Chapter 30 Flashcards
Functions of the circulatory system
1- removal of waste products like co2
2- transport o2 and nutrients
3- transport of hormones
4-defending against pathogens or microbes
5-involved in repair of tissue damage
the circulatory system is composed of
heart blood blood vessels
Heart
a four-chambered msuclar organ. the overall flow of blood is from the heart to tissues throughout the body and back to the heart,. it is located between the lungs but is slightly inclined to the left.
blood vessels
blood flows throughout the body via blood vessels, tubes that form a closed pipeline within the body.blood vessels are tubes that facilitate the circulation and transportation of blood through the body
litres of blood in the body
5 litres, takes 1 minute for all of it to circulate
how long does it take for all the blood in you rbody to make a complete circuit under normal activity
1 minute
what effect does increased actvity have on blood circulation
increased activity causes blood to circulate more quickly in order to keep cells supplied iwth oxygen and nutrients.
types of blood vessels
capillaries veins and arteries
capillaries
-To distribute nutrients and oxygen effectively, the circulatory system must have close contact with all the cells of the body.
-This close contact is accomplished by millions of microscopic blood vessels called capillaries. Some capillaries are so narrow that blood cells must travel through them one at a time. The walls of capillaries consist of a very thin layer of epithelial tissue encased in a moist membrane, the walls of some capillaries are only 1 epithelial cell thick and there are often gaps between these cells. This structure enables the diffusion of nutrients and oxygen out of the blood and the diffusion of waste products into the blood.
arteries
-Blood flows from the heart to the capillaries through a system of thick-walled blood vessels called arteries,
-layers innermost to outermost: -epithelial->smooth muscle->connective tissue The muscle tissue enables the artery to constrict (become more narrow) and to dilate (relax).
-The blood in arteries is under pressure due to the heart’s pumping action. This pressure helps to ensure that blood flows only in one direction-toward the capillaries.
-Further from the heart, the arteries branch into smaller and smaller vessels called arterioles.Eventually the narrowest arteries flow into capillaries.
veins
-Blood returns from the capillaries to the heart through vessels called veins.
-The walls of veins also consist of layers innermost to outermost: -epithelial->smooth muscle->connective tissue. But the muscle layer in veins is thinner than that in arteries.
-The blood in veins is under very little pressure. The main force that pushes blood through the veins comes from the skeletal muscle tissue in which many veins are located. Contracting these muscles squeezes the veins and forces blood through them. -Most veins contain valves that allow blood to flow only toward the heart.
-Small veins called venues merge together into larger veins.
distance limit of body cells from a capillary
most cells in your body are no farther than 10 micrometers (um) from a capillary and the blood inside it.
endocytosis
transfering large molecules through membranes into cells
exocytosis
transfering large molecules through membranes out of cells
what happens at the artery and vein end of a capillary
At the artery end of a capillary, blood pressure forces water, small solutes, and some dissolved proteins through the gaps between cells. However, blood cells and larger proteins are too large to pass easily through these openings, so they remain in the capillary. As a result, the vein end of the capillary is hypertonic compared to the surrounding interstitial fluid.
Thus water tends to reenter the vein end of the capillary via osmosis. Blood pressure is very low at the vein end of the capillary, so it does not oppose the flow of fluid back into the capillary. In fact, 85 percent of the fluid that leaves the artery end of the capillary reenters at the vein end.
hypertonic
a hypertonic solution has a higher solute concentration than another solution
hypotonic
a hypotonic solution has a lower solute concentration than another solution
lymphatic system
Your blood loses about 4 liters of fluid into the interstitial fluid daily. The lymphatic system collects and returns most of this fluid to the circulatory system.
Like the circulatory system, the lymphatic system consists of capillaries and larger vessels
what does the lymphatic system do
Once inside the lymphatic vessels, this collected fluid is called lymph. Like veins, lymphatic vessels are embedded in muscle tissue, and they have valves that prevent lymph from flowing back toward the capillaries. The combination of muscle contractions squeezing the vessels and the one-way valves helps fluid move through the lymphatic system.
Eventually, lymph drains into the circulatory system near the heart through the thoracic duct, allowing the fluid to be reused.
Located at juncture points throughout the lymphatic system are enlargements in the lymph tissue called lymph nodes. Lymph nodes help defend the body against infection. The nodes contain cells that destroy some bacteria and viruses that may enter the body.
pulmonary circuit
transport of deoxygenated blood from the right ventricle, through the pulmonary artery to the lungs (the only artery to carry deoxygenated blood). the blood then becomes oxygenated and goes back to the left atrium by the pulmonary vein (the only vein to carry oxygenated blood)
systemic cicuit
transport of oxygenated blood from the left ventricle through the aorta towards the bodily cells and the subsequent movement of deoxygenated blood back to the right atrium by the vena cava.
ventricle
The two lower chambers are called ventricles, which pump blood out of the heart.
atrium
The two upper chambers, which receive blood returning to the heart, the right arium recieved deoxygentaed blood and the left atrium recieves oxygenated blood
difference between ventricles and atria
The atria, which pump blood a short distance into the ventricles, have fairly thin walls. Ventricles have thicker muscular walls that enable them to pump blood throughout the body. ventricles, which pump blood out of the heart. atria recieve blood. atria are the upper chambers and ventricles the lower chambers
valves
Flaps of tissue in the heart called valves prevent blood from flowing backward. Valves are located between the atria and ventricles (called atrioventricular valves), and also between the ventricles and the arteries leading from the heart (called the pulmonary valve and the aortic valve). With each heartbeat, the valves open, allowing blood to flow through. Then the valves close, preventing blood from flowing back. The familiar heart sound of “lub dupp” is caused by the valves snapping shut. The “lub” sound is the atrioventricular valves closing, while the “dupp” sound happens when the pulmonary and aortic valves close.
pacemaker and the regulation of heartbeat
-A specific region of your heart muscle, known as the pacemaker, sets the rate at which your heart contracts. The pacemaker is located in the wall of the right atrium.
-It generates electrical impulses that spread rapidly over the walls of both atria, making them contract.
-The impulses then spread to a region of the heart called the AV mode (atrioven-tricular node). From there, the electrical impulses spread to the ventricles, causing them to contract. The contracting ventricles propel blood to the rest of the body.
-The pacemaker ensures that the heart beats in a rhythmic cycle. During the relaxation phase, called diastole, the atria and ventricles are relaxed, allowing blood from veins to enter the heart.
systole
the contraction phase of the cardiac cycle
diastole
the relaxation phase of the cardiac cycle
what is the pacemaker controlled by
The pacemaker is controlled by both the nervous system and the endocrine system. Two sets of opposing nerves control the pacemaker by speeding it up and by slowing it down. Hormones secreted into the blood also control the pacemaker. For example, the hormone epinephrine, also called adrenaline, increases heart rate when the body is under stress.
how is blood pressure generated
When the ventricles contract, they increase pressure on the blood.
The resulting force that blood exerts against the artery walls is called blood pressure. This force drives blood through the arteries and into the capillaries. Artery walls are elastic, which enables them to stretch in response to this force.
systolic pressure
systolic pressure, the highest recorded pressure in an artery when the ventricles contract.
diastolic pressure
Diastolic pressure, the second number, is the lowest recorded pressure in an artery during the relaxation phase of the heartbeat.
average heart pressure
120/70
systolic pressure: 120
diastolic pressure: 70
plasma
Blood is the only liquid connective tissue in your body
-Fifty-five per cent of the volume of blood is a solution called plasma.
-Plasma is 90 per cent water.
-The other 10 per cent of plasma consists of dissolved salts, proteins, and other transported substances.
-The remaining 45 per cent of blood volume consists mostly of red blood cells.
red blood cells
By far the most numerous cells in your blood are red blood cells or erythrocytes.
-Red blood cells carry oxygen from the lungs to all the tissues of the body. One drop of blood (1 cubic millimeter) contains about 5 million red blood cells, and the average person has about 25 trillion in all.
-Each red blood cell contains about 250 million molecules of hemoglobin, a protein that temporarily stores oxygen for delivery to the cells.
-red blood cells have a biconcave disk shaped structure because of their loss of mitochondria and nuceli as they mature. this biconcave shape increases the surface area of the cell compared to aspherical shape fo the same volume, which enables the cell to carry more oxygen
-they are created in the bone marrow at a rate of 2 million per second
-life span of 100-120 days. as they have no mitochondria aor nuceli they cannot grow divide or produce proteins, they become fragile as they mature
what is plasma composed of
Plasma (55%)
* Water
* Dissolved salts
* Plasma proteins
* Transported substances:
Nutrients
Metabolic wastes
Oxygen and carbon dioxide
Hormones
cellular components of blood
Cellular components (45%)
* Red blood cells
* White blood cells
* Platelets
white blood cells
-Also called leukocytes,
-white blood cells have nuclei and mitochondria and are responsible for fighting infection and preventing the growth of cancer.
-Normally, there are between 4,000 and 11,000 white blood cells in a drop (one cubic millimeter) of blood. However, when infection invades your body, the number of white blood cells increases.
-Most of the action of white blood cells takes place outside the blood vessels in the interstitial fluid.
blood clotting
When you get a small cut or scrape, your blood usually clots, stopping the bleeding and sealing the wound. The clotting process depends on small fragments of blood cells called platelets that originate in the bone marrow. Each drop of blood contains between 250,000 and 500,000 platelets.
1- The blood clotting process begins when platelets adhere to the site where the blood vessel is damaged.
2-The platelets break apart and release substances called clotting factors.
3-The clotting factors make other nearby platelets sticky and activate a series of reactions among other clotting factors in the plasma.
4-These reactions result in the formation of a protein called fibrin.
5-Fibrin threads trap red blood cells and additional platelets.
6-This network of threads and cells builds up, eventually forming a patch that stretches over the torn tissue. This patch dries into a scab.
haemoglobin
haemooglobin a protein that temporaily stores oxygen fro delivery to the cells . it is a good transporter of of oxygen because wit bind to iton. oxygen molecules bind to theiron portion (also called the heme group) of the haemoglobin moleucle.
plaque
a patchwork of cholesterol, calcium and fat deposits that adheres ti the interior walls of blood vessels
cardiovascular
illness of the heart and/or blood vessels that may be caused by significant plaque buildup
atherosclerosis
- Narrowing of the arteries, results from plaque building up inside the artery wall.
-As the pathway narrows, blood pressure increases.
-Sometimes the narrowing completely blocks the flow of blood. If such a blockage occurs in one of the coronary arteries, the main arteries that supply the heart, the heart becomes deprived of oxygen and other nutrients.
-In mild cases with partial blockage, the person may feel occasional chest pains, called angina pectoris. In cases of severe blockage, a blood clot could close up the artery, leading to a heart attack.
arteriosclerosis
-A more advanced stage of plaque buildup, called arteriosclerosis, occurs when the deposits on the artery wall harden.
-arteries are flexible and can expand and contract, which helps to control blood pressure. With arteriosclerosis, the arteries lose their ability to stretch.
-This disease increases blood pressure and the chance for blood clots to form within the blood vessels.
hypertension
-Anger or fear can temporarily raise a person’s blood pressure. However, if a person has a blood pressure of 140/90 or higher for an extended period of time, that person is said to have hypertension or high blood pressure.
-Prolonged hypertension damages the heart and blood vessels. The heart must work harder to pump blood throughout the body, and over time the heart muscles enlarge.
-If these muscles expand too much, they actually become weakened and incapable of pushing blood throughout the body. Hypertension also exerts greater than normal pressure on the walls of the arteries, which can cause small tears. These tears can speed up atherosclerosis, which further increases blood pressure.
stroke
. If a blood clot forms in an artery going to the brain, it can cause a stroke, and damage to brain tissue resulting from blocked blood flow. Tissue downstream from the blockage dies from lack of oxygen. Some consequences of stroke are partial paralysis, loss of speech, memory loss, and sometimes death. These effects depend in part on where in the brain the blockage occurred.
preventative measures
Although some risk for cardiovascular disease is genetic, there are also many controllable factors that play a role. For example, smoking, lack of exercise, and high-fat diets all increase risk.
limit your intake of cholesteerol
limiting your intake of salt (high salt levels can increase blood pressure) and eating lots of fresh fruits, vegetables, and whole-grain foods.
Some researchers think that the fibre in these types of food helps to lower cholesterol levels. The proper diet, combined with regular exercise to maintain cardiovascular fitness, will help keep your circulatory system healthy.
cholesterol
Cholesterol is one ingredient in the plaque that coats artery walls. Cholesterol is found in foods containing saturated animal fats, such as butter and meat. High cholesterol levels increase the risk for cardiovascular disease.
