- A collective term that refers to all of the blood vessels of the body.

- vasculature

Name the blood vessels that comprise the vasculature transport blood from the heart to the cells of the body and then back to the heart.

heart → arteries → arterioles → capillaries → venules → veins → back to the heart

Arteries.

- outer layer

- connective tissue that is composed of collagen fibers and elastic fibers

- tunica externa

Arteries.

- middle layer

- consists of:

1. smooth muscle

2. external elastic lamina

-- connective tissue that is composed of elastic fibers

- tunica media

Arteries.

- inner layer

- consists of: endothelium, basement layer, and internal elastic lamina

- tunica interna

- single layer of epithelial cells

- surrounds the lumen, which is the hollow space where the blood is located

- This term always refers to the epithelial cells that line the lumen of a blood vessel or a lymphatic vessel.

- endothelium

A thin layer of connective tissue that is composed of collagen fibers

- basement membrane

Connective tissue that is composed of elastic fibers

- internal elastic lamina

Arteries carry oxygenated blood from the heart to ________. 

- arterioles

The structure of an arteriole is intermediate between that of an artery and a capillary; what three layers does an arteriole contain?

- an inner layer of endothelium

- a middle layer of basement membrane

- an outer layer of smooth muscle

Arterioles carry oxygenated blood from the ______ to the ______.

- arteries

- capillaries

Most cells in the body are located near at least one capillary; this is due to the fact that capillaries are the most numerous type of blood vessel. How many exist is the body?

- about 10 billion of them exist in the body

Which tissues in the body lack capillaries? How do they receive nutrients?

- epithelia, cartilage, and the cornea and lens of the eye are all avascular

- Epithelia and cartilage receive nutrients via diffusion from nearby connective tissues.

- The cornea and lens receive nutrients via diffusion from the aqueous humor.

Capillaries connect ______ to ______; in order to accomplish this goal, capillaries interact with one another to form _________.

- arterioles

- venules

- capillary beds

A capillary bed consists of what 2 major types of vessels?

- capillaries

- metarteriole

A ________ is a blood vessel that branches off of an arteriole, courses through the capillaries, and then empties into a venule. 

- metarteriole

The distal end of the metarteriole is called a __________.

- thoroughfare channel

The metarteriole functions as a __________ that bypasses the capillaries when the body cells near the capillaries are not in need of any nutrients.

- vascular shunt

Around the junction of the metarteriole and the capillaries are rings of smooth muscle called ___________ that function to regulate blood flow into the capillaries.

- precapillary sphincters

1. When the precapillary sphincters are _____ (i.e. the smooth muscle is relaxed), blood flows into the capillaries and into the metarteriole.

-- This is the case when nearby body cells are in need of nutrients (i.e. O2, glucose, etc).  2. When the precapillary sphincters are _____ (i.e. the smooth muscle is contracted), blood flows only into the metarteriole and bypasses the capillaries.

--This is the case when nearby body cells are satisfied with existing nutrient supplies and are no longer in need of any more blood.

1. open

2. closed

A capillary is a microscopic blood vessel that consists of 2 layers. What are they?

- endothelium (inner layer)

- basement membrane (outer layer)

- Single layer of epithelial cells

- This* of a typical capillary contains pores (holes) in the form of ________ and ________.

- endothelium

- intercellular clefts

- fenestrations

Pores that exist between the endothelial cells of a capillary.

- intercellular clefts

Pores that run through individual endothelial cells of a capillary.

- fenestrations

This* of a capillary is also porous, but these pores have no specific names.

- basement membrane

_________ are the only blood vessels that permit the exchange of gases, nutrients, and wastes between the blood and the cells of the body, transforming oxygenated blood into deoxygenated blood.

- Capillaries

True or False: Only relatively small molecules (such as gases, H2O, ions, glucose, amino acids, and hormones) are able to move across capillary walls.

True

What substances typically diffuse across capillary walls directly through the lipid bilayer of endothelial cell plasma membranes?

- lipid-soluble (hydrophobic)

- O2, CO2, steroid hormones

Most of these substances, which include ions and polar molecules such as glucose and amino acids, pass across capillary walls through the pores (intercellular clefts and fenestrations).

- water-soluble (hydrophilic)

______  can diffuse across capillary walls in all possible ways: by moving through the pores of the capillary wall or  by moving through endothelial cell plasma membranes.

- Water

- Recall that although water is a hydrophilic molecule, it is small and has no charge.

Which substances are mostly too large to diffuse through the pores of capillary walls and are therefore confined to the blood?

- blood cells and plasma proteins (albumins, fibrinogen, etc.)

____________ are able to move across the capillary wall via transcytosis (endocytosis followed by exocytosis), allowing protein hormones to leave the bloodstream and then bind to specific receptors on their target cells.

- Protein hormones

Note that any H2O that diffuses out of the blood into the interstitium (the spaces between and around body cells) is called __________.

- interstitial fluid (ISF)

- Therefore, interstitial fluid is a type of extracellular fluid located between and around body cells, while blood is a type of extracellular fluid located within blood vessels.

- The H2O in the interstitial fluid can diffuse into body cells if needed.

- If there is too much H2O in the interstitium, the excess interstitial fluid drains into a nearby lymphatic vessel (usually a lymphatic capillary) that transports the fluid back into the blood.

The structure of a venule is intermediate between that of a capillary and a vein; hence, a venule contains an inner layer of ________, a middle layer of ________, and a thin, outer layer of ________. 

- endothelium

- basement membrane

- smooth muscle

Venules transport ____________ from the capillaries to the veins. 

- deoxygenated blood

A vein consists of what 3 layers?

1. tunica externa

2. tunica media

3. tunica interna

Veins.

- outer layer

- connective tissue that is composed of collagen fibers and elastic fibers

- tunica externa

- The tunica externa of a vein is thinner than the tunica externa of an artery because it contains less connective tissue.

Veins.

- middle layer

- consists of smooth muscle

- tunica media

- The tunica media of veins is thinner than the tunica media of arteries because it has less smooth muscle

Veins.

- inner layer

- What does this layer consist of?

- tunica interna

- consists of endothelium and basement membrane

Many veins of the limbs contain valves; a __________ consists of folds of the tunica interna that function to prevent backflow of blood.

- venous valve

1. Contractions of __________ surrounding the veins help push blood up the veins; the valves prevent backflow of blood, making sure that the blood returns to the heart.

2. This ______________ is vital to this process of __________.   

1. skeletal muscles

2. skeletal muscle pump; venous return

Veins transport __________ from venules to the heart.

- deoxygenated blood

Which has more connective tissue, arteries or veins?

- Arteries

Which has less smooth muscle, arteries or veins?

- Veins

Which contains valves, arteries or veins?

- Veins (especially in the limbs)

Describe the overall appearance of arteries and veins.

- Arteries: round, thick wall

- Veins: thin wall, often collapse

1. When a blood vessel undergoes ________, the smooth muscle within its wall contracts. 2. Describe what happens with the blood vessel lumen.

1. vasoconstriction

2.  The blood vessel lumen becomes smaller, which causes a reduction in blood flow.

What are the only blood vessels that do not vasoconstrict or vasodilate? Why?

- Capillaries; this is due to the fact that capillaries lack smooth muscle in their walls.

–The smooth muscle in the precapillary sphincters can constrict or dilate in order to regulate blood flow through the capillary.

Give the % of blood in each cardiovascular component.

1. heart

2. systemic arteries and arterioles

3. systemic capillaries

4. systemic veins and venules

5. pulmonary blood vessels

1. 7%

2. 13%

3. 7%

4. 64%

5. 9%

Most of the blood volume at any given time is found in the ____________; consequently, these* are called the _________ of the body. 

- systemic veins and venules

- blood reservoirs

The ability of an object to stretch.

- Compliance

- Examples:

-- rubber band: has a high compliance because it can be easily stretched

-- crowbar: has a low compliance because it is not easily stretched

Veins have a _____ compliance because they contain thin walls that are easily stretched; consequently, veins are called the ___________.

- high

- capacitance elements

Even though veins contain the majority of blood in the body, venous pressure is _______ (typically near ___mmHg in the large great veins like the inferior vena cava and superior vena cava).

- very low

- 0

1. Arteries have a ____ compliance compared to veins because arteries contain thick walls that are not as easy to stretch.

2. Consequently, arterial pressures are _________, varying between ___mmHg and ___mmHg.

- low

- typically high; 110; 70

- Hence, an increase in the blood volume of arteries causes an increase in arterial pressure because the arteries cannot stretch as much as the veins.

The pressure that blood exerts on the walls of a blood vessel.

- blood pressure

Blood pressure is usually measured in the brachial artery using a device called the __________.

- sphygmomanometer

Blood pressure in any major artery of the body varies between the __________ and the __________.

- systolic pressure

- diastolic pressure

- The maximum pressure exerted by blood on arterial walls

- Normally equals about 110 mmHg

- systolic pressure (during ventricular systole)

- The minimum pressure exerted by blood on arterial walls

- Normally equals about 70 mmHg

- diastolic pressure (during ventricular diastole)

Under normal circumstances, what should be a person's blood pressure?

- 110 mmHg / 70 mmHg

What 4 things affect changes in blood pressure?

1. Stroke volume

2. Heart rate

3. Cardiac output

4. Blood vessel diameter (vasoconstriction, vasodilation)

True or False: An increase in stroke volume and/or heart rate does not cause an increase in cardiac output.

- False

- The increase in cardiac output means that more blood is ejected from the heart, which causes an increase in blood pressure due to the excess blood pushing on the walls of the blood vessels of the body.

True or False: Vasoconstriction also causes an increase in blood pressure since blood pushes more on blood vessel walls due to the smaller volume of the blood vessels.

- True

True or False: A decrease in stroke volume and/or heart rate causes an increase in cardiac output.

- False

- It decreases cardiac output, which means that less blood is ejected from the heart, which causes a decrease in blood pressure due to less blood pushing on blood vessel walls.

_________ also causes a decrease in blood pressure since blood does not push as much on blood vessel walls due to the larger volume of the blood vessels.

- Vasodilation

Blood pressure is regulated via a _________________ that involves the cardiovascular center.

- negative feedback system

1. The cardiovascular center is located in the ________.

2. What is this part of the brain known as?

1. medulla

2. brain stem

Part of the cardiovascular center gives rise to the _______________ that innervate the heart.

- parasympathetic (Vagus) nerves

- Recall that stimulation of these nerves causes a decrease in heart rate.

The cardiovascular center also makes connections with the cardiac accelerator nerves, which are __________  that innervate the heart.

- sympathetic nerves

- Recall that stimulation of these nerves causes an increase in heart rate and an increase in ventricular contraction (stroke volume).

The cardiovascular center has connections with the __________, which are sympathetic nerves that innervate the smooth muscle in the walls of the blood vessels of the body (except the capillaries).

- vasomotor nerves

- Stimulation of these nerves causes vasoconstriction of most blood vessels in the circulation.

What does the cardiovascular center receive information from?

- baroreceptors

1. What are sensory receptors that respond to changes in blood pressure?

2. Name the 2 major types.

1. baroreceptors

2. aortic arch baroreceptors and carotid sinus baroreceptors

- Located in the wall of the aortic arch

- Connect with the cardiovascular center via the Vagus (X) nerves

- aortic arch baroreceptors

- Located in the walls of the carotid sinuses

- The carotid sinuses are dilated regions of the internal carotid arteries just above the area where these arteries branch off of the common carotid arteries

- Connect with the cardiovascular center via the glossopharyngeal (IX) nerves

- carotid sinus baroreceptors

baroreceptor reflex in response to a decrease in blood pressure.

1. A ______ causes a decrease in blood pressure.

2. The decrease in blood pressure causes the baroreceptors to stretch less than normal. Consequently, the baroreceptors send fewer ___________ to the cardiovascular center.

1. stimulus

2. action potentials

baroreceptor reflex in response to a decrease in blood pressure.

3. The cardiovascular center responds by activating the _____________ that supply the heart, which causes an increase in stroke volume and heart rate, and therefore an increase in cardiac output. In addition, the cardiovascular center activates the __________ that supply most of the blood vessels of the body, which causes vasoconstriction.

4. The increase in cardiac output and the vasoconstriction cause an _______ in blood pressure back to normal.

3. cardiac accelerator nerves; vasomotor nerves

4. increase

baroreceptor reflex in response to an increase in blood pressure.

1. A ______ causes an increase in blood pressure.

2. The increase in blood pressure causes the baroreceptors to stretch more than normal. Consequently, the baroreceptors send a large number of action potentials to the ____________.

1. stimulus

2. cardiovascular center

baroreceptor reflex in response to an increase in blood pressure.

3. The cardiovascular center responds by activating the ___________ nerves that supply the heart, which causes the heart rate to decrease. A decrease in heart rate causes a decrease in cardiac output. In addition, the lack of ________ stimulation by the cardiovascular center results in vasodilation of blood vessels.

4. The decrease in cardiac output and the vasodilation result in a ________ in blood pressure back to normal.

3. parasympathetic (Vagus); sympathetic

4. decrease 

Leaky venous veins can cause veins to become dilated and twisted in appearance, a condition called __________. The condition may occur in the veins of almost any body part, but is most common in the esophagus, anal canal, and superficial veins of the lower limbs.

- varicose veins

If filtration greatly exceeds reabsorption, the result is _______, an abnormal increase in interstitial fluid volume.

- edema

______, or fainting, is a sudden, temporary loss of consciousness that is not due to head trauma, follow by spontaneous recovery.

- Syncope

1. Physicians sometimes use _____________, which involves carefully massaging the neck over the carotid sinus, to slow heart rate in a person who has paroxysmal superventricular tachycardia.

2. Anything that stretches or puts pressure on the carotid sinus (hyperextension of the head, tight collars, etc.) may also slow heart rate and can cause _____________.

1. carotid sinus massage

2. carotid sinus syncope

_______ is a failure of the cardiovascular system to deliver enough O2 and nutrients to meet cellular metabolic needs.

- Shock

Persistently high blood pressure

- hypertension

A thin, weakened section of the wall of an artery or a vein that bulges outward, forming a balloon-like sac.

- aneurysm

The removal of atherosclerotic plaque from the carotid artery to restore greater blood flow to the brain.

- carotid endarterectomy

The presence of a blood clot in a deep vein of the lower limbs.

- deep vein thrombosis

Low blood pressure

- hypotension

Normal blood pressure

- normotensive

The closure or obstruction of the lumen of a structure such as a blood vessel.

- occlusion

An excessive lowering of systemic blood pressure when a person assumes an erect or semi-erect posture; it is usually a sign of a disease.

- orthostatic hypotension

Inflammation of a vein, often in a leg

- phlebitist

An operation to remove a blood clot from a blood vessel.

- thrombectomy

1. When a blood vessel undergoes ________, the smooth muscle within its wall relaxes.

2. Describe what happens with the blood vessel lumen.

1. vasodilation

2. The blood vessel lumen becomes wider, which causes an increase in blood flow.