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a) A diagram showing that the spleen is found at the end of the pancreas just under the diaphragm. The part closest to the pancreas is the hilium and contains the splenic artery and vein. B) a close-up of the spleen. Afferent lymphatic vessels are tubes that bring material in. Efferent lymphatic vessels are tubes that take material out of the spleen. Connective tissue forms a capsule around the outside; and a space under the capsule is labeled subcapsular sinus. The cortex of the spleen is the outer layer. And trabeculae are regions of cortex that fold in towards the center. Germinal centers are red structures in the cortex.
(a) The spleen is a lymphatic organ located in the upper left quadrant of the abdomen near the stomach and left kidney. It contains numerous phagocytes and lymphocytes that combat and prevent circulatory infections by killing and removing pathogens from the blood. (b) Lymph nodes are masses of lymphatic tissue located along the larger lymph vessels. They contain numerous lymphocytes that kill and remove pathogens from lymphatic fluid that drains from surrounding tissues.
  • What is the main function of the lymphatic system?

Infections of the circulatory system

Under normal circumstances, the circulatory system and the blood should be sterile; the circulatory system has no normal microbiota. Because the system is closed, there are no easy portals of entry into the circulatory system for microbes. Those that are able to breach the body’s physical barriers and enter the bloodstream encounter a host of circulating immune defenses, such as antibodies, complement proteins, phagocytes, and other immune cells. Microbes often gain access to the circulatory system through a break in the skin (e.g., wounds, needles, intravenous catheters, insect bites) or spread to the circulatory system from infections in other body sites. For example, microorganisms causing pneumonia or renal infection may enter the local circulation of the lung or kidney and spread from there throughout the circulatory network.

If microbes in the bloodstream are not quickly eliminated, they can spread rapidly throughout the body, leading to serious, even life-threatening infections. Various terms are used to describe conditions involving microbes in the circulatory system. The term bacteremia refers to bacteria in the blood. If bacteria are reproducing in the blood as they spread, this condition is called septicemia . The presence of viruses in the blood is called viremia . Microbial toxins can also be spread through the circulatory system, causing a condition termed toxemia .

Microbes and microbial toxins in the blood can trigger an inflammatory response so severe that the inflammation damages host tissues and organs more than the infection itself. This counterproductive immune response is called systemic inflammatory response syndrome (SIRS) , and it can lead to the life-threatening condition known as sepsis . Sepsis is characterized by the production of excess cytokines that leads to classic signs of inflammation such as fever, vasodilation , and edema (see Inflammation and Fever ). In a patient with sepsis, the inflammatory response becomes dysregulated and disproportionate to the threat of infection. Critical organs such as the heart, lungs, liver, and kidneys become dysfunctional, resulting in increased heart and respiratory rates, and disorientation. If not treated promptly and effectively, patients with sepsis can go into shock and die.

Certain infections can cause inflammation in the heart and blood vessels. Inflammation of the endocardium, the inner lining of the heart, is called endocarditis and can result in damage to the heart valves severe enough to require surgical replacement. Inflammation of the pericardium, the sac surrounding the heart, is called pericarditis . The term myocarditis refers to the inflammation of the heart’s muscle tissue. Pericarditis and myocarditis can cause fluid to accumulate around the heart, resulting in congestive heart failure. Inflammation of blood vessels is called vasculitis . Although somewhat rare, vasculitis can cause blood vessels to become damaged and rupture; as blood is released, small red or purple spots called petechiae appear on the skin. If the damage of tissues or blood vessels is severe, it can result in reduced blood flow to the surrounding tissues. This condition is called ischemia , and it can be very serious. In severe cases, the affected tissues can die and become necrotic; these situations may require surgical debridement or amputation.

  • Why does the circulatory system have no normal microbiota?
  • Explain why the presence of microbes in the circulatory system can lead to serious consequences.

Infections of the lymphatic system

Like the circulatory system, the lymphatic system does not have a normal microbiota, and the large numbers of immune cells typically eliminate transient microbes before they can establish an infection. Only microbes with an array of virulence factors are able to overcome these defenses and establish infection in the lymphatic system. However, when a localized infection begins to spread, the lymphatic system is often the first place the invading microbes can be detected.

Infections in the lymphatic system also trigger an inflammatory response. Inflammation of lymphatic vessels, called lymphangitis , can produce visible red streaks under the skin. Inflammation in the lymph nodes can cause them to swell. A swollen lymph node is referred to as a bubo , and the condition is referred to as lymphadenitis .

Key concepts and summary

  • The circulatory system moves blood throughout the body and has no normal microbiota.
  • The lymphatic system moves fluids from the interstitial spaces of tissues toward the circulatory system and filters the lymph. It also has no normal microbiota.
  • The circulatory and lymphatic systems are home to many components of the host immune defenses.
  • Infections of the circulatory system may occur after a break in the skin barrier or they may enter the bloodstream at the site of a localized infection. Pathogens or toxins in the bloodstream can spread rapidly throughout the body and can provoke systemic and sometimes fatal inflammatory responses such as SIRS , sepsis , and endocarditis .
  • Infections of the lymphatic system can cause lymphangitis and lymphadenitis .

Fill in the blank

Vasculitis can cause blood to leak from damaged vessels, forming purple spots called ________.

petechiae

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The lymph reenters the vascular circulation at ________.

the subclavian veins

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Short answer

How do lymph nodes help to maintain a microbial-free circulatory and lymphatic system?

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Questions & Answers

I mportance of microorganisms
azarsh Reply
microbiology is the study of micro organisms those been unicellular multicellular or acelluar
Nwakaego Reply
what is microbiology
Ebuka Reply
why study microbiology
David Reply
to know the cause of certain disease and how to cure them
Racheal
without micro, medicines in term of diagnostic and cure would be far away from realizing its objectives
Louisiaste
It's help to give the best medication.
Olayinka
Unvin Prisca the immune system
Gyabaa Reply
immune system is a complex of organ tissues and specialized cells which identify or kill the pathogens.
Mohammad
Thanks
shamim
explain to me the pathogenesis of plasmodium
Angelo
what is difference between bacillus and ecoil
Rymes Reply
similarities between prokaryotic cell and eukaryotic cell
Ednah Reply
Eukaryotic cells contain membrane-bound organelles, including a nucleus. ... Prokaryotic cells do not contain a nucleus or any other membrane-bound organelle. Prokaryotes include two groups: bacteria and another group called archaea.
Priya
thanks
Sarpong
what is different between plasma and serum?
Alif
difference between plasma and serum is that plasma is liquid n serum is fluid
Priya
what is microbiology
Eliham
what is the diseases caused by the microorganisms
Emmanuel
both cells have plasma membrane, which services as a barrier between the inside of the cell and outside. both prokaryotes and eukaryotes have ribosomes. they receive messages from messanger RNA molecules, telling them what proteins the cell needs.
Abdinur
Thanks
Dominic
Some bacteria infection
Dominic
what is the name given to infection got from the hospital
Mukisa
Nosocomial infection
Gifty
what is the apportion
Riyaaq
what is the main functions of organelles
Ishaq
what is main function of right and left side of the brain.
Theophile
Salifu. microbiology is the study of oganisms that are too small for the naked eyes to see. this include bacteria
Theophile
Cabdi. apportion is to divide or share out
Theophile
yap
bako
what is the parasitic helminths?
bako
what are pathogens
Oluka Reply
any disease causing microorganism that can invade the body and cause harm
famuyiwa
hepatitis b
Oluka
what's da answer
Oluka
any diseases that course harmful to body
Musa
hepatitis is usually implementery of the liver and is commonly course by virus infection
Musa
a type of virus that causes severe illness lasting from two to six weeks it may cause massive lived necrosis and cirrhosis
famuyiwa
hepatitis B are transmitted when in contact with body fluid such as blood,semen,varginal secration that contain the hepatitis b virus
Musa
I understand necrosis,means death of all cell or injury of blood supply, but what is cirrhosis pls
Musa
sorry meant liver cirrhosis
famuyiwa
good evening all
Billy
ok liver damage
Musa
I have a question
Billy
Hey welcome all of you...i think you are discussing about Micro-organisms..what does it Micro?
Gazu
how about, scabies (bacteria) yeah can some one gist me abt it
Billy
sorry what doest it mean Micro organism?
Gazu
microorganism are minute living organisms found almost everywhere. they can be autotrophic heterotrophic or chemotrophic
famuyiwa
Tell me about enzyme kinetics
Jaypal
wowoww thanks a lot farmuyiwa Alice
Gazu
have anyone colony pigmentation of different types of bacteria such as Aeromonas, Edwardsiella, vibros,
Sadiqur
yes dear sadiqur Bacterias are live in everywhere.. .
Gazu
microorganisms are arganism that cannot been seen with 👀 until by the use of microscope
Musa
microorganisms are arganism that cannot been seen with 👀 until by the use of microscope
Musa
yhea organisms are organisms they are naked eye/can't seen by our eyes
Gazu
and scabies are one of the most common skin condition that can course itches and raches.
Musa
and also scabies are not infection, but an infestation
Musa
my Q is what is the contribution of van-leeuwenhoek in field of microbiology
Musa
Antony van leevenhoek is father of microbiology.
Jaypal
Anton Van leewun hook is discovered Microscope it's true or not? who can brief me please
Gazu
micro organisms are organism that cannot be seen with an aided eyes ,but by the use of microscope
Ssmuel
Yes.. He discover first microscope. He take 2 lence at a time and he saw the plant cells... Thus he was called father of microbiology
Jaypal
who examined water from a bathtub and discovered microbes
famuyiwa
for instance any type of Stagnant water is creat there are d/t tupes of small animals.. so those animals are called Micro organism?
Gazu
thank you javpal for Describing.
Gazu
Hi the father of microbiology is Louis Pasteur
bako
Then the father of medical microbiology is Robert Koch
bako
can you please differentiate between vacuoles and inclusion bodies
Noor Reply
vacuoles consists of watery solution called cell sap while bodies are organelles
Prince
5 difference please
Noor
Archaea is an odd type of bacteria that live in extreme environments; high salt, high temperature etc. usually called extremophiles.
Danesia Reply
you know anyone that has delt with enterobacter agglomerans.
Vernon
it is a type of gram negative bacteria and its ubiquitous mostly isolated from plant stuffs and also from faecal material of animals. I heard the name pantoea . it is bacillus in structure.
Sujan
OLUKA MARTIN
Oluka
What are the classification of microorganisms
Portia Reply
Basic classification are eukaryotic and prokaryotic..
micro organisms are classified into three namely: Archaea, eukaryote and prokaryotic organisms
Blandine
Yay that's right
what is archaea
Ateeq
I've got an issue with the message view
Frank Reply
Is there any effective way to learn microbiology.
Frank Reply
I have some basic knowledge of biology. I mean i'm totally beginner in that field.
Frank
Assuming that i'm interested in neuroscience. What is the best way to master that particular subject.
Frank
Hi
Can you wait me just a minute
Iam apologies for guidance you in neuroscience.. I'm not physician.. I'm microbiologist
My pleasure to join to you
Let's begin a conversation
Frank Reply
What would be saying
?
Akram
do you know anything about microbiology
diana
I have so much studying to catch up on🙄
Britnee
any study tips
Britnee
Yas of course
What would you like to know
well i'm studying Pharmacy second year and i just started With Microbiology
diana
if you have any basics to tell us 🤷🏻‍♀️ would be helpful
diana
Yas, first you must know that you will have a very easy lecture..
In second stage you will try to learn the type of microbiology
A simple definition for microbiology
In second stage you will try to learn the type of microbiology.. you must learn the bacteria..its structure.. Classification of bacteria according to shape..
It's so easy

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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