Body Systems L14 Notes Flashcards
Describe an exception to the normal circumstances regarding pulmonary circulation
• In pulmonary circulation
Decr. O2 & incr. CO2
» Arteriole constriction.
Normal conditions -> pulmonary vessels dilate -> allow blood flow through
capillaries -> absorb oxygen -> delivered back to circulation.
Low O2 conc -> pulmonary vessels constrict -> shunt O2 rich blood -> alveoli
cells of lungs -> preventing O2 rich blood returning -> circulation.
Contrast the responses in pulmonary circulation to that of normal circulation in response to decr. O2 & incr. CO2 conc
• In pulmonary circulation
Decr. O2 & incr. CO2
» Arteriole constriction.
Normal conditions -> pulmonary vessels dilate -> allow blood flow through
capillaries -> absorb oxygen -> delivered back to circulation.
Low O2 conc -> pulmonary vessels constrict -> shunt O2 rich blood -> alveoli
cells of lungs -> preventing O2 rich blood returning -> circulation.
Describe the characteristics of coronary circulation
• Coronary circulation:
No. of mediators associated with constriction / relaxation of blood vessels supplying blood tissues.
Mechanical
Metabolic
Neural
Hormonal
Paracrine
Total peripheral resistance of blood vessels
Under control -> sympathetic nervous system -> autonomic control of blood
vessels.
»_space; Form of Regulation dependent -> Expression -> alpha / beta adrenergic
receptors.
List the mediators involved in coronary circulation and what their functions are
• Coronary circulation: No. of mediators associated with constriction / relaxation of blood vessels supplying blood tissues. Mechanical Metabolic Neural Hormonal Paracrine
Describe the total peripheral resistance of blood vessels in the coronary circulation
Total peripheral resistance of blood vessels
Under control -> sympathetic nervous system -> autonomic control of blood
vessels.
»_space; Form of Regulation dependent -> Expression -> alpha / beta adrenergic
receptors.
List factors involved in endocrine responses to integrated control of blood flow & what consequences they incur
• Endocrine Responses -> Integrated control of Blood flow:
Vasoconstriction -> incr. blood pressure
Aldosterone -> incr. blood volume
Erythropoietin -> incr. blood volume
» Incr. vol. red blood cells
Antidiuretic hormone (ADH) -> incr. blood volume
» Incr. thirst -> fluid intake.
Describe endocrine response to integrated control of blood flow when there is inadequate autoregulation of low blood pressure
When inadequate autoregulation of low blood pressure.
Liver produces angiotensinogen -> circulates blood.
- Low blood pressure -> detected by kidneys
» Release renin
- Renin binds -> angiotensinogen -> circulation
» Angiotensin I
If sufficiently low blood pressure -> conc. angiotensin I reaches threshold
-> activation of angiotensin II production.
» Angiotensin II produced -> interaction -> angiotensinogen & angiotensin
converting enzymes -> lungs.
> Released -> circulation.
- Angiotensin II binds –
Angiotensin receptors -> blood vessels
» Vasoconstriction
Angiotensin receptors -> adrenal cortex
» Production -> aldosterone.
- Aldosterone stimulates kidney
Incr. Na+ retention through transporters -> epithelial cells of distal collective
tubules.
» Movement -> water -> follows by osmosis.
> Incr. blood volume & venous return
–> Counters fall in blood pressure.
Describe formation of Angiotensin I
Liver produces angiotensinogen -> circulates blood.
- Low blood pressure -> detected by kidneys
» Release renin
- Renin binds -> angiotensinogen -> circulation
» Angiotensin I
Describe formation of Angiotensin II
If sufficiently low blood pressure -> conc. angiotensin I reaches threshold
-> activation of angiotensin II production.
» Angiotensin II produced -> interaction -> angiotensinogen & angiotensin
converting enzymes -> lungs.
> Released -> circulation.
Describe the role of angiotensin II in the endocrine response to integrated control of blood flow when there is inadequate autoregulation of low blood pressure
- Angiotensin II binds –
Angiotensin receptors -> blood vessels
» Vasoconstriction
Angiotensin receptors -> adrenal cortex
» Production -> aldosterone.
Describe the role of aldosterone in the endocrine response to integrated control of blood flow when there is inadequate autoregulation of low blood pressure
- Aldosterone stimulates kidney
Incr. Na+ retention through transporters -> epithelial cells of distal collective
tubules.
» Movement -> water -> follows by osmosis.
> Incr. blood volume & venous return
–> Counters fall in blood pressure.
Describe the endocrine response to integrated control of blood flow when there is high blood pressure
• Endocrine Response -> Integrated Control -> High Blood Pressure:
Incr. blood pressure & volume
- High Blood pressure -> detected by specialised cells -> heart.
» Releases natriuretic peptides
- Some peptides
Incr. loss -> Na+
-> via transporters of epithelia in kidney cells
»_space; Movement of water -> follows -> down osmotic gradient
> Decr. blood volume
Directly incr. water loss -> act on aquaporins in kidney epithelia
»_space; Decr. blood volume
Block action -> hormones
Eg. ADH, Aldosterone / parts -> Sympathetic nervous system
»_space; Decr. blood pressure
Peripheral vasodilation
»_space; Decr. blood pressure.
->> Collectively reduce blood pressure.
Describe the role of natriuretic peptides produced by specialised cells of the heart in response to integrated control of blood flow when there is high blood pressure
- Some peptides
Incr. loss -> Na+
-> via transporters of epithelia in kidney cells
»_space; Movement of water -> follows -> down osmotic gradient
> Decr. blood volume
Directly incr. water loss -> act on aquaporins in kidney epithelia
»_space; Decr. blood volume
Block action -> hormones
Eg. ADH, Aldosterone / parts -> Sympathetic nervous system
»_space; Decr. blood pressure
Peripheral vasodilation
»_space; Decr. blood pressure.
Describe the exchange of molecules into & out of capillaries
• Capillary Structure & Exchange:
Exchange:
Molecules diffuse ; RBCs (arterial blood) -> Body cells
Eg. Water, O2 , Amino acids, Glucose & ions.
Molecules diffuse ; Body cells -> RBCs (venous blood)
Eg. Water, CO2, waste molecules & ions.
What is the equation for the net filtration pressure?
Net Filtration Pressure = Net Hydrostatic Pressure – Net Colloid Osmotic Pressure
What is the net filtration pressure?
Overall exertion of forces on capillaries
What are the principles of net filtration pressure?
Principals:
Capillary hydrostatic pressure -> tends to force -> water & solutes
»Capillaries -> interstitial fluid surrounding tissues.
Capillary hydrostatic pressure opposed -> hydrostatic pressure
-> extracellular fluid
» Formed as a result of colloid osmotic pressures
Describe the net filtration pressure
• Net Filtration Pressure:
Net Filtration Pressure = Net Hydrostatic Pressure – Net Colloid Osmotic Pressure
Principals:
Capillary hydrostatic pressure -> tends to force -> water & solutes
»Capillaries -> interstitial fluid surrounding tissues.
Capillary hydrostatic pressure opposed -> hydrostatic pressure
-> extracellular fluid
» Formed as a result of colloid osmotic pressures
Overall exertion of forces on capillaries -> Net filtration pressure.
What is the equation for net hydrostatic pressure?
• Net Hydrostatic Pressure = Capillary Hydrostatic Pressure (CHP)
[ - Hydrostatic Pressure of Interstitial Fluid (IHP) ]
Describe the net hydrostatic pressure & hydrostatic pressure values
• Net Hydrostatic Pressure = Capillary Hydrostatic Pressure (CHP)
[ - Hydrostatic Pressure of Interstitial Fluid (IHP) ]
• Hydrostatic Pressure Values:
Blood pressure of capillaries declines along length -> capillary bed.
»Pressure gradient along capillary network.
> Impacts rate -> filtration.
Net Hydrostatic Pressure = Capillary Hydrostatic Pressure (CHP) – Hydrostatic Pressure of Interstitial Fluid (IHP)
Capillary Hydrostatic Pressure
Arterial -> 35mmHg
Venous -> 18mmHg
Hydrostatic Pressure -> Interstitial Fluid
0mmHg
Since IHP = 0mmHg
Net Hydrostatic Pressure = Capillary Hydrostatic Pressure (CHP)
What are the values of capillary hydrostatic pressure?
Capillary Hydrostatic Pressure
Arterial -> 35mmHg
Venous -> 18mmHg
What is the value of hydrostatic pressure of the interstitial fluid?
Venous -> 18mmHg
Hydrostatic Pressure -> Interstitial Fluid
0mmHg
Describe why hydrostatic pressure of interstitial fluid can be disregarded in terms of the net hydrostatic pressure
Hydrostatic Pressure -> Interstitial Fluid
0mmHg
Since IHP = 0mmHg
Net Hydrostatic Pressure = Capillary Hydrostatic Pressure (CHP)
What is the eqn for the net colloid osmotic pressure?
• Net Colloid Osmotic Pressure = Blood Colloid Osmotic Pressure (BCOP)
[ – Interstitial Fluid Colloid Osmotic Pressure (ICOP)]
Describe net colloid osmotic pressure & its values
• Colloid Osmotic Pressure Values:
Osmotic pressure differences -> boundaries of capillaries.
Net Colloid Osmotic Pressure = Blood Colloid Osmotic Pressure (BCOP) – Interstitial Fluid Colloid Osmotic Pressure (ICOP)
Blood Colloid Osmotic Pressure (BCOP):
25mmHg
Interstitial Fluid Colloid Osmotic Pressure (ICOP)
Interstitial fluid contains few proteins in suspension
»_space; Low & Negligible value.
-> Insignificant impact -> Net colloid osmotic pressure.
Net Colloid Osmotic Pressure = Blood Colloid Osmotic Pressure (BCOP)
Describe why the Interstitial Fluid Colloid Osmotic Pressure can be disregarded in terms of the net colloid osmotic pressure
Net Colloid Osmotic Pressure = Blood Colloid Osmotic Pressure (BCOP) – Interstitial Fluid Colloid Osmotic Pressure (ICOP)
Blood Colloid Osmotic Pressure (BCOP):
25mmHg
Interstitial Fluid Colloid Osmotic Pressure (ICOP)
Interstitial fluid contains few proteins in suspension
»_space; Low & Negligible value.
-> Insignificant impact -> Net colloid osmotic pressure.
Net Colloid Osmotic Pressure = Blood Colloid Osmotic Pressure (BCOP)
What is the eqn for the net filtration pressure?
• Net Filtration Pressure (NFP) = Net Hydrostatic Pressure – Net Colloid Osmotic Pressure
What is the eqn and value for the Net hydrostatic pressure?
Net Hydrostatic Pressure = Capillary Hydrostatic Pressure (CHP)
[ - Hydrostatic Pressure of Interstitial Fluid (IHP) ]
»_space; 18-35mmHg
What is the eqn and value for the Net Colloid Osmotic Pressure?
Net Colloid Osmotic Pressure = Blood Colloid Osmotic Pressure (BCOP)
[ – Interstitial Fluid Colloid Osmotic Pressure (ICOP)]
»_space; ~25mmHg
Describe the dynamics of capillary exchange at arterial ends of the capillary network
• Dynamics of capillary exchange:
Arterial end
High hydrostatic pressure -> forces fluid out capillary network
»_space; Opposed -> high osmotic potential gradient
Capillary Hydrostatic Pressure (CHP) -> 35mmHg
Blood Colloid Osmotic Pressure (BCOP) -> 25mmHg
-» CHP > BCOP
-» Net filtration pressure -> +10mmHg
»_space; Forces fluid & dissolved substances out -> capillary network
Significant rate of filtration -> 24 L/day
Describe the factors effecting capillary exchange at arterial ends of the capillary network
High hydrostatic pressure -> forces fluid out capillary network
»_space; Opposed -> high osmotic potential gradient
What is the net filtration pressure of the blood at arterial ends of capillaries? What does this value mean and what is the associated rate of filtration?
Capillary Hydrostatic Pressure (CHP) -> 35mmHg
Blood Colloid Osmotic Pressure (BCOP) -> 25mmHg
-» CHP > BCOP
-» Net filtration pressure -> +10mmHg
»_space; Forces fluid & dissolved substances out -> capillary network
Significant rate of filtration -> 24 L/day
Describe the dynamics of capillary exchange at venous ends of the capillary network
Venous end
Hydrostatic pressure decline -> incr. distance -> heart
Same osmotic potential
Capillary Hydrostatic Pressure (CHP) -> 18mmHg
Blood Colloid Osmotic Pressure (BCOP) -> 25mmHg
-» CHP < BCOP
-» Net Filtration Pressure -> -7mmHg
»_space;Movement of fluid -> into capillary network
Significant Rate of reabsorption -> 20.4 L/Day
Describe the factors effecting capillary exchange at venous ends of the capillary network
Hydrostatic pressure decline -> incr. distance -> heart
Same osmotic potential
What is the net filtration pressure of the blood at venous ends of capillaries? What does this value mean and what is the associated rate of filtration?
Capillary Hydrostatic Pressure (CHP) -> 18mmHg
Blood Colloid Osmotic Pressure (BCOP) -> 25mmHg
-» CHP < BCOP
-» Net Filtration Pressure -> -7mmHg
»_space;Movement of fluid -> into capillary network
Significant Rate of reabsorption -> 20.4 L/Day
What happens to the net difference in water from rate of filtration & absorption
Net difference in water -> Rate of filtration & absorption
Collected -> Lymphatic System
Describe the characteristics of the centre of the capillary network and the effects of this on net filtration pressure
Centre -> Capillary Network
Approx. centre -> capillary network
->Equal values -> CHP & BCOP -> Net filtration pressure = 0.
-> No net movement -> fluid.
Max filtration pressure always greater -> max absorption pressure
»_space; Point at which net filtration pressure = 0
-> further towards venous end -> capillary
-» More filtration than absorption along capillary.
¬-» Enables provision -> tissues with required molecules over greater
distance -> capillary network
> Rapid reabsorption -> molecules & waste products -> venous end.
Describe the net filtration value of fluid at the centre of the capillary network and the advantages of this
Centre -> Capillary Network
Approx. centre -> capillary network
->Equal values -> CHP & BCOP -> Net filtration pressure = 0.
-> No net movement -> fluid.
Max filtration pressure always greater -> max absorption pressure
»_space; Point at which net filtration pressure = 0
-> further towards venous end -> capillary
-» More filtration than absorption along capillary.
¬-» Enables provision -> tissues with required molecules over greater
distance -> capillary network
> Rapid reabsorption -> molecules & waste products -> venous end.
Describe the disadvantage of characteristics of the centre of the capillary network in terms of movement of tissue fluid when high blood pressure
• High blood pressure & capillary exchange: If: Capillary Hydrostatic Pressure high Blood Calloid Osmotic Pressure low Fluid balance altered >> Net exit -> Peripheral tissue Fluid collects -> extremities >> Systemic oedema
Describe the values of the net filtration pressure of fluid in the pulmonary capillaries and values of any factors involved in creation of this pressure
• Pulmonary capillary exchange:
Capillary Hydrostatic Pressure -> 10mmHg
Blood Colloid Osmotic Pressure -> 25mmHg
Net Filtration Pressure -> -15mmHg
Describe why the pulmonary capillary values of hydrostatic pressure are different to that of normal capillaries
Hydrostatic pressure -> lung capillary network much lower -> normal networks.
»_space; Lower pulmonary arterial blood pressure (~10mmHg)
compared -> systemic blood pressure (35mmHg)
Lung tissue requires gas exchange over entire period -> cardiac output.
» Arteries of lung capillary network diff structure to normal.
Low pulmonary vascular resistance
»_space; Arterioles -> thinner, wider & shorter
»_space;Elastin -> thinner walls & less elastin.
-» Enables incr. distensibility
Describe the advantage of incr. distensibility in pulmonary capillaries in relation to exchange of substances
Incr. distensibility
Better absorption -> pressure waves -> cardiac pressure.
»_space; Ability -> accommodate incr. cardiac output without sig. pressure changes.
Capillary network -> pulmonary circulation can absorb oxygen across entire
length of capillary network.
»_space; Prevents interference -> gas diffusion.
Describe pulmonary capillary exchange in terms of pressure gradients etc
• Pulmonary capillary exchange:
Capillary Hydrostatic Pressure -> 10mmHg
Blood Colloid Osmotic Pressure -> 25mmHg
Net Filtration Pressure -> -15mmHg
Hydrostatic pressure -> lung capillary network much lower -> normal networks.
»_space; Lower pulmonary arterial blood pressure (~10mmHg)
compared -> systemic blood pressure (35mmHg)
Lung tissue requires gas exchange over entire period -> cardiac output.
» Arteries of lung capillary network diff structure to normal.
Low pulmonary vascular resistance
»_space; Arterioles -> thinner, wider & shorter
»_space;Elastin -> thinner walls & less elastin.
-» Enables incr. distensibility
Incr. distensibility
Better absorption -> pressure waves -> cardiac pressure.
»_space; Ability -> accommodate incr. cardiac output without sig. pressure changes.
Capillary network -> pulmonary circulation can absorb oxygen across entire
length of capillary network.
»_space; Prevents interference -> gas diffusion.
Describe high blood pressure & it’s effects on pulmonary circulation
• High Blood Pressure & Pulmonary Circulation:
Net Hydrostatic pressure -> Pulmonary circulation -> much lower
- Disadvantage -> Hypertensive individual
» Incr. capillary hydrostatic pressure
-» Results in absorption -> fluid -> alveoli of lungs
> Affects respiration.
Describe why low hydrostatic pressure of pulmonary circulation is disadvantageous in some cases
• High Blood Pressure & Pulmonary Circulation:
Net Hydrostatic pressure -> Pulmonary circulation -> much lower
- Disadvantage -> Hypertensive individual
» Incr. capillary hydrostatic pressure
-» Results in absorption -> fluid -> alveoli of lungs
> Affects respiration.
Describe control of blood flow in the brain
• Control -> Blood Flow -> Brain:
Consumes 12% Cardiac output for 2% body mass
» Mass of tissue
Neurons -> poor reserve capacity -> metabolites.
4 arteries supply brain & anastomoses -> cranium
Blood flow constant & preserved
» Even in emergencies.
Peripheral constriction & cerebral vasodilation
» During temporary loss -> arterial supply -> circulation -> Central nervous system unaffected.
Describe blood flow in the brain
• Control -> Blood Flow -> Brain:
Consumes 12% Cardiac output for 2% body mass
» Mass of tissue
Neurons -> poor reserve capacity -> metabolites.
4 arteries supply brain & anastomoses -> cranium
Blood flow constant & preserved
» Even in emergencies.
Peripheral constriction & cerebral vasodilation
» During temporary loss -> arterial supply -> circulation -> Central nervous system unaffected.
Describe coronary circulation of blood flow of the heart
• Coronary Circulation -> Blood Flow -> Heart:
Requires:
Constant maintenance -> O2 supply
»_space; Sufficient O2 -> cardiac demand.
Coronary blood flow varies throughout cardiac cycle
» Influenced -> Heart Rate
Constriction -> coronary arteries during cardiac cycle
» Interruption -> blood flow.
High capillary density
» High O2 extraction capacity (70%)
Few arterial collateral interconnections -> capillaries.
Adrenaline
Promotes vasodilation -> coronary vessels
»_space; Incr. heart rate & myocardial contraction strength
Coronary blood flow incr. when vasoconstriction predominant -> other parts of
body.
Describe maintenance of blood flow in coronary circulation of heart
• Coronary Circulation -> Blood Flow -> Heart:
Requires:
Constant maintenance -> O2 supply
»_space; Sufficient O2 -> cardiac demand.
Coronary blood flow varies throughout cardiac cycle
» Influenced -> Heart Rate
Constriction -> coronary arteries during cardiac cycle
» Interruption -> blood flow.
High capillary density
» High O2 extraction capacity (70%)
Few arterial collateral interconnections -> capillaries.
Describe the role of adrenaline in coronary circulation of heart
Adrenaline
Promotes vasodilation -> coronary vessels
»_space; Incr. heart rate & myocardial contraction strength
Coronary blood flow incr. when vasoconstriction predominant -> other parts of
body.
Describe characteristics to consider when calculating the net hydrostatic pressure
Blood pressure of capillaries declines along length -> capillary bed.
»Pressure gradient along capillary network.
> Impacts rate -> filtration.