Autoregulation

What chemical changes signal smooth muscle cells in the precapillary sphincters to relax and blood flow to increase?

As the cell takes up and uses 02, tissue o2 slows down, c02 rises, and Ph FALLS

What happens in short term regulation?

E and NE from adrenal medullae stimulate CO and peripheral vasoconstriction

Why does blood pressure increase during exercise?

Blood pressure increases during exercise because (1) cardiac output increases and (2) resistance in "nonessential" visceral tissues increases.

Explain the role of aldosterone and ADH in long-term restoration of blood volume.

Both aldosterone and ADH promote fluid retention and reabsorption at the kidneys, preventing further reductions in blood volume.

Chemo receptors monitor what?

chemical composition of arterial blood or they can be on the surface of the medulla oblongata monitoring the composition of CSF

What responds to changes in chemical composition?

chemoreceptor reflexes

Throughout embryonic and fetal stages, lungs are ----

collapsed

Embryonic lungs are ....

collapsed and nonfunctional. All of the nutrients and respiratory needs are provided by diffusion across the placenta

What else can trigger the relaxation of precapillary sphincters increasing blood flow?

histamine at an injury site during inflammation, release of nitric oxide by capillary endothelial cells

These adjustments did what?

increased CO and increased peripheral resistance- work together to elevate blood pressure

The foramen ovale does what?

interatrial opening and is associated with a long flap that acts as a valve. Blood can flow freely from the right atrium to the left atrium, but any backflow closes the valve and isolates the two chambers.

When CO and peripheral resistance lower, what happens?

lowers blood pressure

When blood pressure rises, the increased output from baroreceptors alters activity in the cardiovascular center of the ----

medulla oblongata

The cardiovascular center detects changes in tissues demand by what?

monitoring arterial blood, blood pressure, pH, and dissolved gas concentration

--- feedback regulates these reflexes: the stimulation of a receptor by an abnormal condition leads to a response that counteracts the stimulus and restores normal conditions

negative

If autoregulation fails to normalize tissue conditions, then what happens?

neural and endocrine processes are activated

When there are high concentrations, they can affect arterioles (increasing or decreasing blood flow to all the capillary beds in a given region). This can trigger what?

neural response because significant changes in blood flow to one region of the body immediately affect circulation to other regions

extensive vasodilation

occurs as the rate of o2 consumption in SM increases. Peripheral resistance drops, blood flow through the capillaries increases, and blood enters the venous system at a faster rate

How does it increase CO?

reduced baroreceptor activity stimulates the cardioacceleratory center and inhibits the cardioainhibitory center, and stimulates the vasomotor center. cardioacceleratory will stimulate sympathetic neurons to SA and AV node. The sympathetic stimulation increases HR and SV. CO is increased immediately

Carotid sinus baroreceptors trigger what?

reflexes that maintain adequate blood flow to the brain. They are sensitive because blood flow to the brain must remain constant

What is the endocrine process?

releases hormones that enhance short term adjustments and direct long term changes in cardiovascular performances

Chemoreceptor output also affect what?

respiratory centers in the medulla oblongata

Venous return increases as

skeletal muscle contraction squeeze blood along the peripheral veins. A faster breathing rate also pull blood into the venae cavae by the respiratory pump

The --- muscle of the precapillary sphincters respond to what?

smooth muscles respond automatically to certain changes in the local environment ex. when o2 is abundant, smooth muscle cells in sphincters contract and slow the flow of blood.

Baroreceptors monitor the degree of what?

stretch in walls of expandable organs

What stimulate the constriction of precapillary sphincters?

vasoconstrictors

Inhibition of vasomotor center leads to what?

vasodilation of arterioles reducing peripheral resistance

What are factors that promote the dilation of precapillary sphincters?

vasodilator

CO rises in response to...

1. the rise in venous return 2. atrial stretching Increased CO keeps pace with the greater demand. Arterial pressures are maintained despite the drop in peripheral pressure

The --- center of the medulla oblongata control what?

-vasomotor diameters of arterioles through sympathetic innervation

What are the factors that affect tissue blood flow?

1. CO 2. Peripheral resistance 3. blood pressure

The goal of cardiovascular regulation is to ensure that these blood flow changes take place....

1. appropriate time 2. right area 3. without drastically altering blood pressure and blood flow to vital organs

At higher levels of exercise, what happens?

1. cardiac and vasomotor centers activate the sympathetic nervous system 2. CO increases to max levels 3. Blood pressure increases 4. pattern of blood distribution shifts

The cardiac center has what two centers?

1. cardioacceleratory that increases CO through sympathetic innervation 2. cardioinhibitory that reduced CO through parasympathetic innervation

Where are baroreceptors found?

1. carotid sinus (expanded chambers near the bases of the neck) 2. aortic arch 3. right atrium

The chemoreceptors involved are sensory neurons. Where are they found?

1. cartoid bodies (neck heart cartoid sinus) 2. aortic bodies

This change will inhibit the cardioacceleratory center, stimulate the cardioinhibitory center, and inhibit the vasomotor center. What are the two effects?

1. decrease in CO (under the command of the cardioinhibitory center, the vagus nerves release ACh at the SA node. Parasympathetic stimulation reduces the rate and force of cardiac contractions 2. widespread peripheral vasodilation. The inhibition of the vasomotor center leads to dilation of peripheral arterioles in the body

When you exercise, what happens?

1. extensive vasodilation 2. venous return increases 3. CO rises

When blood pressure falls below normal, baroreceptor output is reduced. This change has to major effect that work to raise blood pressure. What are they?

1. increase in CO 2. widespread peripheral vasocontriction (vasomotor activity, also carried by sympathetic motor neurons produces rapid vasoconstriction. This changes increases peripheral resistance)

An increase in the --- rate speeds up venous return through the action of the --- pump

1. respiratory 2. respiratory

When chemoreceptors are activated by a decrease in pH or in plasma o2, or increase in c02. What happens?

1. stimulates cardioacceleratory and vasomotor center 2. elevates atrial pressure and increases blood flow through the peripheral tissues 3. rise in blood flow and blood pressure is associated with an elevated respiratory rate

Under normal conditions...

CO is stable, peripheral resistance in tissues is adjusted by precapillary sphincters to control local blood flow

Venous feedback gradually increases what?

CO which supports faster blood flow to SM, cardiac muscle, and the skin

What is autoregulation?

Changes in tissue conditions act directly on precapillary sphincters to alter peripheral resistance, producing local changes in the pattern of blood flow within capillary beds. It causes immediate, localized homeostatic adjustment

Aortic baroreceptors monitor blood pressure where?

In the aortic arch. Any changes trigger the aortic reflex, will adjust blood pressure to maintain adequate blood through the systemic circuit

How would applying slight pressure to the common carotid artery affect your heart rate?

Pressure on the common carotid artery would decrease blood pressure at the carotid sinus (the location of the carotid baroreceptors). This decrease would cause the cardioacceleratory center in the medulla oblongata to increase sympathetic stimulation. The result would be an increase in the heart rate.

What effect would the vasoconstriction of the renal artery have on blood pressure and blood volume?

Renal artery vasoconstriction would decrease both blood pressure and flow at the kidney. In response, the kidney would increase the amount of renin it releases, which in turn would lead to an increase in the level of angiotensin II. The angiotensin II would bring about both increased blood pressure and blood volume.

What is venoconstriction?

Strong stimulation causes the constriction of peripheral veins. Increases peripheral resistance

Name the structures in the fetal circulation that stop functioning at birth. What becomes of these structures?

Structures specific to fetal circulation include the two umbilical arteries, an umbilical vein, the ductus venosus, the foramen ovale, and the ductus arteriosus. In the newborn, the foramen ovale closes and persists as the fossa ovalis, a shallow depression. The ductus arteriosus persists as the ligamentum arteriosum, a fibrous cord. The umbilical vessels and ductus venosus persist throughout life as fibrous cords.

What is neural processes?

The NS responds to changes in arterial pressure or blood gas levels at sensed at specific sites. Then ANS will adjust CO and peripheral resistance

What happens when cells are active?

The circulation to that region must increase to deliver the oxygen and nutrients they need to carry away the wast products and carbon dioxide they generate

Name the immediate and long-term problems related to the cardiovascular response to hemorrhaging.

The immediate problem during hemorrhaging is maintaining adequate blood pressure and peripheral blood flow. The long-term problem is restoring normal blood volume.

The interatrial and interventricular septa of the heart develop --- in the fetus, but the interatrial partition remains --- until birth

The interatrial and interventricular septa of the heart develop early in the fetus, but the interatrial partition remains functionally incomplete until birth

A blood sample taken from the umbilical cord contains high levels of oxygen and nutrients, and low levels of carbon dioxide and waste products. Is this sample from an umbilical artery or from the umbilical vein? Explain.

This blood sample was taken from the umbilical vein, which carries oxygenated, nutrient-rich blood from the placenta to the fetus

Name the three vessels that carry blood to and from the placenta.

Two umbilical arteries carry blood to the placenta, and one umbilical vein returns blood from the placenta. The umbilical vein drains into the ductus venosus within the fetal liver. (Remember, arteries carry blood away from the heart, and veins carry blood to the heart.)

Describe the actions of vasodilators and vasoconstrictors.

Vasodilators increase blood flow locally (that is, through their tissue of origin) by promoting dilation of precapillary sphincters. Vasoconstrictors decrease local blood flow by constricting precapillary sphincters.

What is the cardiovascular center of the medulla oblongata responsible for?

adjust CO and peripheral resistance to maintain adequate blood flow to vital tissues and organs

What do short term responses do?

adjust CO and peripheral resistance to stabilize blood pressure and blood flow to tissues

What do long-term adjustments involve?

alterations in blood volume that affect cardiac output and transport of oxygen and carbon dioxide to and from active tissues

Long term cardiovascular regulation involves other hormones like

antidiuretic hormone (ADH), angiotensin II, erythropoietin (EPO), and atrial natriuretic peptide (ANP)

What responds to changes in blood pressure?

baroreceptor reflexes

Baroreceptors initiate what?

baroreceptor reflexes that is an autonomic reflex that adjusts CO and peripheral resistance to maintain normal arterial pressures

vasodilators and vasoconstrictors control what?

blood flow in a single capillary bed

A rise in blood pressure at the atrium means what?

blood is arriving at the heart faster than it is being pumped out. Atrial baroreceptors correct the situation by stimulating the cardioacceleratory center, increasing CO until the backlog of venous blood is removed. Atrial pressure than returns to normal

Chemoreceptor reflexes respond to changes in what?

c02, o2, ph levels in the blood and CSF.