Transport in Humans

Question 1

The Cardiac Cycle

Answer 1

1. Atrial Muscles contract&raquo_space; blood forced into ventricles
2. Ventricular mucles contract&raquo_space; pressure inside ventricle rises»bicuspid & tricuspid valves close (LUB)» semi-lunar valves open
3. Ventricular muscles relax»fall in pressure»semi-lunar valves close (DUB)» bicuspid & tricuspid valves close
4. Atrial muscles contract again»blood pressure in arteries the highest

systole(contract)
diastole(relax)

Question 2

Tricuspid Valve

Answer 2

prevents backflow of blood from right ventricle to right atrium

Question 3

Bicuspid valve

Answer 3

prevents backflow of blood from left ventricle to left atrium

Question 4

Aortic valve

Answer 4

prevents backflow from aorta to left ventricle

Question 5

Pulmonary valve

Answer 5

prevents backflow of blood from pulmonary artery to right ventricle

Question 6

Blood pressure

Answer 6

The force that blood exerts on walls of blood vessels

-highest during ventricular systole when blood is forced into arteries + near aorta

-decreases during ventricular diastole + weaker the further th arteries ae away from the heart +low in veins

Question 7

Pulse

Answer 7

producd aft every ventricular contraction as the heart pumps the blood

high aft exertion, low aft rest

athletes have relatively low pulse rates

Question 8

Heart

Answer 8

muscular pump keeping blood circulating around the body

relaxes - fills up w blood
contracts - blood squeezed out with gr8 force

Question 9

Arteries

Answer 9

Carry blood away from the heart
-carry oxygenated blood (exc pulmonary)

• has thick, muscular, elastic walls, thicker near heart, to withstand high blood pressure
  -elasticity allows artery wall to stretch & recoil, pushing blood in spurts which gives rise to pulse

-large artery leaving left side = aorta
-branches to form smaller arteries

-constrict: lumen narrower, less blood flows per unit time
-dilates: lumen wider, more blood flows per unit time

Question 10

Arterioles

Answer 10

Tiny vessels branched from arteries

-branches even more to form capillaries

Question 11

Blood capillaries

Answer 11

Microscopic + found bw cells of alm all tissues

-walls made from only a single layer of flattened cells + partially permeable + some substances diffuse quickly thru them

-numerous branches: provide large S.A. for exch of substances bw blood & tissue cells

-if branched from arteriole: total cross-sectional area of blood vessels increases, lowerin blod pressure in capillaries

Question 12

Veins

Answer 12

Carry blood back to heart
-carry deoygenated blood (exc for pulmonary)

-blood pressure much lower than that in arteries

-blood flows more slowly & smoothly

-thinner walls + less elastic tissue + have internal valves along their length preventing backflow of blood

Question 13

Pulmonary Arteries

Answer 13

carry deoxygenated blood from heart to lungs

Question 14

Pulmonary Veins

Answer 14

carry oxygenated blood from lungs to heart

Question 15

Atria

Answer 15

2 upper chambers, receiving blood from veins

• have comparatively thin muscular walls, as they only force blood into the ventricles lying directly below them

Question 16

Ventricles

Answer 16

2 larger lower chambers

-have comparatively thick muscular walls

-left ventricle muscle thicker as it pumps blood ard the whole body
-right ventricle has thinner walls as it only pumps blood to lungs

Question 17

Median septum

Answer 17

Muscular wall running down middle of the heart, separating right & left sides of the heart

• prevents mixing of deoygented blood in the right side w oxygenated blood in left side
  -mixing of oxygenated & deoxygenated blood will reduce amt of oxygen carried to rest of body

Question 18

Hole in Heart

Answer 18

Hole usually present in median septum

-blood will flow from left to right side of heart as as pressure in the left higher than that in the right
: results in mixing of oxy & deoxy blood, causing less oxygen to be transported to body cells for respiration

-shortness of breath, fatigue, heart failure

Question 19

Arteries leaving Heart

Answer 19

-Pulmonary arteries from right ventricle
-Aorta from left ventricle

Question 20

Arteries leaving Heart

Answer 20

-Pulmonary arteries from right ventricle
-Aorta from left ventricle

Question 21

Arteries leaving Heart

Answer 21

-Pulmonary arteries from right ventricle
-Aorta from left ventricle

Question 22

Arteries Arising from Aorta

Answer 22

-arteries to the head,neck,arms

-hepatic artery to the liver

-artery to the stomach and intestines

-renal arteries, one to each kidney

Question 23

Main Veins of the Body

Answer 23

Pulmonary veins
- bring blood from lungs to left atrium of heart

Upper vena cava
- returns blood from neck, head and arms to right atrium

Lower vena cava
- brings blood from rest of the body to right atrium
-receives blood from renal vein (bring blood from kidneys)
& hepatic vein (bring blood from liver

Question 24

Heart attack

Answer 24

-Blood flow to a particular part of the heart may be completely blocked

-Due to blocked blood flow, that pt of the heart does not receive sufficient nutrients & oxygen

-That region of the heart muscle dies

-Extensive heart muscle damage is often fatal as hart is no longer able to pump blood to rest of the body

Question 25

Atherosclerosis

Answer 25

• Fatty substances (ie cholesterol & saturated fats) deposited on inner surface of coronary arteries,
  narrowing lumen these arteries, and increasing blood pressure .

-Affected arteries develop a rough inner surface, increasing risk of blood clot being formed in the artery

-If occurs in coronary arteries, supply of blood & oxygen to heart muscles may be completely cut off

-Oxygen is needed in aerobic respiration to release energy for activities of muscle cells,
w/o oxygen, heart muscles may be damaged and heart attack occurs

Question 26

Risk factors of Heart disease

Answer 26

-Smoking

-Genetic factors

-Age

-Unhealthy Diet

-Sedentary Lifestyle

Question 27

Steps to reduce Coronary Heart Disease

Answer 27

Healthy diet
-sub animal fats with polyunsaturated plant fats, that dont stick to inner surface of arteries
-lowers cholesterol level in blood

Avoid Smoking
-nicotine & carbon monoxide increases risk

Regular Physical Exercise
-Strengthens heart+ Maintains elasticity of arterial walls

Question 28

Plasma

Answer 28

transports
-blood cells ard the body
-nutrients from small intestine to rest of the body
-excretory products from organs whr they r produced to excretory organs for removal
-hormones from endocrine glands to target organs

Question 29

RBC

Answer 29

Transport oxygen from lungs to rest of the body

Adapt
-haemoglobin: combines reversibly w oxygen, forming oxyhaemoglobin

-biconcave shape: incr SA-to-Vol ratio, incr rate of absorption & release of oxygen

-no nucleus: more space for more haemoglobin to be stored

-flexible: can change into bell-shaped structure to flow easily thru narrow blood capillaries

Question 30

WBC

Answer 30

Irregular in shape + Have nucleus

Phagocytes: perform phagocytosis, whereby WBC engulfs & destroys foreign particles like bacteria

Lymphocytes: produce antibodies that
-recognise foreign particles
-destroy disease-causing organisms like bacteria & viruses
-cause bacteria to clump tgt fo easy ingestion by phagocytes
-neutralise toxins produced by bacteria

Question 31

Platelets

Answer 31

Contain enzyme that catalyse conversion of fibrinogen to fibrin threads that form a network entangling RBC to form clots,
preventing excessive blood loss & entry of harmful organisms of bloodstream

Question 32

Blood Clot

Answer 32

1. Platelets are involved in converting soluble protein fibrinogen to insoluble threads of fibrin using thrombokinase
2. Fibrin threads entangle blood cells and the whole mass forms a clot that seals the wound,
   preventing entry of microorganisms & excessive loss of blood