Body Systems L13 Flashcards
What is contractility?
Contractile ability -> cardiac muscle at a given period.
Describe the effect of incr. ventricular contraction on stroke volume
Incr. ventricular contraction -> incr. stroke volume
What is an inotropic effect?
Effects which alter the contractility of the heart.
What are positive inotropic effects? Give an example.
Positive inotropic effects:
Effects which incr. contractility -> heart
Eg. Sensory Nervous System & adrenaline
->SNS also incr. conduction velocity & cardiac impulse.
What are negative inotropic effects? Give an example & incl. how this is carried out.
Negative inotropic effects:
Effects which decr. contractility -> heart
Eg. Peripheral Nervous System (ACh)
->Mainly exerted on atria
»_space;Vagal nerve doesn’t innervate ventricles.
Describe contractility & filling times of the heart when Heart rate is 70bpm
- HR -> 70bpm
Total Filling time: 0.8s
Diastole: 0.53s
Systole: 0.27s
Describe contractility & filling times of the heart when Heart rate is 150bpm and no sensory nervous system tone is present. Explain the consequences of these statistics.
- HR -> 150bpm -> No SNS tone
Total filling time: 0.4s
Diastole: 0.13s
Systole: 0.27s
–> Not enough time to refill ventricles for effect.
–> Without sympathetic nervous system intervention -> contraction of ventricles too severe & rapid for sufficient refill of ventricles for transport of adequate blood supply to tissues.
Describe contractility & filling times of the heart when Heart rate is 150bpm and sensory nervous system tone is present. Explain the consequences of such statistics.
- HR -> 150bpm -> SNS tone
Total filling time: 0.4s
Diastole: 0.22s
Systole: 0.18s--> Enables sufficient filling time by extension of diastolic phase ***
What is the afterload?
Pressure opposing ejection of blood from heart
What factor is the afterload affected by?
Influenced -> Blood vessel tone -> Vasoconstriction/dilation
What does the afterload have an affect on?
Major effect -> cardiac output.
What is the equation for blood pressure?
Include the units/eqns. for facors in the eqn.
• Blood Pressure = Cardiac Output x Total Peripheral Resistance
Cardiac Output -> ▲HR & SV
Total Peripheral Resistance -> ▲Arteriolar Radius
Describe how the blood vessel tone is controlled
• Blood vessel tone controlled -> interrelated processes Automatic / intrinsic Short term Long term Control measures.
What affect does decr. oxygen and incr. co2 have on pulmonary circulation?
• Pulmonary Circulation:
- Decr. O2 & Incr. CO2 -> constriction -> arterioles.
Describe factors which may result in altered blood pressure / volume
Physical stress
Eg. Trauma, high temp, etc.
Chemical changes
Eg. Decr. O2 / decr. pH / Incr. CO2 / Incr. vasodilatory metabolites
Increased tissue activity / Intrinsic Control
Describe homeostasis/ regulation & response of blood pressure
• Response & Regulation of Blood Pressure:
Homeostasis:
- Altered Blood pressure / volume
Physical stress
Eg. Trauma, high temp, etc.
Chemical changes
Eg. Decr. O2 / decr. pH / Incr. CO2 / Incr. vasodilatory metabolites
Increases tissue activity / Intrinsic Control
- Inadequate blood pressure & flow
»Autoregulation:
Decr. resistance & incr. blood flow
> Homeostasis returned.
- Insufficient Autoregulation:
Stimulates receptors -> sensitive to systemic changes -> blood pressure /
Chemistry.
Activates cardiovascular centres -> Central Nervous System
Elevates Blood pressure -> Short Term
»_space;Stimulation -> heart rate & peripheral vasoconstriction
–» Sensory Nervous System.
Return -> Homeostasis.
Describe the process of autoregulation of blood pressure & how it may have been caused.
• Response & Regulation of Blood Pressure:
Homeostasis:
- Altered Blood pressure / volume
Physical stress
Eg. Trauma, high temp, etc.
Chemical changes
Eg. Decr. O2 / decr. pH / Incr. CO2 / Incr. vasodilatory metabolites
Increases tissue activity / Intrinsic Control
- Inadequate blood pressure & flow
»Autoregulation:
Decr. resistance & incr. blood flow
> Homeostasis returned.
Describe what occurs if autoregulation of blood pressure is insufficient
- Insufficient Autoregulation:
Stimulates receptors -> sensitive to systemic changes -> blood pressure /
Chemistry.
Activates cardiovascular centres -> Central Nervous System
Elevates Blood pressure -> Short Term
»Stimulation -> heart rate & peripheral vasoconstriction
–» Sensory Nervous System.
Return -> Homeostasis.
Give examples of vasodilatory metabolites
• Vasodilatory metabolites
H+ / CO2 / K+ / Adenosine / Lactate
Describe the state of the vessel & causative factors of this for active tissues.
• Active tissues:
Vessel vasodilated
»_space;Response -> metabolites
>Incr. Blood flow -> tissue.
Describe the state of the vessel & causative factors of this for inactive tissues.
• Inactive tissues:
Vessel vasoconstricted
»_space;Absence -> excess metabolites
State where the chemoreceptors can be located.
• Chemoreceptors:
Medulla oblongata:
» Cardioregulatory centre
Carotid Body
State where the baroreceptors can be located.
• Baroreceptors:
Wall -> internal carotid artery
Aorta
Describe actions of the baroreceptors during times of inadequate blood supply / blood pressure
• Inadequate Blood supply / Decr. Blood Pressure: - Inhibition -> baroreceptors Activation Cardioacceloratory Centre Vasomotor Centres Inhibition Cardioinhibitory Centre >> Incr. Cardiac Output & Heart Rate - Vasoconstriction
Describe actions of the baroreceptors during times of increased blood pressure
• Rise -> Blood Pressure: - Stimulation -> Baroreceptors Activation Cardioinhibitory Centre Inhibition Cardioacceloratory Centre Vasomotor Centres >> Decr. Cardiac Output & Heart Rate - Vasodilation.
Describe the actions of the chemoreceptors found in the medulla oblongata when detection of incr, Co2 & decr. pH
• Chemoreceptors -> Medulla Oblongata:
- Detect incr. CO2 decr. pH
- Vasodilation -> Cerebral Vessels
» Incr. Blood flow -> Brain.
Describe the actions of the chemoreceptors found in the carotid body when detection of incr, Co2 & decr. pH
• Chemoreceptors -> Carotid Body: - Detect incr. CO2 / decr. pH Stimulate cardioaccelatory centre Inhibit cardioinhibitory centres Stimulate vasomotor centres >> Incr. Cardiac Output, Vasoconstriction & Heart Rate
Describe the actions of the chemoreceptors when detection of incr. Co2 & decr. pH
• Chemoreceptors -> Medulla Oblongata:
- Detect incr. CO2 / decr. pH
- Vasodilation -> Cerebral Vessels
» Incr. Blood flow -> Brain.
• Chemoreceptors -> Carotid Body: - Detect incr. CO2 / decr. pH Stimulate cardioaccelatory centre Inhibit cardioinhibitory centres Stimulate vasomotor centres >> Incr. CO & incr. Heart Rate
Describe the actions of the chemoreceptors when decr. oxygen detected.
- Detect decr. O2
- Incr. respiratory rate
Describe intrinsic/autoregulation of blood flow & both methods of recovery if autoregulation insufficient
• Intrinsic / Autoregulation -> Blood Flow:
- Homeostasis Disturbed
Physical Stress
Eg. Trauma , High Temp
Chemical Changes
Eg. Decr. O2 / decr. pH / Incr. CO2 / Incr. vasodilatory metabolites
Incr, tissue activity
- Inadequate blood pressure & blood flow
- Autoregulation:
Decr. resistance
Incr. blood flow
- If autoregulation insufficient:
1.
- Stimulation -> receptors
Sensitive -> changes -> systemic blood pressure / chemistry
- Activation -> Cardiovascular centres -> Central Nervous System
- Short-term incr. -> Blood pressure
Sensory nervous system stimulates Heart rate & peripheral vasoconstriction
If response to control of blood flow still insufficient following stimulation -> cardiovascular centre sensory receptors
- Endocrine response stimulated
- Long-term incr. -> Blood pressure
Angiotensin II -> Vasoconstriction
Aldosterone, ADH etc. -> Blood Volume
»Return -> homeostasis.
Describe both methods of recovery of blood flow if intrinsic / autoregulation insufficient
- If autoregulation insufficient:
1. - Stimulation -> receptors
Sensitive -> changes -> systemic blood pressure / chemistry - Activation -> Cardiovascular centres -> Central Nervous System
- Short-term incr. -> Blood pressure
Sensory nervous system stimulates Heart rate & peripheral vasoconstriction
If response to control of blood flow still insufficient following stimulation -> cardiovascular centre sensory receptors
- Endocrine response stimulated
- Long-term incr. -> Blood pressure
Angiotensin II -> Vasoconstriction
Aldosterone, ADH etc. -> Blood Volume
»Return -> homeostasis.
Describe recovery of blood flow using the cardiovascular centres of central nervous system if autoregulation insufficient
- Stimulation -> receptors
Sensitive -> changes -> systemic blood pressure / chemistry - Activation -> Cardiovascular centres -> Central Nervous System
- Short-term incr. -> Blood pressure
Sensory nervous system stimulates Heart rate & peripheral vasoconstriction
Describe recovery of blood flow using the endocrine system if autoregulation & stimulation of cardiovascular centre insufficient
If response to control of blood flow still insufficient following stimulation -> cardiovascular centre sensory receptors
- Endocrine response stimulated
- Long-term incr. -> Blood pressure
Angiotensin II -> Vasoconstriction
Aldosterone, ADH etc. -> Blood Volume
»Return -> homeostasis.
What is a requirement of inotropic influences?
• Inotropic influences must be integrated with chronotropic influences.
What is blood pressure?
Force placed on walls of blood vessels by blood as it flows.
Briefly describe how change of blood flow is controlled
Changes -> blood flow -> controlled by changes in diameter -> arteries & cardiac output.
What is the capillary hydrostatic pressure?
• Capillary hydrostatic pressure:
Minimum pressure required -> capillary exchange -> exchange of fluids & substances across capillary networks.