Human Circulatory System
Significance
- Ensure continuous supply of useful substances to target cells and removal of waste
from body
- Unicellular orgs: small > substances transported by diffusion/ cytoplasmic
streaming w/o body system
- Large multicellular organisms: cells in diff parts of body far away from
each other > diffusion is too slow, inefficient
- Transport system: circulatory system + lymphatic system
Cellular RBCs, WBCs, blood platelets
Tissue blood
Organs heart, blood vessels
↓↑←→
Blood— centrifugation (> composition of blood)
- Tissue comprising of blood cells suspended in plasma
Plasma (55%) Blood cells (45%)
- Watery yellow layer (top) - Dark red layer (bottom)
1. Medium for transporting 1. Red blood cells (erythrocytes)
substances throughout body - Biconcave disc shape
- (main 90% by volume) water ↑ SA, ↓ volume (high SA to volume ratio)
- Dissolved substances > rapid diffusion of gases in gaseous
- Plasma proteins: antibodies, exchange
fibrinogen(clot) - Highly flexible membrane > squeeze
- Nutrients: glucose, amino thru narrow capillaries
acids - Contain haemoglobin > transport O2
- Metabolic waste: urea in blood
- Dissolved gases - Quite small, ~5.4M/mm3, red
- Mineral salts - Formation @bone marrow of some
- Hormones bones (limb bones, ribs, vertebrae)
2. Distribute heat throughout body > - Life span: 120 days
maintain stable body temperature - Mature: NO nucleus
- Damaged/dead: haemoglobin
broken down by phagocytes in
liver/spleen
- recycle Fe to make RBCs
- excrete bile pigment as part
of bile thru intestine
2. White blood cells (leucocytes)
, -
Irregular shape
-
Quite large/ small, ~7000/mm3,
colorless
- Formation @bone marrow, spleen
- Maturation @lymph nodes
- Life span: <3 days
- > body defence
- Destruction: killed by germs/ passed
out of body in faeces
a. Phagocytes
- 1 lobed nucleus
- engulf/digest germs/dead body cells
b. Lymphocytes
- smaller
- Large, round nucleus
- Produce antibodies
3. Blood platelets 血小板
- Irregular shape, (bone marrow) cell
fragments
- Very small, 250 000/mm3, colorless
- Life span: 7-10 days
- NO nucleus
- Destruction: @liver, spleen
- > blood clotting: ruptured, release
clotting factor (activate enzyme
prothrombin) catalyse
- Fibrinogen (soluble plasma
glycoprotein) >(solidify)>
fibrin (insoluble plasma
protein, form net trapping
blood cells, plug wound)
- Prevent further blood loss +
entry of germs into body thru
cut wound
Blood vessels
Arteries Veins Capillaries
<heart to body tissues> <body tissues to heart> <connect arteries to veins>
Deep inside body Closer to body surface
1. NO muscle layer
Largest: aorta > venules 2. Lumen
> arterioles Largest: vena cava - Slightly larger than
diameter of a RBC
1. Fibrous tissue 1. Fibrous tissue 3. Endothelium
- Thick: withstand high 2. Smooth muscles - Differentially
blood pressure from - thinner permeable
pumping action of 3. Elastic tissues - One-cell thick/ thin: ↓
Significance
- Ensure continuous supply of useful substances to target cells and removal of waste
from body
- Unicellular orgs: small > substances transported by diffusion/ cytoplasmic
streaming w/o body system
- Large multicellular organisms: cells in diff parts of body far away from
each other > diffusion is too slow, inefficient
- Transport system: circulatory system + lymphatic system
Cellular RBCs, WBCs, blood platelets
Tissue blood
Organs heart, blood vessels
↓↑←→
Blood— centrifugation (> composition of blood)
- Tissue comprising of blood cells suspended in plasma
Plasma (55%) Blood cells (45%)
- Watery yellow layer (top) - Dark red layer (bottom)
1. Medium for transporting 1. Red blood cells (erythrocytes)
substances throughout body - Biconcave disc shape
- (main 90% by volume) water ↑ SA, ↓ volume (high SA to volume ratio)
- Dissolved substances > rapid diffusion of gases in gaseous
- Plasma proteins: antibodies, exchange
fibrinogen(clot) - Highly flexible membrane > squeeze
- Nutrients: glucose, amino thru narrow capillaries
acids - Contain haemoglobin > transport O2
- Metabolic waste: urea in blood
- Dissolved gases - Quite small, ~5.4M/mm3, red
- Mineral salts - Formation @bone marrow of some
- Hormones bones (limb bones, ribs, vertebrae)
2. Distribute heat throughout body > - Life span: 120 days
maintain stable body temperature - Mature: NO nucleus
- Damaged/dead: haemoglobin
broken down by phagocytes in
liver/spleen
- recycle Fe to make RBCs
- excrete bile pigment as part
of bile thru intestine
2. White blood cells (leucocytes)
, -
Irregular shape
-
Quite large/ small, ~7000/mm3,
colorless
- Formation @bone marrow, spleen
- Maturation @lymph nodes
- Life span: <3 days
- > body defence
- Destruction: killed by germs/ passed
out of body in faeces
a. Phagocytes
- 1 lobed nucleus
- engulf/digest germs/dead body cells
b. Lymphocytes
- smaller
- Large, round nucleus
- Produce antibodies
3. Blood platelets 血小板
- Irregular shape, (bone marrow) cell
fragments
- Very small, 250 000/mm3, colorless
- Life span: 7-10 days
- NO nucleus
- Destruction: @liver, spleen
- > blood clotting: ruptured, release
clotting factor (activate enzyme
prothrombin) catalyse
- Fibrinogen (soluble plasma
glycoprotein) >(solidify)>
fibrin (insoluble plasma
protein, form net trapping
blood cells, plug wound)
- Prevent further blood loss +
entry of germs into body thru
cut wound
Blood vessels
Arteries Veins Capillaries
<heart to body tissues> <body tissues to heart> <connect arteries to veins>
Deep inside body Closer to body surface
1. NO muscle layer
Largest: aorta > venules 2. Lumen
> arterioles Largest: vena cava - Slightly larger than
diameter of a RBC
1. Fibrous tissue 1. Fibrous tissue 3. Endothelium
- Thick: withstand high 2. Smooth muscles - Differentially
blood pressure from - thinner permeable
pumping action of 3. Elastic tissues - One-cell thick/ thin: ↓
