Circulatory system(sub topic) Flashcards
Whats the Circulatory system?
- mass transport system
-carries raw materials, waste products around the body
Why do multicellular organisms, like mammals need a circulatory system?
-low surface area to volume ratio
- specialised mass transport system to carry raw materials from specialised exchange organs to their body cells
What is the circulatory system is made up of?
-heart
-Blood vessels:
-arteries
-arterioles
-veins
-capillaries
What carries blood from heart to the lungs?
-Pulmonary artery
What carries blood from the lungs to the heart?
-Pulmonary vein
What blood vessel carries blood from the heart to the body?
-Aorta
What carries blood from the body to the heart?
-Vena cava
What carries blood from the body to the Kidneys?
-Renal artery
What carries blood from the Kidneys to the Vena Cava?
-Renal vein
What do Arteries do ?
-carry blood away from the heart and to the rest of the body
-carry oxygenated blood except for the pulmonary arteries (deoxygenated blood to the lungs)
What are Arteries structure?
-thick and muscular walls
-elastic tissue (helps them recoil as the heart beats, and maintain the high pressure)
-endothelium /inner lining is folded (allows artery to stretch which maintain high pressure)
What are Arterioles and what do they do?
-arteries divide into smaller vessels
-form a network throughout the body
-muscles inside the arterioles contract to restrict the blood flow or relax to allow full blood flow.(to meet demands of blood)
What do Veins do ?
- take blood back to the heart under low pressure
-carry deoxygenated blood apart from pulmonary veins (oxygenated blood from lungs to heart)
What are the structures of veins?
-wider lumen
-very little elastic or muscle tissue (due to low pressure)
-pocket valves (prevent backflow of blood)
-Blood flow is helped by the contraction of the body muscles surrounding them
What do Capillaries do?
-Arterioles branch into capillaries
-smallest of the blood vessels
-adapted for efficient diffusion.
-form networks (capillary beds)
What are Capillary structure?
-found close to cells in exchange tissues (e.g. alveoli), so there’s a short diffusion pathway
-walls are only one cell thick, short diffusion pathway
-large number of capillaries, increase surface area
Whats in the blood?
Cells:
-Red blood cells
-White blood cells
-Platelets
Plasma:
-Glucose
-Amino acids
-Mineral ions
-Oxygen
-Plasma proteins (albumin)
What is tissue fluid?
-fluid that passes out of blood and bathes the tissue cells
How does tissue fluid move in and out of the capillaries?
-forced out of the blood at the arterial end of the capillaries
- transfers molecules like oxygen and glucose to tissue cells
-waste is transferred to the fluid
-returns back to the blood at the venous end of the capillaries
What are the competing factors for movement of tissue fluid?
-hydrostatic pressure
-oncotic pressure
How do substances move in and out of the capillaries, into the tissue fluid?
-pressure filtration
-tissue doesn’t contain RBCs or big proteins, too large to be pushed out the capillary walls
-Cells take in oxygen and nutrients from the tissue fluid, and release metabolic waste into it.
What pressure is high and why at the arterial end?
-hydrostatic pressure
-blood has just passed through an artery to an arteriole so still under high pressure
-pushes fluid out of blood to tissue
How can water move back into the blood by osmosis?
-Plasma proteins = hydrophillic
-they lower water potential in the blood plasma
-so water can move back into the blood by osmosis
What pressure is high and why at the venous end?
-Oncotic pressure is high
-plasma proteins in the blood plasma
What is ultrafiltration?
-tissue fluid being forced out of the capillary through the gaps in the endothelial cells
What happens to the remaining 10% of water not absorbed?
-drains into a series of blind-ended vessels called lymph capillaries
Why is the water potential at the venule end of the capillary bed is lower than the water potential in the tissue fluid?
-the fluid loss
-increasing concentration of plasma proteins(don’t leave the capillaries)
-SO some water re-enters the capillaries from the tissue fluid at the venule end by osmosis.
