intake of ——- as well as insure there is —– flow going up to your —– that has a high —– content.
The carotid bodies sit at the base of the brain and monitor blood pressure and the amount of oxygen in the blood going to the brain. When it senses the brain is receiving less oxygen it gets activated as a reflex arc, you increase breathing to try and get more oxygen in, if its not enough you also increase sympathetic drive to your kidney and peripheral vasculature, so those arteries vasoconstrict to increase total peripheral resistance (TPR), which increases mean arterial pressure and redirects blood flow going to the brain.
So the carotid bodies are trying to increase the intake of oxygen as well as insure there is blood flow going up to your brain that has a high oxygen content.
The aortic bodies
The aortic bodies sit at the origin at the ——- arch and the activation ———- the fusion of the heart (they are guarding the fusion of the heart)
The aortic bodies sit at the origin at the aortic arch and the activation increases the fusion of the heart (they are guarding the fusion of the heart)
If your chemoreflex is blunted because the —— content is ——- you can’t increase ——– and —— — enough to get enough ——- to the carotid body and brain
If your chemoreflex is blunted because the oxygen content is low you can’t increase respiration and blood pressure enough to get enough oxygen to the carotid body and brain
Do carotid bodies have a role in hypertension?
Yes - they might
Respiratory arrest
There is an increased effort to ——- followed by loss of ——. If delivery of —— continues to be absent, death will follow.
There is an increased effort to breath followed by loss of consciousness. If delivery of oxygen continues to be absent, death will follow.
As you hold your breath and no more ——- is coming in and all of your cells are utilising the ——–, the increased drive you feel to ——- a large part of that comes from the ——— bodies as well as ——- chemoreceptors, but the ——– is dropping which is sending more signals to the —– and ——— to contract and drag oxygen in.
As you hold your breath and no more oxygen is coming in and all of your cells are utilising the oxygen, the increased drive you feel to breathe a large part of that comes from the carotid bodies as well as central chemoreceptors, but the PaO2 is dropping which is sending more signals to the brain and diaphragm to contract and drag oxygen in.
What happens to your heart rate and blood pressure when you dive?
Heart rate decreases - bradycardia
Blood pressure - usually maintained or even elevated despite the increase in HR
What is the bradycardia response during dive most driven by? How was this proved?
Driven by increased parasympathetic/vagal activity.
Atropine blocks vagal/parasympathetic (increase=decrease HR) drive to the heart. The HR doesn’t diminish as much when the subject has atropine.
Holding your breath/ Voluntary apnea
There is ——— inhibition of respiratory muscles. There is a decrease in Pa— and an increase in Pa—– which is sensed by ———–. There is a small increase in ———- activity so —- —–decreases and an increase in ———- activity causing ——- in specific areas. This means the —— —– —– doesn’t change much.
There is increased inhibition of respiratory muscles. There is a decrease in PaO2 and an increase in PaCO2 which is sensed by chemoreceptors. There is a small increase in parasympathetic activity so heart rate decreases and an increase in sympathetic activity causing vasoconstriction in specific areas. This means the mean arterial pressure doesn’t change much.
Facial immersion in cold water
There is ——— inhibition of respiratory muscles. There is a decrease in Pa— and an increase in Pa—– which is sensed by ———–. There is a small increase in ———- activity so —- —–decreases and an increase in ———- activity causing ——- in specific areas. This means the —— —– —– doesn’t change much.
You activate certain receptors near your —– and —- which causes a big increase in ——– and ——— activity. The large increase in parasympathetic activity decreases —– —– and —- —-. The large increase in sympathetic activity causes ———– which causes an increase ——– —– —- and therefore an ——— in mean arterial pressure.
There is increased inhibition of respiratory muscles. There is a decrease in PaO2 and an increase in PaCO2 which is sensed by chemoreceptors. There is a small increase in parasympathetic activity so heart rate decreases and an increase in sympathetic activity causing vasoconstriction in specific areas. This means the mean arterial pressure doesn’t change much.
You activate certain receptors near your nose and cheeks which causes a big increase in parasympathetic and sympathetic activity. The large increase in parasympathetic activity decreases heart rate and cardiac output. The large increase in sympathetic activity causes vasoconstriction which causes an increase total peripheral resistance and therefore an increase in mean arterial pressure.
