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Distribution of materials Chapter 6

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Blood circulatory system of mammals Transport of materials to and from the cells of tissues (eg, brain, muscles) is carried out by a blood circulatory system The circulatory system consists of: Blood vessels: arteries, veins, capillaries The heart: a muscular pump to keep the blood moving Refer to Figure 6.4 pg 131

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Components of blood Blood is made up of many components: Plasma Is about 90% water, the rest is molecules dissolved in the water Makes up about 55% of blood Refer to table 6.1 pg 132 for the dissolved molecules of plasma Blood cells Red blood cells (erythrocytes)- contain haemoglobin- the oxygen carrying component of blood. White blood cells (leucocytes)- part of the immune system, combat infection. There are different types of WBCs. Platelets- involved in clotting of the blood

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Vessels to transport blood Arteries- carry blood away from the heart. Have thick walls to withstand blood pressure pumped out of heart, however, these walls are too thick to allow easy movement of substances in and out of blood and tissue Smaller arteries are called arterioles Veins Transport blood back to the heart Have thin walls, blood is under lower pressure as it has travelled further from the heart Veins have valves that prevent the backflow of blood (think about blood travelling from your feet back to your heart) Capillaries Thin walled small blood vessels- walls are 1 cell thick, allowing for easy passage of substances in and out of blood Heart Arteries Arterioles Capillaries Venules Veins Heart

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Questions Quick check pg 136 1-3 When you finish, read through pages 129-136 paying particular attention to the diagrams Next we will be going through answers to the homework questions from pgs 125-126

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The heart The heart is effectively 2 pumps joined together The right side receives blood from around the body and pumps it to the lungs to receive O 2 and drop off CO 2 The left side receives blood from the lungs (O 2 rich) and transports it to the body via the main artery- the aorta

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Pathway of blood in the heart Aorta the body inferior vena cava & superior vena cava RIGHT ATRIUM tricuspid valve RIGHT VENTRICLE pulmonary artery Lungs Pulmonary vein LEFT ATRIUM bicuspid valve LEFT VENTRICLE Aorta Italics = blood vessel CAPITALS = significant structure in the heart

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Inside the heart The septum separates the right and left sides from each other Each side has two chambers- an atrium and a ventricle. The two atria have thin walls as their job is to receive blood into the heart The ventricles have thick walls as their job is to pump blood. (LEFT ventricle has the thickest as it has the bigger job to do) Pulmonary artery & vein = responsible for blood traffic between heart & lungs

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Heartbeat Average adult HR between 60 & 90 beats per minute Rhythmic beating controlled by a pacemaker called sinoatrial node- electrical impulse that spreads throughout the heart

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Different circulatory systems Closed: blood remains in blood vessels at all times (things may enter and leave it but the blood stays) Open: blood is sometimes in vessels and sometimes in tissues

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The lymphatic system When O 2 and nutrients leave capillaries some fluid escapes. The lymphatic system picks up this fluid and returns it to the blood stream- it is a one-way system The lymphatic system does not have a pump- it relies on valves to prevent backflow, muscular movements, pressure from nearby blood vessels.

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Transport of nutrients The products of digestion need to be transported to cells in a form that is small enough to cross the cell membrane Questions 4-10 pg 142 Enter the body asDigested to PolysaccharidesSimple sugars (eg glucose) FatsGlycerol & fatty acids ProteinsAmino acids

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Transport of gases Blood transports O 2 to cells and takes CO 2 away Gas exchange occurs at sites where O 2 enters and CO 2 is removed (or vice versa) eg at cells, at the lungs

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http://www.vcaa.vic.edu.au/vce/studies/biology/biologystd.pdf

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Pharynx and Larynx When we breathe in, air passes through the pharynx (throat) and the larynx (voice box)

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Trachea After the larynx, air travels down the trachea (windpipe) which is reinforced with rings of cartilage to ensure that it does not collapse

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Bronchi & bronchioles Air moves from the trachea into 2 bronchi (singular = bronchus) If the trachea can be compared to a tree trunk then each bronchus is a very large branch coming off the trunk. Smaller and smaller branches exist throughout the lungs Trachea bronchus bronchioles alveolar duct alveolar sac alveoli There are around 300 million alveoli in our lungs. These are the site of gas exchange.

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Transport of wastes Wastes are produced by metabolic activity. [For instance, when protein is metabolised (broken down) in a cell ammonia is formed] Removal of wastes is called excretion CO2 excreted via lungs (breathing out) Nitrogenous wastes (eg urea) excreted via kidneys Ammonia is converted to urea or uric acid depending on how much water is available. The urinary system in animals deals with waste products such as urea

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The urinary system In humans, the urinary system consists of 2 kidneys, 2 ureters, a bladder, and a urethra Kidneys: filter the blood and remove wastes Ureter: transports urine from kidney to bladder Bladder: stores urine Urethra: transports urine from bladder to outside the body

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Kidneys Functional units of the kidneys are called nephrons Each kidney contains about 1 million nephrons Refer to page 152 Read page 153-154 together

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Transport in plants The plant transport system consists of phloem and xylem Xylem transports water and dissolved minerals Phloem transports sucrose (produced by photosynthesis) to other regions of the plant

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Movement of water in xylem Water is absorbed by root hairs, moves through the cortex (layer of tissue between hair and xylem) and into the xylem How can trees be up to 100 m tall? When stomata open, water loss occurs as vapour evaporates from them. As water evaporates from mesophyll cells, water from the xylem moves into mesophyll cells. This sets off a chain reaction where water is drawn up the xylem All of this is possible because water molecules like to stick together a property called cohesion

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Movement of organic substances through phloem Soluble (dissolvable in water) organic substances are transported by phloem tissue from the leaves (where they are made) to other parts of the plant (that dont photosynthesize) Transport also occurs between storage sites (where excess sugars are stored) to parts of the plant requiring energy This process is called translocation Sugars exit the phloem via active transport and move into cells for storage or immediate use.

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Gaseous exchange in plants CO2 is needed for photosynthesis CO2 must enter the plant from the air surrounding it Stoma (or stomata- pl) are the gateway for CO2 to enter

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Stomata: gateways in leaves for gaseous exchange Stomata are surrounded by 2 guard cells which can be either turgid or flaccid Turgid: high water content- cell is upright and full of water Flaccid: lower water content- cell is relaxed See picture pg 164 When guard cells are turgid, the stoma is open and allows CO2 to enter

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Open Stomata: potential loss of water vapour When stomata are open, water loss occurs. Under ordinary conditions, the concentration of water vapour in the area surrounding the stoma will be lower than in the cells of the stoma, therefore water will move from area of high conc, to the area of low conc. Under dry conditions, there is the potential for this water loss to become excessive as water will move at a faster rate. Some plants have adaptations to protect from excess water loss (eg sunken stomata)

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Gaseous exchange across root hair surfaces Living cells in roots require O2 for respiration Soil has spaces containing air that can diffuse into root hairs

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Excretion in plants Plants have a higher tolerance for fluctuations in their environment (ie the build up of toxic substances) than animals do. In plants, ergastic substances is the term used (instead of excretory products) This term refers to the products of photosynthesis as well as waste products. Wastes are often stored in vacuoles (dissolved in water) and cell walls Plants are able to shed parts of themselves to rid themselves of wastes- eg shedding of some leaves. (imagine animals needed to lose part of their body to get rid of wastes)

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Comparison of plants & mammals PlantsMammals Are heart-less- oxygen enters via diffusion or as a result of photosynthesis Have a heart and continuous supply of oxygen via the circulatory system Do not have bulk transport of oxygen Have haemoglobin in RBCs that carries oxygen Make their own food via photosynthesis at locations around the plant Have bulk intake of food and oxygen which requires transport around the organism