Chapter 21 - The Cardiovascular System: Blood Vessels and Hemodynamics Flashcards
What are the Layers of a Blood Vessel?
In general, a Blood Vessel has 3 layers:
1- Tunica Interna (Tunica Intima):
Innermost layer
Adjacent to Lumen
2- Tunica Media:
Middle layer
Smooth muscle and Elastic Fibers
Thicker in arteries than in veins
3- Tunica Externa:
Outermost layer
Adjacent to surround tissue
(veins have more blood flow because of larger lumen compared to arteries)
What is Components of Tunica Interna in Arteries?
From deep to superficial:
1- Endothelium
2- Basement Membrane
3- Internal Elastic Lamina
What is Components of Tunica Media in Arteries?
From deep to superficial:
1- Smooth Muscle
2- External Elastic Lamina
What is Components of Tunica Interna in Veins?
From deep to superficial:
1- Endothelium
Valves made from Endothelium
2- Basement Membrane
What is Components of Tunica Media in Veins?
Smooth Muscle
What is Components of a Capillary?
From deep to superficial:
1- Endothelium
2- Basement Membrane
What is Artery?
Artery:
Carry blood away from heart to tissues
Walls of arteries are elastic, which allows them to absorb the pressure created by ventricles of the heart as they pump blood into the arteries
Because of smooth muscle in the Tunica Media, arteries can regulate their diameter
What are the Types of Arteries?
1- Elastic Arteries (Conducting Arteries):
Large diameter
More elastic fibers
Less smooth muscle
Function as pressure reservoirs
2- Muscular Arteries (Distributing Arteries):
Medium diameter
More smooth muscles
Fewer elastic fibers
Distribute blood to various parts of the body
What is Anastomosis?
Anastomosis:
Union of the branches of 2 or more arteries supplying the same region of the body
Provide alternative route for blood flow
End Arteries:
Arteries that do not form an Anastomosis
If an End Artery is blocked, blood cannot get to that particular region of the body, and Necrosis can occur
What is Capillary?
Thin Squamous Cells
Capillaries:
Microscopic vessels that usually connect Arterioles and Venules
Capillary Wall:
Composed of a single layer of cells and a Basement Membrane
Because their walls are so thin, Capillaries permit the exchange of nutrients and wastes between blood and tissue cells
What is Blood Flow Through Capillaries?
Capillaries branch to form an extensive capillary network throughout the tissues and are found near almost every cell in body
Eases off BP
1- If Precapillary Sphincters relaxed:
Arteriole
Metarteriole
Capillary and Thoroughfare Channel
Postcapillary Venule
Venule
2- If Precapillary Sphincters contracted:
Arteriole
Metarteriole
Thoroughfare Channel
Postcapillary Venule
Venule
What is Types of Capillaries?
1- Continuous Capillary:
Basement Membrane complete
Pinocytic Vesicles
Intercellular Clefts small
2- Fenestrated Capillary:
Basement Membrane complete
Pinocytic Vesicles
Intercellular Clefts small
Fenestrations (pores)
3- Sinusoid Capillary:
Basement Membrane incomplete
No Pinocytic Vesicles
Intercellular Clefts large
Bigger molecules can pass through
What is Venule?
Venules:
Small vessels that are formed by the union of several capillaries
Darin blood from capillaries into Veins
What is Vein?
Veins:
Formed by union of several Venules
Compared to arteries, veins have:
Thinner Tunica Interna and Tunica Media
Thicker Tunica externa
Less Elastic tissue
Less smooth muscle
Contain Valves that allow blood to flow through
What is Size, Description of Layers, and Function of Elastic Artery?
1- Size:
Largest in body
2- Tunica Interna:
Well-defined Internal Elastic Lamina
3- Tunica Media:
Thick dominated by elastic fibers
Well-defined External Elastic Lamina
4- Tunica Externa:
Thinner than Tunica Media
5- Function:
Conduct blood from heart to Muscular Arteries
What is Size, Description of Layers, and Function of Muscular Artery?
1- Size:
Medium-sized arteries
2- Tunica Interna:
Well-defined Internal Elastic Lamina
3- Tunica Media:
Thick dominated by smooth muscle
Thin External Elastic Lamina
4- Tunica Externa:
Thicker than Tunica Media
5- Function:
Distribute blood to Arterioles
What is Size, Description of Layers, and Function of Arterioles?
1- Size:
Microscopic
2- Tunica Interna:
Thin with a Fenestrated Internal Elastic Lamina that disappears distally
3- Tunica Media:
1 or 2 layers of circularly oriented smooth muscle
Distalmost smooth muscle cell forms a Precapillary Sphincter
4- Tunica Externa:
Loose collagenous connective tissue and sympathetic nerves
5- Function:
Deliver blood to capillaries
Help regulate blood flow from arteries to capillaries
What is Size, Description of Layers, and Function of Capillary?
1- Size:
Microscopic
Smallest in body
2- Tunica Interna:
Endothelium
Basement Membrane
3- Tunica Media:
None
4- Tunica Externa:
None
5- Function:
Permit exchange of nutrients and wastes between blood and interstitial fluid
Distribute blood to Postcapillary Venules
What is Size, Description of Layers, and Function of Postcapillary Venule?
1- Size:
Microscopic
2- Tunica Interna:
Endothelium
Basement Membrane
3- Tunica Media:
None
4- Tunica Externa:
None
5- Function:
Pass blood into Muscular Venules
Permits exchange of nutrients and wastes between blood and interstitial fluid
Function in WBC Emigration (Diapedesis)
What is Size, Description of Layers, and Function of Muscular Venule?
1- Size:
Microscopic
2- Tunica Interna:
Endothelium
Basement Membrane
3- Tunica Media:
1 or 2 layers of circularly oriented smooth muscle
4- Tunica Externa:
Sparse
5- Function:
Pass blood into Veins
Act as a reservoir for accumulating large volumes of blood along with Postcapillary Venules
What is Size, Description of Layers, and Function of Veins?
1- Size:
0.5mm to 3cm
2- Tunica Interna:
Endothelium
Basement Membrane
No Internal Elastic Lamina
Contain Valves
Lumen larger than in accompanying artery
3- Tunica Media:
Much thinner than arteries
No External Elastic Lamina
4- Tunica Externa:
Thickest of the 3 layers
5- Function:
Return blood to heart
Facilitated by Valves in limb veins
What is Blood Distribution?
At rest, largest portion of blood is in Systemic Veins and Venules, which are considered Blood Reservoirs
1- Systemic Veins and Venules: 64%
2- Systemic Arteries and Arterioles: 13%
3- Pulmonary Vessels: 9%
4- Heart: 7%
5 Systemic Capillaries: 7%
What is Capillary Exchange?
Substances cross Capillary Walls by:
1- Diffusion
2- Transcytosis
3- Bulk Flow
What is Diffusion?
Diffusion:
Substances such as oxygen, CO2, Glucose, Amino Acids, and some hormones cross capillary walls via simple diffusion
(Passive)
What is Transcytosis?
Transcytosis:
Large, Lipid-insoluble molecules (like Insulin) cross capillary walls in vesicles
Endocytosis then pass through membrane then Exocytosis
What is Bulk Flow?
Bulk Flow:
Passive process in which large numbers of ions, molecules, or particles in a fluid move together in same direction
Occurs from area of higher concentration/pressure to area of lower concentration/pressure, and it continues as long as a gradient exists
More important for regulation of the relative volumes of blood and interstitial fluid
What is Filtration?
Filtration:
Pressure-driven movement of fluid and solutes from blood capillaries into interstitial fluid
Both promote Filtration:
1- Blood Hydrostatic Pressure (BHP):
Pressure against walls
2- Interstitial Fluid Osmotic Pressure (IFOP)
What is Reabsorption?
Reabsorption:
Pressure-driven movement of fluid and solutes from interstitial fluid into blood capillaries
Both promote Reabsorption:
1- Interstitial Fluid Hydrostatic Pressure (IFHP)
2- Blood Colloid Osmotic Pressure (BCOP):
How many bulky molecules are inside
What is Net Filtration Rate?
Net Filtration Rate (NFR):
NFR = ( BHP - IFOP ) - ( BCOP + IFHP )
Arterial End: Net Filtration
Venous End: Net Reabsorption
What is Starling’s Law of the Capillaries?
Under normal conditions, the volume of fluid and solutes reabsorbed is almost as large as the volume filtered
NFR = ( BHP - IFOP ) - ( BCOP + IFHP )
What is Factors Affecting Blood Flow?
Blood Flow:
Volume of blood that flows through any given tissue in a given period (ml/min)
Total Blood Flow:
Cardiac Output (CO), the volume of blood that circulates through systemic (or pulmonary) blood vessels each minute
CO = HR x SV
CO = Mean Arterial Pressure (MAP) / Resistance (R)
CO = MAP / R
MAP = Diastolic BP + (1/3) x (Systolic BP - Diastolic BP)
What is Blood Pressure (BP)?
BP:
Contraction of the ventricles generate BP
BP is determined by:
1- CO
2- Blood Volume
3- Vascular Resistance
The higher the BP, the greater the Blood Flow
What is Vascular Resistance (R)?
R:
Opposition to Blood Flow due to friction between blood and the walls of blood vessels
The higher the R, the smaller the Blood Flow
R depends on:
1- Size of blood vessel lumen
2- Blood Viscosity
3- Total blood vessel length
What is Venous Return?
Venous Return:
Volume of blood flowing back to the heart through systemic veins
Occurs due to pressure generated by contractions of the heart’s Left Ventricle
Venous Return is assisted by:
1- Valves
2- Respiratory Pump
3- Skeletal Muscle Pump
What is Skeletal Muscle Pump?
Unique Valves and muscles contractions act as pumps
Allow backflow to feet and up against gravity
What is Velocity of Blood Flow?
Blood Flow:
Volume of blood that flows through a tissue in a given period of time
Blood Flow is inversely related to the cross-sectional area of blood vessels
What is Control of BP and Blood Flow?
Medulla Oblongata contains a Cardiovascular Center
CV Center:
Group of neurons that regulate:
1- HR
2- Contractility
3- Blood vessel diameter
Baroreceptors are important pressure-sensitive sensory neurons that monitor stretching of the walls of blood vessels and the Atria
What is Negative Feedback Loop of BP?
1- BP decrease
2- Baroreceptors in Carotid Sinus and Arch of Aorta stretch less which decreases rate of nerve impulse
3- CV Center in Medulla Oblongata increase Sympathetic stimulation and decrease Parasympathetic stimulation
4- Adrenal Medulla increase secretion of Epinephrine and Norepinephrine
5- Heart increase SV and HR which increase CO
6- Blood vessels constrict which increases Systemic Vascular Resistance
7- BP increase
What is the Effect on BP from Increased HR and Contractility?
1- Hormone:
Norepinephrine
Epinephrine
2- Effect on BP:
Increase
What is the Effect on BP from Vasoconstriction?
1- Hormone:
Angiotensin II
ADH
Norepinephrine
Epinephrine
2- Effect on BP:
Increase
What is the Effect on BP from Vasodilation?
1- Hormone:
Atrial Natriuretic Peptide (ANP)
Epinephrine
NO
2- Effect on BP:
Decrease
What is the Effect on BP from Blood Volume Increase?
1- Hormone:
Aldosterone
ADH
2- Effect on BP:
Increase
What is the Effect on BP from Blood Volume Decrease?
1- Hormone:
Atrial Natriuretic Peptide (ANP)
2- Effect on BP:
Decrease
What is Autoregulation of BP?
Autoregulation:
Ability of a tissue to automatically adjust its own blood flow to match its metabolic demand for delivery of oxygen and nutrients, and removal of wastes
Physical and chemical stimuli can lead to autoregulation
What are Pulse Points for Checking Circulation?
1- Superficial Temporal Artery:
Medial to ear
2- Facial Artery:
Mandible on line with corners of mouth
3- Common Carotid Artery:
Lateral to Larynx
4- Brachial Artery:
Medial side of Biceps Brachii
5- Femoral Artery:
Inferior to Inguinal Ligament
6- Popliteal Artery:
Posterior to knee
7- Radial Artery:
Lateral aspect of wrist
8- Dorsal Artery of Foot (Dorsalis Pedis Artery):
Superior to instep of foot
What is Shock and Hemoestasis?
Shock is an inadequate CO that results in failure of the CV System to meet the metabolic demands of body cells
Cell membranes dysfunction, cell metabolism is abnormal, and cell death may occur
What are the 4 Types of Shock?
1- Hypovolemic Shock:
Most common, bleeding a lot, diarrhea, low blood volume
2- Cardiogenic Shock:
After heart attack or not effective blood pumping (genetic/medication…)
3- Vascular Shock:
Injury in big vessels, dilate, septic shock, allergy
4- Obstructive Shock:
Physical obstruction, not pumping effectively
What are the Homeostatic Responses to Shock?
1- Activation of the Renin-Angiotensin-Aldosterone (RAA) System
2- Secretion of ADH
3- Activation of the Sympathetic division of ANS
4- Release of Local Vasodilators
What are Signs and Symptoms of Shock?
Clammy, cool, pale skin
Tachycardia
Weak, rapid pulse
Sweating
Hypotension (SBP<90mmHg)
Altered mental status
Decreased urinary output
Thirst
Acidosis
What are Circulatory Routes?
1- Systemic Circulation
2- Pulmonary Circulation
3- Hepatic Portal Circulation
4- Fetal Circulation
What is Hepatic Portal Circulation?
1- Blood goes from heart to Abdominal Aorta to Proper Hepatic Artery to Liver
2- Blood coming from Tributaries from portions of Stomach, Pancreas, and Large Intestines (and from Lower Mesenteric Vein) go to Splenic Vein
3- Blood coming from Tributaries from Small Intestine, and portions of Large Intestine, Stomach, and Pancreas go to Superior Mesenteric Vein
4- Blood from Splenic Vein and Superior Mesenteric Vein go to Hepatic Portal Vein (not a true vein since connects to Liver not heart)
5- Blood coming from Hepatic Portal Vein and Proper Hepatic Artery go to Liver
6- Blood from Liver go to Hepatic Veins then Inferior Vena Cava then Heart
What is Fetal Circulation Components that Change at Birth?
Mixing of oxygenated and deoxygenated blood
After birth no more mixing
1- Ductus Arteriosus:
Pulmonary Trunk and Arch of Aorta
Become Ligamentum Arteriosum at birth
2- Foramen Ovale:
Interatrial foramen between left and right Atria
Becomes Fossa Ovalis at birth
3- Ductus Venosus:
Between Portal Vein and Placenta
Becomes Ligamentum Venosum at birth
4- Umbilical Vein:
From Placenta to Ductus Venosum to Inferior Vena Cava
Becomes Ligamentum Teres at birth
5- Umbilical Arteries:
Between Placenta and Left and Right Internal Iliac Arteries
Becomes Medial Umbilical Ligaments at birth
What is Fetal Circulation?
1- Inferior Vena Cava
2- Right Atrium to Right Ventricle to Pulmonary Trunk to Lungs to Pulmonary Veins to Left Atrium
3- Right Atrium to Foramen Ovale to Left Atrium
4- Left Atrium to Left Ventricle to Aorta
5- Pulmonary Trunk to Ductus Arteriosus to Aorta
6- Aorta to Systemic Circulation
7- Systemic Circulation to Umbilical Arteries to Placenta
to Umbilical Vein to Ductus Venosus and Liver
8- Systemic Circulation and Ductus Venosus and Liver to Inferior Vena Cava
What is Development of Blood Vessels and Blood?
Blood vessels develop from isolated masses of Mesenchyme in the Mesoderm called Blood Islands
How does Aging affect CV System?
Aging results in:
1- Loss of compliance of the Aorta
2- Reduction in cardiac muscle fiber size
3- Progressive loss of cardia muscular strength
4- Decline in maximum HR
5- Increased Systolic BP
What are some High BP Imbalances?
1- Normal:
Systolic: <120
Diastolic: <80
2- Prehypertension:
Systolic: 120-139
Diastolic: 80-89
3- Stage 1 Hypertension:
Systolic: 140-159
Diastolic: 90-99
4- Stage 2 Hypertension:
Systolic: >160
Diastolic: >100
