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Chapter 6

Chapter 6. Distribution of materials. 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

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Chapter 6

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  1. Chapter 6 Distribution of materials

  2. 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

  3. 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 WBC’s. • Platelets- involved in clotting of the blood

  4. 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

  5. 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

  6. 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 O2 and drop off CO2 • The left side receives blood from the lungs (O2 rich) and transports it to the body via the main artery- the aorta

  7. 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

  8. 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

  9. 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

  10. 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

  11. The lymphatic system • When O2 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.

  12. 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

  13. Transport of gases • Blood transports O2 to cells and takes CO2 away • Gas exchange occurs at sites where O2 enters and CO2 is removed (or vice versa) eg at cells, at the lungs

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

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

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

  17. 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.

  18. 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

  19. 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

  20. 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

  21. 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

  22. 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’

  23. 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 don’t 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.

  24. 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

  25. 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

  26. 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)

  27. 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

  28. 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)

  29. Comparison of plants & mammals

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