Human Physiology- Blood Pressure- Goodnotes
Page 1: Arteries
Arteries measure blood pressure only in this part of the circulatory system.
Tunica Interna:
Internal layer of arteries.
Tunica Media:
Middle layer; thicker smooth muscle layer.
Smooth muscle can contract to decrease lumen diameter, leading to increased blood pressure without stretching the artery walls.
Tunica Externa:
Outermost layer of the artery walls, providing additional support.
Page 2: Veins
Veins have a thinner tunica media with less smooth muscle.
Lumen:
Extremely stretchy; can collapse and then refill like a water balloon when blood is added.
Veins do not significantly change blood pressure because they are too stretchy.
Page 3: Capillaries
Capillaries have a single layer of endothelial cells (one cell thick).
Function: Main site for gas exchange (O2 and CO2) as well as the transport of nutrients, hormones, and chemicals.
Page 4: Blood Pressure
Definition: The force of blood against arterial walls.
Relationship with blood volume:
Less blood results in decreased pressure against walls.
More blood increases pressure.
Control Mechanisms:
Influenced by heart rate and peripheral resistance.
Increased peripheral resistance also leads to increased stroke volume, which relates back to blood pressure.
Page 5: Blood Pressure Control
Baroreceptors: Located in carotid arteries, aortic arch, kidneys; detect changes in blood pressure.
Stimulation of cardiac center in the medulla oblongata will release epinephrine/norepinephrine to:
Increase heart rate
Increase peripheral resistance and stroke volume.
Page 6: Cardiac Output
Definition: Volume of blood ejected from the ventricles per minute.
Formula:
CO = HR x SV (where HR is heart rate and SV is stroke volume).
Increased cardiac output leads to increased blood pressure.
Page 7: Funny Leak Gates
Funny Leak Gates: Channels that regulate cardiac function.
When epinephrine/norepinephrine bind to beta-receptors on these gates, heart contractions increase heart rate.
Page 8: Baroreceptor Function
Monitoring Changes:
Baroreceptors respond to changes in blood pressure and alert the cardiac center in the medulla oblongata.
They monitor blood pressure in the head, thoracic cage, and abdominal regions.
Page 9: Blood Flow Dynamics
Blood flows from the left ventricle into the aorta (highest blood pressure point in the body).
As blood travels through arteries to arterioles, the pressure decreases until reaching capillaries and veins (lowest pressure at right atrium).
Capillaries can use sphincters to regulate blood flow and prevent excess pressure.
Page 10: Venous System
The venous system relies on pressure from surrounding muscles to push blood back to the heart.
Increased physical activity enhances venous return due to muscle contractions.
Page 11: Peripheral Resistance
Definition: Resistance caused by blood flowing against arterial walls.
Blood moves fastest in the center of arteries and slowest along the edges, creating friction.
Page 12: Stroke Volume
Stroke Volume Definition: The volume of blood ejected by the ventricles with each heart beat.
Stroke volume affects cardiac output directly.
The amount of blood remaining in the ventricles post-contraction influences the amount available for the next contraction.
Page 13: Increasing Stroke Volume
Strategies to increase stroke volume include increasing end diastolic or decreasing end systolic volume.
More blood in the ventricles (increased end diastolic volume) can lead to improved contraction force when the ventricle squeezes.
Page 14: Frank-Starling Law
This law states that greater stretch of the heart muscles results in stronger contractions.
Key to increasing stroke volume through enhanced venous return.
Page 15: Increasing Blood Volume
Kidney Function:
Juxtaglomerular cells in the kidneys secrete renin when they detect low blood volume.
This stimulates a cascade that ultimately leads to increased blood volume through hormonal changes.
Page 16: Aldosterone
Role of Aldosterone:
Increases sodium reabsorption in the kidneys.
This in turn draws water into the bloodstream, increasing blood volume and blood pressure.
Page 17: Erythropoiesis
Process: Triggered by low oxygen saturation detected by chemoreceptors in the kidneys.
Leads to secretion of erythropoietin, which stimulates red blood cell production and subsequently increases blood viscosity and pressure.
Page 18: Effects of High Altitude
At high altitudes, lower oxygen prompts increased erythropoietin release, thickening the blood to improve oxygen transport.
This adaptation can strain the heart under normal atmospheric pressure due to increased blood viscosity.
Page 19: Blood Volume and Fluid Balance
Monitoring fluid intake and urine output can indicate kidney function.
If no urine is produced despite fluid intake, kidneys may be failing.
Page 20: Conclusion
Understanding the relationship between cardiovascular factors is crucial for diagnosing and treating conditions related to blood pressure and volume.