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Questions and Answers
What defines homeostasis in living systems?
What defines homeostasis in living systems?
Which of the following is NOT an example of the parameters regulated during homeostasis?
Which of the following is NOT an example of the parameters regulated during homeostasis?
Which components make up the regulatory mechanism of homeostasis?
Which components make up the regulatory mechanism of homeostasis?
What is primarily regulated by the renin-angiotensin system?
What is primarily regulated by the renin-angiotensin system?
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Which of the following correctly distinguishes between neural and hormonal regulation of blood pressure?
Which of the following correctly distinguishes between neural and hormonal regulation of blood pressure?
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Which receptors are primarily involved in the regulation of temperature?
Which receptors are primarily involved in the regulation of temperature?
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What is the significance of maintaining pre-set normal limits in homeostasis?
What is the significance of maintaining pre-set normal limits in homeostasis?
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How does blood loss typically affect homeostasis?
How does blood loss typically affect homeostasis?
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What primarily determines blood flow to individual tissues?
What primarily determines blood flow to individual tissues?
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How does blood flow velocity relate to cross-sectional area?
How does blood flow velocity relate to cross-sectional area?
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What is the formula for calculating cardiac output (CO)?
What is the formula for calculating cardiac output (CO)?
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Which factor contributes to increased vascular resistance?
Which factor contributes to increased vascular resistance?
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What is the major function of arterioles in the circulatory system?
What is the major function of arterioles in the circulatory system?
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What mechanism primarily regulates blood pressure during a drop in blood volume?
What mechanism primarily regulates blood pressure during a drop in blood volume?
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What is the primary function of baroreceptors in blood pressure regulation?
What is the primary function of baroreceptors in blood pressure regulation?
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How is mean arterial pressure (MAP) calculated?
How is mean arterial pressure (MAP) calculated?
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Which component does NOT affect resistance to blood flow?
Which component does NOT affect resistance to blood flow?
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In the context of blood flow, what effect does dehydration have?
In the context of blood flow, what effect does dehydration have?
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What role does the vasomotor center in the medulla oblongata play?
What role does the vasomotor center in the medulla oblongata play?
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What happens to blood flow when the lumen size decreases?
What happens to blood flow when the lumen size decreases?
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What hormone is primarily responsible for sodium retention during blood pressure regulation?
What hormone is primarily responsible for sodium retention during blood pressure regulation?
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What effect does increased systemic vascular resistance have on blood pressure?
What effect does increased systemic vascular resistance have on blood pressure?
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Study Notes
Homeostasis and Haemodynamics
- Homeostasis is the state of steady internal physical and chemical conditions maintained by living systems
- It allows optimal functioning of the organism
- This includes pre-set norms for temperature, fluid balance, pH, and ions (e.g., potassium, sodium, calcium) and blood sugar
- Homeostasis is regulated via a mechanism involving:
- Receptors (e.g., thermoreceptors, mechanoreceptors)
- Control centers (e.g., respiratory center, renin-angiotensin system)
- Effectors (targets acted upon to return to normal)
Blood Flow
- Blood flow is the volume that flows through a tissue in a given time (mL/min)
- Blood flow requirements vary between tissues
- The speed of blood flow is inversely proportional to the cross-sectional area of the vessel
- Extensive branching of blood vessels (like capillaries) is essential for efficient diffusion
- Haemodynamics factors affect blood flow
Haemodynamics
- Total blood flow is equivalent to cardiac output (CO)
- CO = heart rate (HR) x stroke volume (SV)
- Stroke volume is the volume of blood pumped out of the ventricle with each contraction
- CO is dependent on pressure difference driving blood through the vessel and the resistance to blood flow
Vascular Resistance
- Vascular resistance is the opposition to blood flow
- Factors affecting resistance include:
- Size of the lumen: smaller lumen = increased resistance
- Blood viscosity: higher viscosity = increased resistance (e.g., dehydration or increased red blood cells)
- Total blood vessel length: longer vessel = increased resistance
Systemic Vascular Resistance
- Systemic vascular resistance is the total peripheral resistance
- It is the resistance to blood flow offered by the systemic vessels (e.g., arterioles, venules, capillaries)
- Smaller vessels, particularly arterioles, have high resistance and are crucial in controlling systemic vascular resistance
- Larger vessels like veins act as reservoirs with lower resistance.
Blood Pressure
- Blood pressure is the force exerted on the blood vessel wall during ventricular contraction
- Highest in the aorta (systolic 120mmHg/diastolic 80mmHg)
- Mean arterial pressure (MAP) is the average pressure through the arteries
- MAP = CO x systemic vascular resistance
- Blood pressure regulation is essential for life, achieved via constant automatic (neural) and hormonal control
Autonomic Control of Blood Pressure
- Cardiovascular center (CVC) in the medulla oblongata controls the autonomic nervous system (ANS)
- This includes the sympathetic (stimulatory) and parasympathetic (inhibitory) nervous systems influencing heart rate
- Vasomotor centre (VC) in the medulla oblongata controls blood vessel constriction or dialation.
Baroreceptors
- Baroreceptors in the aorta and carotid sinus detect changes in blood pressure
- These sensors affect the blood pressure regulation in a negative feedback loop.
Hormonal Control of Blood Pressure
- Renin-angiotensin-aldosterone system (RAAS) regulates blood pressure.
- Reduced blood flow to the kidneys triggers renin release leading to Angiotensin II formation.
- Angiotensin II constricts blood vessels and triggers aldosterone and vasopressin (ADH) release, increasing blood volume and pressure.
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Description
Test your knowledge on the concepts of homeostasis and haemodynamics. This quiz covers the mechanisms involved in maintaining internal balance and the factors affecting blood flow in the body. Dive into the details of receptors, control centers, and the impact of vessel branching on circulation.
