Download Blood and blood vessels

Blood and blood vessels
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Blood
Blood, a specialised transport and defensive tissue, is composed of
cells and watery plasma.
10ml
Plasma
(55% of
blood total
5ml
White blood cells
(Leucocytes)
Red Blood cells
(Erythrocytes)
Plasma supernatant
composed of:
Water, solutes, waste
substances, proteins.
Cellular components 40% of total blood
volume:
Erythrocytes (red blood
cells) and Leucocytes
(white blood cells).
Erythrocytes
Erythrocytes (red blood cells) = Biconcave discs
6-8mm
Elastic membrane reduces damage in
high pressure blood flow.
2mm
Lack of nucleus and organelles allows
packing space for haemoglobin.
Haemoglobin binds with oxygen (and carbon dioxide) and is important
for oxygen transport in the body.
Very small thus providing a large (total) exchange surface.
Small size allows cells to come into close and intimate contact with
exchanging tissues.
Leucocytes
• Leucocytes (white blood cells) are defensive, protecting the body
from invading pathogens.
• The blood contains two types of leucocytes.
Granulocytes - cytoplasmic granules and
lobed nuclei.
Agranulocytes - no cytoplasmic granules
and smooth nuclei.
Neutrophils - Phagocytosis
Phagocytosis is a non-specific immune response: a general defence
against all infective particles. 3 stages:
• Ingestion
• Intracellular digestion
• Release of products of digestion
1. Bacteria become
attached to the
neutrophil.
2. The neutrophil
engulfs the
bacteria.
3. Bacteria are enclosed
in a vacuole.
Lysosomes fuse with
the vacuole and
release digestive
enzymes that destroy
the bacteria.
Antibody Actions
•
•
Antibodies protect against pathogens by:
Agglutination sticking them together, preventing dispersal.
antibody
antigen
pathogen
A different antibody will be
made for this antigen
•
Lysis (bursting), causing death of pathogen and host cell.
antibodies
Foreign particle
(pathogen)
Bursting host cell
containing
pathogens
Leucocytes summary
Leucocytes
Basophils
Granulocyte
Agranulocyte
(granules lobed nuclei)
(no granules smooth nuclei)
Neutrophils
• Migrate through
capillary walls to
infections
• Phagocytic
Eosinophils
Lymphocytes
Monocytes
(round nucleus)
•Produce antibodies
•Phagocytic
(bean-shaped
nucleus)
•Phagocytic
Cell Functions
What do these cells do?
Cell
Function
Plasma cell
Produce antibodies
Neutrophil
Migrate through capillary
wall to site of infection
Monocyte
Phagocytosis
Red blood
cell
Carry oxygen
Artery Structure
Lumen
Elastic tissue
Endothelium
thin lining
Elastic tissue and
smooth muscle
Diameter: 4mm to 25mm
(aorta)
Connective tissue (collagen
& elastic tissue)
Arteries and Muscle
Elastic tissues absorb the high
pressure, expand and ‘smooth’ large
pressure changes
Arteries mass transport
blood away from the heart
Elastic
tissue
Elastic
tissue
Elastic and
muscle
tissue
Elastic and
muscle
tissue
•
•
•
Thick muscular walls contain the
high blood pressure.
Smooth muscle fibres contract
rhythmically on the blood, exerting
pressure.
•
•
As pressure falls the artery recoils
releasing energy.
Elastic tissue ensures a continuous
blood pressure.
The pulse remains as evidence of
the surge in blood pressure
produced by ventricular contraction.
Capillary Structure
Capillaries are smaller in diameter than the cells they supply, allowing
close and intimate contact.
Endothelium –
thin lining
Lumen (Hole)
Basement
membrane
Diameter: 8mm
Fenestration
•
•
•
The endothelium, supported on the basement membrane, is one cell
thick allowing easy exchange across the capillary.
Fenestrations or gaps between endothelial cells increase the rate of
exchange with the tissues.
Very low blood pressure at the capillary produces low velocity blood
flow.
Vein Structure
Lumen (Hole)
Elastic tissue
Endothelium –
thin lining
Elastic and
muscle tissue
Connective tissue
Diameter: Up to 2.5cm (vena cavae)
Veins
Connective tissue
Small amount
elastic and smooth
muscle tissue
Endothelium
Basement
membrane
valve
• Veins carry blood at low pressure and velocity.
• Venous walls do not require the thickness and strength of arteries
to contain high blood pressure.
Veins
•
•
Pressure differences within the venous system are low.
One-way valves ensure blood flows only towards the heart after
leaving the capillaries.
Veins
• Muscles pushing on veins increase localised pressure and push
blood, producing flow.
• Valves ensure flow is one way.