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Human Bio 122 > Blood flow and pressure > Flashcards

Blood flow and pressure Flashcards

1
Q

Blood flow is defined as the volume of blood that flows through any tissue in a given time period.

The total blood flow is called the cardiac output (volume of blood that circulates through systemic blood vessels each minute).

The formula to calculate cardiac output is…?

A

Cardiac output = stroke volume x heart rate

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2
Q

Name some factors that affect blood pressure (4).

A
  • cardiac output
    [an increase in heart rate or stroke volume increases cardiac output which leads to an increase in blood pressure]
  • blood volume
  • vascular resistance
  • elasticity of arteries
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3
Q

Describe systolic or diastolic blood pressure.

A

Systolic blood pressure is the highest pressure attained in the arteries during systole.

Diastolic blood pressure is the lowest pressure attained in the arteries during diastole.

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4
Q

Factors affecting vascular resistance?

A
  • size of blood vessel lumen
  • blood viscosity
  • total vessel length

(these can be influenced by factors such as polycythemia or obesity)

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5
Q

Venous return (volume of blood flowing back to the heart through systemic veins) occurs through…?

A
  1. pressure generated by left ventricular contractions
  2. skeletal muscle pump
  3. respiratory pump
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6
Q

Blood velocity is inversely related to the total cross-sectional area of blood vessels. Where does blood flow slowest in the cardiovascular system?

A

Capillaries

(the slow rate aids the exchange of materials between blood and interstitial fluid)

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7
Q

Circulation time is the time required for a drop of blood to pass from the right atrium, through the pulmonary circulation, back to the left atrium, through the systemic circulation down to the foot, and back again to the right atrium. What is the average circulation time in a resting person?

A

1 minute

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8
Q

Blood pressure and blood flow are controlled by adjusting the heart rate, stroke volume, systemic vascular resistance, and blood volume.

This is done through 4 interconnected negative feedback mechanisms. What are they?

A
  1. Cardiovascular centre
  2. Nervous system
  3. Hormones
  4. Auto regulation
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9
Q

Input into the cardiovascular centre (a group of neurons in the medulla oblongata) comes from the higher brain regions and also three sensory receptors. What are these receptors?

A
  1. proprioceptors (monitor joint/muscle movements)
  2. baroreceptors (monitor blood pressure)
  3. chemoreceptors (monitor chemical concentrations)
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10
Q

Do parasympathetic impulses (from the cardiovascular centre) increase or decrease heart rate?

A

Decrease

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11
Q

Do sympathetic impulses (from the cardiovascular centre) increase or decrease heart rate?

A

Increase

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12
Q

Baroreceptors are pressure-sensitive sensory neurons located in the aorta, internal carotid arteries, and other large arteries in the neck/chest.

They monitor the stretching of the walls of blood vessels and the artia.

There are two main baroreceptors reflexes…

A
  1. carotid sinus reflex - maintains normal blood pressure in the brain
  2. aortic reflex - maintains general systemic blood pressure (initiated from the arch of the aorta)
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13
Q

Chemoreceptors are sensory receptors that monitor the chemical composition of blood and are located close to the baroreceptors of the carotid sinus and arch of aorta.

Their main function is to detect changes in blood levels of O2, CO2 and H+ which provides input to adjust breathing accordingly.

A
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14
Q

Several hormones help regulate blood pressure and flow. How do they do this?

(Renin-angiotensin-aldoserone system; epinephrine/norepinephrine; ADH [antidiuretic hormone]; and ANP [antrial natriuretic peptide]

A
  • alter cardiac output
  • change systemic vascular resistance
  • adjust total blood volume
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15
Q

Auto regulation is the ability of a tissue to automatically adjust its own blood flow to match its metabolic demand for the supply of oxygen and nutrients, and the removal of wastes.

What are the 3 stimuli that cause autoregulatory changes?

A
  1. Physical changes (e.g. warming/cooling)
  2. Vasodilating and vasoconstricting chemicals (e.g. lactic acid, histamines)
  3. Changes in oxygen level
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16
Q

Pulse is a pressure wave created by alternate expansion and recoil of an elastic artery after each systole of the left ventricle.

What is a normal pulse in a healthy person at rest?

A

70-80 beats/min

17
Q

What is a sphygmomanometer?

A

Instrument used to measure blood pressure

18
Q

What are korotkoff sounds?

A

The various sounds that are heard while taking blood pressure

19
Q

Hypertension is persistently elevated blood pressure (systolic blood pressure of 140mm Hg or greater, and diastolic blood pressure of 90 mm Hg or greater).

It can cause damage to the vessels, heart, brain and kidneys before it causes pain or symptoms.

There are two types of hypertension…

A
  1. primary - can’t be attributed to any particular organic cause (90-95% of all cases)
  2. secondary - identifiable underlying cause such as obstruction of renal blood flow, a tumour of the adrenal gland, etc.
20
Q

Systemic circulation carries oxygen and nutrients to body tissues and removes carbon dioxide and other wastes and heat from the tissues.

Oxygenated blood is supplied through systemic arteries branching from the aorta that arise from the left ventricle.

Deoxygenated blood returns to the heart through systemic veins that drain blood back into the right atrium through. What are the 3 draining arteries called?

A
  1. Superior vena cava
  2. Inferior vena cava
  3. Coronary sinus

[all empty into the right atrium]

21
Q

The aorta is the largest artery in the body. What are its 3 branches?

A
  1. ascending aorta
  2. arch of aorta
  3. descending aorta (thoracic aorta/abdominal aorta)
22
Q

Which branch of the aorta contains the right and left coronary arteries?

A

Ascending aorta

23
Q

The brachiocephalic trunk, right/left common carotid artery and right/left subclavian artery belong to which branch of the aorta?

A

Arch of the aorta

24
Q

The subclavian arteries pass superior to the first rib. They supply blood to:

  • the armpit (axillary artery)
  • the arm (brachial artery)
  • forearm (radial and ulnar branches)

They also supply blood to the WHAT on the base of the brain?

A

Circle of Willis

25
Q

The common carotid arteries supply structures in the…?

(broadly)

A

Head

26
Q

The superior vena cava drains which parts of the body?

A

The head and upper extremities

27
Q

The inferior vena cava drains which parts of the body?

A

Abdomen, pelvis and lower limbs

28
Q

The coronary sinus drains…?

A

The heart muscle back into the heart

29
Q

What is the hepatic portal circulation system and its broad function?

A

A subdivision of the systemic circulation that carries blood between two capillary networks, from the capillaries of the GI tract to the liver.

The function is to collect blood from veins of the pancreas, spleen, stomach, intestines and gallbladder to direct it into the hepatic portal vein of the liver before returning it to the heart. This enables nutrient utilisation and blood detoxification by the liver.

30
Q

In its course, what does the ascending aorta continue as?

A

The arch of aorta

31
Q

After the thoracic aorta passes through the aortic aperture of the diaphragm it becomes the…?

A

Abdominal aorta

32
Q

The head and upper extremities are drained by which vein?

A

Superior vena cava

33
Q

Venous drainage of the liver enters the heart through which vein?

A

Inferior vena cava

34
Q

The large arteries located on the right and left in the neck extending superiorly to supply the head are the…?

A

Common carotid arteries

Human Bio 122 (13 decks)

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