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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

compare and contrast the operation of homeostasis
Dinelle Reply
what is the difference between an ionic, polar covalent and nonpolar covalent bond?
Dinelle
the definition of distal
Dinelle Reply
farthest away from the attachment point.
felix
exercise physiologist how ?
Noor Reply
can I get the questions of human physiology that is present in HSC 2nd semester
Rafiullah Reply
how can I memorize
mukhtaar Reply
which part of the body produces blood
aadil
give me answer
aadil
Red blood cells are formed in the red bone marrow ofbones. Stem cells in the red bone marrow called hemocytoblasts give rise to all of the formed element
mukhtaar
what is hemocytoblasts
Fatima
hemocytoblasts are stem cells in red bone marrow which give rise the all of formed elements
Khawaja
Discuss clonal theory in physiology and its application in measles infection in a 6yr child? Can anyone help me
Isaac Reply
Capillary permeability
what do you want to know about it?
Ramsin
Hello, I want to search about the topic, information and pictures
syncitium is the property of which of the following muscle
Shahab Reply
can I get the questions of human physiology that is present in HSC 2nd semester
Sai Reply
i now madam
irpa
ha can u please send me the PDF of questions
Sai
it's important to me to have that information please send as fast as u can
Sai
me too if possible?
Ramsin
of course
mukhtaar
I want too
Nazirullah
If a molecule can only pass through a membrane with the assistance of a membrane protein, but the direction of its travel is controlled only by its concentration, the process is called?
osmosis
chozen
A 52 year old woman turned her head quickly, during a tennis game and suddenly felt a sharp pain in her neck along her upper limb. Physical examination and medical imaging revealed a herniated degenerated IV disc in the cervical region of her vertebral column.
Isaac
a. What probably caused the IV disc herniation? b. What cause IV disc degeneration? c. What are the result of disc degeneration?
Isaac
b
Mirasol
Describe the neural control of erection and ejaculation.
Nana Reply
A 52 year old woman turned her head quickly, during a tennis game and suddenly felt a sharp pain in her neck along her upper limb. Physical examination and medical imaging revealed a herniated degenerated IV disc in the cervical region of her vertebral column. a)What probably caused the IV di
Isaac
a) What probably caused the IV disc herniation? b) What cause IV disc degeneration? c) What are the result of disc degeneration?
Isaac
iv disc herniation compress the nerve cause numbness tingling sensation even paralysis in severe cases...
Khawaja
explain more
DANIELLA Reply
yes
Ramzan
function of skeleton
Josiah Reply
- for movement - blood production by the bone marrow
Daniel
production of calsium and phosphorus
Juma
Shortly after childbirth, a woman consulted her physician about a tender swelling in her perineal region. 8. What fossa related the perineal swelling? 9. Describe what vessel may cause the collection of blood in the fossa after childbirth?
Isaac
what is heart
Subhajit Reply
it is the tissue..which pump blood to the all parts of body
GRAY
the heart is a conical , hollow, muscular organ which works continuously through out the life of a person ,it is about the size of a clenched fist and weighs about 300 grams and also the heart is in the chest just behind the breast bone and between the two lungs
Mary
a hollow muscular organ that pumps blood through the circulatory system by regular contractions
Johnny
is a muscular organ that pumps blood lungs and other body tissues through vessels
Nolosha
Shortly after childbirth, a woman consulted her physician about a tender swelling in her perineal region. 8. What fossa related the perineal swelling? 9. Describe what vessel may cause the collection of blood in the fossa after childbirth?
Isaac
Shortly after childbirth, a woman consulted her physician about a tender swelling in her perineal region. 8. What fossa related the perineal swelling? 9. Describe what vessel may cause the collection of blood in the fossa after childbirth?
Isaac Reply
inguinal fossa femoral vein?
Jeen
if you dont the answer by now you should seek another line of work. as a professor it is my duty to let you know about your lacking.
Arif

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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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