Recursos+de+refuerzo+de+la+unidad+4


 * [[image:Summary answer key0002.jpg width="800" height="1089"]]



.. The internal environment is made up of extracellular liquids found inside the organism. The cells extract nutrients from these liquids and collect waste substances. A stable internal environment is called **homeostasis.**
 * Internal environment

Lymph is a liquid made from **interstitial fluid**. It is similar to blood, but with no erythrocytes or platelets. The lymphatic system returns **lymph to the veins** by way of three components. Each one has a specific function: • Lymphatic capillaries: **collect excess interstitial fluid.** • Lymphatic vessels: **return excess lymph to the circulatory system.** • Lymph nodes: **their defence cells locate and fight microorganisms that can cause infection.**
 * The lymphatic system
 * Blood

Blood is made up of **blood plasma** and three types of cells: • Erythrocytes transport **oxygen and pick up carbon dioxide.** • Leucocytes defend against **infection and foreign substances.** • Platelets **help blood to clot at wounds.**

The circulatory system This system is made up of blood vessels and the heart. • The arteries carry blood from **the heart to the organs.** • The veins carry blood from **the organs to the heart.** • The capillaries distribute blood to the cells. • The heart is a muscular organ that **pumps the blood.** • To do this, the heart makes two movements: **contraction (systole) and relaxation** • The inside of the heart is divided into four chambers: **right atrium, left atrium, right ventricle, left ventricle.** • A partition separates the **right and left sides of the heart**, but the **chambers** on the same side are connected. • Excretion is the elimination of **waste products that are produced by cell metabolism from the blood.** • This process is carried out by four organs: **kidneys, lungs, liver and sweat glands.** • The kidneys filter **blood** and produce **urine.** • The formation of urine takes place __**in the nephrons**__. There are about __**one million**__ nephrons in each kidney.
 * (diastole).**
 * Excretion

Unit 5 Reinforcement and extension

a. What is the internal environment? **The fluids that surround the cells in the body.**
 * Answer the questions to complete the summary

b. What systems make up the circulatory system? **The blood circulatory system and the lymphatic system.**

c. What makes up the lymphatic system? **Lymph capillaries, lymphatic vessels and lymph nodes**.

d. What are the principal parts of the heart? **The right and left atria, right and left ventricles, aorta, pulmonary artery, superior and inferior vena cava, pulmonary veins; pulmonary, tricuspid, mitral and semilunar valves; septum.**

e. What are the names of the contraction phase and the relaxation phase of the heart? **Systole and diastole respectively.**

f. What are two diseases that affect the circulatory system or the blood? .
 * Arteriosclerosis and leukaemia.**

g. What are two healthy habits for the circulatory system? **Drink two litres of water a day; eat a low-salt diet**.

h. What is excretion? What organs are involved**? Excretion is the elimination of**
 * waste products of metabolism from the blood. The kidneys, lungs, liver and sweat glands are involved.**

i. What does the urinary system consist of? **The kidneys: renal artery and vein;**
 * urinary tract: ureters, bladder and urethra.**

j. How and where is urine formed in the nephrons? **It is formed by filtration and reabsorption in the glomerulus, Bowman’s capsule, PCT, DCT, collecting duct,**
 * loop of Henle.**

k. What are two diseases of the excretory system? . Renal colic and kidney disease.

l. What are two healthy habits for the excretory system? **Drink a lot of** Scientific analysis. 2. a. **A complete cardiac cycle lasts about 0.8 seconds.** b. **Atrial contraction lasts about 0.1 seconds.** c. **Ventricular contraction lasts about 0.3 seconds.** d. **Diastole lasts about 0.4 seconds.**
 * liquids; avoid self-medication.**
 * Electrocardiograms

Patient 1: platelets above normal; other components are normal. Patient 2: WBC and platelets above normal; other components are normal. Patient 3: RBC and haemoglobin below normal; other components are normal. Patient 4: RBC above normal; other components are normal.
 * Page 62**
 * 1.**
 * 2.** . Patient 3 may have anaemia.
 * 3.** Patient 2 may have an infection.
 * 4.** Blood tests show any abnormal levels of the components in blood. The results enable the doctor to identify problems.

Page 63

body || Iron deficiency; tissues do not receive enough oxygen. || abnormal WBCs || Cells cannot fight infection; cancer. || People bleed longer after injuries. ||
 * **Disease** || **Cause** || **Effects** ||
 * Anaemia || Low level of iron in the
 * Leukaemia || A large number of
 * Haemophilia || Inherited disease || Blood clots slowly or not at all.


 * 6.** . A person with anaemia feels tired or weak.

Bad habits: I put too much salt on my food. I do not drink enough water
 * 7.** . Good habits: I exercise every day. I do not smoke. I do not eat a high-fat diet.


 * Page 67**


 * 3.** In **chronic kidney disease**, kidney function decreases gradually. Nephrons are damaged if too much waste accumulates in the blood.
 * In acute kidney disease,** the kidneys suddenly stop filtering waste; urine production is low.

. I drink more water after exercise because I sweat and feel thirsty.
 * 4.** Kidney stones are deposits that can cause renal colic when they pass through the ureters.
 * 5.** If you drink less than 2 L a day, it is not enough.
 * 6.** A dialysis machine cleanses the blood when patient is connected to it.
 * Page 68**

system || Network of capillaries, vessels and nodes throughout the body. || Collect excess interstitial fluid; return excess lymph to the circulatory system and fight infections. || blood cells and platelets. || Transport oxygen and nutrients; eliminate carbon dioxide; protect against infection and clots. || capillaries. || Transport the blood around the body. Capillaries connect arteries to veins. ||
 * Activity Round Up**
 * 1.**
 * **Structure or**
 * system** || **Description** || **Function** ||
 * Lymphatic
 * Blood || A thick red liquid made up of red blood cells, plasma, white
 * Blood vessels || Network of three types of tubes: arteries, veins and


 * 3.**
 * a.** A: atrial systole. B: ventricular systole.
 * b.** Mitral and tricuspid valves open. They allow blood into the ventricles.
 * c.** Mitral and tricuspid valves close. They prevent the blood from flowing backwards.
 * 4.** A; renal artery, renal vein, renal pelvis, ureter, renal pyramid, renal medulla and renal cortex. Labels for drawing B; glomerulus, Bowman’s capsule, proximal convoluted tubule, collecting duct, loop of Henle, distal convoluted tubule.

bacterial infection. Symptoms: pain when urinating, frequent and difficult urination. Healthy habits: drink plenty of water, good hygiene of the external genital area. Disease: **Anaemia.** Organ: blood cells. Cause: low levels of haemoglobin caused by a lack of iron in the diet. Symptoms: fatigue, heavy menstruation. Healthy habits: balanced diet, food rich in iron.
 * 5.** Disease: **cystitis.** Organ: inflamed bladder wall or urinary tract. Cause:

55% plasma which consists of: 99% water 8% proteins 1% mineral salts, amino acids, glucids, lipids, hormones and urea. || 95% water 2% mineral salts 3% urea and uric acid || Composition varies: 99% water 0.4% mineral salts 0.6% urea and uric acid || nephron cleanses the blood automatically by filtration and reabsorption.
 * 7.**
 * **Blood** || **Sweat** || **Urine** ||
 * 45% cells
 * 8.**
 * a.** Cerebral blood flow decreases as blood pressure drops.
 * b.** To increase blood pressure. This position improves blood flow to the brain.