Blood SDL - blood cells and blood plasma

what is blood

connective tissue and provides a means of communication between cells of diff parts of the body and external environment

what does blood carry

-oxygen from lungs to tissues, co2 from tissues to lungs

-nutrients to tissues and waste products for excretion

-hormones from endocrine glands

-heat

-antibodies

-clotting factors

what is blood propelled by

in a regular unidirectional movement propelled mainly by the rhythmic contractions of the heart

what does the continual flow of blood provide

a constant environment for the body

what is blood made up of

1) blood cells

2) plasma

what blood cells are in the blood

erythrocytes or RBCs

thrombocytes or Platelets

leucocytes or WBCs

what is the plasma

liquid component of blood

about 5.6 L in a 70kg man

definition of plasma

a straw coloured transparent fluid in which the blood cells are suspended

what is the function of plasma in transporting metabolites

from absorption or synthesis site, distribute them to diff areas of organism

what is the function of plasma in transporting residues

waste materials to excretory organs to facilitate their removal from body

what is the function of plasma in transporting hormones

helps regulate heat distribution and participates in acid-base balance and osmotic balance

what is the composition of plasma

aqueous solution with 90-92% made of water and dissolved substances

what dissolved substances are in plasma composition

• plasma proteins (7%) - retained in blood as too large to escape thru capillary pores

• inorganic salts (sodium chloride)

• amino acids, vitamins, hormones, lipids, e.t.c

• organic waste (urea)

• gases: o2, co2, n2

what are plasma proteins responsible for

maintaining osmotic pressure of the blood

what are some important plasma proteins

albumin, immunoglobulins, clotting factors

describe albumin

most abundant plasma protein, formed in liver, role in maintaining osmotic pressure of blood at 25mm Hg, act as carrier molecules for lipids and steroid hormones

describe immunoglobulins

formed in liver and lymphoid tissue

3 main functions:

• antibodies IgA, IgE, IgG, IgM

• transportation of some hormones and mineral salts

• inhibition of some proteolytic enzymes

describe clotting factors

substances essential for coagulation of blood

fibrinogen is synthesised in the liver, necessary for formation of fibrin, in final step of blood clotting

plasma from which blood clotting factors has been removed is called serum

what is plasma viscosity due to

plasma proteins, mainly albumin and fibrinogen

what do all blood cells originate from

pluripotent stem cells and go through several stages before entering the blood

what are erythrocytes

red blood cells

have no nuclei and shaped like biconcave discs - large SA to facilitate gas exchange

conc in blood is approx 4.5-5 mill per microlitre in female

where are erythrocytes produced

within the bone marrow and released into the blood

young erythrocytes are called reticulocytes

how are worn out erythrocytes removed

from the blood by cells of the macrophage system of the body

what is the function if erythrocytes

to transport oxygen from the lungs to the tissue where it is released

able to do this due to complex protein haemoglobin which has high affinity for oxygen

what is haemoglobin

Hb is composed of global and 4 iron harm groups, each can combine with one molecule of oxygen to form oxyhaemoglobin (HbO8) - unstable compounds

HbO8 then distributed to tissues where O2 is released

fill in the diagram

describe release and distribution of co2

25% released from cells combines with Hb to form carbaminohaemoglobin (HbCO2) - also unstable

8% remains in plasma

67% converted into bicarbonate ions and hydrogen

fill in the blanks

describe the formation of carbonic acid

carbon dioxide diffuses from blood into erythrocytes where it combines with water to form carbonic acid, accelerated by enzyme carbonic anhydrase - causes co2 to be bound to RBC rather than remain in plasma

describe how haemoglobin acts as a buffer

carbonic acid dissociates into bicarbonate ions and hydrogen ions

if H+ allowed to accumulate, would cause acidosis and cell death - when resp. ceases

Hb acts as buffer as H+ ions causes oxyhaemoglobin to take up free H+ ions - forms weak acid, decreases acid levels within cell

carboxygaemoglobin

if Hb combines with carbon monoxide carboxyhemoglobin is formed, stable compound, causes death as Hb cant take up O2 any more

what are leucocytes

WBCs, important in defending body against microbes and other foreign material

some are phagocytic and one of main defences against infection

what are wbc’s involved in

cellular and humeral defence of the body against foreign material alive or dead

describe the shape of WBCs

spherical cells in suspension in circulating blood, change shape and by diapedesis, leave capillaries and pass into connective tissue - participate in inflammation process

largest wbcs, contain nuclei and have some granules in cytoplasm

how are WBCS classified

on basis of specific granules in the cytoplasm

classified into:

1. granulocytes

2. agranulocytes

what are some granulocytes

neutrophils, eosinophils, basophils

what are agranulocytes

lymphocytes, monocytes

describe granulocytes

irregular shaped nuclei in cytoplasm and sometimes called polymorphonuclear leukocytes

granules stain different colours according to whether they’re neutrophils, eosinophils, basophils

what are neutrophils

formed in bone marrow and constitute first line of cellular defence against invasion of microorganisms

actively phagocytose small particles

how do neutrophils phagocytose

touch solid substance and send out pseudopodia which fuse around the particle, particle eventually occupies a vacuole, granules and vacuole fuse and granules empty contents into vacuole, granules contain enzymes which digest bacteria

what are eosinophils

capable of phagocytosis, slower way, increase in number in the blood is noted in allergic reactions,also function in keeping blood a liquid

what are basophils

have large granules, secrete histamine and heparin and may participate in allergic reactions, can phagocytose but not very active

describe agranulocytes

have nuclei with definite shape and cytoplasm doesn’t contain granules, depending on nuclei stain, classified into lymphocytes or monocytes

what are lymphocytes

round cells - various types, various survival times

how can we separate lymphocytes

according to function into B cells and T cells

precursor cells originate in bone marrow and then differentiate into one of two types once in blood

describe B cells

become plasma cells, produce antibodies to specific antigens, concerned with humoral immunity and thought to originate from lymphoid tissue in GIT

describe T cells

involved in cellular immunity of the body (thymus dependant), in blood most lymphocytes are t cells and responsible for minor reactions

what can lymphocytes also function as

memory cells

what are monocytes

originate in bone marrow and found in blood, connective tissue and other tissue and body cavities, belong to reticulo-endothelial system and have receptor sites on surface membrane for immunoglobulins and complement

may be phagocytic and important in recognising/interacting with antigen

what are platelets

no nuclei, fragments of cytoplasm covered with cell membrane, derived from giant cells of bone marrow called megakaryocytes

describe agglutination of platelets

clump together in blood during haemostasis

functions of platelets in haemostasis

1. formation of platelet plug

2. participate in formation of thromboplastin, factor essential to transformation of fibrinogen into fibrin which forms the clot

what important substances are transported in the platelet

adrenalin - vasoconstrictor and aids occlusion of ruptured blood vessels by promoting contractions of vascular smooth muscle

how is adrenalin released from platelets

liberated from platelets through actions of thrombin, enzyme synthesised in plasma during blood coagulation

what is a decreased platelet count known as

thrombocytopenia