transport in humans

Question 1

what is a double circulatory system?

Answer 1

blood flows through the heart twice in one circuit

Question 2

advantages of a double circulatory system

Answer 2

ensures blood is pumped at a low pressure to the lungs so it can be properly oxygenated and oxyenated blood can be pumped out at a high pressure to all body cells

Question 3

name of blood vessels connecting the LIVER

Answer 3

• hepatic artery and vein
• hepatic portal vein (gut to liver)

Question 4

name of blood vessels connecting the KIDNEY?

Answer 4

renal artery and vein

Question 5

blood vessels in cardiac cycle?

Answer 5

1. pulmonary vein
2. pulmonary artery
3. vena cava
4. aorta

Question 6

components of blood?

Answer 6

1.plasma (55%)
2.erythrocytes(red blood cells)
3.leukocytes (white blood cells)
4.platelets

Question 7

main functions of blood?

Answer 7

(a) to transport:
* oxygen
* food substances
* hormones
* waste materials
* heat
from one part of the body to another

(b) to protect the body by preventing entry of foreign bodies and fighting infections

Question 8

details about PLASMA

Answer 8

• 55% of blood volume
• 90% water, 10% dissolved substances
• substances dissolved in plasma: mineral ions, digested food substances, plasma proteins, metabolic waste products, hormones

Question 9

details about ERYTHROCYTES

Answer 9

1.produced in bone marrow and broken down in the spleen
2.lifespan of about 4 months

Question 10

structural adaptations of erythrocytes

Answer 10

(1) haemoglobin
- binds reversibly to oxygen to form oxyhaemoglobin
- each molecule of haemoglobin can bind up to 4 molecules of oxygen

(2) absence of nucleus
- more space for haemoglobin –> more oxygen transported

(3) circular and biconcave shape
- increases surface area to volume ratio, allowing for quicker diffusion of oxygen

(4) elastic/flexible cell surface membrane
- allows cell to change shape while squeezing throuh capillaries

Question 11

details about leukocyte

Answer 11

1. less numerous than erythrocyte
2. lifespan of about a few days

Question 12

details of platelets (thrombocytes)

Answer 12

1. fragments of larger bone marrow cells called megakaryocytes
2. clots blood by forming sticky plugs at wound sites

Question 13

importance of blood clotting

Answer 13

1. prevents entry of foreign bodies through the wound
2. prevents excessive loss of blood

Question 14

mechanism of blood clotting

Answer 14

1.damaged tissues produce thrombokinase (enzyme).
2.thrombokinase catalyses process of prothrombin (inactive) turning into thrombin (active enzyme)
3.fibrinogen turns into fibrin threads with the help of thrombin
4.fibrin threads form a mesh to trap blood cells

Question 15

details of ABO blood groups

Answer 15

blood type A
* anti-B antibodies
* A antigens

blood type B
* anti-A antibodies
* B antigens

blood type AB (universal recipient)
* no antibodies
* A and B antigens

blood type O (universal donor)
* anti-A and anti-B antibodies
* no antigens

Question 16

what is agglutination?

Answer 16

clumping of red blood cells which is fatal
* when anti-A antibodies bind with antigen A
* when anti-B antibodies bind with antigen B

Question 17

structural features of an ARTERY

Answer 17

• THICKER, MORE ELASTIC AND MUSCULAR WALLS:
  withstand high pressure of blood flowing through it, and mantain high pressure of blood by stretching and recoiling to push blood in splurts
• smaller lumen

Question 18

structural features of a VEIN

Answer 18

• RELATIVELY THINNER, LESS ELASTIC AND LESS MUSCULAR WALLS:
  blood flowing through it is of lower pressure
• PRESENCE OF SEMILUNAR VALVES:
  prevent backflow of blood due to low pressure of blood in veins
• larger lumen

Question 19

structural features of CAPILLARY

Answer 19

• ONE CELL THICK WALLS THAT ARE PARTIALLY PERMEABLE:
  short distance, substances are able to diffuse through the walls quickly
• WALLS BRANCH REPEATEDLY:
  provides a large surface area for the quick exchange of substances

Question 20

what is tissue fluid caused by?

Answer 20

blood plasma pushed out of the small gaps in capillaries by hydrostatic pressure

Question 21

what does tissue fluid contain and not contain?

Answer 21

CONTAINS:
* dissolved food substances (glucose, amino acids)
* waste products (urea, hydrogencarbonate ions)
* phagocytes

DOES NOT CONTAIN:
* proteins (they are too large to pass through the gaps)
* red blood cells

Question 22

name of the wall that keeps left and right side of heart seperated

Answer 22

median septum

Question 23

types and location of heart valves

Answer 23

1. semilunar valves: in aorta and pulmonary artery
2. bicuspid valve: betweenleft atrium and ventricle
3. tricuspid valve: between right atrium and ventricle

Question 24

what do heart valves help ensure?

Answer 24

unidirectional flow of blood, preventing backflow of blood

Question 25

why are ventricular walls thicker than those of the atria?

Answer 25

muscular walls of **ventricle contract** to **pump blood** to the **rest of the body (far distance)** so walls are **thicker and more muscular** to **exert a higher pressure**, ensuring blood **reaches all areas of the body.** however, muscular walls of **atria contract** to **pump blood to the ventricles (short distance)**, thus their walls **less thick and muscular** as blood can be pumped at a **lower pressure.**

Question 26

cardiac cycle?

Answer 26

(1)*ATRIAL SYSTOLE* * **muscles** surrounding **both atria contract**, forcing **blood into ventricles. pressure in atria rises**. * **tricuspid + bicuspid valves open** to **allow blood to flow through** * **semilunar valves close** to **prevent backflow of blood** into **vena cava and pulmonary vein.** (2) *VENTRICULAR SYSTOLE* (**"dub" sound**) * **muscles** surrounding **both ventricles contract** and **pressure in ventricles rises** * **blood from ventricles** is **pumped out of heart** and into **aorta and pulmonary artery** * **tricuspid and bicuspid valves** **close** to **prevent backflow of blood** * **semilunar valves** in **aorta and pulmonary artery open** to **allow passage of blood.** (3) *DIASTOLE* (**"lub" sound**) * **muscles** surrounding **both atria and ventricles relax,** **pressure in chambers fall** * **blood** enters **relaxed atria and ventricles.** * **tricuspid and bicuspid valves open** to **allow blood to pass through** * **semilunar valves** in **pulmonary artery and aorta close** to **prevent backflow of blood**

Question 27

what do coronary arteries do

Answer 27

supplies **nutrients and oxygen** to **heart muscles**

Question 28

how can coronary arteries result in coronary heart disease

Answer 28

**narrowing of arteries** and **blocked arteries** due to **build up of fatty deposits containing cholesterol**

Question 29

how can coronary heart disease cause a heart attack

Answer 29

**blocked** coronary artery **cuts off blood supply** to **heart muscle**. **heart muscle cells** are **deprived of oxygen and nutrients** , thus **cannot respire**. heart **cannot continue to contract**, resulting in **heart attack**

Question 30

causes of coronary heart disease

Answer 30

1. **diet high in cholesterol** and **saturated animal fats** 2. **lack of exercise** 3. **stress and smoking** (increase in blood pressure and narrowing of artery walls due to buildup of plague)

Question 31

how to prevent coronary heart disease

Answer 31

1. **reduce intake** of **cholesterol** and **saturated animal fats** 2. **regular physical exercise** 3. **manage stress and avoid smoking**