Regulation of blood gases and blood pressure HBS3A

Regulation of blood gases The body needs a constant supply of o_________ in order to Carbon dioxide (produced in r________________) must be constantly removed because The two systems involved in control of the blood gases are the c___________________ and r__________________ systems

Regulation of blood gases The body needs a constant supply of oxygen in order to maintain respiration Carbon dioxide (produced in respiration) must be constantly removed because it is toxic, and it alters the pH of blood The two systems involved in control of the blood gases are the cardiovascular and respiratory systems

Blood gases Oxygen can travel in the blood dissolved in plasma but mostly travels attached to h______________, in red blood cells. Carbon dioxide travels in the blood dissolved in plasma, attached to haemoglobin, in r____ b______ cells, but mostly as _________________ ions and ________________________ ions. This is due to the reaction: carbon dioxide + water  __________  ___________ + __________

Blood gases Oxygen can travel in the blood dissolved in plasma but mostly travels attached to haemoglobin, in red blood cells. Carbon dioxide travels in the blood dissolved in plasma, attached to haemoglobin, in red blood cells, but mostly as hydrogen ions and hydrogen carbonate (bicarbonate) ions. This is due to the reaction: carbon dioxide + water  H2CO3  H+ + HCO3-

Respiratory control systems

Respiratory control systems Chemoreceptors in the medulla detect levels of ___________________ in the blood. These are most sensitive to changes in ____________ and are responsible for _____% of the change in breathing rate. This response is s_________ Chemoreceptors in the carotid and aortic bodies detect levels of ______ in the blood. These are most sensitive to changes in _____________ and are responsible for _____% of the change in breathing rate. This response is f_________ There is interaction between oxygen, carbon dioxide and pH and all contribute to changes in the breathing rate, but the most sensitivity is to _____________________________________ These chemoreceptors send information to the respiratory centre of the m__________, which (along with other areas) controls the activity of the respiratory system. Voluntary control can by-pass the respiratory centre.

Respiratory control systems Chemoreceptors in the medulla detect levels of CO2, H+ and O2 in the blood. These are most sensitive to changes in CO2 and H+ and are responsible for 70 – 80 % of the change in breathing rate. This response is slow Chemoreceptors in the carotid and aortic bodies detect levels of CO2, H+ and O2 in the blood. These are most sensitive to changes in CO2 and H+ and are responsible for 20 – 30 % of the change in breathing rate. This response is fast There is interaction between oxygen, carbon dioxide and pH and all contribute to changes in the breathing rate, but the most sensitivity is to H+ and CO2 These chemoreceptors send information to the respiratory centre of the medulla, which (along with other areas) controls the activity of the respiratory system. Voluntary control can by-pass the respiratory centre.

The level of blood gases is controlled by a negative feedback system: breathing rate decreases CO2 increases pH _______________ Negative feedback Chemoreceptors in medulla Chemoreceptors in aorta and carotid bodies CO2 levels _________ breathing rate _________ respiratory muscles _____________ Respiratory centre in medulla

The level of blood gases is controlled by a negative feedback system: breathing rate decreases CO2 increases pH decreases Negative feedback Chemoreceptors in medulla Chemoreceptors in aorta and carotid bodies CO2 levels drops breathing rate increases respiratory muscles Increase activity Respiratory centre in medulla

Changes in blood gases Hyperventilation is It can cause levels of carbon dioxide to fall. This can cause During exercise carbon dioxide production _________________ and oxygen consumption _________________________ so the breathing rate will _____________________________

Changes in blood gases Hyperventilation is rapid shallow breathing to blow off carbon dioxide It can cause levels of carbon dioxide to fall. This can cause decrease a decrease in carbon dioxide that is so great, that there is no longer any stimulation to breath, so you stop breathing & fall unconscious. After a time unconscious, the carbon dioxide levels rise & you breath again. The problem is if you are swimming, you will start to breath under water & drown, or if you have hurt yourself when falling unconscious (ie falling off a bridge, etc) During exercise carbon dioxide production increases and oxygen consumption increases so the breathing rate will increase

Feedback control of breathing Stimulus Negative feedback Receptor Response Modulator Effector Increased carbon dioxide

Feedback control of breathing Stimulus Negative feedback Receptor Response Modulator Effector Increased carbon dioxide Decreased pH Decreased oxygen Decreased carbon dioxide Chemoreceptors – medulla and aortic and carotid bodies Increased breathing rate Respiratory centre medulla Respiratory muscles – diaphragm and intercostals

Feedback control of breathing 2 Stimulus Negative feedback Receptor Response Modulator Effector Decreased carbon dioxide

Feedback control of breathing 2 Stimulus Negative feedback Receptor Response Modulator Effector Decreased carbon dioxide Increased pH Increased oxygen Increased carbon dioxide Chemoreceptors – medulla and aortic and carotid bodies Decreased breathing rate Respiratory centre medulla Respiratory muscles – diaphragm and intercostals

Cardiovascular control systems Define heart rate Define stroke volume Define cardiac output Cardiac output can be calculated by (CO = ) Define venous return It depends on Define blood pressure

Cardiovascular control systems Define heart rate - (HR) beats per minute Define stroke volume - (SV) volume of blood leaving the heart each beat Define cardiac output - (CO) volume of blood leaving the heart each minute Cardiac output can be calculated by multiplying heart rate by stroke volume (CO = SV x HR) Define venous return – volume of blood returning to the heart It depends on cardiac output and muscle activity Define blood pressure – (BP) force with which the blood presses on the walls of blood vessels It depends on cardiac output and diameter of blood vessels

The heart

Control of the heart The pacemaker (sino-atrial node or SA node) is found and is responsible The activity of the heart is controlled by the m___________, by means of the s____________ and p___________________ nervous systems. Fibres from both systems run down the spinal cord as part of the cardiac nerves to the cardiac muscle of the atria in the heart and the sino-atrial and atrio-ventricular nodes. The cardiac muscle of the ventricles get mainly the s____________________ The sympathetic fibres release n__________________ and cause The parasympathetic fibres release a____________________ and cause

Control of the heart The pacemaker (sino-atrial node or SA node) is found in the wall of the right atrium just below the superior vena cava and is responsible for the rhythmical contractions of the heart The activity of the heart is controlled by the medulla, by means of the sympathetic and parasympathetic nervous systems. Fibres from both systems run down the spinal cord as part of the cardiac nerves to the cardiac muscle of the atria in the heart and the sino-atrial and atrio-ventricular nodes. The cardiac muscle of the ventricles get mainly the sympathetic fibres The sympathetic fibres release noradrenaline and cause increased heart rate and stroke volume The parasympathetic fibres release acetylcholine and cause decreased heart rate and force of contraction

Control of the heart Autonomic control is balancing opposing effects of the sympathetic and parasympathetic systems. At rest, p___________________________ activity is dominant. During exercise, s____________________ activity increases. Other influences on heart rate and stroke volume include

Control of the heart Autonomic control is balancing opposing effects of the sympathetic and parasympathetic systems. At rest, parasympathetic activity is dominant. During exercise, sympathetic activity increases. Other influences on heart rate and stroke volume include temperature, blood pressure, age, sex and emotional state

Control of the heart 2 The cardiovascular regulating centre controls The three main influences on stroke volume are: length of diastole – this influences venous return – this and is influenced by activity of s_____________ muscles, r_______________ movements, tone of v___________ and sympathetic nervous system – this causes

Control of the heart 2 The cardiovascular regulating centre controls heart rate, stroke volume and blood pressure The three main influences on stroke volume are: length of diastole – this influences stroke volume as it affects how much blood can enter the heart venous return – this affects stroke volume and is influenced by activity of skeletal muscles, respiratory movements, tone of veins and ease of blood flow through arterioles in the muscles sympathetic nervous system – this causes increased stroke volume and heart rate

Control of the heart 2 Other factors that affect heart rate include age – sex – emotional state – During exercise heart rate, stroke volume and blood pressure will tend to rise due to

Control of the heart 2 Other factors that affect heart rate include age – HR is fastest at birth and slows as we age sex – males have a slower HR than females emotional state – strong emotions eg fear, anger, anxiety increase HR, depression & grief lower HR During exercise heart rate, stroke volume and blood pressure will tend to rise due to increased sympathetic activity, increased muscle and respiratory movements, increased temperature and effects of adrenaline and noradrenaline

Factors affecting cardiac output Degree of stretch of h_______ m_______ Length of d_________ Venous r_________ A_________________ nervous system A___________ nervous system Ventricular f_________ N_________________ T__________ Strength of c___________ A___________ Heart rate Stroke volume Cardiac output

Factors affecting cardiac output Degree of stretch of heart muscle Length of diastole Venous return Autonomic nervous system Autonomic nervous system Ventricular filling Noradrenaline Temperature Strength of contraction Adrenaline Heart rate Stroke volume Cardiac output

Factors affecting blood pressure Rising blood pressure Falling blood pressure I__________ in blood pressure D________ in blood pressure Arteries stretch m_______ Arteries stretch l_______ Pressoreceptors send f________ impulses Pressoreceptors send m________ impulses Cardiovascular regulating centre in m____________ oblongata I___________ in sympathetic and d_____________ in parasympathetic output D__________ in sympathetic and i___________ in parasympathetic output I__________ cardiac output D__________ cardiac output Vaso_________ Vaso_______

Factors affecting blood pressure Rising blood pressure Falling blood pressure Increase in blood pressure Decrease in blood pressure Arteries stretch more Arteries stretch less Pressoreceptors send fewer impulses Pressoreceptors send more impulses Cardiovascular regulating centre in medulla oblongata Increase in sympathetic and decrease in parasympathetic output Decrease in sympathetic and increase in parasympathetic output Increased cardiac output Decreased cardiac output Vasoconstriction Vasodilation

Blood flow Define vasodilation - Describe factors that increase vasodilation Define vasoconstriction – Describe factors that increase vasoconstriction

Blood flow Define vasodilation - widening of blood vessels (arterioles) to increase blood flow Describe factors that increase vasodilation sympathetic system to muscles and heart wastes eg carbon dioxide and lactic acid Adrenaline (muscle and heart) Define vasoconstriction - narrowing of blood vessels (arterioles) to decrease blood flow Describe factors that increase vasoconstriction sympathetic system to abdominal organs Adrenaline (abdominal organs)

Receptors How are the following receptors involved in the regulation of the cardiovascular system? Thermoreceptors Chemoreceptors Mechanoreceptors Pressoreceptors

Receptors How are the following receptors involved in the regulation of the cardiovascular system? Thermoreceptors – detect heat – increased temperature stimulates increased breathing rate which increases venous return, increased heart rate and vasodilation of blood vessels near the skin Chemoreceptors – detect concentrations of carbon dioxide, oxygen and pH – these affect breathing rate which affects venous return, and heart rate Mechanoreceptors – detect movement of muscles and joints during exercise – increased movement stimulates increased breathing rate which increases venous return, increased heart rate and release of adrenal hormones Pressoreceptors – detect blood pressure – changes in blood pressure stimulates changes in sympathetic and parasympathetic output, changing cardiac output and degree of vasodilation

Blood pressure Describe factors that increase blood pressure Describe factors that decrease blood pressure

Blood pressure Describe factors that increase blood pressure Increased force of contraction Vasoconstriction or narrowing of blood vessels (eg arteriosclerosis) Increased cardiac output Describe factors that decrease blood pressure Decreased force of contraction Vasodilation of blood vessels Decreased cardiac output Reduced blood volume (eg loss of blood)