biology Flashcards
what are the four functions of the circulatory system?
- transports O2 and nutrients
- transports heat throughout the body
- distributes energy thought the body
- defends against pathogens
what does a heartbeat consist of?
a complete contraction (systole) and a complete relaxation (diastole)
which direction do arteries carry blood in?
away from the heart
what is the largest artery in the body?
the aorta
what do arteries branch off into?
arterioles
what do coronary arteries supply blood to?
the heart
what kind of vessels are arteries?
they are thick and muscular and can withstand high pressure
what happens if coronary arteries are blocked?
it can cause a heart attack
what happens if an artery in the brain is blocked?
it can cause a stroke
which direction do veins carry blood in?
towards the heart
what kind of vessels are veins?
smaller and thinner than arteries, low pressure
what type of blood vessels contain valves?
veins
why do veins contain valves?
to prevent back flow because blood is usually travelling against gravity
what does blood movement in veins depend on?
the contractions of surrounding muscles
what is the largest vein called?
the vena cava (superior and inferior)
what are smaller branches of veins called?
venules
what happens when valves in the veins are faulty?
varicose veins
what are capillaries?
tiny blood vessels that connect to the smallest branches of arterioles and venules
how thick are capillaries?
one cell thick
what do capillaries do?
bring nutrients and oxygen to tissues and remove waste products
what makes the lub-dub sound of a heartbeat?
the valves opening and closing
what does a heartbeat consist of?
a complete contraction (systole) and a complete relaxation (diastole)
what does a contraction consist of?
the atria contracting followed by the ventricles
about how much blood do we have in our bodies?
5L
how much of the blood does plasma make up?
about 55%
what is plasma made of?
- water
- dissolved CO2
- waste
- hormones
- proteins
what is the lifespan of a RBC?
about 120 days
where are RBCs, WBCs and platelets produced?
bone marrow
why is the shape of RBCs beneficial?
provides a large surface area for gas exchange and allows them to travel easily through the blood vessels
what is the benefit of RBCs not having a nucleus?
provides more room for hemoglobin on the surface of the cell
what iron binds to oxygen to transport it through the body?
hemoglobin
what is it called when hemoglobin bonds to oxygen?
oxyhemoglobin
what is sickle cell anemia?
a disorder that results in abnormally shaped RBCs which deliver less oxygen to the body
what is the lifespan of a white blood cell?
13-20 days
what are platelets responsible for?
clotting
what is the clotting process?
- dissolved fibrinogen comes in contact with a rough surface
- fibrinogen converts to active form: fibrin
- fibrin forms a mesh that traps RBCs to form a clot
is fibrinogen active or inactive?
inactive
what is the active form of fibrinogen?
fibrin
what is “bad” cholesterol?
LDL (from land animals) - it contributes to fatty buildups in arteries
what is “good” cholesterol?
HDL (from marine animals) - it carries LDL out of the body
what is atherosclerosis?
the build up of cholesterol inside the arteries (aka. coronary heart disease)
what is angina?
a cramping pain behind the breastbone, stretching out to the neck and arms caused by a lack of oxygen to the heart. often a symptom of atherosclerosis
what is a pathogen?
disease causing agent
what does fungi live off of?
dead or decaying organisms
what are examples of fungi?
athletes foot, ring worm
what is bacteria?
single celled organisms, no nucleus, can reproduce themselves
what are viruses?
microorganisms, require a host cell to reproduce, contain genetic information
what type of pathogen responds to antibiotics?
bacteria
what type of pathogen responds to vaccinations?
viruses
what are examples of bacteria?
strep throat, meningitis
what are examples of viruses?
HIV, flu, herpes
what is the first line of defence?
barriers that prevent the pathogen from entering the body
what prevents most pathogens from entering the body?
skin
how does skin prevent pathogens from entering the body?
it produces sweat and acidic oil secretions
how does the nose prevent pathogens from entering the body?
nasal hairs and mucus secretions
how do the eyes defend against pathogens?
they produce an antiseptic liquid
how does the stomach defend against pathogens?
HCl
what is the second line of defence?
occurs when the pathogen has entered the body, inflammation and fever help to fight against pathogens
what is the third line of defence?
this is an immune response specific to the pathogen
what are antigens?
unique proteins on the surface of a pathogen that triggers the immune response
what are antibodies?
proteins molecules produces in WBCs that bind to specific antigens to disable the pathogen
what is the first WBC to respond to a pathogen?
macrophages
what do helper T-cells do?
they bind to the antigens and send out hormone signals to coordinate the response of other cells
what do killer T-cells do?
if the pathogen is a virus they release a protein to destroy infected cells
what to B-cells do?
they produce antibodies
what do memory B and T cells do?
they remain in the body after the infection and remember the antibody so the immune response can be quicker next time that pathogen enters the body
what do suppressor T-cells do?
they signal the immune response to stop
where do T-cells mature?
in the thymus gland
where do B-cells mature?
in the bone marrow
where do antigens appear?
on the surface of the pathogen, then on the surface of the macrophage after it engulfs the pathogen
what cells respond specifically to viruses?
killer T-cells
what cells signal the immune response to stop?
suppressor T-cells