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By the end of this section, you will be able to:
  • Distinguish between systolic pressure, diastolic pressure, pulse pressure, and mean arterial pressure
  • Describe the clinical measurement of pulse and blood pressure
  • Identify and discuss five variables affecting arterial blood flow and blood pressure
  • Discuss several factors affecting blood flow in the venous system

Blood flow refers to the movement of blood through a vessel, tissue, or organ, and is usually expressed in terms of volume of blood per unit of time. It is initiated by the contraction of the ventricles of the heart. Ventricular contraction ejects blood into the major arteries, resulting in flow from regions of higher pressure to regions of lower pressure, as blood encounters smaller arteries and arterioles, then capillaries, then the venules and veins of the venous system. This section discusses a number of critical variables that contribute to blood flow throughout the body. It also discusses the factors that impede or slow blood flow, a phenomenon known as resistance    .

As noted earlier, hydrostatic pressure is the force exerted by a fluid due to gravitational pull, usually against the wall of the container in which it is located. One form of hydrostatic pressure is blood pressure    , the force exerted by blood upon the walls of the blood vessels or the chambers of the heart. Blood pressure may be measured in capillaries and veins, as well as the vessels of the pulmonary circulation; however, the term blood pressure without any specific descriptors typically refers to systemic arterial blood pressure—that is, the pressure of blood flowing in the arteries of the systemic circulation. In clinical practice, this pressure is measured in mm Hg and is usually obtained using the brachial artery of the arm.

Components of arterial blood pressure

Arterial blood pressure in the larger vessels consists of several distinct components ( [link] ): systolic and diastolic pressures, pulse pressure, and mean arterial pressure.

Systolic and diastolic pressures

When systemic arterial blood pressure is measured, it is recorded as a ratio of two numbers (e.g., 120/80 is a normal adult blood pressure), expressed as systolic pressure over diastolic pressure. The systolic pressure    is the higher value (typically around 120 mm Hg) and reflects the arterial pressure resulting from the ejection of blood during ventricular contraction, or systole. The diastolic pressure    is the lower value (usually about 80 mm Hg) and represents the arterial pressure of blood during ventricular relaxation, or diastole.

Systemic blood pressure

This graph shows the value of pulse pressure in different types of blood vessels.
The graph shows the components of blood pressure throughout the blood vessels, including systolic, diastolic, mean arterial, and pulse pressures.

Pulse pressure

As shown in [link] , the difference between the systolic pressure and the diastolic pressure is the pulse pressure    . For example, an individual with a systolic pressure of 120 mm Hg and a diastolic pressure of 80 mm Hg would have a pulse pressure of 40 mmHg.

Generally, a pulse pressure should be at least 25 percent of the systolic pressure. A pulse pressure below this level is described as low or narrow. This may occur, for example, in patients with a low stroke volume, which may be seen in congestive heart failure, stenosis of the aortic valve, or significant blood loss following trauma. In contrast, a high or wide pulse pressure is common in healthy people following strenuous exercise, when their resting pulse pressure of 30–40 mm Hg may increase temporarily to 100 mm Hg as stroke volume increases. A persistently high pulse pressure at or above 100 mm Hg may indicate excessive resistance in the arteries and can be caused by a variety of disorders. Chronic high resting pulse pressures can degrade the heart, brain, and kidneys, and warrant medical treatment.

Questions & Answers

Its a fusion of bones where the bones becomes flexible or stiff.. Its a kind of arthritis
rumana Reply
what is ankylosis
Adam Reply
master gland Kon si h
kajal Reply
Pituitary gland
pituitary gland because it give harmonies and control other gland
glands often secrete hormones which play an important role in maintaining homeostasis.
pituitary gland
pituitary gland is master gland because it present in biran and secrtehormones and play other gland of human body and function its gland so that also called master gland.
pituitary glandis the master gland of our body
how do you study for A&P? lab and lecture?
Aubrey Reply
depends how your lab exams and lecture exams are structured. but either way, you want to study two weeks before any of the exams. study in a way that you would be teaching it to someone. lec is mostly physio. and a lil' anatomy. lab is all anatomy and motion- so memorization is key.
record the lectures in both cases. read the lessons for that class day. have questions. go to office hours. this will help you in A&P- if anything the teacher would give you a little bit of points for making so much of an effort
When one is suffering from motion sickness what area of the brain may trigger emesis?
amy Reply
that is the sign of stroke. if the patient have a stroke. the left side of body is weakness, the affected right of cerebrum but if right side of the body is weakness surely in left side!
thank you sooo much bro
Fatima Reply
Fatima hw a u
any one elaborate fr me foramens of the skull and features which they transmit
icant undrestand plz
zahruuzh Reply
try to read I hop you will understand
state and explain 20 radiology uses
what are chemicals in anatomy and physiology?
Mike Reply
what can I do to find it easy for me in anatomy and physiology course
study up on the basics of the periodic chart, learn bones and muscles attachments, and learn muscles. Those take the longest to memorize. After that it should be a little easier.
what are the two types of body cells
Jennifer Reply
what is malnutrition
malnutrition refers to faulty nutrition resulting from malabsorption,poor diet or overeating. Sometimes too these food do not contain all the six food nutrients in their right proportion.
thank you
Will u be malnourished?
What's the difference between radiology and radiology
Nothing! Radiology it means the study or using of radiation in medical science it can be 1.diagnose or treatment diagnosed radiology! x- ray. ultrasound. ct-scan. mammogram. MRI. 2. treatmen- radiation oncology, like Cobalt 60. and nuclear medicine
what is X-ray?
X-ray is type of light that make it possible to see inside any object. as human body
How the nervous system develops
ayiesher Reply
From the cells at the back of an embryo
breifly explain anatomy of thorax
Hadiza Reply
How many region the rib is divided
how many bon of human being
how to study for the skeletal system
and anatomy
I really need sources immediately
I printed out all the different bones. Put them in the see through protective sheaths and got dry erase markers. I could right on them and erase to help me learn to spell the names of markings and bones.
Or go to a book store, Barnes and Noble(doesn't have to be this) and they have coloring books for anatomy. $16. Really helpful.
okay thanks and are what study tools you use to study the materials and get a better understanding
*what are
I prefer diagrams, pictures that lay out each step with the information in each step. For Example: how action potential creates muscles to move. A pictured diagram gives me a better understanding of how each piece plays a role in each step of the process.
Also for basics, such as memorizing vocab. Flash cards are great. Don't become discouraged if you don't get them all right the first times through. The more you go through them, your brain will remember pieces of information from each and help you to pull out the information 😉
okay thanks
what is the functions of the lips in human
Momboi Reply
could I say sensation?
for protection
Lips assist in speech and eating
Too many easy questions. Which bones are the axial and appendicular? What are the abbreviations for TEE, TTE, AED, A-Mode, B-Mode, and LTH? What is the difference between hypothalamus and thalamus? Where is the parathyroid located? How many True Ribs do we have?
Sovilace Reply
Transesophageal echocardiography Transthoracic Echocardiography automated external defibrillator brightnees mode Los Hermanos Taverna
what is anatomy
okello Reply
anatomy is scientific study of body structures and how they relate to each other

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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