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Samenvatting Homeostasis And Organ Systems
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Samenvatting van case 1 t/m 10 van het eerste jaar biomedische wetenschappen, blok 2 (Homeostasis And Organ Systems)
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CASE 1: RIVER OF LIFEBLOOD
COMPOSITION OF BLOOD
Blood = specialized fluid that moves through the vessels of a circulatory system. It has 4 main components:
1. PLASMA
Liquid component of blood. It is a pale-white watery solution (90% water) of carbohydrates, lipids,
electrolytes, plasma proteins, wastes, and dissolved gases.
• Electrocytes (Na+, Cl-, etc): maintain a plasma osmotic pressure and normal blood pH.
• la
1. Albumin (54%): manufactured by the liver, serve as binding proteins, and is the most significant
contributor to the osmotic pressure of blood (keeps water in the bloodstream).
2. Globulins (38%): three main subgroups:
• Alpha/beta: transport iron, lipids, and the fat-soluble vitamins (A,D,E,K) to cells.
Contribute to osmotic pressure. Alpha include HDL (keeping cholesterol in transport
within the blood and building various substances and energy metabolism). Beta include
LDL (promotes cholesterol plaque, transport fat to cells for steroid and cell membrane
synthesis).
• Gamma (antibodies): produced by specialized leukocytes.
3. Fibrinogen (7%): soluble plasma clotting factor precursor, converted to protein, fibrin, on
contract with a sticky surface. The fibrin treads form in this way trap platelets to form the
primary platelet clot on which a stable blood cot is formed by the process of coagulation.
Produced by the liver.
• Amino acids: recycled for use in the synthesis of other biological structures.
• Nutrients: absorbed from the gut or from other organs are carried in the plasma.
2. ERYTHROCYTES (RED BLOOD CELLS/RBCS)
About 40-45% of blood volume. Shape is a biconcave disk with a flattened centre and no nucleus → effectively
perform their tasks of oxygen transport (in RBCs is Hb which binds O2 and CO2, and it gives the red colour to
blood) because they can move through membranes.
Production: controlled by erythropoietin. RBCs starts as immature cells in the bone marrow and after 7 days
released into the bloodstream.
3. LEUKOCYTES (WHITE BLOOD CELLS/WBCS)
About 1% of blood volume. Protect the body from infection. Larger than RBCs and have a nucleus and
organelles. Leave the capillaries or other small vessels through emigration or diapedesis (squeeze through
adjacent cells in blood vessel wall). Out the bloodstream they move through the tissue spaces by amoeboid
motion. This total process: leukocyte extravasation. WBCs can be divided into two groups:
1. Granular leukocytes: lobed nucleus.
• Neutrophils (50-70%): the granules appear light lilac and the nucleus has 2 to 5 lobes.
• Eosinophils (2-4%): nucleus has 2-3 lobes (telephone shaped) and the granules will have a red to
orange colour.
, • Basophils (<1%): large granules that are dark blue and the 2 lobed nucleus is hard to see.
2. Agranular leukocytes: smaller, less-visible granules.
• Lymphocytes (20-30%): large spherical nucleus and pale blue cytoplasm. 3 major groups:
1. Natural killer (NK): recognizing cells that do not express ‘self’ proteins on the plasma
membrane.
2. B cells: play role in defending the body against specific pathogens and produce
antibodies.
3. T cells: same role as B cells, and act directly against the virus-infected cells.
• Monocytes (2-8%): originate from myeloid stem cells. Indented or horseshoe-shaped nuclei.
When they leave the bloodstream, they differentiate into macrophages.
List from most abundant to lest abundant: Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils →
(Never Let Monkeys Eat Bananas)
4. PLATELETS
Fragment of the cytoplasm of a cell called a megakaryocyte (contain an enlarged, lobed nucleus) that is
surrounded by a plasma membrane. Platelets do not have a nucleus.
FORMATION OF BLOOD
Blood cells are formed in the
blood marrow through
haematopoiesis.
Formation of RBCs:
erythropoiesis and happens in
the red bone marrow. Originated
from common myeloid
progenitor
Formation of WBCs: leukopoiesis
and happens in bone marrow.
Originated from common
lymphoid progenitor.
,ROLE OF BLOOD
Blood delivers necessary substances to the cells and transport metabolic waste products away from those
same cells. It plays an important role regulating the body’s systems and maintaining homeostasis.
So, blood transport nutrients, oxygen, hormones and picks up cellular wastes. It protects the body from
external threats or destroys internal threats. It also regulates the temperature, maintain the chemical balance
(pH) and it regulate the water content of the body cells. At last the blood clotting, this prevent excessive
bleeding when a blood vessel is injured.
CIRCULATION OF BLOOD
PULMONARY CIRCULATION
Movement of blood from the heart to the lungs for oxygenation, the back to the heart again.
Systemic circulation →(superior and inferior venae cavae) right atrium →(tricuspid valve) → right ventricle →
(pulmonary artery) lungs → (pulmonary veins) left atrium.
SYSTEMIC CIRCULATION
Movement of blood from the heart through the body to provide oxygen and nutrients to the tissues of the
body, while brining deoxygenated blood back to the heart.
(pulmonary veins) left atrium → (mitral valve) left ventricle → (aortic valve, aorta) tissue of the body → (venae
cavea) right atrium → pulmonary circulation.
TRANSPORT MECHANISM OF CAPILLARY FLUID EXCHANGE
MEMBRANE TRANSPORT
There is no continuous traffic across the plasma membrane, but it is a permeable barrier. Substances move
through the plasma membrane in two ways – passively or actively.
PASSIVE PROCESSES / DIFFUSION
Substances cross the membrane without any energy input from the cell. Diffusion: tendency of molecules or
ions to move from an area, where they are in higher concentration to an area where they are in lower
concentration, that is down or along their concentration gradient. Rules: (1) lipid soluble, (2) small enough to
pass through membrane channels, or (3) assisted by a carrier molecule.
FACTORS THAT AFFECT DIFFUSION
Extent of the concentration gradient: the greater the difference in concentration, the more rapid the diffusion.
Mass of the molecules diffusing: heavier is slower.
Temperature: high temperature increases the energy and therefore the movement of the molecule, increasing
the rate of diffusion.
Solvent density: increase in this the diffusion decrease.
Solubility: nonpolar or lipid-soluble materials pass through easier.
Surface are and thickness of the plasma membrane increases surface are increase the diffusion, thicker
membrane reduces it.
Distance travelled: greater distance, slower diffusion.
TYPES OF DIFFUSION
, 1. SIMPLE DIFFUSION
Nonpolar and lipid soluble substances diffuse directly through the lipid bilayer. [O2] higher in the blood than in
tissue cells → diffuse from blood into the cells. [CO2] higher in the cell → diffuse from tissue cells into the
blood.
2. FACILITATED DIFFUSION
Some molecules are not able to pass through the lipid bilayer, so they diffuse in 2 ways:
1. Carrier-mediated: carriers are transmembrane integral proteins that are specific for transporting
molecules. The shape allows it to first envelop and then release the transported substance, shielding
it and route from the nonpolar regions of the membrane.
2. Channel-mediated: transmembrane proteins. Selective due to pore size and the charges of the amino
acids lining the channel. Leakage are always open, and gated are controlled.
• Potassium channel: have a tetrameric structure consisting of four identical protein subunits
surround a central pore. On top are pore loops that form a narrow selectivity filter. Lining
this filter are carbonyl oxygens. Hydrated potassium ions interact with these and shed most
of their bound water molecules → dehydrated potassium ions pass through the channel.
• Sodium channel: inner surface is lined with amino acids that are strongly negatively charged
→ pull dehydrated sodium ions into these channels.
• Opening and closing of gates are controlled in 2 principal ways:
1. Voltage gating: response to the electrical potential across the cell membrane.
2. Chemical (ligand) gating: binding of a chemical substance (ligand) with the protein,
which causes a conformational or chemical bonding change in the protein molecule
that opens or close the gate.
3. OSMOSIS
The diffusion of a solvent, such as water, through a selectively permeable membrane. It occurs whenever the
water concentration differs on the two sides of a membrane. Water moves from a lower concentration to a
higher concentration.
ACTIVE PROCESSES
Processes in which cell uses energy to move solutes across the membrane.
PRIMARY ACTIVE TRANSPORT
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