circulatory system 🔃

what does the circulatory system consist of? (3)

heart, blood vessels and blood

what is the total length of the blood vessels in the body?

100, 000 kilometers

what is the function of the circulatory system?

to transport various substances around the body

what 5 substances does the circulatory system transport and where are they transported to?

1) oxygen: lungs to all cells

2) nutrients: SI to all cells

3) carbon dioxide: all cells to lungs

4) urea: liver to kidney to urine

5) hormones: endocrine glands to all cells

what are the three main types of blood vessels and what do they do?

1) arteries- carry blood away from the heart

2) veins- carry blood towards the heart

3) capillaries- carry blood from arteries to veins

what is the smallest blood vessel?

capillaries

what is interstitial fluid? (3)

\-fluid that all the cells of the body “bathe” in

\-helps materials pass between body cells and blood

\-consists of water, salts, proteins and nutrients

what is a closed circulatory system? do humans have an open or closed circulatory system?

\-all blood is found in blood vessels/the heart

\-humans have closed systems

what do heart valves do?

prevent blood from flowing backwards

what does the heart do?

pumps blood throughout the circulatory system

where is the heart found?

the chest cavity

what is another name for the chest cavity?

thoracic cavity

what is the heart also known as?

a double pump

what is the pericardium?

a sac surrounding the heart that protects it

define:

a) peri

b) cardium

a) around

b) relating to the heart

what are the four chambers of the heart?

right and left atria, right and left ventricles

which of the two types of heart chambers has thicker walls?

the ventricles

what is the wall that separates the right and left sides of the heart?

the septum

what are the 2 main periods of the heart’s pumping?

systole and diastole

what happens during diastole?

the heart muscle relaxes

what happens during systole?

the heart muscles contract

which heart chambers contract first?

the atria

what causes the lub-dup noise?

heart valves closing

which valves make the ___ sound?

a) lub

b) dub

a) bicuspid and tricuspid

b) semilunar valves

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what is a special ability of the heart/cardiac muscle?

it can keep beating after being removed if it is in a certain substance

what are the two special muscle regions in the heart?

the AV-atrioventricular node and the SA-sinoatrial node

what is the sinoatrial node also known as?

the pacemaker

where is each node found and what do they do?

SA-upper right wall of the r atrium, sets the rate at which the heart contracts

AV- base of the r atrium, has long projections passing down into the ventricle walls

how do the nodes help the heart beat?

1) the SA node sends out an electrical signal, causing the atria to contract

2) when the signal reaches the AV, it causes the ventricles to contract

what does blood pressure refer to?

the fact that blood pushes against blood vessels

what happens to blood pressure as blood moves away from the

🫀?

it decreases

what causes a pulse?

arteries bulging during systole

how does blood move through the veins?

skeletal muscles beside the vein contract

why are there valves in veins?

to prevent blood from flowing backwards

what is the purpose of coronary circulation?

to supply the heart muscle with blood

which ventricle has the thickest walls?

left

which veins drain directly to the heart’s chambers?

coronary veins

what is atherosclerosis and what does it increase the risk of?

the arteries narrow due to buildup of plaque which increases the risk of heart attacks and strokes

what is coronary artery disease also known as?

atherosclerosis

what causes heart attacks?

buildup of plaque in a coronary artery prevents blood flow to a section of the heart and it dies

what are heart attacks also known as?

myocardial infarction

define:

a) myo

b) infarction

a) muscle

b) death

what are the 3 methods of treatment for coronary artery disease?

coronary bypass surgery, balloon angioplasty and stenting

what happens during coronary bypass surgery?

a vein is removed from somewhere else in the body and grafted behind and in front of the blockage so blood can flow

what happens during a balloon angioplasty?

a small balloon is threaded through the aorta to the blockage and inflates for 60 seconds, flattening the plaque

what happens during a stenting?

a stent is guided to the blockage and remains there, keeping the blood vessel open

what is a stent?

a tiny mesh cylinder

which two treatments for coronary artery disease are often done together?

balloon angioplasty and stenting

what happens during an angiography? (3)

\-a catheter is inserted into a blood vessel in the arm or leg and moved to the desired artery

\-dye is injected through the catheter which allows X-rays to be taken

\-blocked regions are visible

what is an angiogram?

the image/ results from an angiography

what is the placenta and when does it form?

an organ that forms only in pregnant women

what happens to the placenta after birth?

it detaches from the uterus and exits the body

what is afterbirth?

when the placenta exits a woman’s body after a baby is born

what is the point of fetal adaptations?

to divert blood flow away from the lungs

what are the 2 fetal adaptations and what do they do

1. foramen ovale-a hole in the septum between the right and left atria
2. ductus arteriosus-artery that connects the pulmonary artery to the aorta

what happens to blood that passes through the foramen ovale and ductus arteriosus?

it bypasses the fetal lungs

what are varicose veins?

veins that have lost their elasticity because valves do not work properly

how do red blood cells pass through capillaries?

in single file

what are the atrioventricular valves? (2)

tricuspid and bicuspid valves

what percent of the ventricle is full after diastole?

70%

what causes a heart murmur?

damaged heart valves

what is an electrocardiogram?

a recording of the hearts electrical currents that is used to determine if the heart is healthy

which nerves regulate the pacemaker? what does each one do? (2)

\-vagus nerve: slows the pacemaker

\-cardioaccelerator nerve: speeds up the pacemaker

what happens if the natural pacemaker fails?

an artificial pacemaker is surgically placed

what is the average…

a) systolic pressure

b) diastolic pressure

a) 120mmHg

b) 80mmHg

how is blood pressure measured?

using an instrument called a sphygmomanometer

how is blood pressure usually stated?

systolic pressure/ diastolic pressure

what is hypertension?

high blood pressure

what increases the risk of atherosclerosis?

high cholesterol intake

what would happen if all capillaries opened at the same time?

there wouldn’t be enough blood to fill them

what is located at the end of every arteriole?

a ring of muscle

what are the two major pathways of circulation?

pulmonary and systemic circulation

what happens to blood flow when we eat?

it is diverted to the digestive tract

what are the three branches of systemic circulation? what does each branch do?

1) coronary- supplies the heart muscle with blood

2) hepatic portal- carries blood from the digestive tract to the liver

3) renal circulation-carries blood to and from the kidneys where waste is removed

what is interstitial fluid also known as?

intercellular fluid

how is extra fluid and protein in the intercellular space returned to the blood?

the lymphatic system

what is the portal vein?

a vein that brings nutrient rich blood from the digestive tract to the liver

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what happens to blood in the portal vein once it reaches the liver?

nutrients are collected by hepatic sinuses and blood continues to the vena cava

what is a function of the liver?

to absorb and store excess glucose as glycogen

what does the lymphatic system do?

returns excess fluid and protein to the blood

what would happen without the lymphatic system? (2)

\-the circulatory system would drain because of the loss of fluid

\-body tissue would become flooded and swell up

what is fluid called once it enters the lymphatic system?

lymph

what are lymph capillaries?

microscopic tubes that join together to form larger vessels

what do lymphatic vessels have in common with veins?

they have valves

what is the thoracic duct?

the largest lymphatic vessel in the body

where do the thoracic and right lymph ducts empty into?

a large vein in the neck

what do lymph nodes do? (3)

\-filter foreign matter from lymph

\-produce some white blood cells

\-become swollen around infected areas

what do lymphoid tissues do in the spleen?

filter bacteria and worn out red blood cells from the blood

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