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Cellular Physiology - Coggle Diagram
Cellular Physiology
Cellular structure
Homeostasis
The maintaining of the internal balance of human body despite
changes in the external environment called steady states.
Homeostasis imbalance
❖Normal equilibrium oof body processes are disrupted
❖Moderate imbalance
•Disorder or abnormality of structure and function
•Disease specific for an illness with recognizable signs and symptoms
•Signs are objective changes such as a fever or swelling
•Symptoms are subjective changes such as headache
❖Severe imbalance
•Death
Unit of human body
All organ functions of the body help
maintain the homeostatic conditions
•Human
•Organs
•Tissues
•Cells
-
Basic cell functions
- Transportation
- Performing chemical reactions
- Synthesis protein and other components needed for cell functions growth, and
survival
- Providing structural support for tissue and protecting the body against injury
- Being sensitive and responsive to changes in the surrounding environments
- Reproduction
Nucleus
• Nuclear membrane: outer and inner membranes
• Nucleoplasm
Contains large quantities of DNA, which comprise the genes
(Genes determine the characteristics of the cell’s proteins)
• Nucleolus
An accumulation of large amounts of RNA and proteins
Cytoplasm & Organelles
❖ Cytoplasm
• Filled with both minute and large dispersed particles and organelles
• Cytosol : jelly-like fluid portion that contains mainly dissolved proteins, electrolytes,
and glucose
❖ Organelles
• Endoplasmic reticulum
• Golgi apparatus
• Mitochondria
• Lysosomes
• Peroxisomes
Endoplasmic reticulum (ER)
Rough ER: Ribosomes attach to outer surfaces
• Synthesize new protein molecules in the cell
• Immunoglobulin, enzyme, hormone
Agranular/smooth ER
• Synthesis and secrete steroid hormone
• Cholesterol synthesis and breakdown
• Fat metabolism
• Detoxification of drugs
Golgi apparatus
❖ Composed of 3-20 stacked layers of thin, flat, enclosed vesicles lying near one side of
the nucleus
❖ Golgi apparatus functions in association with the ER → add carbohydrate ex.
glycoprotein, glycolipid
❖ Cis face near ER
→ fused together with transport vesicles from RER
❖ Trans face
→ newly forming vesicle and secretion
Lysosomes
❖ Vesicular organelles formed by breaking off from the Golgi apparatus
❖ Composed of various hydrolytic enzymes, are produced by RER
❖ Allow cell to digest
- macromolecules
- damaged organelle (autophagy)
- unwanted matter ex. bacteria
Peroxisomes
❖ Differ from lysosomes in 2 important ways
-Peroxisomes bud off from the ER and Self-replicating by dividing
-Contain oxidases → form hydrogen peroxidase
❖ Major function
-Catabolize long chain fatty acids
-Detoxification → detoxifies alcohol
-Degradation of purine to uric acid
-Participate in the formation of amine and bile salts
Mitochondria “ Powerhouses”
❖ 2 lipid bilayer– protein membranes
➢ Outer membrane
➢ Inner membrane : cristae
- Oxidative enzymes are attached at cristae
- Synthesize a “high-energy” substance
Adenosine triphosphate (ATP)
Cytoskeleton
❖ Originate as fibrillar protein molecules synthesized by ribosomes
❑ Tubules → microtubule
❑ Filaments → actin and myosin filaments
❑ Intermediate filament
❖ Functions of cytoskeleton
- Providing rigid physical structures
-Determining cell shape
-Participating in cell division
-Cells movement
-Trafficking of organelles
Cell membrane
• Thin and elastic structure (7.5-10 nm)
• Semipermeable membrane
• Composed of proteins, lipids, and carbohydrates
• 55% proteins: integral and peripheral protein
• 25% phospholipids
• 13% cholesterol
• 4% other lipids
• 3% carbohydrates: glycoprotein, glycolipid, proteoglycans
Phospholipid bilayer
Structure
Phosphate group (Polar head) >> Hydrophilic
Fatty acid tails (Non-polar) >> Hydrophobic
Arranged as a bilayer
Membrane proteins
Classified depending on type of interaction with bilayer
1. Integral protein
extend into or through the lipid bilayer
2. Peripheral membrane protein
attached to the inner or outer surface of the membrane by non-covalent interactions, do
not extend through it
Membrane carbohydrates “Glycocalyx”
The entire outside surface of the cell often has a loose carbohydrate coat
Integral protein
Protein pores
-Integral cell membrane proteins that form open tubes through the
membrane and are always open
-Diameter of a pore and its electrical charges provide selectivity that permits
only certain molecules
Channels
-Selectively permeable to certain substances
-opened or closed by gates that are regulated by electrical signals or
chemicals
Carrier protein
-Bind with molecules or ions, induced conformational change of protein, then
transport substances through the membrane
Gating of protein channels
Means of controlling ion permeability of the channels
Voltage gating:
responds to the electrical potential across the cell membrane
-Na+ and K+ channels
Chemical (ligand) gating:
opened by the binding of a chemical substance (a ligand) with the protein
-Nicotinic acetylcholine receptors at NMJ
Membrane transport
Endocytosis (Ingestion by the cell):
Phagocytosis “Cell eating”
- Ingestion of large particles ex. bacteria, dead cell
- Pseudopodium
- Fuse with lysosome for digestion
Pinocytosis “Cell drinking”
- Ingestion of minute particles or soluble macromolecules
ex. protein molecules
Receptor-mediated endocytosis
- Triggered by molecular signal, binding to receptor
Exocytosis: moving large molecules out of cell
- Exocytosis
Movement of materials out of a cell via membranous vesicles.
- Transcytosis
Movement of a substance
through a cell as a result of endocytosis on one side and
exocytosis on opposite side.
Membrane transport: Simple diffusion and passive transport
- Kinetic movement of molecules/ions occurs through membrane opening or
intermolecular spaces without any interaction with carrier proteins
Net diffusion:
❖ Fick’s first law of diffusion
J = -DA (dC/dX)
❖ Simple diffusion: 2 pathways
- Lipid soluble substances: Through lipid bilayer, CO2 O2
- Lipid insoluble substances: Through protein channels
water & other ex. ions
Facilitated transport
- Substance diffuses through the membrane with the help of
a specific carrier protein
- Rate of diffusion approaches a maximum, called Vmax
-Glucose transporter (GLUT)
-Amino acid transporter
Carrier-mediated transport
-Saturation
-Stereospecificity
-Competition/Inhibition
Osmosis: Net diffusion of water
- Osmosis: the diffusion of water through a semi-permeable membranefrom a region of lower solute concentration (hypo-osmotic solution) to higher (hyper-osmotic solution) solute concentration (concentration difference of water).
Osmotic pressure
❖ The amount of pressure required to stop osmosis
❖ The osmotic pressure difference across the membrane causes water to flow from one solution
to the other solution
Van’t Hoff’s theory
¶ = iRTC
Osmole, Osmolality, and Osmolarity
- Osmole
- The concentration of a solution in terms of numbers of particles
- One osmole is 1 mole of osmotically active solute
- Osmole = n x mole (n=number of mEq of produced particles during solvation)
- Osmolality
- Osmolar concentration expressed as osmoles per kilogram of water
- Normal osmolality of ECF and ICF 300 mOsm/Kg
- Osmolarity
- Osmolar concentration expressed as osmoles per liter of solution
Osmolarity & TonicityOsmolarity
- Hypo-osmotic solution
- Solution with the lower osmolarity
- Iso-osmotic solution
- Two solutions with the same osmolarity
- Hyper-osmotic solution
- Solution with the higher osmolarity
Tonicity
- Hypotonic solution
- Solution with the lower effective osmotic pressure
- Isotonic solution
- Two solutions separated by a semipermeable membrane have the same
effective osmotic pressure
- Hypertonic solution
- Solution with the higher effective osmotic pressure
RBCs as osmometer of body fluid
- Hypertonic
- Isotonic
- Hypotonic
Membrane transport: Primary active transport
❖ Energy is derived directly from breakdown of adenosine triphosphate (ATP) or some other high-energy phosphate compound
❖ Against an electrochemical gradient
- Na+ -K+ ATPase
- Ca++ ATPase
- H+ ATPase
Secondary active transport
- Energy is derived secondarily from energy that has been stored in the form of ionic concentration differences of secondary molecular or ionic substances between the two sides of a cell membrane, created originally by primary active transport
- One of the solutes transports “downhill” and provides energy for the “uphill” transport of the other solutes
Co-transport
- Na+-glucose co-transport
- Na+-amino acid co-transport
Counter-transport
- Na+-Ca++ counter transport
- Na+-H+ counter transport
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