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Flashcards in Blood Deck (15):

What is the structure of veins.

The outer layer is connective tissue a middle layer of smooth muscle and the inner layer lined with endothelial cells. Veins are blood vessels that carry blood toward the heart. The middle layer is the smoothest, thickest layer. Veins contain a valve which stops back flow due to low pressure.


What is the structure of arteries.

Arteries have three main layers or tunics known as the adventitia (outer), media (middle) and intima (inner). The outer layer is made of connective tissue with collagen fibers, the middle layer consists of smooth muscle and elastic fibers, and the innermost layer is composed of specialized squamous cells supported by the basement membrane of connective tissue.


What is the function of capillaries

Capillaries, the smallest and most numerous of the blood vessels, form the connection between the vessels that carry blood away from the heart (arteries) and the vessels that return blood to the heart (veins). The primary function of capillaries is the exchange of materials between the blood and tissue cells. This involves oxygenated and de-oxygenated blood.


What is the structure of capillaries

Some capillaries are so small that they can only be seen under a microscope, and tiny blood cells can only pass through them one at a time. Because capillaries are so small, their walls are correspondingly thin. Nutrients carried by the blood are able to pass through these walls to the cells of the body. Waste materials from the cells and tissues can also pass through the walls and be carried away. In the lungs, the capillaries exchange oxygen and carbon dioxide. It is so thin so diffusion can quickly occur.


What is the function of veins.

Veins are an important part of our circulatory system. They are responsible for returning deoxygenated blood back to the heart after arteries carry blood out. The vena cava is the largest vein in the body. Veins have much thinner walls than arteries. Due to the blood being low pressure.


What is the function of arteries.

The function of the arteries is to carry oxygenated blood to organs and cells in the body. Because of this, arterial blood has a bright red color and flows away from the heart. This is why it has such thick walls to prevent the high blood pressure from causing splits in the cell walls.


What are the percentages of blood in the body.

55% percent plasma 45% red blood cells. <0.1% white blood cells and platelets.


What is the function of plasma

Carries dissolved substances around the body. E.g. Waste, carbon dioxide and maintains constant body temperature.


Function of red blood cells

Haemoglobin bonds ,plecules and carries oxygen molecules around as oxyhemoglobin.


White blood cells

Defends the body against pathogens. Phagocytes engulf pathogens, after hunting them and finding them. The function of the arteries is to carry oxygenated blood to organs and cells in the body. Because of this, arterial blood has a bright red color and flows away from the heart. lymphocytes are specific to a certain virus and produce anti bodies that latch onto and kill the virus.


What is the function of platelets

Platelets help form blood clots, platelets along with fibrinogen help seal wounds. All reactions controlled by enzymes.


Structure of plasma

Yellow liquid. Only liquid in blood that contains suspended blood cells.


Structure of red blood cells

Biconcave shaped discs are very small so they can fit through blood vessels and have a very high surface area to volume ratio. No nucleus. Contain haemoglobin


Structure of white blood cells.

No definite shape, bigger than red blood cells, fewer than red blood cells, have a nucleus.


Structure of platelets.

Small fragments of cells with no nucleus, formed in bone marrow.