Exam 3- Respiratory and blood pressure

What is the function of arteries in the circulatory system?

Arteries carry blood away from the heart and are typically oxygenated (except for the pulmonary artery).

What is the function of veins in the circulatory system?

Veins carry blood toward the heart and are typically deoxygenated (except for the pulmonary vein).

What is the function of capillaries?

- connect arterioles and venules

- the site of gas and nutrient exchange.

How are arteries classified based on size?

Elastic arteries → muscular arteries → arterioles.

How are veins classified based on size?

Large veins → medium veins → venules.

What are three key differences between arteries and veins?

- Arteries have thicker walls and more smooth muscle.

- Arteries operate under high pressure and have no valves.

- Veins have thinner walls, less smooth muscle, lower pressure, and contain valves to prevent backflow.

What are the three layers of blood vessel walls?

Tunica intima (internal)

Tunica media (middle)

Tunica externa (external)

What are the characteristics of the tunica intima (internal layer)?

- consists of simple squamous epithelium,

- a subendothelial layer in larger vessels

- an internal elastic membrane (present in arteries).

What are the characteristics of the tunica media (middle layer)?

- contains smooth muscle and elastic fibers

- is responsible for vasoconstriction and vasodilation

- thicker in arteries than in veins.

What are the characteristics of the tunica externa (external layer)?

- made of collagen fibers

- contains the vasa vasorum in larger vessels

- provides structural support.

What are continuous capillaries and where are they found?

- the most common type

- found in the skin, muscle, lungs, and central nervous system (CNS).

What are fenestrated capillaries and where are they found?

-have pores

- found in the kidneys, small intestine, and endocrine glands.

What are sinusoidal capillaries and where are they found?

- have large openings

- found in the liver, bone marrow, and spleen.

What is the equation for blood flow?

Blood Flow (F) = pressure difference (ΔP) / resistance (R)

What does F represent in the blood flow equation?

blood flow.

What does ΔP represent in the blood flow equation?

pressure difference between two points.

What does R represent in the blood flow equation?

resistance.

What is the main factor that determines resistance in blood vessels?

Vessel diameter.

How does resistance affect blood flow?

As resistance increases, blood flow decreases.

Where is blood pressure highest in the systemic circuit?

In the aorta.

Where does the greatest drop in arterial pressure occur?

Across the arterioles, which are the site of greatest resistance.

How does arterial pressure change after the arterioles?

It continues to decrease in capillaries, venules, and veins.

Where is blood pressure the lowest in the systemic circuit?

In the vena cavas as they enter the right atrium.

What is the formula that shows the relationship between cardiac output and blood pressure?

BP = CO × PR (Blood Pressure = Cardiac Output × Peripheral Resistance)

What does CO stand for?

Cardiac Output

What does PR stand for?

Peripheral Resistance

How are cardiac output and blood pressure related?

They are directly related — as CO increases, BP increases.

What is the formula for cardiac output?

CO = HR × SV (Heart Rate × Stroke Volume)

What happens to blood pressure when cardiac output increases?

Blood pressure increases.

How does blood volume affect blood pressure?

It is directly related — more blood volume increases venous return, which increases EDV, stroke volume, cardiac output, and thus BP.

What is the relationship between vessel diameter and blood pressure?

They are inversely related — smaller diameter (vasoconstriction) increases BP, while larger diameter (vasodilation) decreases BP.

How does vasoconstriction affect blood pressure?

It increases resistance and raises blood pressure.

How does vasodilation affect blood pressure?

It decreases resistance and lowers blood pressure.

Where is the vasomotor center located?

In the medulla oblongata.

What does the vasomotor center do?

It regulates the diameter of blood vessels via sympathetic nerves.

What do baroreceptors detect?

Changes in arterial blood pressure.

What happens when baroreceptors detect stretching?

They increase signaling to the vasomotor center, which inhibits it.

What is the result of baroreceptor-induced inhibition of the vasomotor center?

Dilation of arteries and veins, reduced peripheral resistance.

How do baroreceptors affect the sympathetic nervous system?

They inhibit it, leading to decreased heart rate and contractility.

What do chemoreceptors monitor?

Levels of oxygen (O₂), carbon dioxide (CO₂), and pH.

Where are chemoreceptors located?

In the carotid and aortic bodies.

What triggers increased sympathetic activity via chemoreceptors?

Low O₂, high CO₂, or low pH levels.

What is the effect of increased sympathetic activity due to chemoreceptor stimulation?

Increased blood pressure.

How does norepinephrine (NE) from the adrenal medulla affect blood pressure?

It causes vasoconstriction, which increases blood pressure.

How does epinephrine (EPI) from the adrenal medulla affect blood pressure?

It increases heart rate and contractility, which increases cardiac output and blood pressure.

How does nicotine affect blood pressure?

it mimics NE and EPI as a monoamine agonist, increasing BP.

What is atrial natriuretic peptide (ANP) and what does it do?

- ANP is released by atrial cells in response to high blood volume

- reduces blood pressure by inhibiting aldosterone and increasing sodium and water excretion by the kidneys.

Where is antidiuretic hormone (ADH) released from, and what does it do?

ADH is released by the posterior pituitary and increases water reabsorption in the distal tubules and collecting ducts; at high levels, it also causes vasoconstriction.

What triggers the release of angiotensin II?

renin release from the juxtaglomerular apparatus (JGA) in response to low renal perfusion.

Q: What does renin do in the renin-angiotensin system?

converts angiotensinogen into angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme (ACE).

What are the effects of angiotensin II?

It causes vasoconstriction, stimulates aldosterone release, and triggers ADH release.

How does aldosterone affect blood pressure?

Aldosterone increases sodium and water reabsorption, which raises blood volume and blood pressure.

How does the kidney directly control blood pressure?

By regulating water excretion in urine, which alters blood volume and affects cardiac output and blood pressure.

How does blood volume affect cardiac output?

Through increased venous pressure → increased venous return → increased EDV → increased stroke volume → increased CO → increased BP.

What happens to blood pressure when the kidneys excrete more water?

Blood volume decreases, leading to lower blood pressure.

What happens to blood pressure when the kidneys excrete less water?

Blood volume increases, leading to higher blood pressure.

What is the indirect renal mechanism for controlling blood pressure?

The renin-angiotensin-aldosterone mechanism.

What triggers the release of renin?

Low renal perfusion.

What does angiotensin II stimulate in the indirect mechanism?

Release of aldosterone and ADH.

How do aldosterone and ADH affect blood pressure in the indirect renal mechanism?

They promote water retention, which increases blood volume and blood pressure.

What are the four basic processes involved in respiration?

Pulmonary ventilation, external respiration, transport of respiratory gases, internal respiration.

What is pulmonary ventilation?

The movement of air in and out of the lungs (breathing).

What is external respiration?

the gas exchange between alveoli and blood — O₂ enters blood, CO₂ exits.

What is the transport of respiratory gases?

The movement of O₂ and CO₂ between the lungs and tissues via the blood.

What is internal respiration?

The gas exchange between blood and body tissues.

What are the components of the respiratory zone?

Respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.

What is the function of the respiratory zone?

It is the site of actual gas exchange.

What forms the respiratory membrane?

The alveolar wall, capillary wall, and their fused basement membranes.

What is the function of the respiratory membrane?

It facilitates rapid diffusion of gases (O₂ and CO₂) between air and blood.

What is the apex of the lung?

The top portion of the lung.

What is the base of the lung?

The bottom portion of the lung that rests on the diaphragm.

How many lobes does each lung have?

The right lung has 3 lobes; the left lung has 2 lobes.

What is the hilum of the lung?

The medial entry/exit site for bronchi, blood vessels, lymphatics, and nerves.

What are bronchopulmonary segments?

Subdivisions of lung lobes, each served by its own bronchus.

What is the visceral pleura?

The membrane that covers the lungs.

What is the parietal pleura?

The membrane that lines the thoracic cavity.

What is the pleural cavity?

The space between the pleurae that contains lubricating fluid to reduce friction.

What happens during quiet inspiration?

- Diaphragm contracts and flattens

- External intercostals contract, expanding the rib cage

- Thoracic volume increases → pressure drops → air flows in

What happens during quiet expiration?

- Passive process

- Diaphragm and intercostals relax

- Thoracic volume decreases → pressure increases → air flows out

What muscles are used during forced inspiration?

Sternocleidomastoid, scalene, and pectoralis minor.

What happens during forced expiration?

It is an active process; internal intercostals and abdominal muscles contract.

What is atmospheric pressure (Patm)?

The pressure of air outside the body, approximately 760 mmHg.

What is intrapulmonary pressure (Ppul)?

The pressure in the alveoli; it equalizes with Patm during normal breathing.

What is intrapleural pressure (Pip)?

The pressure in the pleural cavity; it is always negative relative to Ppul, typically around -4 mmHg.

What happens to Ppul during inspiration?

Ppul becomes less than Patm (Ppul < Patm).

What happens to Ppul during expiration?