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Lecture Test 2
Terms in this set (54)
Understand the role of the central nervous system and autonomic nervous system in regulating heart rate and stroke volume.
The CNS has a feedback system to ensure that the body has sufficient oxygen and gets rid of CO2. It can alter CO to make sure the body stays in homeostasis with oxygen. It doesn't start or stop the heart from beating, but it can adjust heart rate and stroke volume if needed. It acts like a dimmer switch vs acting like an on/off switch (like skeletal muscles)
1. Chemoreceptors: measures CO2, H2O and pH. Found in Carotid Sinus and Aortic Sinus
2. Baroreceptors: measures pressure. Found in Carotid Sinus and Aortic Sinus.
Cardioregulatory center in medulla oblongata.
1. Sympathetic neurons: Effect HR and SV
2. Parasympathetic neurons: Effect HR only
Describe ways in which the body attempts to compensate for low and high cardiac output
NEURAL REGULATION OF CO
Sympathetic nervous system: Increases CO
Regulates Heart Rate: Has neurons that make connections with SA Node
Regulates Stroke Volume: Has neurons that make connections with ventricle muscle
Parasympathetic nervous system: Decreases CO
Regulates Heart Rate: Has neurons that make connections with SA Node
HORMONAL REGULATION OF CO
Neurotransmitters bath SA node -- can turn both sympathetic and parasympathetic up or down depending on need (like hot water and cold water in a bath)
in a normal, resting heart, the parasympathetic input is dominant. Resting HR is lower than the natural rate of SA Node
List the major types of blood vessels as blood flows from the left ventricle to the right atrium.
1. Elastic arteries
2. Muscular arteries
6. Larger Veins
7. Vena Cava
8. Right Atrium.
Identify the major functions of each of these vessels within the systemic circuit.
Elastic arteries: Are the first arteries taking blood away from the heart. Can stretch due to pressure when blood is pumped. Returns to original shape when ventricles are in diastole.The elastic rebound keeps blood moving when ventricles are in diastole.
Muscular arteries: Most numerous arteries in the body. Have a thick tunica media made of smooth muscle that distributes blood to organs and tissues.
Arterioles (resistance vessels): Smallest arteries -- have no tunica externa.
Feed blood into capillaries
Controls blood pressure.
Contraction/relaxation of arterioles causes vasoconstriction and vasodilation.
Vasionrestriction and vasodialation
Controls blood flow
Place of exchange between arteries and veins.
O2, CO2, and nutrients are exchanged
Describe the structure of a typical blood vessel wall including the types of tissues found in the layers.
Tunica Intima: Endothelium (simple squamous epithelium) and Areolar tissue. Innermost layer that surrounds lumen of the blood vessel.
Tunica Media: Smooth Muscle with Collagen and Elastic fibers.
Tunica Externa: Collagen and Elastic fibers. Attaches the vessel to other structures.
Describe the differences in structure between arteries and veins and relate each difference to the functions of arteries and veins.
Arteries have a thicker wall than veins due to a thicker tunica media.
Arteries have a smaller lumen than veins. Blood going through arteries at a higher pressure than veins. Veins have lower pressure but higher volume.
Veins have a one-way valve to prevent backflow of blood. This is because the pressure in veins is lower than in the arteries, and it helps fight against gravity.
Briefly describe the role of diffusion in the exchange of oxygen, carbon dioxide, ions, and nutrients at the capillary beds. Which molecules move more quickly? Which molecules will not cross the capillary wall?
Capillaries only have an endothelium and basement membrane so that molecules can be exchanged quickly. All molecules are exchanged at the capillaries. Fat soluble things (steroid hormones, O2, CO2 will go straight across the membrane via simple diffusion and will be the fastest. Small ions (Na+, K+, H2O, amino acids, glucose will fit through the gaps between the cells. They rely on the blood pressure to push them out. Big molecules like proteins cannot cross and are going to stay in the blood. They must move through endocytosis and exocytosis.
Compare the structure, function, and location of continuous and fenestrated capillaries and sinusoids. Describe the types of compounds that will diffuse across each type
Most capillaries. Endothelial cells do not contain any holes. There are gaps between the cells but the cells themselves are complete. Water soluble things must fit through those gaps. Rules for diffusion apply. Water, small solutes, lipids, CO2 and O2 go across freely. Cells, cell fragments, most plasma proteins will stay in the blood.
Endothelial cells have tiny holes in them. Found in places where rapid exchange is needed. They don't let bigger things go through; they let small things go through faster. Rules for diffusion apply. Found in intestines, kidneys, endocrine organs.
Have big gaps in between the endothelial cells. Will let any solute across. Sometimes they will let whole cells and platelets across. Found in bone marrow, liver, spleen. Have a lot of phagocytes to kill bacteria that could leave the blood and spread to the rest of the body.
Describe how adequate blood flow is maintained in veins in spite of low pressures.
Veins get some help from:
One-way valves and push fluid up to the heart.
Deep veins run between skeletal muscles. Everytime the muscles contract, it pushes on the vein and pushes the fluid towards the heart
Breathing -- the increase and decrease of pressure on vena cava and pushes the blood back into the heart
Define blood flow
The amount of blood flowing through a vessel, organ, tissue, or system at any given time. Measured in mL/min. Determined by the balance between blood pressure and resistance.
F= Changes in pressure (top # - bottom #) / resistance.
Define venous reserve and discuss its importance during hemorrhaging.
ou have more blood in the veins than any other place in the body. 60-70% of the blood in the veins. The veins acts like a reservoir of blood. If your blood volume and blood pressure goes up, the veins will stretch and accommodate some of that blood so your arterial blood pressure doesn't increase as much. If a person goes into shock or blood pressure drops a lot, the veins will constrict and push blood from the veins into the arteries to keep blood pressure up. The extra blood in the veins that can be pushed up to regulate blood pressure is called venus return.
The force exerted on a vessel wall by the blood inside. Measured in mmHg.
The opposition to blood flow. Caused by friction between the blood and blood vessel wall.
Blood flows from an area of high pressure to an area of low pressure.
List the four factors that contribute to resistance. Discuss the effect of each factor on blood flow and blood pressure under normal and abnormal conditions.
1 Diameter of blood vessel: Decreasing the diameter by 2 increase the pressure by 16
2. Length of blood vessel: Increasing the length by 2 increases the pressure by 2
3. Turbulence of blood vessel: More turbulence = more resistance
4. Blood Viscosity: More viscosity = more resistance
Give values for pressure at key points within the systemic circuit (aorta, entering capillary beds, exiting capillary beds, vena cava).
Normal BP: 120/80
Normal MAP: 93
Pressure entering capillary beds: 35
Pressure exiting capillary beds: 18
Pressure at Vena Cava: 2
Describe the way that blood flow is maintained during ventricular diastole.
Blood flow is maintained during ventricular diastole due to the elastic rebound of the arteries. As they return from their stretched position during ventricular diastole, the snap back of the elastic return pushes the blood through and that maintains blood flow during diastole.
Describe the ways that blood pressure is measured clinically.
Blood pressure is measured clinically at a large artery (usually brachial). Is reported systolic/diastolic.
Define pulse pressure
Pulse Pressure: Difference between systolic and diastolic blood pressure
MAP: diastolic pressure +⅓ pulse pressure
Example: Blood pressure of 120/80 mmHg:
80 + 120-80/3
Describe the effects of chronic hypertension on the heart and blood vessels.
Hypertension increases the workload on the heart. Ventricular mass increases, which can lead to lowered CO.
Hypertension increases pressure on arteries, which cause damage that accelerates development of arteriosclerosis.
Identify compounds/neurotransmitters that cause vasodilation and vasoconstriction.
Norepinephrine: Causes vasoconstriction of systemic arterioles.
Aceytocholine: Causes a release of nitric oxide, which causes vasodilation
List and describe the elements of the neural reflex arc responsible for rapid regulation of blood pressure and cardiac output.
Chemoreceptors and Baroreceptors found in the Carotid Sinus and Aortic Sinus send signal to Medulla Oblongata
Medulla Oblongata has two groups of neurons:
Vasomotor center: Control blood pressure
Cardioregulatory center: Controls HR and SV
Vasomotor Center: Neurons send signals to the sympathetic neurons that control blood pressure and flow. They signal arterioles causing vasoconstriction or vasodilation, therefore controlling pressure. They use norepinephrine to cause vasoconstriction.
Cardioregulatory Center: Neurons regulate both HR and SV
HR: Regulated by both sympathetic and parasympathetic
SV: Regulated by sympathetic only
Define vasomotor tone.
There is always a baseline amount of vasoconstriction due to vasomotor neurons in the medulla and sympathetic neurons that are active all the time
Identify effects of agents that suppress central nervous system activity on HR, SV, and blood pressure.
HR: Goes up due to lack of parasympathetic autonomic tone
SV: Goes down due to lack of sympathetic autonomic tone
Vasodialation due to lack of sympathetic vasomotor tone
BP goes down
Describe the process of autoregulation in regulating blood flow
Autoregulation is local changes in patterns of blood flow in individual capillary beds. Precapillary sphincters open or close based upon chemical changes in the interstitial fluid.
List local vasodilators.
-High CO2 and low O2
-High extracellular K+
-Histamines (released from inflammation)
-Elevated local temperature
Contrast the effects of O2 and CO2 on systemic vessels and pulmonary vessels.
Low O2 and High CO2: Blood pressure is too low. CO and blood flow increases
High O2 and Low CO2: Blood pressure is too high. CO and blood flow decreases
Epinepherine / Norepinepherine:
Used for rapid change to raise BP. Released by the adrenal gland. Acts on the SA Node and Ventricular Muscle to increase CO. Causes vasoconstriction.
Used for slow change to increase BP. Released from pituitary gland in response to decreased BP. Increases water retention at the kidneys, causing an increase in blood volume.
ANP and BNP
Used for rapid change to lower BP. Released from the heart in response to increased stretching of the heart muscle. It's the only hormone to directly lower BP. Causes vasodilation to decrease BP.
Used for slow change to increase BP. Released from adrenal gland in response to electrolyte balance or to angiotensin II. Reduces water loss at the kidneys by reducing sodium loss. Reduced water loss increases blood volume.
Used for slow change to increase BP. Released from kidneys in response to low renal blood flow. Stimulates RBC production. Increases oxygen-transport capacity. Slowly increases BP.
Identify conditions that may cause circulatory shock.
Hypovolemic shock (loss of blood volume, often due to hemorrhage or severe vomiting) Vascular shock (loss of blood pressure, often due to anaphylactic shock ,neurogenic shock, or septic shock.
Used for both fast and slow changes to increase BP. Activated by the kidneys when renal blood pressure decreases. Short term effects: causes vasoconstriction, increases CO. Long term effects: Increases aldosterone production, increases ADH production, increases thirst to increase blood volume.
Describe the composition of whole blood and of blood plasma.
Whole Blood is made of:
Formed Elements: RBC, WBC, Platelets
Plasma: Made of
Describe short and long-term mechanisms that the body will use to compensate following circulatory shock.
Short term mechanisms: Raising BP by increasing CO, vasoconstriction, utilizing venus return, secretion of norepinephrine and epinephrine.
Long term mechanisms: Release of hormones like Angiotensin II, EPO, Aldosterone, and ADH to increase blood volume.
Define filtration (or CHP) and resorption (or BCOP). Describe how CHP and BCOP interact to create NFP at the capillary beds.
Filtration (CHP): Movement of fluid out of the capillary. Caused by blood pressure
Reabsorption (BCOP): Movement of fluid into the capillary. Caused by osmosis
NFP= CHP - BCOP
Describe the pathway for overall fluid movement through the body.
Moves from blood to interstitial fluid in tissues at the vascular capillaries
It's picked up by lymphatic capillaries
Returned to venous blood through lymphatic vessels to subclavian veins
Describe the location and structure of lymphatic capillaries and lymphatic vessels.
They are found in every tissue where there is blood supply.
Lymphatic capillaries are found near vascular capillaries.
They are a little larger than vascular capillaries. They work at lower pressure.
The wall is just endothelial cells that overlap to form one way valves. Let fluid and things in but don't let them back out.
They will let anything across.
The capillaries join into larger lymphatic vessels, which join into even larger lymphatic vessels.
2 sets: deep lymphatic (run right next to deep veins) and superficial vessels
All fluid drains into either the thoracic duct (drains into the left subclavian vein) or right lymphatic vessel (drains into the right subclavian vein).
Define edema and loss of turgor.
Edema: Build of interstitial fluid above normal. May be caused by local damage to blood vessel wall, blockage of lymphatic vessels or lymph nodes, or changes in either CHP or BCOP.
Loss of Turgor: Interstitial fluid below normal levels. May be caused by: dehydration, changes in either CHP or BCOP.
Bulge in the arterial wall, caused by a weak spot in elastic fibers. Blood pressure may rupture vessel
Describe how changes in CHP or BCOP will cause edema or loss of turgor.
If CHP goes up and BCOP stays the same-- More fluid flows out of blood plasma and causes Edema
If CHP goes down and BCOP stays the same -- Less fluid flows out of blood plasma and causes Loss of Turgor
If CHP stays the same and BCOP goes up -- More fluid goes back into the blood and causes loss of turgor
If CHP stays the same and BCOP goes down -- Less fluid goes back into the blood and causes Edema
Lipid deposits in tunica media following damage to endothelium. Often caused by high lipids in the blood.
Any thickening of arterial walls. Will restrict blood flow. Can result from calcium deposits in tunica media and Atheroscierosis
Enlarged, swollen, and twisting veins, often appearing blue or dark purple. They happen when faulty valves in the veins allow blood to flow in the wrong direction or to pool.
A blood clot
Deep Vein Thrombosis (DVT)
A blood clot that is formed in a deep vein
Abnormally high blood pressure -- greater than 140/90 mmHg
Abnormally low blood pressure.
Occurs when the body is not getting enough blood flow and cells do not get enough oxygen.
Build up of interstitial fluid above normal
Edema caused by blockage of lymph drainage
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