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Circulatory system Flashcards

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Biology 101 flashcards
1
Q

The circulatory system

A

A closed system of the heart and blood vessels. Blood vessels allow blood to circulate to all parts of the body
The function of the circulatory system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products.

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2
Q

The heart

A

Pump that pushes blood around the body. Located to the middle of chest cavity, behind and slightly on left of sternum.
Pointed apex directed toward left hip. Conical shape. (12 cm long, 9cm widest pt, 6cm thick) About the size of your fist

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3
Q

Pericardium

A

a membrane which surrounds the heart. Holds the heart in place allows it to move as it beats and prevents the heart from overstretching. Serous fluid fills the space between the layers of pericardium.

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4
Q

Chambers

A

Receiving chambers- Right atrium (receives blood from body + pass to R ventricle) Left atrium (receives blood from lungs + pass to L ventricle)
Ventricles (thick walls pump blood into arteries)
Discharging chambers- Right ventricle (pumps blood to lungs) Left ventricle (pumps blood to body)

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5
Q

Atria

A

thin walls receive blood from veins

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6
Q

Right and left sides and ventricle

A

Right side of heart collects blood from body and pumps to lungs. Left side of heart receives blood from lungs and pumps it to the rest of the body.

The left ventricle wall is much thicker than the Right ventricle as the left side of the heart needs to pump blood further all over the body, whereas the right side only has to send the blood to the lungs.

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7
Q

Valves of the heart

A

Valves open as blood is pumped through, Held in place by chordae tendineae (“heart strings”) therefore can’t turn inside out, Close to prevent backflow, Papillary muscle anchors the chordae tendineae
Atrioventricular valves – between atria and ventricles
-Bicuspid valve (left) (2 flaps)
-Tricuspid valve (right) (3 flaps)
Semilunar valves between ventricle and artery
-Pulmonary semilunar valve (3 cusps)
-Aortic semilunar valve (3 cusps)

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8
Q

Blood flow through the heart

A

Veins carry blood towards the heart, Arteries carry blood away from the heart, Superior Vena Cava + Inferior Vena cava return deoxygenated blood from the upper and lower parts of the body respectively, Both push blood into R. atrium through the tricuspid valve then into R ventricle, Through the Semilunar valve to the Pulmonary arteries (left + right) which takes blood to the lungs to be oxygenated, Pulmonary Veins (4, 2 per lung) return the oxygenated blood to the Left Atrium through the bicuspid valve and into the L Ventricle, Through the Semilunar valve to the Aorta which pumps the oxygenated blood to the head and body.

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9
Q

Blood flow

A

Blood delivers oxygen and nutrients and removes wastes from cells. Requirements of cells vary on their level of activity. Eg exercising compared to rest. To cater for these changes, blood flow to and from the cells must be able to change and this can occur by:
- changing the output of blood from the heart
- changing the diameter of the blood vessels supplying the tissues.

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10
Q

The cardiac cycle

A

the events that occur in 1 complete beat of the heart.
- Atria contract simultaneously
Atrial systole contraction and remaining blood in atria are forced into ventricles.
- Atria relax, then ventricles contract (ventricular systole)
Both atria + ventricles in diastole for a short time. Atria fills + ventricles also receive some blood as atrioventricular valves are open.
- Systole = contraction
Ventricular systole pushes blood into the arteries to take the blood away from the heart.
- Diastole = relaxation or filling phase

The heart has its own inbuilt rhythm of contraction + relaxation. It can be increased or decreased by nervous stimulation from the cardiac centre in the brain or by chemicals carried in the blood.

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11
Q

Cardiac output

A

how much blood your heart can pump in a minute

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12
Q

Blood vessels

A

Take blood to the cells of body/lungs + back to heart.
Three main blood vessels: Arteries, Capillaries, Veins.
Arteries – Take blood away from the heart.
Arterioles – Small Arteries.
Capillaries – Tiny vessels that carry blood between the cells.
Venules – Small Veins.
Veins – Carry blood back to the heart.

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13
Q

Arteries

A

As the heart pumps directly into the arteries they have a higher pressure than veins= The walls are thicker, stronger, made of smooth muscle with elastic fibres that expand + recoil.
When muscles relax or contract in the artery wall they decrease or increase the blood flow by altering the diameter of the artery.

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14
Q

Cellular respiration

A

produces wastes eg Co2 + lactic acid, these act as vasodilators, increasing blood flow through muscle tissues.

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15
Q

Blood Flow in Arteries and Arterioles

A

Vasoconstriction: Muscle of artery wall contracts to decrease the diameter of the artery which reduces blood flow to an organ.

Vasodilation: Muscle of artery wall relaxes to increase the diameter of the artery which increases blood flow to an organ.

These two processes help with the varying needs of the body. Does not happen in veins or venules.

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16
Q

Capillaries

A

Are the link between arteries and veins, Are microscopic bv’s that carry blood close to every cell in the body, Capillaries deliver nutrients and remove the wastes.
-Capillary walls are only 1 cell thick , therefore substances pass very easily between the blood + the surrounding cells.
- Diameter of capillary is about the diameter of a RBC.
No valves, walls non elastic.

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17
Q

Capillary beds

A

Capillary beds are a network of small blood vessels that allow the exchange of gas, water, and nutrients. Capillary beds are often located to metabolic organs, such as the lungs, kidneys, or brain, to exchange vital materials and rid waste.

True capillaries – exchange Oxygen and nutrients cross to cells. Carbon dioxide and metabolic waste products cross into blood.

18
Q

Veins

A

Veins carry blood towards the heart
-Capillaries join up to form small veins called venules. Venules become veins. Venous blood is low in pressure hence the walls of the veins are very thin but have a large lumen (diameter).
-Gravity may cause blood to flow backwards. To overcome this, veins have valves especially in the legs to stop backflow of blood.
-When you move, the skeletal muscles contract which squeezes the veins pushing the blood along

19
Q

Movement of Blood Through Vessels

A

Most arterial blood is pumped by the heart
Veins use the milking action of muscles to help move blood

20
Q

Circulation

A

Pulmonary Circulation – heart to lungs to heart.
-Right side of heart, pulmonary arteries, capillaries in the lungs, pulmonary veins, left side of heart

Systemic Circulation – heart to body to heart.
-Left side of heart to various parts of the body, to the right side of the heart.

Double circulation- A mechanism in which blood circulates twice through the heart in one complete cycle is known as double circulation. Systemic circulation and pulmonary circulation are two pathways in which the blood flows in double circulation. Double circulation is present in birds and mammals.

21
Q

Main arteries

A

Carotid arteries: Neck and head region.
Coronary arteries: Heart muscle
Subclavian arteries: Arms
Hepatic artery: Liver and stomach
Mesenteric artery: intestines
Renal arteries: kidneys
Femoral arteries: legs

22
Q

Pulse

A

pressure wave of blood where the arteries stretch and then recoil. Monitored at “pressure points” where pulse is easily palpated. Average between 70 + 90 bpm.

23
Q

Blood pressure

A

Measurements by health professionals are made on the pressure in large arteries

Systolic – pressure in the arteries during ventricular contraction. This is when the blood 1st spurts through. Pressure in artery is = to the pressure in the bladder.

Diastolic – pressure when ventricles relax. When you can no longer hear.

Pressure in blood vessels decreases as the distance away from the heart increases, Measured in millimeters of mercury (mmHg)

24
Q

Variation in blood pressure

A

Human normal range is variable
Normal- 140–110 mm Hg systolic, 80–75 mm Hg diastolic

Hypotension- Low systolic (below 110 mm HG), Often associated with illness

Hypertension- High systolic (above 140 mm HG), Can be dangerous if it is chronic

25
Q

Coronary Circulation

A

Coronary circulation is the circulation of blood in the arteries and veins that supply the heart muscle (myocardium). Coronary arteries supply oxygenated blood to the heart muscle.

Blood in the heart chambers does not nourish the myocardium, The heart has its own nourishing circulatory system

26
Q

AV valves

A

The mitral and tricuspid atrioventricular (AV) valves separate the atria from the ventricles, while the aortic and pulmonary semilunar (SL) valves separate the ventricles from the great arteries. AV valves have leaflets and SL valves have cusps.

27
Q

Semilunar valves

A

act in concert with the AV valves to direct blood flow through the heart. When the atrioventricular valves are open, the semi lunar valves are shut and blood is forced into the ventricles. When the AV valves shut, the semilunar valves open, forcing blood into the aorta and pulmonary artery.

28
Q

Functions of blood

A

Transport nutrients and O2 to all cells.
Transport CO2 and other waste products away from the cells.
Transport hormones to cells.
Maintain the pH of body fluids.
Distribute heat and maintain body temperature.
Maintain water content and ion concentration of body fluids.
Protections against disease causing organisms.
Blood clotting

29
Q

Features of blood

A

Temperature 37 0C
pH 7.35-7.45
Salinity 0.9%
Total body weight 8%
Volume- Men – 5-6 L, Women 4-5 L

30
Q

Formed elements in blood

A

The formed elements are cells and cell fragments suspended in the plasma. The three classes of formed elements are the erythrocytes (red blood cells), leukocytes (white blood cells), and the thrombocytes (platelets). Instead, they serve as temporary, hemoglobin-filled containers that transport oxygen throughout the body. They are part of the immune system and that helps protect the body from foreign invaders

31
Q

Plasma in blood

A

The main role of plasma is to take nutrients, hormones, and proteins to the parts of the body that need it. Cells also put their waste products into the plasma. The plasma then helps remove this waste from the body. Blood plasma also carries all parts of the blood through your circulatory system.

32
Q

Red blood cells

A

Erythrocytes. 40-45% volume of blood (haematocrit)
-Biconcave – increases surface area to carry oxygen and carbon dioxide
-Produced in Red bone marrow (ribs, vertebrae, pelvis)
-Begin with nucleus, loose nucleus when mature RBC, therefore more room for haemoglobin.
-Haemoglobin protein which combines with oxygen gives blood red colour
-can change shape to an amazing extent, without breaking, as it squeezes single file through the capillaries.
-120 days destroyed in liver and spleen

33
Q

White blood cells

A

Leucocytes (larger than RBC’s but fewer of them) 1% blood
1. Granular (granular cytoplasm, lobed nucleus + made in Red bone marrow)
- Neutrophils: most common. Contain enzymes to digest pathogens.
- Eosinophils: lead to inflammatory responses eg defend against worms.
- Basophils: allergic reactions, produce heparin/histamine defend bacteria/parasite

  1. Agranular (spherical nucleus, agranular cytoplasm)
    - Lymphocytes (made in spleen, tonsils, thymus gland, lymph nodes) involved in immune response; cell mediated immunity (T lymphocytes) antibody mediated immunity (B lymphocytes produce antibodies)
    - Monocytes (made in red bone marrow) form other cells (eg macrophages) engulf pathogens/aged/damaged cells via phagocytosis
34
Q

Platelets

A

Their primary function is to prevent and stop bleeding. If a blood vessel is damaged, the body sends signals to platelets which cause them to travel to the injured area. Once the platelets arrive at the site, they clump together to form a clot that helps stop bleeding.
- Small cell fragments with no nucleus 1/3 size of RBC’s
- Made in Red Bone Marrow
- Last 7 day and are involved in normal blood clotting.

35
Q

Transport of oxygen

A

Oxygen is carried in the blood in two forms: (1) dissolved in plasma and RBC water (about 2% of the total) and (2) reversibly bound to hemoglobin (about 98% of the total).

36
Q

Transport of carbon dioxide

A

Oxygen is carried both physically dissolved in the blood and chemically combined to hemoglobin. 7 - 8% CO2 dissolved in blood plasma, 22% carried with hemoglobin in Red Blood Cells as Carboxyhemoglobin (carbaminohemoglobin), 70% carried in plasma as bicarbonate ions

37
Q

Nutrients and waste in the blood

A

Nutrients and wastes are dissolved and transported in the blood plasma. Inorganic nutrients are transported as ions.eg Na, Ca, K, Cl, I. Organic nutrients dissolved in blood plasma eg glucose, vitamins, amino acids, fatty acids and glycerol.
Metabolic wastes transported are urea, creatinine and uric acid.

38
Q

Blood clotting- damage

A

When an injury occurs damaged blood vessels need to reduce blood loss and stop microorganisms from entering the body. Steps:
1. Vasoconstriction
2. Platelet Plug
3. Coagulation (For serious injuries)

39
Q

Vasoconstriction

A

Muscles in the blood vessel walls decrease blood flow by constricting if they are damaged or injured.

40
Q

Platelet plug formation

A

Damaged blood vessels develop a rough surface and platelets stick to that surface, Stuck platelets attract other platelets and form a plug- The plug of platelets helps reduce blood loss.
- Platelets release vasoconstrictors.
- Plugging of platelets + constriction of bv’s stops bleeding in small cuts.

41
Q

Blood Coagulation

A

This is a complex process involving clotting factors that are in the plasma.
1. Following damage to a blood vessel, blood platelets and the injured cells release an enzyme called thromboplastin.
2. Thromboplastin interacts with Ca ++ , Vitamin K and prothrombin (an inactive plasma protein in the plasma) to form thrombin.
3. Thrombin is an enzyme that converts fibrinogen (another inactive plasma protein) to long, stretchy fibers of fibrin.
4. The fibrin fires form a mesh at the site of the wound that traps platelets and blood cells. This is called a clot.
5. Within a few minutes the clot starts to contract, which pulls the edges of the broken blood vessel together. (clot retraction)
6. As the clot retracts serum a clear yellow fluid oozes out of the clot – this is plasma minus the fibrinogen.
7. When the clot solidifies it forms a scab. Hence no bacteria can get in.
8. After a couple of days an enzyme in the clot activates fibrinolysis - this starts the break-down of the clot.

If the clot forms inside a blood vessel it forms a thrombus.
If a thrombus breaks loose it can lodge in a vital blood vessel in the heart or brain causing a heart attack or stroke.

Human Bio (14 decks)

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