Chapter 6

Distribution of materialsChapter 6Blood circulatory system of mammalsTransport of materials to and from the cells of tissues (eg, brain, muscles) is carried out by a blood circulatory systemThe circulatory system consists of:Blood vessels: arteries, veins, capillariesThe heart: a muscular pump to keep the blood moving

Refer to Figure 6.4 pg 131Components of bloodBlood is made up of many components:PlasmaIs about 90% water, the rest is molecules dissolved in the waterMakes up about 55% of bloodRefer to table 6.1 pg 132 for the dissolved molecules of plasmaBlood cellsRed 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 bloodVessels to transport bloodArteries- 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 tissueSmaller arteries are called arteriolesVeinsTransport blood back to the heartHave thin walls, blood is under lower pressure as it has travelled further from the heartVeins have valves that prevent the backflow of blood (think about blood travelling from your feet back to your heart) CapillariesThin 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 QuestionsQuick check pg 136 1-3When you finish, read through pages 129-136 paying particular attention to the diagramsNext we will be going through answers to the homework questions from pgs 125-126

The heartThe heart is effectively 2 pumps joined togetherThe right side receives blood from around the body and pumps it to the lungs to receive O2 and drop off CO2The left side receives blood from the lungs (O2 rich) and transports it to the body via the main artery- the aortaPathway of blood in the heartAorta 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 vesselCAPITALS = significant structure in the heart

Inside the heartThe septum separates the right and left sides from each otherEach side has two chambers- an atrium and a ventricle.The two atria have thin walls as their job is to receive blood into the heartThe 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

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

Different circulatory systemsClosed: 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

The lymphatic systemWhen 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 systemThe lymphatic system does not have a pump- it relies on valves to prevent backflow, muscular movements, pressure from nearby blood vessels.

Transport of nutrientsThe 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 142Enter the body asDigested toPolysaccharidesSimple sugars (eg glucose)FatsGlycerol & fatty acidsProteinsAmino acidsTransport of gasesBlood transports O2 to cells and takes CO2 awayGas exchange occurs at sites where O2 enters and CO2 is removed (or vice versa) eg at cells, at the lungs

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

Pharynx and LarynxWhen we breathe in, air passes through the pharynx (throat) and the larynx (voice box) TracheaAfter the larynx, air travels down the trachea (windpipe) which is reinforced with rings of cartilage to ensure that it does not collapseBronchi & bronchiolesAir 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 alveoliThere are around 300 million alveoli in our lungs. These are the site of gas exchange.

Transport of wastesWastes are produced by metabolic activity. [For instance, when protein is metabolised (broken down) in a cell ammonia is formed]Removal of wastes is called excretionCO2 excreted via lungs (breathing out)Nitrogenous wastes (eg urea) excreted via kidneysAmmonia 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 ureaThe urinary systemIn humans, the urinary system consists of 2 kidneys, 2 ureters, a bladder, and a urethraKidneys: filter the blood and remove wastesUreter: transports urine from kidney to bladderBladder: stores urineUrethra: transports urine from bladder to outside the bodyKidneysFunctional units of the kidneys are called nephronsEach kidney contains about 1 million nephrons

Refer to page 152Read page 153-154 together

Transport in plantsThe plant transport system consists of phloem and xylemXylem transports water and dissolved mineralsPhloem transports sucrose (produced by photosynthesis) to other regions of the plant

Movement of water in xylemWater is absorbed by root hairs, moves through the cortex (layer of tissue between hair and xylem) and into the xylemHow 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 xylemAll of this is possible because water molecules like to stick together a property called cohesion

Movement of organic substances through phloemSoluble (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 energyThis process is called translocationSugars exit the phloem via active transport and move into cells for storage or immediate use.

Gaseous exchange in plantsCO2 is needed for photosynthesisCO2 must enter the plant from the air surrounding itStoma (or stomata- pl) are the gateway for CO2 to enter

Stomata: gateways in leaves for gaseous exchangeStomata are surrounded by 2 guard cells which can be either turgid or flaccidTurgid: high water content- cell is upright and full of waterFlaccid: lower water content- cell is relaxed See picture pg 164When guard cells are turgid, the stoma is open and allows CO2 to enterOpen Stomata: potential loss of water vapourWhen 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)

Gaseous exchange across root hair surfacesLiving cells in roots require O2 for respirationSoil has spaces containing air that can diffuse into root hairs

Excretion in plantsPlants 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 wallsPlants 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)

Comparison of plants & mammalsPlantsMammalsAre heart-less- oxygen enters via diffusion or as a result of photosynthesisHave a heart and continuous supply of oxygen via the circulatory system Do not have bulk transport of oxygenHave haemoglobin in RBCs that carries oxygenMake their own food via photosynthesis at locations around the plantHave bulk intake of food and oxygen which requires transport around the organism