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 systemsChemoreceptors 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 systemsChemoreceptors 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.

CO2 increases

CO2 levels _________ Chemoreceptors in medulla

respiratory muscles_____________

Respiratory centre in medulla

breathing rate _________

pH _______________

Chemoreceptors in aorta and carotid bodies

breathing rate decreases

The level of blood gases is controlled by a negative feedback system:

Negative feedback

CO2 increases

CO2 levels drops Chemoreceptors in medulla

respiratory musclesIncrease activity

Respiratory centre in medulla

breathing rate increases

pH decreases

Chemoreceptors in aorta and carotid bodies

breathing rate decreases

The level of blood gases is controlled by a negative feedback system:

Negative feedback

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 Chemoreceptors –

medulla and aortic and carotid bodies

Respiratory centremedulla

Respiratory muscles – diaphragmand intercostals

Increased breathing rate

Decreased carbon dioxide

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 dioxideIncreased pHIncreased oxygen Chemoreceptors –

medulla and aortic and carotid bodies

Respiratory centremedulla

Respiratory muscles – diaphragmand intercostals

Decreased breathing rate

Increased carbon dioxide

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

It depends on

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 heartThe 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 heartThe pacemaker (sino-atrial node or SA node) is found in the wall of the

right atrium just below the superior vena cavaand 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 – thisand 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 includeage – 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

Ventricular f_________

Venous r_________

Length of d_________

Strength of c___________

N_________________

Heart rate

A_________________ nervous system

Stroke volume

Degree of stretch of h_______ m_______

Cardiac output

A___________ nervous system

T__________

A___________

Factors affecting cardiac output

Ventricular filling

Venous return

Length of diastole

Strength of contraction

Noradrenaline

Heart rate

Autonomic nervous system

Stroke volume

Degree of stretch of heart muscle

Cardiac output

Autonomic nervous system

Temperature

Adrenaline

Factors affecting cardiac output

D__________ in sympathetic andi___________ in parasympathetic output

Cardiovascular regulating centre in m____________ oblongata

Vaso_______D__________ cardiac output

D________ in blood pressure

Pressoreceptors send m________ impulses

Arteries stretch m_______

Rising blood pressure

Vaso_________ I__________ cardiac output

I___________ in sympathetic andd_____________ in parasympathetic output

I__________ in blood pressure

Falling blood pressure

Arteries stretch l_______

Pressoreceptors send f________ impulses

Factors affecting blood pressure

Decrease in sympathetic andincrease in parasympathetic output

Cardiovascular regulating centre in medulla oblongata

VasodilationDecreased cardiac output

Decrease in blood pressure

Pressoreceptors send more impulses

Arteries stretch more

Rising blood pressure

Vasoconstriction Increased cardiac output

Increase in sympathetic anddecrease in parasympathetic output

Increase in blood pressure

Falling blood pressure

Arteries stretch less

Pressoreceptors send fewer impulses

Factors affecting blood pressure

Blood flowDefine vasodilation -

Describe factors that increase vasodilation

Define vasoconstriction –

Describe factors that increase vasoconstriction

Blood flowDefine 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

ReceptorsHow 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)