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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

Card 5 / 12: For whom would an appreciation of the structural characteristics of the human heart come more easily: an alien who lands on Earth, abducts a human, and dissects his heart, or an anatomy and physiology student performing a dissection of the heart on her very first day of class? Why?
Gelowe Reply
what are regular shaped cells with granules in the cytoplasam
Kabita Reply
PMNL
Dinu
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Omary Reply
cholesterol normal value is
BISWANATH Reply
less than 200mg/dl
Ashis
100 to159mg/dL
Dinu
Early this wk. I had some "A & P" questions & answers unfortunately didn't save them, Is there any way I can have them back ,so as 2 save them?. Thnx.
Kechi
what are the functions of the female reproductive system
Lister Reply
it produces the female egg necessary for reproduction, called the Ova or Oocytes. The system is designed to transport the Ova to the site of fertilization.
Kechi
Female reproductive system was mainly functioned to produce ova(ovum) (female eggs) Into which will be fertilized by male gamete to produce zygote
Omary
absolutely right
nimco
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Khaliil
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Ahmed
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Khaliil
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Khaliil
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Ahmed
asc if I try female reproductive system has two function the first is to produce egg cell and the second is to protact and nourish the offspring until birth
Muriidi
what is stercobilinogen
Hancerich Reply
fecal urobilinogen. Created by bacteria in the gut. a chemical that gives feces brown color.
Blayne
next question pls.
Kechi
The rate of diffusion increases if the
stella
What's the answer?
Kechi
it's a breaking down of haemoglobin and it's a chemical made by bacteria
Dev
Thnx Dev Raj.
Kechi
yup so any more
Dev
yes I sure do need more "Questions" & "Answers". I'm learning whole lot. Thnx.
Kechi
what is the greatest muscle of the body
Lungu Reply
gluteus maximus
ABDULLAH
pls!!! more "A&P" questions & answers. Thnx.
Kechi
Gluteus maximus
THE
Describe anatomy of cardiovascular system?
cardiovascular system is a group of organs coming together to perform the circulation of blood. The organs invoked are the heart and the blood vessels with blood being the tissue. The heart is a pump and it pumps oxygenated blood through the systemic circuit and deoxygenated blood through the pulmon
bernard
pulmonary circuit.
bernard
more A&P questions pls. Thnx.
Kechi
If an ANOVA yields a significant F value, you could rely on ________ to test significant differences between group means.
Dane Reply
what's ANOVA
Cassandra
analysis of variance
Blayne
plz what you mean with "ANOVA" first
Fatima
anova means analysis of variance, a statistical method in which the variation in a set of observations is divided into distinct components.
Blayne
M value ot test
ABDULLAH
What does it mean by M value ot test?
Orpha
formation of red blood cells
Biketi Reply
explain why... lower back pain in ovarian cancer
Srijoni Reply
we says that protoplasm is the living part of us How?
Muzamil Reply
is the leaving part of our cellular structure.
Eric
it is the leaving part of our blood cellular structure also
ABDULLAH
what is receptor?
Preity Reply
an organ or cell able to respond to light, heat, or other external stimulus and transmit a signal to a sensory nerve.
Jessi
Has anyone taken the first exam?
Sandra
yes
yahye
yes
Allan
hey what is the process after your food is swallowed? how long does it take to get to the stomache until it is released as waste?
Fednise Reply
that is such a broad question. as you begin to swallow its various doses down the alimentary canal that brings the food into your stomach.then depending on whether it's a protein carbohydrate fat that dictates what function takes place in your stomach. these are all steps of digestion.
Joseph
typo sorry it's peristalsis , wave-like projections that push food down your alimentary canal etc. digestion starts in your mouth ends in your large intestines (colon anus)
Joseph
some of the many processes of digestion include hydrolysis dehydration synthesis denaturation of proteins etc. you have to be more specific.
Joseph
there's many different contributing factors the how long it takes food to convert into waste. remember fats, triglycerides proteins and carbohydrates all breakdown two different monomers and structures. you should be looking up metabolic processes.
Joseph
depending how much fiber you have in your diet dictates how much water is brought to your intestines that has to do with excretion whether fiber is insoluble or soluble. this is an anatomy and physiology app. to simply say the stomach will empty its contents in 2 to 3 hours would do you a disservice
Joseph
can the study of anatomy relate to medical technologies
Lean Reply
yes
Khh
absolutely
Jessi
yes...
Sherif
how can I understand micro biology and anatomy better.
Cassandra
yes
Kevin
someone to help me understand glycogeneogenesis
abel
what are the major branches of the aorta?
Kevin
look youtube video
Jessi

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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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