Transcript Regulation of blood gases and blood pressure

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:
CO2 increases
breathing rate
decreases
pH _______________
Negative feedback
Chemoreceptors in
medulla
CO2 levels _________
Chemoreceptors in aorta and
carotid bodies
breathing rate _________
respiratory muscles
_____________
Respiratory centre
medulla
in
The level of blood gases is controlled by a negative feedback system:
breathing rate
decreases
CO2 increases
pH decreases
Negative feedback
CO2 levels drops
Chemoreceptors in
medulla
Chemoreceptors in aorta and
carotid bodies
breathing rate increases
respiratory muscles
Increase activity
Respiratory centre
medulla
in
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
Increased
carbon dioxide
Negative feedback
Receptor
Response
Modulator
Effector
Feedback control of breathing
Stimulus
Negative feedback
Decreased carbon dioxide
Increased
carbon dioxide
Decreased pH
Decreased
oxygen
Response
Receptor
Chemoreceptors –
medulla and aortic
and carotid bodies
Modulator
Increased
breathing rate
Effector
Respiratory muscles – diaphragm
and intercostals
Respiratory centre
medulla
Feedback control of breathing 2
Stimulus
Decreased
carbon dioxide
Negative feedback
Receptor
Response
Modulator
Effector
Feedback control of breathing 2
Stimulus
Negative feedback
Increased carbon dioxide
Decreased
carbon dioxide
Increased pH
Increased
oxygen
Response
Receptor
Chemoreceptors –
medulla and aortic
and carotid bodies
Modulator
Decreased
breathing rate
Effector
Respiratory muscles – diaphragm
and intercostals
Respiratory centre
medulla
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 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 sinoatrial 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
Length of
d_________
A___________
nervous system
Venous
r_________
Ventricular
f_________
T__________
Degree of stretch of
h_______ m_______
A_________________
nervous system
N_________________
Strength of c___________
A___________
Heart rate
Stroke volume
Cardiac output
Factors affecting cardiac output
Length of
diastole
Autonomic
nervous system
Temperature
Venous
return
Ventricular
filling
Degree of stretch of heart
muscle
Autonomic nervous
system
Noradrenaline
Strength of contraction
Adrenaline
Heart rate
Stroke volume
Cardiac output
Factors affecting blood pressure
Falling blood
pressure
I__________ in
blood pressure
Arteries stretch
l_______
Pressoreceptors send
f________ impulses
Rising blood
pressure
D________ in
blood pressure
Arteries stretch
m_______
Pressoreceptors send
m________ impulses
Cardiovascular regulating centre in m____________ oblongata
I___________ in sympathetic and
d_____________ in
parasympathetic output
Vaso_________
I__________
cardiac output
D__________ in sympathetic and
i___________ in parasympathetic
output
D__________
cardiac output
Vaso_______
Factors affecting blood pressure
Falling blood
pressure
Increase in
blood pressure
Arteries stretch
less
Pressoreceptors send
fewer impulses
Rising blood
pressure
Arteries stretch more
Decrease in
blood pressure
Pressoreceptors send
more impulses
Cardiovascular regulating centre in medulla oblongata
Increase in sympathetic and
decrease in parasympathetic
output
Vasoconstriction
Increased
cardiac output
Decrease in sympathetic and
increase in parasympathetic
output
Decreased
cardiac output
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)