Chapter 15

absorption (of water)

fluid movement into capillaries. Driven by colloid osmotic pressure in capillary. Net movement at venous end of capillary bed.

filtration

fluid out of capillaries into body. driven by hydrostatic pressure. Most common at arteriole end of capillary bed. higher pressure.

material exchange at capillaries

- movement of biomolecules across capillary walls - nutrients absorbed close to arterioles, water pulled into blood close to venules

Norepinephrine

hormone for vasoconstriction. released onto alpha 1 receptors by medulla oblongata.

Epinephrine

hormone for vasodilation. released onto beta 2 receptors by adrenal medulla.

Ph is greater

hydrostatic pressure and osmotic pressure at arteriole end of capillary bed

osmotic pressure is greater

hydrostatic pressure and osmotic pressure at venule end of capillary bed

respiratory pump

Pressure changes in the thoracic cavity during breathing helps to move blood against gravity from the abdominal region towards the heart.

low perfusion

if precapillary sphincters constrict, blood flow bypasses capillaries and flows through shunts.

during skeletal muscle exercise

blood diverted to more vital organs. Heart, lungs, (prioritized) muscles receive more blood flow.

High-density lipoprotein (HDL)

blood fat that helps transport cholesterol out of the arteries, thereby protecting against heart disease

low-density lipoprotein (LDL)

blood fat that transports cholesterol to organs and tissues; excess amounts result in the accumulation of fatty deposits on artery walls

arterioles and blood distribution

smooth muscles of arterioles are under autonomic control. most numerous blood vessels. Adjustments to arteriole diameter have the largest, systematic impact on TPR and blood pressure.

high perfusion

when precapillary sphincters are relaxed, blood flows through all capillaries in the bed

high

- (High or low) carbon dioxide in tissue will cause relaxation of sphincter muscles and increase blood flow to that tissue. - (High or low) body temperature in tissue will cause relaxation of the sphincter muscles and increase blood flow to that tissue.

low

- (High or low) oxygen in tissue will cause relaxation of sphincter muscles and increase blood flow to that tissue. - (High or low) pH in tissue will cause relaxation of sphincter muscles and increase blood flow to that tissue. - (High or low) nutrient in tissue will cause relaxation of sphincter muscles and increase blood flow to that tissue. - (High or low) blood pressure will cause relaxation of the sphincter muscles and increase blood flow through capillary beds.

decrease

- Angiotensin II and vasopressin cause a (increase or decrease) in arteriole diameter. - When arteries become partially blocked, as in arteriosclerosis, their elasticity will (increase or decrease), which causes an increase in overall blood pressure. - If there is a decrease in total blood volume, this will (increase or decrease) blood pressure. - Parasympathetic signaling to the heart will decrease cardiac output, which will (increase or decrease) blood pressure.

increase

- As diameter of a vessel decreases, resistance to flow and blood pressure will (increase or decrease). - If viscosity of blood were to (increase or decrease), more resistance would occur, and therefore blood pressure would increase - During development, the total length of blood vessels in the body increases, which will (increase or decrease) total peripheral resistance - Sympathetic signaling to the heart will increase the factor named in cardiac output, which will (increase or decrease) blood pressure.

parasympathetic

- Increased (parasympathetic or sympathetic) signaling via the Vagus nerve onto the heart will decrease heart rate and contractility, thereby lowing blood pressure. - (sympathetic or parasympathetic) to the heart's pacemaker will decrease, which will also allows blood pressure to rise.

sympathetic

- When blood pressure needs to be reduced, (parasympathetic or sympathetic) signaling to the heart's pacemaker and contractile cells of the ventricles is also decreased. - Blood pressure can also be decreased by decreasing (parasympathetic or sympathetic) signaling to alpha receptors at most arterioles

congestive heart failure

A condition resulting from the heart's inability to pump out all the blood that returns to it; blood backs up in the veins leading to the heart, causing an accumulation of fluid in various parts of the body

bradykinin and histamine

paracrine signals that increase blood pressure. The latter comes from mast cells.

dilation

Decreased sympathetic activity on alpha receptors at the arterioles causes what sort of response?

diffusion

Gases (CO2 and O2) and lipid soluble molecules move across the capillary wall, down their concentration gradient, by this process.

norepinephrine

High amounts of this neurotransmitter released onto alpha receptors on arteriole smooth muscle will cause them to constrict and blood pressure rises.

shunt

If all of the smooth muscle rings are closed in a capillary bed, blood will still flow from the terminal arteriole to the post-capillary venule through this kind of vessel.

constriction

Increased sympathetic activity on alpha receptors at the arterioles causes what sort of response?

transcytosis

Large hydrophilic molecules must move across the capillary wall by this process.

foam cells

Lipid-loaded white blood cells that have surrounded large amounts of a fatty substance, usually cholesterol, on the blood vessel walls. The characteristic initial lesion of atherosclerosis, also known as a fatty streak. Macrophages that have consumed lipid, seen in atherosclerosis pathogenesis

baroreceptors

Rising blood pressure stimulates increased signaling by _________ located in the carotid artery and aorta. These receptors sense stretch.

sensory neurons

Signals are sent from baroreceptors to the brain via ________.

total blood volume

Sweating will temporarily decrease this factor that affects blood pressure, whereas eating salty foods will cause it to temporarily increase.

Stroke Volume (SV)

The amount of blood ejected from the heart per beat is called _____. An increase in this factor will increase blood pressure; a decrease in this factor will decrease blood pressure.

lumen

The central, blood-containing space within a blood vessel

tunica intima

The innermost layer of a blood vessel is called the __________. It is mostly composed of a thin layer of endothelial cells.

medulla oblongata

The integration center for cardiovascular control is located in this area of the brain.

muscle pump

The mechanism known as the _________ includes skeletal muscles contracting and pressing on veins, which forces blood back towards the heart.

tunica media

The middle layer of a blood vessel is called the _________. It largely contains smooth muscle and elastin fibers.

tunica externa

The outermost layer of a blood vessel is called the __________. It is made of collagen fibers that act to protect the vessel and anchor it to neighboring structures.

fenestrations and clefts

These are physical characteristics of capillaries that allow materials to move from the lumen into the interstitial fluid. Small, water-soluble solutes like amino acids and sugars move across the capillary wall through these.

arterioles

These blood vessels are almost entirely made of smooth muscle. They also receive input from the autonomic nervous system. The frequency of these signals triggers constriction or dilation. Blood flow no longer pulses after moving through these vessels due to their high resistance.

veins

These blood vessels have the lowest internal pressure and also have one-way valves to prevent back flow. They also have the thickest outer layer.

venules

These blood vessels receive deoxygenated blood directly from capillary beds.

arteries

These vessels have the thickest middle layer, composed largely of smooth muscle and elastin to allow them to stretch.

capillaries

These vessels link arteries to veins and are the thinnest vessels in the cardiovascular system.

cardiac output

This factor affecting blood pressure is the total amount of blood pumped by the heart in a given time (usually per minute). It can be calculated by multiplying the heart rate by the stroke volume.

precapillary sphincter

This is a ring of smooth muscle that regulates blood flow through a capillary bed.

osmotic pressure

This pressure is the "pull" on water exerted by large, nondiffusible solutes like plasma proteins. It is this pressure that pulls fluid out of the interstitial space and into capillaries at the venous side of capillary beds.

hydrostatic pressure

This pressure is the pressure exerted by a fluid on the walls of its container. This pressure forces fluid out of the capillaries and into the interstitial fluid at the arterial side of a capillary bed.

more

When the precapillary sphincters relax (more or less) blood will flow into a bed of true capillaries. These sphincters can be regulated locally by several important chemical signals

arteriosclerosis

abnormal hardening of the walls of an artery or arteries

parasympathetic arterioles

all dilated about the same diameter. - equal distribution of blood to organs - no distribution priority

Metarterioles (shunts)

allow blood to pass from arterioles to venules. Do not have precapillary sphincters.

sympathetic arterioles

arterioles that lead to less vital organs are constricted, while those leading to the heart, lungs, and muscles are dilated.

Total Peripheral Resistance (TPR)

as friction goes up (due to three key factors), more pressure must be applied by the heart to move the blood around the body. This situation describes which key factor that affects blood pressure.

lymphatic system

collects excess fluid and proteins, which returns them to the circularity system at the vena cava. - picks up fat absorbed by the digestive system, transfers it to CVS. - serves as a filter for pathogens.

atherosclerosis

condition in which fatty deposits called plaque build up on the inner walls of the arteries. The plaque can burst, triggering a blood clot.

precapillary sphincters

contain chemoreceptors to detect blood content for local capillary vasodilation/constriction.

arteriole dilation

determines delivery of blood to organs. Main focus of feedback loops that increase blood circulation.

edema

fluid accumulation in tissue. Can happen either from lymph drainage damage, or if the filtration rate is greater than absorption rate.

pulmonary edema

fluid in the air sacs and bronchioles

vasodilation

epinephrine by sympathetic nervous system (adrenal medulla) binds to beta 2 receptors. Less numerous. Works in combination with vasoconstriction to concentrate blood pressure toward vital organs during exercise.

acidosis

excessive acidity of body fluids

Hyperkalemia

excessive potassium in the blood

- increase in hydrostatic pressure in vessels (Increase filtration) - decrease in plasma protein concentration (due to liver failure) decreases absorption - increase in interstitial proteins (normally zero!) due to tissue damage. Decreases absorption.

factors that affect absorption rate (3)

Natriuretic peptides

paracrine signal that reduces blood pressure in atrial myocardium.

decrease oxygen, increase carbon dioxide, hydrogen ions, and potassium ions

increase blood flow to match metabolism. Hormone and neurotransmitter effects.

Angiotensin II

increase blood pressure. Hormone.

vasopressin

increase in blood pressure in a hemorrhage. Neurohormone.

angiogenesis

increased capillary density. Related to meeting the metabolic demands of the tissue. Increases with exercise.

vasocontriction of veins

increases venous return and blood pressure. Exercise increases sympathetic stimulation, which tenses/fortifies veins, which allows for efficient blood conduction.

partial pressures of carbon dioxide and oxygen, concentration of glucose, temperature.

local tissue conditions that control capillary blood flow.

serotonin, vasopressin, angiotensin 2, bradykinin, histamine, natriuretic peptides, gas levels.

localized smooth muscle diameter modulators

continuous capillaries

located all over the body except for where fenestrated capillaries are located. Have leaky junctions that allow water and small dissolved solutes (sodium, chloride, glucose) to pass through.

fenestrated capillaries

located in the kidneys (urinary system) and GI tract. Have large pores, which make them more "leaky" than continuous capillaries. Allow for maximum exchange.

at rest

most of blood id being sent to the kidneys and digestive tract. - housekeeping, toxin removal - ignore skeletal muscle here :)

serotonin

muscle relaxation. neurotransmitter.

vasoconstriction

norepinephrine by sympathetic nervous system binds to alpha 1 receptors. Arterioles are more numerous. Increases TPR, which increases blood pressure.

tonic

the control system related to arteriole dilation and constriction

autoregulation

the process by which organs and tissues self-regulate blood delivery.