Vasculature I & II

Arteries =

Carry oxygen-rich blood away from the heart

Arterioles =

Small branches of arteries that control blood flow

Capillaries =

Smallest blood vessels that facilitate exchange of oxygen, nutrients, and waste between blood and tissues

Venules =

Small blood vessels that collect blood from capillaries and transport it to veins.

Veins =

Carry oxygen-poor blood back to the heart

Lumen =

Central blood containing space

What are the three layers in arteries and veins?

• Tunica intima - endothelium (lining)

• Tunica media - smooth muscle and elastin (controls diameter)

• Tunia externa - collagen fibers (outer layer)

Elastic arteries =

Large thick-walled arteries with elastin in all three tunics; inactive in vasoconstrictions

Muscular arteries =

Medium-sized arteries, think tunica media with more smooth muscle, delivers blood to specific organs, active in vasoconstriction

Composition of capillaries

Consist of a single layer of endothelial cells allowing for easy exchange of substances between blood and tissues; fragile walls of tunica intima

Capacitance vessels (blood reservoirs) =

Veins that contain up to 60% of blood supply

Venous valves =

Prevent backflow of blood in veins; most abundant in veins of limbs

Resistance equation =

8Ln/πr^4

Blood pressure equation =

BP = CO x PR, where CO is cardiac output and PR is peripheral resistance

Pulse pressure equation =

Systolic pressure - diastolic pressure

How to find Mean Arterial Pressure (MAP) =

Diastolic pressure + 1/3(pulse pressure)

Blood flow equation =

Blood pressure/peripheral resistance

Systolic pressure =

Pressure exerted in aorta during ventricular contraction (~120 mmHg average)

Diastolic pressure =

Lowest level of aortic pressure (~80 mmHg average)

What is venous blood pressure?

The pressure exerted by blood in the veins

What is the primary function of capillary blood pressure in the circulatory system?

To push nutrients and oxygen out of the blood into tissue

What does having a larger cross-sectional area in a material generally affect?

It decreases the material's resistance to electric current

Local Autoregulation =

• Blood flow adjusts itself in tissue based on needs

• Metabolic controls increase blood flow when tissues need more oxygen or nutrients

• Myogenic controls respond to pressure changes by constricting or relaxing blood vessels

What primarily controls local blood flow in tissue?

Local metabolic activity

What does 'myogenic' mean in the context of systemic circulation?

The heart's ability to generate its own electrical impulses without external nervous stimulation

What is the primary cause of colloid osmotic pressure in blood vessels?

The presence of large plasma proteins like albumin

What does Filtration Pressure (NFP) primarily represent in the context of kidney function?

The net pressure that drives fluid out of the glomerular capillaries into Bowman's capsule

Which hormone primarily helps increase systemic blood pressure when it falls below normal?

Antidiuretic Hormone (ADH)

Which type of control primarily adjusts blood flow in systemic circulation based on muscle contraction?

Myogenic controls

What primarily determines the direction of fluid movement across capillary walls?

The balance between colloid osmotic and hydrostatic pressures

What is the primary function of the lymphatic system in the human body?

To remove waste and fight infections

What is local regulation (auto-regulation) of blood flow?

Local regulation controls blood flow to specific tissues or organs based on their metabolic needs and local tissue stretch

• General rule is that fresh blood reaching tissue can fix the local problem

Metabolic controls =

Regulate blood flow through changes in blood vessel diameter in response to local; Vasodilation vs Vasoconstriction

List of things that cause vasodilation in local regulation:

Vasodilation:

• Increase local blood flow

• Metabolically active

• Low O2

• High CO2

• High H+, K+, adenosine

• Nitric oxide (NO)

  • Nitrous, viagra

• Histamine and prostaglandins

List of things that cause vasoconstriction in local regulation: 

Vasoconstriction:

• Decrease local blood flow

• Metabolically inactive

• High O2

• Low CO2, H+, K+

• Endothelin

• Angiotensin II

• Norepinephrine

Myogenic controls =

Regulation of blood vessel diameter in response to changes in blood pressure, ensuring constant blood flow despite variations in perfusion pressure

• Increased stretch due to increased intravascular pressure, promotes vasoconstriction 

• Reduced stretch due to lower pressure, promotes vasodilation

Angiogenesis =

Number of vessels to region increases and existing vessels enlarge to supply adequate blood flow and nutrients during growth or healing.

Metabolic control in the pulmonary circuit =

Regulates blood flow based on tissue oxygen and carbon dioxide levels to optimize gas exchange in the lungs.

• High O2 —> Vasodilation

• High CO2 —>Bronchiole dilation

Perfusion =

Changes in Po2 in alveoli cause changes in diameter of arterioles 

Ventilation =

Changes in Pco2 in alveoli cause changes in diameter of bronchioles

What are the three forms of capillary exchange?

1. Diffusion (O2, nutrients, waste)

2. Vesicle transport (hormones, endocytosis, exocytosis)

3. Bulk Flow (Distribution of extracellular fluid volume)

Capillary osmotic pressure =

the pressure exerted by proteins in plasma that draws water into the capillary.

Interstitial fluid osmotic pressure =

the pressure exerted by proteins in interstitial fluid that draws water out of the capillary.

Capillary hydrostatic pressure =

the pressure exerted by blood within the capillary that tends to force fluid out of the capillary into the interstitial space.

Interstitial fluid hydrostatic pressure = 

the pressure exerted by the interstitial fluid against the capillary wall that tends to push fluid into the capillary.

Edema =

Excess accumulation of interstitial fluid in tissues, often due to increased capillary permeability or obstruction of lymphatic drainage

What are the two types of systemic regulation?

1. Neural control

2. Hormone control

What is neural control?

Regulation of blood vessel diameter and blood flow by the autonomic nervous system, impacting vascular resistance and overall circulation (short term)

• Baroreceptors (mechanical sensors)

• Chemoreceptors (chemical sensors)

Vasoconstriction is caused by what in neural control?

Vasoconstrictions:

• Heart rate increases when

  • Low O2

  • High CO2

  • High H+

  • Low pH

  • Low pressure

Vasodilation is caused by what in neural control?

• Heart rate decreases when

  • High O2

  • Low CO2

  • Low H+

  • High pH

  • High pressure

High blood pressure is caused by what in hormonal control?

• Epinephrine and norepinephrine

• ADH

• Aldosterone

• Angiotensin II

Low blood pressure is caused by what in hormonal control?

• Atrial natriuretic peptide (ANP)