Transport in humans

#blood #bio #typeshiiiii (CHAP 6.1-6.3)

What are the 4 main components of blood?

Red blood cells

White blood cells

Plasma

Platelets

Role of Plasma

Plasma transports:

• blood cells around the body

• nutrients from the small intestines to other parts of the body

• excretory products from organs where they are produced to excretory organs for removal

• hormones from endocrine glands to target organs

Structure of Plasma

Yellowish fluid part of blood

Roles of RBC

The main function is to transport oxygen from the lungs to the other parts of the body

Contains haemoglobin that can combine reversibly with oxygen. In lungs where oxygen concentration is high, haemoglobin binds to oxygen to form oxyhaemoglobin

What are the features of a RBC and explain how they help

• Key RBC adaptations (and why they matter):

  Adaptation	How it helps
  Biconcave shape	Increases surface area to volume ratio → faster diffusion of oxygen in & out
  No nucleus	More space for haemoglobin → more oxygen can be carried
  Contains haemoglobin	Binds to oxygen → forms oxyhaemoglobin for transport
  Flexible	Can squeeze through narrow capillaries easily
  Thin cell membrane	Short diffusion distance → faster exchange of gases

What are the 2 main types of WBC?

Phagocytes and Lmphocytes

What is Phagocytosis?

The process by which a WBC surrounds and covers and destroys foreign particles such as bacteria

What does the lymphocytes do?

Lymphocytes produce antibodies that:

• recgnise foreign particles

• destroy disease-causing organisms such as bacteria and viruses

• cause bacteria to clump together for easy ingestion by phagocytes

• neutralise the toxins produced by bacteria

What is the role of Platelets?

Entangles red blood cells to form a clot. Preventing excessive blood loss and the entry of harmful organisms into the bloodstream.

How does the blood clot?

🩸 How Blood Clots (Simple Explanation):

1. Cut or injury happens
   → blood vessels get damaged.

2. Platelets rush to the area
   → they stick together to form a plug.

3. Platelets release chemicals that turn a protein called fibrinogen into fibrin.

4. Fibrin forms a net over the wound
   → this traps more blood cells.

5. A clot (scab) forms and seals the wound.

What are the 4 groups of blood?

A , B , AB , O

Name the antigens on RBC and antibodies in plasma for the 4 blood groups

Blood Group	Antigens on RBC	Antibodies in Plasma
A	A antigen	Anti-B
B	B antigen	Anti-A
AB	A and B antigens	None
O	None	Anti-A and Anti-B

who can receive from who?

Recipient	Can receive from	Why?
A	A, O	No Anti-A attacking
B	B, O	No Anti-B attacking
AB	A, B, AB, O (universal recipient)	Has no antibodies
O	O only	Has both Anti-A and Anti-B

who can donate to who?

Donor	Can donate to	Why?
A	A, AB	Has A antigen, safe for A & AB
B	B, AB	Has B antigen
AB	AB only	Has both A & B antigens, risky for others
O	A, B, AB, O (universal donor)	No antigens, won’t trigger any antibodies

Why is O a universal donor?

• It does not have any antigens

• It will not clump with the donors red blood

State the function of …

• heart

• arteries

• arterioles

• blood cappilaries

• venules

• veins

❤ Heart

• Pumps blood throughout the body to transport oxygen, nutrients, and remove waste.

---

🔴 Arteries

• Carry blood away from the heart (usually oxygenated) at high pressure.

---

🔸 Arterioles

• Small branches of arteries that control blood flow into capillaries by adjusting their diameter.

---

🩸 Blood Capillaries

• Tiny vessels where exchange of substances (oxygen, nutrients, waste) happens between blood and body cells.

---

🔹 Venules

• Small veins that collect blood from capillaries and carry it toward veins.

---

🔵 Veins

• Carry blood back to the heart (usually deoxygenated) at low pressure, and have valves to prevent backflow.

How are substances transferred between capillaries and tissue fluid?

• Blood enters capillaries from arterioles under high pressure.

• This pressure forces plasma (without proteins) out through the capillary walls — this forms tissue fluid.

• Tissue fluid surrounds the body cells and allows exchange of substances.