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By the end of this section, you will be able to:
  • Discuss the mechanisms involved in the neural regulation of vascular homeostasis
  • Describe the contribution of a variety of hormones to the renal regulation of blood pressure
  • Identify the effects of exercise on vascular homeostasis
  • Discuss how hypertension, hemorrhage, and circulatory shock affect vascular health

In order to maintain homeostasis in the cardiovascular system and provide adequate blood to the tissues, blood flow must be redirected continually to the tissues as they become more active. In a very real sense, the cardiovascular system engages in resource allocation, because there is not enough blood flow to distribute blood equally to all tissues simultaneously. For example, when an individual is exercising, more blood will be directed to skeletal muscles, the heart, and the lungs. Following a meal, more blood is directed to the digestive system. Only the brain receives a more or less constant supply of blood whether you are active, resting, thinking, or engaged in any other activity.

[link] provides the distribution of systemic blood at rest and during exercise. Although most of the data appears logical, the values for the distribution of blood to the integument may seem surprising. During exercise, the body distributes more blood to the body surface where it can dissipate the excess heat generated by increased activity into the environment.

Systemic Blood Flow During Rest, Mild Exercise, and Maximal Exercise in a Healthy Young Individual
Organ Resting
(mL/min)
Mild exercise
(mL/min)
Maximal exercise
(mL/min)
Skeletal muscle 1200 4500 12,500
Heart 250 350 750
Brain 750 750 750
Integument 500 1500 1900
Kidney 1100 900 600
Gastrointestinal 1400 1100 600
Others
(i.e., liver, spleen)
600 400 400
Total 5800 9500 17,500

Three homeostatic mechanisms ensure adequate blood flow, blood pressure, distribution, and ultimately perfusion: neural, endocrine, and autoregulatory mechanisms. They are summarized in [link] .

Summary of factors maintaining vascular homeostasis

This flowchart shows the various factors that control the flow of blood. The top panel focuses on autoregulation, and the bottom panel focuses on neural and endocrine mechanisms.
Adequate blood flow, blood pressure, distribution, and perfusion involve autoregulatory, neural, and endocrine mechanisms.

Neural regulation

The nervous system plays a critical role in the regulation of vascular homeostasis. The primary regulatory sites include the cardiovascular centers in the brain that control both cardiac and vascular functions. In addition, more generalized neural responses from the limbic system and the autonomic nervous system are factors.

The cardiovascular centers in the brain

Neurological regulation of blood pressure and flow depends on the cardiovascular centers located in the medulla oblongata. This cluster of neurons responds to changes in blood pressure as well as blood concentrations of oxygen, carbon dioxide, and hydrogen ions. The cardiovascular center contains three distinct paired components:

  • The cardioaccelerator centers stimulate cardiac function by regulating heart rate and stroke volume via sympathetic stimulation from the cardiac accelerator nerve.
  • The cardioinhibitor centers slow cardiac function by decreasing heart rate and stroke volume via parasympathetic stimulation from the vagus nerve.
  • The vasomotor centers control vessel tone or contraction of the smooth muscle in the tunica media. Changes in diameter affect peripheral resistance, pressure, and flow, which affect cardiac output. The majority of these neurons act via the release of the neurotransmitter norepinephrine from sympathetic neurons.

Questions & Answers

all of the following substance move in in and out of cell except
Mohd Reply
all of the following substance move in and out of cells except
Mohd
Which signaling molecule is most likely responsible for an increase in digestive activity?
Tonya Reply
Hi I think it is DNA
libim
Homeostatasis return to the body to a healthy state after a stressful stimuli by producing
Ofosu Reply
There are some people suffering serious injured what will we do in doing X-ray?
Jefford Reply
observe bone arrangements n associated structures like soft tissues muscles in general the radiographical changes
Terry
epithelial tissue lines blood vessels
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what is difference between anabolism and catabolism in simple language
Chinaza Reply
anabolism simply means building up while catabolism breaking down
Maaruf
building up and breaking down
odeh
explain respiratory centers
Tharshana Reply
which enzyme help in excretion of bile
Sakshi Reply
how conversion of Beta-carotiene into vitamin-A takes place
Sakshi
best reference books for anatomy pls suggest that
Sakshi
what is gross anatomy
Saroj Reply
The study of large structure of the body
Mablean
macroscopic anatomy (Gross anatomy)
odeh
manipulation of structures without aid of microscope due to their size
libim
what is scrotum
Dakshit Reply
a bag of skin near the penis which contains the testicles
Mablean
hi
Sardar
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Sardar
Why are you on my digits
Mablean
hi
Kryme
it is part if male organ that hold testis in position it also regulates temperature
libim
how does it work?
Uriah Reply
I want to know the fertilization process in human
Nana Reply
Which plane divides the body into right and left parts
Kaeze
sagittal plane
Irvin
Thank you
Kaeze
Homestatic regulations usually involves a (n) _ that detects a particular stimulus, and a(n) _that respond to the stimulus by communicating with a (n) _whose activity has an effect on the same stimulus.
Kaeze
A cell is producing proteins to be transported out of that cell. They will be processed on ribosomes that are
Kaeze
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Azoyenime Reply
Haemophilia
Aliyu
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Diabetes insipidus or diabetes mellitus would most likely be indicated by ________.
Ganesh
oral cavity how miean
Ganesh Reply
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Suresh
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Muhammad
they know what to ask the problem is how to ask it.too much broken english.
George
dear George ongeche I think if they ask these kind questions and telling themselves as HCPs or medical student's .these are the basic ones go ask something more interesting .
Muhammad

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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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