Regulation of VentilationThe ventilating muscles are skeletal muscles and are not spontaneously active but innervated by alpha motor neuronsThese are spinal motor neurons going to the respiratory muscleIn the brainstem there are 2 groups of nerve cells called the dorsal and ventral respiratory groups where the rhythms that run the respiratory system originate. Exert these APs in burstsThis goes to the spinal and brainstem motor neurons that innervate these musclesThe control of this outflow is determined by the level of the respiratory gasesOxygen does not play a major role in quiet breathing but rather CO2 plays a bigger roleCO2 is a direct waste product of metabolism and directly indicates the need for respirationGas sensitive nerves: chemoreceptors which are reflexes that will sense the levels of respiratory levels1. Central chemoreceptorsIn the brainstemSense respiratory gasesSensitive to CO2Are involved in moment to moment regulation of rate and depth of breathingThe neurons in the central chemorecpetors are not actually CO2 sensitive but H+ ion sensitive- get excited by low pH and stimulate respirationProtons cannot cross the blood brain barrier- but CO2 readily diffuses through- CO2 diffuses out of the blood when it is high (when metabolism exceeds respiration) and the acidification of the CSF will be what the neurons sense and respond toSlight changes in pH is what determines the need for respiration2. Peripheral chemoreceptorsIn aortic body and carotid bodyMeasure the oxygen levels in systemic circulationCalled glomus cells (like hair cells-don’t have axons) and they sense oxygen and in response to hypoxia (low O2) they release dopamine as a NT and this excites afferent sensory nerves which signals to the respiratory control groups to stimulate respirationUsually not very active- only in severe hypoxiaMay come into play during high altitudesCome into play in COPD where hypoxia can occurThere are also reflexes that trigger coughing and sneezing, vocalization, herring breuer reflex (protective when exercise, breath more deeply and rapidly, at the point where the tidal volume reaches about twice normal (1L) then this reflex protects the lungs from overinflating by inhibiting the respiratory – cannot hold breath to commit suicide because of these reflexes (brain hypoxia will make you pass out)SIDSSudden infant death syndromeA form of sleep apneaLeading cause of death in babies under 1 in the USPrevent nose and mouth from being obstructed by loose stuffResulted in a lot of misshapen heads (get flat in the back)Deficiency in serotonin in the brainstem- usually a lot of serotonin containing neurons around the respiratory neuronsAppears that serotonin is important in arousal and waking up during sleepMechanism not really understoodIdea is that we all seldom suffocate after 1 but we always are tossing and turning because these neurons prevent you from suffocatingNot fully developed reflex in infants (cannot be triggered to change position so suffocate)HyperventilationBlow off excess CO2 when you hyperventilateMakes you feel dizzy and faintBlowing off excess CO2 causes hypocapnia which triggers vasoconstriction of brain arterioles which makes the cerebrum ischemic which triggers dizziness and causes acidosis in the brain (low CO2 level in the brain accumulates CO2 in the brain in the cerebral spinal fluid) this stimulates the central chemoreceptors and trigger more breathing because of acidosis. This ends with people passing outUsually recommended to breath in a paper bag because you are breathing in more CO2 which relieves hypocapnia and brings up CO2 levels back in the bloodKidney Functionfunctions of kidneys1. Regulation of blood pressure2. Involve thirst and drinking behavior3. All the major ions in plasma and ECF are regulated by the kidney (especially Na+, K+(must be kept low) HCO3- main blood buffer, Ca2+ ions must be kept at low level,4. +/- 1/10 in pH is dangerous and +/- 2/10 is fatal. Does not act rapidly for change in pH but the kidney has a n unlimited capacity to excrete protons in the body (needs to get rid of acid all the time)5. Most abundant waste are nitrogenous wastes like urea and uric acid and some ammonia which are produced by metabolism and break down of amino acids. Creatin is also cleared out. All kinds of toxins and drugs are also excreted6. Produces calcitriol and EPO and activates renin which converts angiotensin to angiotensin 1Anatomy of Urinary SystemKnow that you have 2 kidneys and that they have big blood vessels going into them (20% of the cardiac output even though only a small portion of the body)The artery is very high pressureThe ureter is the tube that convey urine down the bladderThe kidney has renal pyramids (has cortex and medulla)the inner most part is called the pelvisUrine is collected in the pelvis after being in the medullaNo further modification once reaches the pelvisCortical And Juxtamedullary Nephrons2 kinds of nephrons1. 80% are confined to the cortex called cortical nephrons2. The other ones are deeper these are called juxtamedullary nephronshave the loop of henleBlood comes from the renal artery and goes into arterioles (afferent) and supplies blood to the glomerulus capillaries and drains out into another arteriole (efferent) which feeds another capillary bed (peritubular capillaries) and come up again and all drains into a vein so it is like a portal system (glomerular capillaries and peritubular capillaries)BISC 307L 1st Edition Lecture 35 Current Lecture- Regulation of Ventilationoo The ventilating muscles are skeletal muscles and are not spontaneously activebut innervated by alpha motor neuronso These are spinal motor neurons going to the respiratory muscle o In the brainstem there are 2 groups of nerve cells called the dorsal and ventral respiratory groups where the rhythms that run the respiratory system originate. Exert these APs in burstso This goes to the spinal and brainstem motor neurons that innervate these muscleso The control of this outflow is determined by the level of the respiratory gaseso Oxygen does not play a major role in quiet breathing but rather CO2 plays a bigger roleo CO2 is a direct waste product of metabolism and directly indicates the need for respirationo Gas sensitive nerves: chemoreceptors which are reflexes that will sense the levels of respiratory levels  1. Central chemoreceptors In the brainstem  Sense respiratory gases Sensitive to CO2 Are involved in moment to