Unit 3 Human Biology All Parts (3) PDF - Leaving Certificate Biology 2024-2025

Biology Wesley Hammond 5th Year Leaving Certificate Higher Level 2024-2025 Unit 3 (Human Biology): Blood/Heart/Lymphatic System/Breathing System/Human Nutrition/Excretion/ Endocrine System/Nervous System/Senses/Human Reproduction/Skeleton/Human Defence...

Biology Wesley Hammond 5th Year Leaving Certificate Higher Level 2024-2025 Unit 3 (Human Biology): Blood/Heart/Lymphatic System/Breathing System/Human Nutrition/Excretion/ Endocrine System/Nervous System/Senses/Human Reproduction/Skeleton/Human Defence  CONTENTS Topic Page Blood 1 The Heart 11 Lymphatic System 42 Breathing System 50 Human Nutrition 68 Excretion 96 Nervous System 126 Endocrine System 154 The Senses 167 Human Reproduction 182 Skeleton 220 Human Defence 239 What do you need to know about UNIT 3? Unit 3 is worth at least 55% of the Biology paper (can be worth more if experiments from this section are asked). Two short questions (10%) will be asked from unit 3. Three long question (45%) will be asked from unit 3. An experiment question (7.5%) can also be sometimes asked in section b of paper. Wesley Hammond. Biology. Leaving Certificate. 5th Year. Blood History of topic 2006 9 marks 2007 6 marks 2009 6 marks 2012 9 marks 2018 9 marks 2019 20 marks 1 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Components of blood: Plasma Red blood cells White blood cells Platelets NOTE; pH of blood is 7.4 Plasma Plasma is liquid part of the blood. Golden liquid Makes up 55% of blood Plasma is made of: 90% water 7% proteins 3% dissolved materials that are transported Types of plasma proteins: Antibodies (metabolic protein): produced by white blood cells to help destroy foreign substances. Clotting proteins: help forms blood clots Function of plasma: Transport materials (glucose, amino acids, salts, carbon dioxide, vitamins, urea and hormones). Urea is formed when the liver breaks down amino acids. Carbon dioxide is formed from glucose when it is broken down Plasma carries heat around the body. during respiration in our cells. Note: Serum is plasma which has the clotting proteins removed. It is used in injections to give someone resistance to disease. 2 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Red blood cells (erythrocytes) Produced in the red bone marrow. Contain haemoglobin (a red protein) Only live for 4 months (as they lack a nucleus) Red blood cells that are dead are broken down by the liver and spleen to produce bile. Red blood cells are also known as erythrocytes. Lose nucleus as they mature (making them flexible) Lack mitochondria Biconcave in shape (gives them larger surface area to allow them to exchange more oxygen) Have a flexible membrane that helps the pass through narrow capillaries (made up from a red protein called haemoglobin). - When haemoglobin joins with oxygen in the lungs it forms oxyhaemoglobin. Lungs Haemoglobin Oxyhaemoglobin (red) - When the cells use oxygen, oxyhaemoglobin convert back to haemoglobin. Body cells Haemoglobin Oxyhaemoglobin Note: Haemoglobin is made up of iron. Role of haemoglobin in red blood cells: Transport oxygen by hameoglobin. NOTE: Anaemia is a lack of haemoglobin or red blood cells (caused by a lack of iron in diet). 3 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  White blood cells (leuocyctes) Question – How do red blood cells differ from Larger than red blood cells white blood cells? No definite shape Red blood cells have no mitochondria and no nucleus but white blood cells do. Less numerous (700 red : 1 white) Red blood cells are biconcave in shape Have a nucleus bit white bloods cells are not. Red blood cells contain haemogloblin Made in the red bone marrow and are smaller while white blood cells have no haemogloblin and are larger. Function of white blood cells: Fight infections (attack bacteria, viruses) How do white blood cells fight infections? Some white blood cells (monocyctes/ phagocytes) engulf the harmful bacteria and digest them. Some white blood cells (lymphocytes) produce antibodies. Two types of white blood cells: 1) Monocytes / phagocytes 2) Lymphocytes Monocytes/ phagocytes Large cells that digest other particles by surrounding them. Also known as macrophages (large phagocytes). Made in bone marrow. Can survive up to 9 days. Have a kidney shaped nucleus. 4 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Lymphocytes: Made in bone marrow Mature in lymphatic system Stored in spleen and lymph nodes. Has a round nucleus Makes antibodies to fight infections (Antibodies inactivate antigens) Can survive up to 10 years. Platelets (thrombocytes) Made in the red bone marrow from cell fragments. Role of platelets: Clot the blood Functions of blood clots: 1) Reduce blood loss 2) Prevent the entry of micro organisms. NOTE: Haemophiliacs are unable to clot their blood and may suffer severe bleeding. Thrombosis is the clotting of blood from damaged blood vessel walls which can result in strokes or heart attacks. 5 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Blood groups Karl Landsteiner discovered that humans have four major blood groups. Red blood cells can be placed into four different categories. The four main (ABO) blood groups are: A / B / AB / O Question - Why is it important to know a person’s blood type? In blood transfusions, the blood given must match the person receiving it otherwise the blood may experience clumping. NOTE: Blood group O is called the universal donor as it can be safely given to all other four blood groups. Question – Why is it important that the blood of a mother and an embryo does not mix? They may have different blood types. They have different blood pressures. Rhesus Factor Another important blood group known as the rhesus factor. Features of the rhesus factor: People who have rhesus factor are rhesus positive (Rh +). People who do not have the rhesus factor are rhesus negative (Rh -) Example: Someone in blood group O who has the rhesus factor is said to be O +. NOTE: Rhesus negative blood can be given safely to a rhesus positive person. So O – is blood that can always be used for blood transfusions. NOTE: If rhesus positive blood is given to a rhesus negative it may cause a serious reaction. 6 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Question – How do red blood cells differ to other typical human cells? Red blood cells have no mitochondria and no nucleus. Red blood cells are biconcave in shape, contain haemogloblin and are smaller. Definitions Plasma liquid part of the blood. Transport materials (glucose, amino acids, carbon dioxide, urea, and vitamins) around the body. Red blood cells (erythrocytes) are made in the bone marrow and transport oxygen around the body. Haemoglobin is a protein found in red blood cells which transports oxygen around the body. White blood cells (leucocytes) fight infection. Phagocytes are white blood cells that surround and engulf their prey (bacteria or viruses). Lymphocytes are white blood cells that produce antibodies which help the body to fight infection. Platelets clot the blood which prevents blood loss and prevents the entry of harmful micro- organisms. 7 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Questions Exam Paper 2019, Question 8 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2018, Question 11: Exam Paper 2012 Question 15b i) State two ways, other than colour, in which red blood cells differ from white blood cells: ________________________________________________________________________ ________________________________________________________________________ ii) Name a group of white blood cells, other than lymphocytes: ________________________________________________________________________ ________________________________________________________________________ Solutions: 2012 Question 15b Exam Paper 2006 Question 13a: i) State a precise location in the human body at which red blood cells are made: ________________________________________________________________________ ________________________________________________________________________ 9 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  ii) State two ways in which red blood cells differ from typical body cells, e.g from the cheek lining: ______________________________________________________________________ __________________________________________________________________ Do you know Tick To name the four components of the blood To state the % of the blood that is made up from plasma (liquid part of blood) To name two types of plasma proteins To state the function of plasma To state where red blood cells are formed To name the red protein found in red blood cells To state where dead red blood cells are broken down to form bile To state why mature red blood cells cannot carryout mitosis To name the shape of red blood cells To give two differences between red blood cells and other cells To state the significance of red blood cells having a flexible membrane To state the role of red blood cells To name the molecule in red blood cells that carries oxygen To state where white blood cells are formed To state the function of white blood cells To state two methods in which white blood cells fight infections To name two types of white blood cells To state where platelets are formed To describe two functions of blood clots formed by platelets To main the four main blood groups To know why it is important that different blood types do not mix To distinguish between blood that is rhesus positive and rhesus negative 10 Wesley Hammond. Biology. Leaving Certificate. 5th Year. The Heart History of topic 2004 30 marks 2006 9 marks 2007 9 marks 2009 36 marks 2010 30 marks 2014 54 marks 2016 39 marks 2018 27 marks 2020 30 marks 2022 30 marks 2023 18 marks 11 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Two types of circulatory system: Open circulatory system Closed circulatory system Open circulatory system: The heart pumps blood into vessels that are open ended. The blood leaves these vessels and flows around the body cells and returns back to the heart through blood vessels. Example: Crabs, insects, spiders, slugs. Closed circulatory system: Blood remains in a continuous system of blood vessels. Any substances in the blood are exchanged with the cells by diffusion through the blood vessels thin walls. Example: Humans, dogs. Why is a closed circulatory system more efficient? 1) Animals are much more active as blood can be pumped around the body faster (allows oxygen to be pumped around the body faster). 2) Allows the flow of blood or pressure to be increased or decreased to different organs (more blood to muscles when exercising) 12 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Types of blood vessels: 1) Arteries 2) Veins 3) Capillaries Arteries: Carry blood away from the heart (small arteries are called arterioles) Veins: Carry blood to the heart (small veins are called venules) Capillaries: Small vessels that connects arteries and veins together. Capillaries have very thin walls and are permeable (this allows exchange of oxygen, water, carbon dioxide between blood and body cells) 13 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Structure of arteries and veins: Inelastic protein (collagen) – prevents the walls from over expansion. Involuntary muscles and elastic fibres – can alter the size of the vessel. During exercise the muscles can cause the arteries to dilate (expand) and allow more blood to flow. Endothelium – inner layer of cells lining the lumen. 14 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  What are the differences between arteries and veins? Structural differences Blood pressure and valves: Blood pressure is the force the blood exerts against the wall of an artery. Blood pressure is much higher in arteries than veins. 15 Wesley Hammond. Biology. Leaving Certificate. 5th Year. How does blood flow through veins? Physical activity squeeze the vein pushing blood around in the veins as they are under low pressure. Valves prevent the backflow of blood in veins (ensure blood flows in one direction). Valves L.S of vein L.S of vein The Heart Features of the heart: Located between the two lungs and above the diaphragm. Situated in the thoracic cavity (chest cavity) Made of cardiac muscle and that is contractile (can shorten). The heart is surrounded by a double membrane called the pericardium (Pericardial fluid reduces friction when the heart moves) 16 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Structure of the Heart Pulmonary Artery Aorta Semi-Lunar Valve Vena Cava Pulmonary Vein Right Atrium Left atrium Tricuspid Bicuspid Right Ventricle Left Ventricle Septum Question: What vein behaves differently in that it carries very little carbon dioxide and higher levels of oxygen? The pulmonary vein as it is returning oxygenated blood to the heart from the lungs. What artery behaves differently in that it carries very little oxygen and higher levels of carbon dioxide? The pulmonary artery as it is carrying deoxygenated blood to the lungs from the heart. 17 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Draw a detailed labelled diagram of the heart Atria The two upper chambers of the heart. Atria have thin walls as they only have to pump blood to the ventricles (short distance) Ventricles: Right ventricle pumps blood to the lungs (shorter distance so thinner wall). Left ventricle pumps blood to head and lower body (left ventricle has a much thicker wall as it has to pump blood all over the body) Note: Valves separate the atrium and the ventricle and are held by tendons. 18 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Valves Ensure blood can only flow in one direction (prevent the back flow in the heart). Tricuspid valve: It has three flaps Valve on the right side of the heart (located between right atrium and right ventricle) Bicuspid valve: It has two flaps Located on the left side of the heart between left atrium and left ventricle Semi lunar valves: Allow blood to flow out of the heart into the aorta and the pulmonary arteries. Prevent blood re-entering the heart. Located at the base of the aorta and base of pulmonary artery. How Blood travels through the Heart Deoxygenated Blood This blood is low in oxygen ( deoxygenated ) and enters the heart in the vena cava from the body. Path of deoxygenated blood in the heart: 1) As blood enters the right atrium it contracts and forces blood into right ventricle. 2) The right ventricle then contracts and the tricuspid valve closes. 3) Blood then enters the lungs through the pulmonary artery to receive oxygen. Oxygenated blood Oxygen rich blood (oxygenated). Oxygenated blood enters the heart through the pulmonary vein from the lungs. 19 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Path of oxygenated blood: 1) Left atrium contracts and forces blood into left ventricle 2) Left ventricle contracts and the bicuspid valve closes which allows blood to be pumped out through the aorta to the rest of the body. 3) Semi lunar valves close so blood cannot flow back into heart. NOTE: LORD Left Oxygenated Right Deoxygenated Double Circulation The heart is separated into two sections by septum. The septum allows the separation of the oxygenated and deoxygenated blood. What are the two circuits: The two circuits are the pulmonary circuit and the systemic circuit Pulmonary Artery Pulmonary vein Vena Cava Aorta 20 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Pulmonary circuit (Heart Lungs Heart) Circuit is short (muscles of right ventricle are thin for this reason) Right ventricle pumps blood through pulmonary circuit. Blood gains oxygen and removes carbon dioxide in the lungs (by diffusion). Systemic circuit (Heart Body Heart) Left ventricle pumps oxygenated blood to head, arms and legs in the systemic circuit. Longer circuit so wall on left ventricle is really thick muscle. Question - Name a vein that carries blood lowest in metabolic waste: Renal vein Name a vein that carries blood between the intestine and liver: Hepatic portal vein Name a vein has begins and ends with capillaries: Hepatic portal vein Name a vein that carries blood rich in urea out of the liver: Hepatic vein Name a vein that carries blood rich in oxygen and has low levels of carbon dioxide: Pulmonary vein Question - Name an artery that carries blood into the kidney: Renal artery Name an artery that carries blood into the liver: Hepatic artery Name an artery that carries blood rich in carbon dioxide and has low levels of oxygen: Pulmonary artery Name an artery that the hepatic artery and renal artery arise from: 21 Aorta Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Double Versus Single circulation Advantages of double circulation system: Double circulation system keeps blood separate that is rich in oxygen and blood poor in oxygen. Blood pressure is higher so oxygenated blood can reach every part of the body.. Example: Humans Single circulation system Blood pressure is low which can reduce the organisms metabolism. Example: Fish How the heart beat is controlled Heartbeat is controlled by the pace maker (situated in the top of the right atrium). Pace makers release electrical impulses causing muscle chambers to contract (controlled by the brain) Steps of a heartbeat: 1) The SA node (pacemaker or sino – atrial) releases electrical impulses causing the atria to contract. Function of SA node 2) This SA nodes electrical impulse also stimulates the AV (atrio - ventricular) node. 22 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Function of 3) The AV node sends an electrical impulse down muscle of the AV node septum causing the ventricles to contract. NOTE: Location of SA node – in the wall of right atrium Location of AV node – on the septum between the right atrium and right ventricle. Path of nerve impulses in the heart SA node (pace maker) – located on wall of right atrium AV node – located on septum between right atrium and right ventricle NOTE: It is the brain who controls the rate of pacemaker by sending heart electrical impulses. NOTE: Factors that increase the heartbeat are exercise, excitement and shock. NOTE: Factors that slow down the heartbeat are sleeping and alcohol. 23 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Stages of a heartbeat (cardiac cycle) Diastole: is when heart chambers (muscles) relax Systole: is when the heart chambers (muscles) contract What are the three stages of the heartbeat? Stage 1: When both atrium and ventricles relax (diastole) blood enters the atria. All valves are closed. Stage 2: Electrical impulses from the SA node (pacemaker) cause both atrium to contract (atrial systole) The tricuspid and bicuspid valves open allowing the blood into the ventricles. Semi lunar valves remain closed. Stage 3: Electrical impulses from the AV node cause both ventricles to contract (ventricular systole). Semi lunar valve opens which pushes the blood out of heart through the aorta and the pulmonary artery. The tricuspid and bicuspid valves close. Blood is forced out of heart through the aorta and the pulmonary artery. Semi lunar valve now closes again to prevent blood flowing back into heart. NOTE: The double sound of the heartbeat (LUB – DUB sound) is caused by the valves of the heart closing. Are the bicuspid and tricuspid valves Are the semi-lunar valves opened or opened or closed for the following? closed for the following? 1. Atrial diastole = closed 1. Atrial systole = closed 2. Atrial systole = opened 2. Ventricular diastole = closed 3. Ventricular systole = closed 3. Ventricular systole = opened 24 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Blood supply to the heart Oxygenated blood is supplied to the muscle of the heart by the coronary arteries (Blood in the coronary artery originates from the aorta) The coronary artery is located on the front surface of the heart. The coronary vein removes deoxygenated blood from the muscle of the heart (This blood is returned directly to the right atrium of the heart). NOTE: When the coronary arteries block they can cause a heart attack. Question: Name a vein that transports blood out of the muscle of the heart? Coronary vein Pulse What is a pulse? A pulse is the expansion and contraction of the arteries. The average pulse rate per minute is 72. NOTE: The neck and wrist have a strong pulse and therefore this is the easiest location to measure your pulse rate (artery is closer to the surface). 25 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  To investigate the effect of exercise on the pulse rate of a human Method 1) Locate a strong pulse in your neck of wrist (artery is closer to the surface). 2) Count the number of pulses per minute at rest five times to find an average (This is the control). 3) Walk slowly for 4 minutes and count your pulse a number of times until it returns to normal. 4) Exercise strenuously for 4 minutes and count your pulse rate per minute. Repeat this every minute until it returns to its resting rate. Results Pulse per minute at rest (bpm) Person 1 Person 2 Trial 1 54 78 Trial 2 56 80 Trial 3 54 79 Trial 4 56 78 Average 55 78 Pulse per minute after exercise Person 1 Person 2 1st minute 70 98 2nd minute 62 90 3rd minute 58 86 4th minute 56 83 5th minute 55 80 6th minute 55 78 Conclusion: Person 1 is a fitter person as they have a lower heartbeat and their heartbeat returns to normal faster after exercise. How might you measure recovery time? - Immediately after exercise count the pulse rate per minute. Measure length of time until it returns to resting rate. 26 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Person 2 Person 1 Pulse rate Duration of exercise Blood pressure Blood pressure is the force the blood exerts against the wall of an artery. Arteries Arteriole Capillaries Venules Veins Direction of blood flow from the heart Blood pressure generally decreases Typical blood pressure is 120/80 (units = mm or Hg) Note: The higher pressure occurs when ventricle contracts (systolic pressure) 120 The lower pressure occurs when there is no pulse and ventricle is relaxed (diastole 80 pressure) Effects on the circulatory system 1) Smoking Nicotine increases the heart rates. It can also raise a person’s blood pressure. Carbon monoxide reduces levels of oxygen in the blood. This can make the heart work harder. 27 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  2) Exercise Aerobic exercises such as running causes the muscle of the heart to become stronger and therefore having to do less work. Helps weight loss and speeds up the intake of oxygen. 3) Diet When people have a high salt intake in their food it can cause high blood pressure. Foods such as fats are high in cholesterol which increases the chances of blockages in blood vessels (plaque). To dissect, display and identify the parts of a heart 1) Rinse heart in water and place heart on dissecting board. 2) Identify the front (Ventral) and back (Dorsal) side of heart. (Front is more rounded and the back is flatter). 3) Identify all the major blood vessels that enter and leave the heart (should be 4) 4) Note that the two atrium chambers are small with thin walls. The two ventricle chambers are larger 5) Draw a labelled diagram of external surface of heart before dissection. Semilunar valve Tricuspid valve Bicuspid valve Dissection - Using a scalpel cut open right ventricle with two cuts. You should see: a thin wall 28 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  tendons (white strings) three flaps (tricuspid valve) - Using a scalpel cut open the left ventricle. You should you see: a thick wall tendons (white strings) two flaps of the bicuspid valve. - Locate the septum that separates the left and right side. - Cut open both atrium with two cuts. You should see: very thin walls bicuspid and tricuspid valves - Cut down the length of aorta. You should see: Semi lunar valve at the base (has three flaps) Origin of coronary artery NOTE: Coronary arteries are visible on the front surface of heart (They supply blood to the heart muscle). - Cut down the length of the pulmonary artery. You should see: Semi lunar valve at the base (has three flaps) - Wash your hands and place dissecting board in disinfectant. - Safety procedure: wear gloves, lab coat, tie back hair Question – Give one difference between walls of right ventricle and left ventricle: Left ventricle have thick walls of muscle and firmer, right ventricle have thinner walls of muscle. 29 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Question - How do you expose the tricuspid valve? Using a scalpel and a dissecting board, create a shallow cut on the right side of heart. Cut between the right atrium and right ventricle. Wear gloves. Question - How do you expose the bicuspid valve? Using a scalpel and a dissecting board, create a shallow cut on the left side of heart. Cut between the left atrium and left ventricle. Wear gloves. Question – Describe the dissection to locate the semi lunar valve. - Using a scalpel and a dissecting board, create a shallow cut at the base of the aorta or base of pulmonary artery. Question – Describe the dissection to locate the origin of coronary artery: - Using a scalpel and a dissecting board, create a shallow cut on the base of the aorta. Definitions Blood pressure is the force of blood against the wall of an artery. Closed circulatory system is when blood remains in the blood vessels. Open circulatory system is when blood leaves the blood vessels. Valves prevent the back flow of blood. A tricuspid valve is found on right side of heart and has three flaps. A bicuspid valve is found on left side of heart and has two flaps. Semi-lunar valves found in the base of pulmonary artery and aorta prevent blood from re- entering the heart. Diastole occurs when the heart chamber relaxes. Systole occurs when the heart chambers contract. A pacemaker sends out electrical impulses causing the muscle of the heart to contract. A pulse is the expansion and contraction of an artery. A portal system is when the transport of blood begins and ends in the capillaries. 30 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Questions Exam Paper 2023, Question 10: Exam Paper 2023, Question 17: Exam Paper 2022, Question 17: 31 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2020, Question 9: 32 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2018, Question 11b: 33 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2016, Question 8: 34 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Solutions 2016, Question 8: Exam Papers 2016, Question __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ 35 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam paper 2014, Question 9b: Exam Paper 2007 Q13a i) Name the blood vessel that returns blood to the heart from the lungs: __________________________________________________________________ ii) Name the main gas that is transported in the blood vessel that you have named in part (i). How is this gas transported? __________________________________________________________________ __________________________________________________________________ 36 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Paper 2009 Q13 a, b The human circulatory system has two circuits. a) i) Give the name of each of these circuits: ________________________________________________________________________ ii) Which of these circuits involves the pumping of blood by the left ventricle: __________________________________________________________________ b) i) Write a short note on each of the following: 1) Pulse: _________________________________________________________________ 2) Blood Pressure: _________________________________________________________________ ii) Comment on the effect of each of the following on the circulatory system: 1) Diet: _________________________________________________________________ _________________________________________________________________ 2) Exercise: _________________________________________________________________ _________________________________________________________________ iii) What is the role of the SA (sinoatrial) and AV (atrioventricular) modes in the heart: _____________________________________________________________________ _____________________________________________________________________ iv) Give the precise locations of both the SA and AV nodes in the heart: _____________________________________________________________________ _____________________________________________________________________ 37 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2004, Question 9: 38 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Solution 2004, Question 9: Sample Paper 39 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Do you know Tick To distinguish between the open and closed circulatory system (include an organism for each) To state why the closed circulatory system is more efficient To describe the direction of the blood flow in an artery and vein To draw and label a diagram of the T.S of an artery To draw and label a diagram of the T.S of a vein To state the role of inelastic protein (collagen) layer and the involuntary muscle layer in an artery To list three structural differences between artery and veins To state if arteries or veins have higher blood pressure To give one adaption capillaries have that allow for easier exchange of substances in and out of blood stream To define the term blood pressure and state the typical blood pressure To state how blood flows through veins as blood pressure is lower To draw and label diagram of the heart To explain why the pulmonary vein behaves differently to other veins To name the chamber of the heart that has the thickest layer of muscle and state why To explain why the muscle in the left and right atrium is quite thin To state the exact location of tricuspid valve, bicuspid valve and semi-lunar vales in the heart To distinguish between deoxygenated and oxygenated blood To describe the pathway through the heart in which deoxygenated blood travels To describe the pathway through the heart in which oxygenated blood travels To describe how the levels of oxygen and carbon dioxide change at the blood travels pass the lungs To name the blood vessels involved in the pulmonary circuit and systemic circuit To state which circuit is the longest To name the chamber of the heart that pumps blood through the pulmonary circuit To name the chamber of the heart that pumps blood through the systemic circuit To describe how the composition of the pulmonary artery behaves differently to other arteries To state an advantage of having a double circulation system compared to a single circulation system To describe how the pacemaker controls the heart beat To describe the location of the pacemaker (SA node) To state what the letters SA are an abbreviation for To describe the location of the AV node To state what the letters AV are an abbreviation for To name the chambers of the heart that the SA node causes to contract 40 Wesley Hammond. Biology. Leaving Certificate. 5th Year. To name the chambers of the heart that the AV node causes to contract To state two factors that increase the heart beat and slow it down To define the term systole and diastole To describe the term atria systole To describe the term ventricle diastole To be able to state if the bicuspid, tricuspid and semi-lunar valves are open or closed as each chamber contracts or relaxes To name the blood vessel that supplies oxygenated blood to the heart muscle To state the origin of the blood vessel mentioned above To name the blood vessel that removes deoxygenated blood away from heart muscle To state what chamber of the heart this deoxygenated blood re-enters the heart To define the term pulse and state the average pulse rate per minute To describe why the neck or wrist are the best places to locate a pulse When investigating the effect of exercise on the pulse rate, state why you counted the pulse rate per minute at rest To name the chamber of the heart that pumps blood through the pulmonary circuit, state how you might measure the recovery time To describe how smoking, exercise and diet impact on the circulatory system When dissecting the heart, state how you identified the front (ventral) and back (dorsal) of the heart When dissecting the heart, state where you identified the bicuspid valve, tricuspid valve and semi lunar valve When dissecting the heart, name the instrument used to dissect the heart When dissecting the heart, state a safety procedure When dissecting the heart, describe how you dissected the heart 41 Wesley Hammond. Biology. Leaving Certificate. 5th Year. The Lymphatic System History of topic 2006 24 marks 2014 20 marks 42 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  The Lymphatic System What is the lymphatic system? It’s a second circulatory system. It’s a one-way system Lymph vessels collect any fluid surrounding the body’s cells and returns it to the blood. What is the structure of the lymphatic system? Consists of lymph nodes, lymph vessels, tonsils, spleen and thymus gland. State organs located in lymphatic system: Tonsils Spleen Thymus gland What are lymph nodes? Lymph nodes are swellings in the lymph vessels. Found in clusters (glands) in the tonsils, neck, armpit, spleen and groin. How do lymph nodes fight infection? They fight infections by the nodes filtering bacteria. Contain large amounts of lymphocytes (white blood cells). 43 Wesley Hammond. Biology. Leaving Certificate. 5th Year. How does lymph fluid form? Arteries contain blood that has higher blood pressure than veins. This forces out some fluid and small proteins out of blood at the capillaries in the arteriole side (This fluid is called tissue fluid). Tissue fluid surrounds all the cells of the body and helps with exchanging substances in and out of cells. Note: Tissue fluid is formed at a rate of 1 litre per hour. To prevent swelling it is removed and returned to the blood. Diagram showing the formation of lymph 44 Wesley Hammond. Biology. Leaving Certificate. 5th Year. How does tissue fluid differ from blood (plasma)? Tissue fluid does not have platelets or red blood cells or clotting proteins but blood does. How is tissue fluid removed? 10% of the tissue fluid enters lymph vessels (referred to as lymph) 90% of tissue fluid is returned back into the plasma in the capillaries (occurs by osmosis) and is helped by the reduced blood pressure in the veins. Question: Give two ways lymph What does lymph fluid contain? differs from blood: Lymph has higher levels of lipids, no red blood Contains white blood cells, proteins and higher level of fats. cells, no platelets or no clotting proteins Note: Tissue fluid is formed at a rate of 1 litre per hour. To prevent swelling it is removed and returned to the blood. Lymph Vessels: 45 Wesley Hammond. Biology. Leaving Certificate. 5th Year. NOTE: Similar to blood in veins, lymph fluid is under low pressure. So how is Lymph moved slowly through the lymph vessels? Physical activity squeezes (presses) on the vessels Muscular walls of the vessels Valves prevent lymph fluid flowing backwards. NOTE: Valves ensure that the lymph fluid only flows in one direction towards the shoulder region (so it can return to the blood). What are the two main lymph vessels? 1) The thoracic duct (left side of body) 2) Right lymphatic duct (right shoulder) Note: Lymph fluid in these ducts is emptied into the blood at the Subclavian veins which is located near the collar bone. 46 Wesley Hammond. Biology. Leaving Certificate. 5th Year. What are the functions of the lymphatic system? 1) To absorb fats from the digestive system into the lacteal. These fats are transported in the lymph vessels of the lymphatic system (Lymph is found in the lacteals in villi). 2) To collect tissue fluid and return it to the blood. 3) To defend the body against infections: i) Lymph nodes filtering harmful bacteria. iii) Stores and matures lymphocytes which produce antibodies that neutralise foreign substances. Definitions Tissue fluid is plasma without red blood cells and platelets. Lymph is made from tissue fluid and contains white blood cells, fats and proteins. Lymph nodes are swelling found along the lymph vessels. 47 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Questions Exam paper 2006 Question 13c i) Describe the structure of the lymphatic system: __________________________________________________________________ ii) Give an account of three functions of the lymphatic system: __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ Exam Paper 2014, Question 3: 48 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Do you know Tick To describe the structure of the lymphatic system To name organs located in the lymphatic system To describe what are lymph nodes and how they fight infections To describe how lymph fluid forms To state how tissue fluid differs from plasma To describe how tissue fluid is removed from area surrounding cell To state what lymph fluid contains As lymph fluid is under low pressure in the vessels, explain what helps the movement of this fluid To name the two main lymph vessels in the human body To name the vein at which these main lymph vessels return to the blood in To describe in detail all the functions of the lymphatic system To name structure in a villi that the lymph vessels are connected with 49 Wesley Hammond. Biology. Leaving Certificate. 5th Year. The Respiratory System History of topic 2007 51 marks 2009 24 marks 2014 45 marks 2016 24 marks 2017 30 marks 2019 20 marks 2021 30 marks 2023 18 marks 50 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Why do we inhale oxygen and exhale carbon dioxide? Respiration takes place in every cell to supply them with energy. We use oxygen and produce carbon dioxide and water in the process of respiration. Introduction Pair of lungs are located in the chest (thorax) region known as the thoracic cavity. Ribs and intercostal muscles surround the thoracic cavity. Diaphragm muscles form at the bottom of the thoracic cavity. Air moves in and out of the lungs by the contraction of these muscles. Parts of the respiratory system Pharynx 51 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Diagram of Human Breathing System Nose Air is inhaled in through the nose (nostrils) Nostrils are separated by a nasal septum (made of cartilage) Benefits of breathing through the nose: 1) Hairs and mucous filters air in the nose 2) Air is moistened Helps oxygen diffuse into blood 3) Air is warmed passing through nose more easily 52 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Pharynx (known as the throat): Consists of the epiglottis and larynx. - The epiglottis closes the trachea (windpipe) when we swallow. This prevents food from entering the windpipe and lungs. - The larynx (voicebox) produce vibrations to create sound. Trachea, bronchi and the bronchioles: These parts are all made up of muscle and rings of cartilage. NOTE: - The rings of cartilage prevent these tubes from collapsing. - Trachea, bronchus and bronchiole are lined with mucous and tiny hairs (cilia). These trap any dust, bacteria or viruses. - When we clear our throat it helps force mucous up and into the oesophagus. Lungs Spongy material (can expand and contract in size) Gas exchange with blood stream occurs here (diffusion). The lungs are enclosed by pleura membranes (a double membrane that contains fluid). Pleural cavity reduces friction on the lungs as a person inhales and exhales. 53 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Alveoli: Function: to allow gas exchange At the end of each bronchiole you have an air sac called an alveoli (700 million). Adaptions of alveoli 1. Large surface area for gas exchange as they are so numerous. 2. Thin walled for easier gas exchange 3. Moist surfaces (helps with diffusion) 4. Have a rich blood supply from surrounding capillaries. Arises from pulmonary artery Joins up with the pulmonary vein Gas exchange: Carbon dioxide and water diffuses out of the cell and into the blood. The carbon dioxide and water then diffuse out of the blood and into the alveoli of the lungs (from high to low concentration). Also, oxygen diffuses from the alveoli into the blood and then into the cells (from high to low concentrations) Question: Name the structures at the end of the breathing tract that are involved in the gas exchange. Alveoli 54 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Inhaled and exhaled air: Inhaled Exhaled % oxygen 21 14 % carbon dioxide 0.04 5.6 Water concentration Low High Breathing disorders Asthma Symptoms: Wheezy and breathlessness. Cause – external: Allergens that might be inhaled (pollen, scales from skin, house dust, dust mites) Stress or anxiety Exercise in cold air Cause internal: Bronchioles become narrower. Prevention Avoiding allergens Preventative inhalers Treatment Steroids inhaled 55 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Control of human breathing The levels of carbon dioxide in the blood is detected by the brain which controls breathing rate. Carbon dioxide is acidic when it dissolves in blood which lowers its pH. The brain (medulla oblongata) detects this low pH and sends an electrical message to the diaphragm and intercostals muscles which causes us to breathe faster especially when we exercise. NOTE: The medulla oblongata is the part of brain that controls breathing. NOTE: It is higher levels of CO2 in our blood (from exercise) and not low levels of oxygen that controls our breathing rate. NOTE: carbon dioxide controls rate of gas exchange in both animals and plants Question: How does the breathing system respond to high levels of CO 2? Increase rate and depth of breathing. Processes involved in breathing At rest the breathing rate is approx. 15 times per minute. Inhalation = breathing in Exhalation = breathing out Steps involved in inhalation: 1) The medulla oblongata registers levels of CO2. 2) A message is sent from the brain (medulla oblongata) to diaphragm causing it to contract which moves the diaphragm down. 3) The intercostal muscles also contract which allows the ribs to be pulled up and out. 4) The volume of the chest cavity (thorax) increases and the pressure in the chest falls (outside air pressure is higher than the pressure of air in lungs). 56 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  5) Air is now forced into the lungs (inhalation). 6) As muscles contract it requires energy and therefore inhalation is an active process. Steps involved in exhalation (breathing out): 7) The diaphragm and intercostals muscles relax (a passive process as no energy is needed). 8) Ribs move down and in, diaphragm moves up. 9) Volume of chest cavity (thorax) decreases and the pressure increases. 10) Air is pushed out of lungs back into the air. 57 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  To investigate the effect of exercise on the breathing rate: 1) Record the number of inhalations per minute for two minutes to get an average (this is the control). 2) Exercise slowly for 4 minutes and record the number of inhalations per minute until the breathing rate returns to normal resting rate. 3) Exercise quickly for 4 minutes and record the number of inhalations per minute until breathing rate returns to normal resting rate. Result: Exercise increases the breathing rate. 58 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Questions Exam Paper 2023, Question 17: 59 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2021, Question 16: 60 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Papers 2019, Question 6: 61 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2017, Question 15a: 62 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Solutions 2017, Question 15a: 63 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2014, Question 12b,c: 64 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam paper 2009 and 2007 1) State the function of the following: epiglottis, larynx: ___________________________________________________________________________ ___________________________________________________________________________ 2) The diagram shows microscopic detail from a human lung: i) Name the parts labelled A, B and C: ________________________________________________________________________ ________________________________________________________________________ ii) Give two features of the structures in the diagram that allow for efficient gas exchange: ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ 3) Describe briefly the role of the diaphragm and intercostal muscles in inhalation. In your answer refer to the volume and thoracic air pressure: ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 65 Wesley Hammond. Biology. Leaving Certificate. 5th Year. 4) Name the process involved in the passage of gas between the alveolus and the blood: ___________________________________________________________________________ 5) Name a breathing disorder: ___________________________________________________________________________ 6) In the case of the breathing disorder that you have named above, state: i) A cause: ______________________________________________________________ ii) A means of prevention: ______________________________________________________________ iii) A treatment: _________________________________________________________ 66 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Do you know Tick To explain why we inhale oxygen into our lungs To name the cavity in which the lungs are located in To name the two muscles used to help us inhale and exhale To draw and label a diagram of the respiratory system (human breathing system) To list the benefits pf inhaling through the nose To state the function of the epiglottis To state the function of the larynx To state the function of the rings of cartilage in the trachea and bronchus To state the function of the hairs (cilia) in the trachea and bronchus To name the membrane that surrounds the lungs and state the function of the membrane To state the function of the alveoli To give three adaptions of the alveoli To name the process by which oxygen and carbon dioxide are exchanged between alveoli and the blood stream To name one breathing disorder, it’s symptom, cause and treatment To name the gas that controls the rate of breathing and how the brain detects it To name the part of the brain that controls the breathing rate To state the number of times a human breaths per minute at rest To describe in detail the steps involved for inhalation To describe in detail the steps involved in exhalation To state for inhalation or exhalation is a passive process and give a reason To state for inhalation or exhalation is an active process and give a reason 67 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Human Nutrition History of topic 2004 20 marks 2005 20 marks 2006 20 marks 2008 60 marks 2010 33 marks 2011 20 marks 2012 30 marks 2015 60 marks 2016 24 marks 2019 30 marks 2021 36 marks 2022 20 marks 2024 29 marks 68 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  The Digestive System Large intestine Glands that aid digestion: Liver Pancreas Salivary glands Components of small intestine: Duodenum Ileum Components of large intestine: Colon Rectum Anus Appendix Caecum 69 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Types of nutrition: Autotrophic: an organism that can make its own food (plants). Heterotrophic: an organism that cannot make its own food (all animals). What are the types of heterotrophic nutrition? Herbivores: animals that only eat plants. Carnivores: animals that eat other animals only. Omnivores: animals that eat plants and animals. Parasites: feeds on a live host causing harm. Saprophytes: feeds on dead organic matter. What is the alimentary canal? Starts at the mouth and ends at the anus. What are the steps in human digestion? 1) Ingestion: food enters mouth 2) Digestion: Breakdown of food 3) Absorption: food absorbed into the blood (by a process called diffusion) 4) Egestion: removal of unwanted food waste (not the same as excretion) What is digestion? Digestion is the breakdown of food into smaller particles. Why is digestion necessary? To make food more soluble and easier to transport This allows the food to be absorbed into the bloodstream. Two types of digestion: 1) Mechanical digestion (involves physical breakdown of food) 2) Chemical digestion (involves enzymes or stomach acid breaking down food) 70 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Location of physical and chemical digestion Physical digestion Chemical digestion Mouth Mouth Oesophagus Stomach Stomach Duodenum Duodenum The Mouth Mechanical digestion in the mouth: (food broken down into smaller pieces by your teeth). Types of teeth: Incisors: cut, slice and bite (chisel shape) Canines: Tear and grip food (long and pointed) Premolars: crush and chew food (flat surface) Molars: crush and chew food (flat surface) Human dental formula: = 32 teeth Chemical digestion in the mouth: The enzyme amylase breaks down the food in the mouth. NOTE: amylase made in salivary gland. 71 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Saliva: softens and dissolves the food. Saliva consists of water and salts. Oesophagus: Carries food from the mouth to the stomach during which it is digested mechanically. Food is moved along the alimentary canal by the muscular contractions called peristalsis. Peristalsis helps break down food mechanical (physical). Peristalsis in the Oesophagus: Role of fibre: Fibre helps us to absorb water from large intestine. Fibre helps stimulate peristalsis. Plant cell walls contain cellulose, which provides us with fibre. Sources of fibre: cereals, vegetables. NOTE: Peristalsis also occurs throughout the small intestine and large intestine. Question: Name two parts of the alimentary canal where peristalsis occurs that helps with mechanical digestion: Oesophagus and small intestine. 72 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Question: Name the two types of digestion that occurs in the stomach: Stomach: Mechanical digestion (churns food) and chemical digestion (involves Muscular bag that stores food and digests food. enzyme pepsin). Churns food causing mechanical digestion. Stomach Creates a mixture known as chyme. pH 2 Food enters and leaves the stomach through the sphincter muscle. Stomach lining (mucosa) releases gastric juices. What is in gastric juices? Mucous Pepsinogen Hydrochloric acid: kill harmful bacteria in the stomach. How does the stomach prevent self-digestion? 1) Mucous lines the stomach and is alkaline which reduces acidity (neutralises) near the stomach wall. 2) Pepsin is released as inactive pepsinogen (so it doesn’t damage the stomach wall). NOTE: Pepsinogen is converted to active pepsin when reacting with acid. Pepsin The end product of protein Proteins Peptides digestion is amino acids. NOTE: pepsin is a protease enzyme 73 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Glands and the small intestine: What glands are associated with digestive system? Salivary glands Pancreas is located Liver Linked to small behind the stomach in the Pancreas intestine upper abdomen. Pancreas (gland): Secretes sodium bicarbonate into duodenum through pancreatic duct. Sodium bicarbonate neutralises the chyme from the stomach in the duodenum (allows enzymes to digest food at the optimum pH). Question: State the two digestive functions of the pancreas: Releases enzymes and neutralises chyme (food). Also releases enzymes amylase and lipase which are secreted into the duodenum to help digestion. Both these enzymes work best at the pH of 7/8 (optimum pH). Amylase Starch Maltose (end product) Lipase Lipids Fatty acids and glycerol (end product) 74 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Functions of the liver (gland): Produces bile (digestive function). Breaks down excess amino acids to form urea (deamination). Converts excess carbohydrates to fats. Converts glucose to glycogen (polysaccharide) for storage. Stores vitamins (D) and makes cholesterol. Breaks down red blood cells. Detoxifies the body. What is bile? Liver is located under the Formed from dead red blood cells. diaphragm, above the stomach Yellow/ green liquid. in the upper abdomen. Made in liver and stored in gall bladder. Bile passes through the bile duct to reach the duodenum. Functions of bile: 1) It emulsifies Fats in the duodenum( breaks down fats and oils into tiny droplets). 2) Contains sodium bicarbonate which helps neutralise the chyme from the stomach (helps enzymes to digest the food in the duodenum). Small intestine: Mechanical digestion by peristalsis and chemical digestion using enzymes Consists of two parts: Duodenum --- 25 cm long --- carries out digestion (Food enters the duodenum from the stomach). Ileum --- 5.5 metres long --- absorption of food (by a process called diffusion). 75 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Structure of duodenum: Inner lining of small intestine contain villi (foldings). Villi have microvilli. Villi increase surface area for digestion and absorption. What are the end products of digestion? Ileum: Ileum absorbs the nutrients into the blood by a process called diffusion (passive transport). NOTE: Passive transport does not require energy. What is the function of villi? Villi increase surface area to absorb glucose, amino acids and vitamins in the blood stream. 76 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Adaptions of villi: Have numerous microvilli Rich supply of blood to carry away products Villi are only one cell thick (very thin) Each villi has a lacteal to absorb and carry away fats. Villi increase surface area for absorption Diagram showing structure of villi Question: What is the process called when the muscle of the villi contracts? Peristalsis Important facts about the lacteal: Contains lymph fluid Absorbs fats which are transported by lymph in the lymph vessels. NOTE: They may ask how ileum is adapted for absorption? It is long. Use the same adaptions that are given for the villi above. 77 Wesley Hammond. Biology. Leaving Certificate. 5th Year. What is the relationship between Liver, small intestine and hepatic portal vein? Nutrients (glucose/ amino acids) are carried from the small intestine to the Liver by the hepatic portal vein. Oxygenated blood Deoxygenated blood Small intestine Amino acids are broken down in the liver to form urea (deamination). Urea leaves the liver in the hepatic vein which travels to the heart and then the kidneys. Questions: Name the blood vessel that supplies oxygenated blood to liver: Hepatic artery Name the blood vessel that removes deoxygenated blood from the liver: Hepatic vein Name the blood vessel that the hepatic artery arises from: Aorta To which organ does digested nutrients get first transported to? Liver Name a vein that carries blood between the intestine and liver: Hepatic portal vein Name a vein has begins and ends with capillaries: Hepatic portal vein Name a vein that carries blood rich in urea out of the liver: Hepatic vein Remember: What is deamination? Deamination is the process in which excess amino acids are broken down in the liver to form urea (example of a catabolic reaction). NOTE: Amino acids that are not used, cannot be stored in the body so have to be broken down. 78 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Portal system A portal system is a blood vessels that begins and ends in the capillaries It is not connect directly to the heart). Small intestine NOTE: an example of this is the hepatic portal vein which connects intestines to the liver. Large intestine (colon): What makes up the large intestine? Colon, caecum, appendix, rectum and anus Functions: Colon is used to reabsorb water. Egestion. NOTE: Rectum stores faeces NOTE: The appendix and caecum are vestigial organs (lost their function) NOTE: Diarrhoea is formed when not enough water has been reabsorbed. Constipation occurs when too much water is reabsorbed. Colon Caecum Appendix Rectum Anus 79 Wesley Hammond. Biology. Leaving Certificate. 5th Year. What is Symbiosis? Symbiosis: where two organisms live in a close association with each other and at least one benefits. What are symbiotic bacteria? Bacteria that live on another organism and involves benefit for both organisms. Benefits of symbiotic bacteria: Symbiotic bacteria feed on waste products to produce vitamins B and K. Symbiotic bacteria break down food (cellulose) which is absorbed into the body. Symbiotic bacteria help prevent the growth of disease causing bacteria. NOTE: These bacteria get shelter and food. What is a balanced diet? A balanced diet consists of eating the right amount of each of food for better health: 1) Proteins 2) Carbohydrates 3) Lipids 4) Vitamins 5) Minerals 6) Fibre 7) Water 80 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  Definitions Ingestion is the intake of food to the body through the mouth. Digestion is the breakdown of food. Absorption is the passing of nutrients into the blood by a process called diffusion (passive transport). Egestion is the removal of unabsorbed food through the anus. Mechanical digestion is the physical breakdown of food (e.g teeth). Chemical digestion is the breakdown of food using enzymes. Peristalsis helps food move through the alimentary canal by muscle contractions. Incisors are teeth used to cut and slice the food. Canines are teeth used grip and tear the food. Premolars are teeth used to crush and grind the food. Molars are teeth used to crush and grind the food. Bile is made in the liver and stored in the gall bladder. It helps break down fats and neutralises chime from the stomach. Deamination is the breakdown in the liver of amino acids into urea. A lacteal is used to absorb fatty acids and glycerol into the blood stream. Symbiosis: where two organisms live in a close association with each other and at least one benefits. Symbiotic bacteria lives on a host and creates benefits. (e.g produce vitamins B and K and prevent the growth of disease causing bacteria in the large intestine). A balanced diet consists of eating the right amount of each of food for better health 81 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Questions Exam Question 2004, Question 6: Exam Question 2005, Question 6: 82 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam paper 2006, Question 5: Exam paper 2006, Question 3: 83 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam paper 2008, Question 12: __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ 84 Wesley Hammond. Biology. Leaving Certificate. 5th Year. __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ Solutions 2008, Question 12: 85 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2010, Question 15b: __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ _________________________________________________________________________________ Exam paper 2010, Question 15c (iii): __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ Solutions 2010, Question 15c(iii): 86 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam paper 2011, Question 5: Exam Paper 2012, Question 15a: __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ 87 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2015, Question 11: 88 Wesley Hammond. Biology. Leaving Certificate. 5th Year.  89 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2018, Question 15b: Exam Paper 2019, Question 15b: 90 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2021, Question 91 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2022, Question 92 Wesley Hammond. Biology. Leaving Certificate. 5th Year. Exam Paper 2024, Question 3: Exam Paper 2024, Question 17: 93 Wesley Hammond. Bi