Teaching block 2 [2] Flashcards

Question

# **Circulatory system** The heart What does a section through heart show Why is the left side of heart thicker?

Answer 1

- A **double pump** with 4 chambers [ LEARN LABELLED DIAGRAM OF HEART] A section through heart = - a circle represents the **Left ventricle** (**thicker** muscle as pump blood all around body) - A thin 'moon like' shape represents the **Right ventricle** (**thinner** muscle as pumps blood to lungs only)

Answer 2

surface area to volume ratio That ratio is smaller in big organism so you need to pump oxygen etc across membrane and that requires a blood flow.

Answer 3

Valves - prevent backflow of blood - **Atrioventricular valves** – *between* the *atria* + the *ventricles* [tricuspid + bicuspid] - **tricuspid valve** = *right* side of heart - **bicuspid valve** [mitral valve] = *left* side of heart - **Semi-lunar valves** = valves in *aorta* + *pulmonary artery* at the point where the blood leaves the heart. - [Semi-lunarvalves are found in **veins**. Not arteries.. except aorta + pulmonary artery at place where they leave the heart]

Answer 4

muscles contract = get fatter + press on vein = causing blood to be pushed along vein Leg muscles relaxed, valves closed

Answer 5

**Lub-dup** = normal heart sounds **Lub** = sound of closure of atrioventricular valves **Dup** = closure of semi-lunar valves **Murmur** = sound caused by valve leakage

Answer 6

- Chordae Tendineae Tendons - stop valves turning back on itself + leaking

Answer 7

The cardiac cycle 1. Blood enters **atria** from **vena cava** or **pulmonary vein** 2. Blood goes from **atria** into **ventricles**, through **atrio-ventricular valves** [Initially this is a fairly passive process, but atria do contract] 3. Atrio-ventricular valves close, **ventricles** contract 4. Blood leaves **ventricles** going through **semi-lunar valves**and into the **pulmonary artery** or **aorta** 5. Process repeats.

Answer 8

Vena cava > right atrium > tricuspid valve > right ventricle > semi-lunar valves > pulmonary artery > lungs > pulmonary vein > left atrium > mitral or bicuspid valve > left ventricle > semi-lunar valves > aorta > renal artery > kidney

Answer 9

The hepatic portal vein is a blood vessel that carries **deoxygenated blood from** the **digestive organs** (like the stomach, intestines, spleen, and pancreas) **to** the **liver**.

Answer 10

- mum lays down on back = foetus ontop of ven cava = makes it difficult for blood to return to heart - varicose veins = bulging, enlarged veins To fix this: - mum could sleep on her side - or raise the bottom of the bed slightly by standing it on books/bricks eg..

Answer 11

1. **Sino-atrial node** (SAN) produces electrical impulses 2. Electrical impulse travels through atrial walls causing contraction. 3. Electrical impulse picked up by **atrio-ventricular node** (AVN). 4. Electrical impulse travels along conductive **bundle of His**. 5. Electrical impulse travels along **Purkinje fibres**. 6. Ventricles contract | wrtie whole name of SAN + AVN in exam and then abbreviate after!

Answer 12

**Electrocardiogram** (ECG) – a means of monitoring heart electrical activity - **P-wave** = electrical activity + contraction in *atria*. - **QRS complex** = electrical activity + contraction in *ventricles*. - **T-wave** electrical recovery of heart.

Answer 13

**Atrial fibrillation (AF) ECG trace** - In AF = heart’s electrical signals R all over the place = heart beats irregularly. - On ECG - it looks like a bumpy, irregular line with no clear P wave [signals from atria] **Anti-coagulant therapy** - People with AF take blood thinners (warfarin, apixaban) to help prevent blood clots - This is important because blood clots can form in the heart = cause a heart attack - blood clot in brain = stroke **Cardioversion** – electrical shock to heart – like defibrillation - reset the heart's rhythm. - doctor gives heart small electric shock to make it beat normally again. - It’s similar to the shock used in defibrillation, but cardioversion is for less dangerous heart problems.

Answer 14

**Platelets** - cell fragments - 0.25 million per mm3 - Involved in blood clotting - Made in red bone marrow **Plasma** - Straw coloured liquid of blood - contains water, proteins, glucose, lipids, amino acids, salts, hormones, antibodies, urea, fibrinogen

Answer 15

**1. Erythrocytes** = red blood cells - biconcave disc, No nucleus, Contain haemoglobin - Haemoglobin carries oxygen = RBC carry oxygen - Oxygen + haemoglobin --> oxyhaemoglobin (reversible reaction) - Carbon monoxide + haemoglobin --> carboxyhaemoglobin (not reversiblE - ≈ 5 million RBC per mm3. - Last for 4 months - 9000 million rbc made per hour in red marrow of bones - Old red blood cells destroyed by phagocytic cells in liver, spleen and red bone marrow

Answer 16

**2. Leucocytes** – white blood cells - 7000 per mm3. - Defence against disease, phagocytosis, antibody production. - Neutrophils, lymphocytes, eosinophils, monocytes, basophils (different types of WBC). - Have nuclei - Made in lymphatic system, bone marrow. - Destroyed by phagocytes in liver and spleen

Answer 17

1. Haemoglobin 2. Because they contain haemoglobin 3. carbon monoxide... - Carbon monoxide bonds permanently with haemoglobin to form carboxyhaemoglobin and then it is no longer possible for that haemoglobin to carry oxygen, until the red blood cell is replaced 3-4 months later. - You cannot smell carbon monoxide so you cannot detect it - Potential sources include car exhausts, cigarettes, central heating systems.

Answer 18

- **Thromboplastin** catalyses soluble proteins **prothrombin** (in plasma) into **thrombin** (soluble protein, enzyme) - **Thrombin** acts on **soluble fibrinogen** - converting it to **insoluble fibrin** - = forms **fibre mesh** to cover wound - platelets + blood cells pouring from wound get trapped in fibrin mesh = **forms a clot** - Clot hardens = becomes a **scab** - protects the skin + vessels underneath as they heal

Answer 19

**Arteries**: - Carry oxygenated blood away from the heart (except the pulmonary artery). - Have thick, muscular, elastic walls to handle high pressure. - Have smaller lumens (inner space). - No valves (except in the heart). **Veins**: - Carry deoxygenated blood towards the heart (except the pulmonary vein). - Have thinner walls and larger lumens. - Contain valves to prevent backflow of blood. - Blood pressure is lower compared to arteries

Answer 20

**Tissue fluid** = the fluid that surrounds all cells in body As blood passes through capillaries, some plasma leaks out through gaps in the walls of the **capillary** to surround the cells of the body = This results in the formation of tissue fluid Composition of plasma + tissue fluid = virtually the same, although tissue fluid contains far fewer proteins

Answer 21

1. Contract external intercostal muscles. 2. Ribs move up and out. 3. Contract diaphragm – it becomes flatter and lower. 4. Lung volume increases. 5. Air pressure inside the lungs decreases. 6. Air enters the lungs.

Answer 22

1. Relax external intercostal muscles. 2. Ribs move down and in. 3. Relax diaphragm – it becomes dome shaped and higher 4. Lung volume decreases. 5. Air pressure inside the lungs increases. 6. Air leaves the lungs.

Answer 23

**Pneumothorax = collapsed lung** - This is where you get a hole through one or possibly both pleural membranes. E.g due to a broken rib or stab wound. - This means air can get into the space between the pleural membranes = you cannot inflate your lung properly - Pleural membranes are joined by suction due to pleural fluid.

Answer 24

**Composition of gases in the air** - Nitrogen 78% - Oxygen 21% - Carbon dioxide 0.04% For a spirometer to work we need to be able to absorb carbon dioxide = use sodium hydroxide or soda lime.

Answer 25

- A device used to measure lung volumes and oxygen usage - measures volume of air breathed in + out (inhaled + exhaled) - is used in respiratory tests to diagnose conditions like asthma or COPD

Answer 26

Types of measurement: - vital capacity - inspiratory reserve volume - tidal volume - expiratory reserve volume - rate of oxygen useage - ventilation (breathing rate) - peak flow – which might help detect obstructions of the airway caused by asthma or a tumour

Answer 27

**COMPONENTS** - Motor - Pen - Air or medical grade oxygen - Hinge - Water in spirometer tank - Hinge - Soda lime or sodium hydroxide - Mouthpiece - Kymograph **SODA LIME** - Carbon dioxide that is exhaled gets absorbed by the soda lime = CO₂ removed = any decrease in air volume inside spirometer is due to O2 consumption = accurate measure of oxygen uptake only

Answer 28

- A person breathes through the mouthpiece. - As they inhale, air is drawn from the spirometer, making the lid of the spirometer chamber move down. - As they exhale, air goes back into the chamber, making the lid move up. - Soda lime Absorbs CO₂ from exhaled air, ensuring only oxygen is measured. - The movement of the spirometer lid is recorded using a pen attached to a rotating drum (kymograph), creating a graph of breathing patterns. kymograph - A rotating cylinder covered with paper used to record breathing patterns

Answer 29

``` line represents changes in lung volume as a person breathes in and out. ``` - inhales - the spirometer lid moves down = the pen draws a downward curve on the rotating drum (kymograph) - exhales = the lid moves up = the pen draws an upward curve

Answer 30

**Tidal Volume** ``` The amount of air breathed in + out during normal breathing ``` **Inspiratory Reserve Volume** ``` The extra air that can be forcibly inhaled after a normal breath ``` **Expiratory Reserve Volume** ``` The extra air that can be forcibly exhaled after a normal breath ``` **Residual Volume** ``` - The air that remains in the lungs after maximum exhalation. - keeps the lungs partially inflated = prevents lung collapse + protects structures from being damaged ``` **Vital Capacity** ``` - the maximum amount of air a person can exhale after taking a deep breath in. - It includes tidal volume + inspiratory reserve volume + expiratory reserve volume ```

Answer 31

1. **peak flow** – help detect obstructions of the airway caused by asthma or a tumour [assesses how quickly air can be exhaled from the lungs] 2. Uses: Detecting asthma and sometimes lung cancer

Answer 32

Total volume of oxygen decreases because it is converted to carbon dioxide + the carbon dioxide is then absorbed by the soda lime Can use this to measure oxygen use against time.

Answer 33

- As exercise increases = breathing rate + change in lung volumes increase. - The gradient of the graph will change as oxgen is being used faster - The spirometer trace changes with different activity levels. - Oxygen is used faster as exercise intensity increases = lines get closer together + longer + more frequent

Answer 34

- Liver is made of many **lobules** ≈ 1 mm in diameter [basic functional unit of the liver] - Large organ in the body [1.5 kg] - 3-4% of body weight - 1 litre of blood goes through the liver per minute. - More blood per unit time than any other organ.

Answer 35

```1. Hepatic portal vein``` - **Deoxygenated nutrient-rich blood** from the **digestive system** (stomach, intestines, spleen, pancreas) - **Brings nutrients** (like glucose, amino acids) to the liver for processin + storage ```2. Hepatic artery``` - **Oxygenated** blood from the **heart** (via aorta) - **Supplies** the liver cells (hepatocytes) with **oxygen** for their metabolic activities

Answer 36

```1. Hepatic vein``` - **Deoxygenated** blood goes to **heart** via the **inferior vena cava** ```2. Bile duct``` - **Bile** goes to the gallbladder for storage or directly to the **small intestine** (duodenum) for digestion - Bile helps **emulsify fats** in digestion

Answer 37

Liver structure contains: - Liver Lobules - Central vein (intralobular vein) = branch of the hepatic vein. - Branch of hepatic artery, branch of hepatic portal vein and bile ductile (=branch of the bile duct).

Answer 38

- Blood flows from **Interlobular blood vessels** to Branch of **hepatic artery** + Branch of **hepatic portal vein** > to **Central vein** (intralobular vein), branch of hepatic vein - Bile flows to **Bile ductile** (branch of bile duct)

Answer 39

- nearly all 500 function of liver is carries out by **liver cells [hepatocytes]** - structurally undifferentiated, lots of mitochondria + golgi bodies - However **Kupffer cells** in walls of **sinusoids** are phagocytic + destroy old RBC = bile produced

Answer 40

1. Regulation of blood glucose 2. Regulation of lipids 3. Regulation of amino acids 4. Production of heat 5. Production of bile 6. Formation of cholesterol 7. Elimination of sex hormones 8. Formation of red blood cells 9. Elimination of haemoglobin 10. Storing blood 11. Synthesis of plasma proteins 12. Storage of vitamins A, D, B12 + some minerals eg potassium, iron and copper. Summary – the liver regulates the physical + chemical composition of the internal environment = **homeostasis**

Answer 41

1. **Regulation of blood glucose** ``` - GLUCOSE converted to GLYCOGEN by INSULIN - GLYCOGEN stored in liver / or as fat - GLYCOGEN can be converted back to GLUCOSE by GLUCAGON ``` 2. **Regulation of lipids** ``` - liver cells remove lipids from the blood - + either break them down or send for storage ``` 3. **Regulation of amino acids** ``` liver converts excess amino acids to urea using deamination and the ornithine cycle. ```

Answer 42

4. **Production of heat** ``` - High metabolic activity - large size - high blood supply = these 3 make liver good for heat production ``` 5. **Production of bile** ``` – bile salts which emulsify fats. ``` 6. **Formation of cholesterol** ``` - made from fat - used in cell membranes - excess secreted in bile - considerable excess of cholesterol may precipitate as gall stones in gall bladder = leading to obstructive jaundice = associated with yellow skin or eyes ```

Answer 43

7. **Elimination of sex hormones** 8. **Formation of red blood cells** ``` - in foetus = liver makes RBC - In adult = RBC made in red bone marrow - but the liver still produceschemical needed - haematinic principle = used in making RBC + requires vitamin B12 ``` 9. **Elimination of haemoglobin** ``` - leaves liver through bile duct – known as bile pigments - = is responsible for the brown colour of faeces ```

Answer 44

10. **Storing blood** ``` - veins can expand + contract - storing between 300 - 1500 cm3 of blood - Regulating the amount of blood in circulation ``` 11. **Synthesis of plasma proteins** ``` - eg fibrinogen = involved in blood clotting - Also makes albumen + globulin ``` 12. **Storage of vitamins A, D, B12 and some minerals e.g. potassium, iron and copper** ``` - makes Liver a very nutritious meat to eat - however polar bear liver has so much vitamin A that is toxic to humans - + pilot whale liver in the Faroe Islands is too toxic to eat because of pollution ```

Answer 45

excess amino acids cannot be stored = are broken down through deamination - `Deamination` = The removal of the amine group from excess amino acids in liver - **Amine group** is converted to **ammonia** = very toxic - = converted to **urea** through the **ornithine cycle** = which is then excreted at kidneys - occurs in the mitochondria of the liver

Answer 46

1. TWO **Ammonia NH3** enter cycle 2. **1 Ammonia** combines with 1 molecule of **CO2** (from respiration) + **Ornithine** to form **Citrulline** [happens in mitochondria] 3. **Citrulline** converted into **Arginine** as a SECOND **Amonia NH3** is added to the citrulline 4. **Arginine** is **hydrolised** (water added) to release urea = **urea** is **released** here + one molecule of **ornithine** 5. **Orthinine** is regenrated from this **arginine** to continue cycle | 2 molecules of NH3 : 1 molecule of urea

Answer 47

**Excretion** = removal of metabolic waste substances. [ metabolic waste substances = chemicals produced by your cells eg urea, CO2, bile pigments] Examples of excretion - Urine - Sweat - Lungs – carbon dioxide - Leaf fall in the Autumn

Answer 48

**Excretion** = removal of metabolic waste substances [urea, CO2, bile pigments, sweat ] **Egestion** = includes substances that have just passed through your gut [ cellulose ]

Answer 49

- vena cava + aorta - diaphragm - Left kidney - Renal artery - Renal vein - Ureter - Bladder - Sphincter muscle [around bladder] - Urethra

Answer 50

- **C**ortex [**C** = **C** shaped part of the kidney] - **M**edulla [**M** = **M**iddle] - Pelvis [spiky inside section] - Nephron - Ureter

Answer 51

1. Blood enters kidney from **renal artery** --> glomerulus via afferent vessel 2. Blood in **glomerulus** under high pressure as afferent blood vessel has larger diameter than efferent blood vessel. 3. **Ultrafiltration** – small molecules (water, salt, glucose and urea) can go through holes into **Bowman’s capsule**. Large molecules (proteins) + blood cells are too large to go through holes. 4. **Bowman’s capsule** contains glomerular filtrate of water, salts, glucose + urea. 5. Substances (water, glucose, some salt) reabsorbed from urine - **selective reasorption** 6. “cleaned” blood returns to **renal vein**. 7. Urine goes to **bladder**.

Answer 52

- Blood enters glomerulus from afferent blood vessel - Afferent blood vessel has a larger diameter than efferent blood vessels - = blood in glomerulus is under high pressure - small molecules [water/ urea/ salt/ glucose/ amino acids/ ions eg Na+ Cl-] go through small holes into bowmans capsule - Big molecules [proteins + blood cells] cannot go through to glomerulus as too big to fit through holes = stay in blood - The liquid in the bowmans capsule is called the glomerular filtrate podocyte - specialized cell in the Bowman’s capsule that form part of the filtration barrier..Prevent large molecules + Allow small molecules through into Bowman's capsule ["sieve / filter"]

Answer 53

- A **nephron** (with microvilli inside =1 μm long) + **capillary** - close contact between nephron + capillary for exchange of molecules - The total area of proximal convoluted tubules in a person = about 50m2 - **Selective Reabsorption occurs** in the proximal convoluted tubule - Most water is reabsorbed by osmosis

Answer 54

occurs in the proximal convoluted tubule Filtrate from Bowman's capsule flows into the Proximal Convoluted Tubule (PCT) for reabsorption **Useful substances are reabsorbed into the blood, including**: - All glucose [by active transport] - Most water [osmosis]+ salts - site of **glucose + amino acid reabsorption** by **active transport** into blood

Answer 55

LEARN DIAGRAM + WHERE EACH PART OCCURS IN **Descending Limb:** - permeable to water = water leaves by osmosis - Conc of Na+ and Cl- in filtrate inside increases - high conc esp near bottom of it **Ascending Limb:** - Sodium Chloride NaCl actively removed from ascending limb [NaCl diffuses into descending limb = raising NaCl concentration in urine..??] - Causes region of high NaCl conc in surrounding tissue = medulla **Collecting Duct:** - water taken up by osmosis from collecting duct by osmosis - as surrounding tissues [medulla] contain a high conc of NaCl + therefore low water potential - water uptake depends on ADH + body's need - filtrate becomes urine atp ``` - for every 120 cm3 of water ultrafiltrated per minute, only 1cm3 gets to the ureter + bladder = other 119 cm3 of water is reabsorbed - Animals that live in deserts (little water) have extra long loops of Henle = indicating that loop of Henle has a role in reducing water loss ```

Answer 56

Remaining filtrate (water, urea, excess salts) flows into the renal pelvis, then the ureter, stored in the bladder, and excreted through the urethra.

Answer 57

- **Osmoregulation** = a type of homeostasis controlling water content in body - **Homeostasis** is maintaining a constant internal physical + chemical environment. - Quantity of water in blood varies depending on whether you have drunk a lot, or whether it is hot weather + sweating. - Osmoreceptor cells in the hypothalamus (part of the brain) measure the water potential of your blood - dehydration can increase the risk of blood clots (stroke or heart attacks).

Answer 58

1. If you get **dehydrated**. 2. **Water potential** in blood **decreases**. 3. Detected by **osmoreceptor** cells in hypothalamus. 4. **Anti-diuretic hormone** (ADH) **produced** by hypothalamus, travels along hollow neurosecretory cells + enters blood at pituitary gland. 5. ADH travels in blood to kidney 6. ADH makes the walls of the collecting duct more **permeable** to water (as **more aquaporins**), so **more water** is **reabsorbed**. 7. Reducing rate of losing water in urine

Answer 59

1. If you drink too much. 2. **Water potential** in blood **increases**. 3. Detected by **osmoreceptor** cells in the hypothalamus. 4. Produce **less ADH**. 5. Walls of the collecting duct becomes **less permeable** to water [**less aquaporins**] , so **more urine** is **produced**. 6. Increasing the rate of urine production.

Teaching block 2 [2] Flashcards

(83 cards)