SBI241 - Week 1 .docx

Cell Biology **Plasma membrane --** Phospholipids main structure - Acts a barrier separating inside and outside of the cell - Controls the flow of substances in and out of the cell - Helps identify the cell to other cells and participates in intercellular signalling **Membrane Transpo...

Cell Biology **Plasma membrane --** Phospholipids main structure - Acts a barrier separating inside and outside of the cell - Controls the flow of substances in and out of the cell - Helps identify the cell to other cells and participates in intercellular signalling **Membrane Transport** *[Passive transport]* -- Does not require energy\* [Simple diffusion] -- Movement of solutes from an area of high concentration to low concentration. High -\> Low [Facilitated diffusion] -- Down the concentration gradient and 'facilitated' by integral proteins (carriers and channels) [Osmosis] -- Water travels through a selective permeable membrane so that concentrations of a solute are the same on both sides of the membrane, crucial for normal fluid balance [Filtration] -- Pressure pushes water and solutes against cell membrane **Active transport** [ ] -- requires energy *[Active transport carriers (pumps)]* - Can transport molecules against the concentration gradient - It is a sodium-potassium pump *[Transport by vesicle formation]* - Endocytosis Pinocytosis Phagocytosis - Exocytosis **Cytoplasm** - Is a ground substance/matrix in which various cellular components are found - 75-90% water plus solid compounds, mainly carbohydrates, lipids and inorganic substances and it is the substance in which chemical reactions occur. **Nucleus -** Brain of the Cell as it contains DNA **Cell division** - Ages and dies. Remaining cells divide to replace the cells which are lost. Occurs through a process call *[mitosis]* -- a cell passes through an ordered series of events in which the cell duplicates its contents and divides into two cells - *[Meiosis]* -- type of cell division which occurs in sexual organs, testes and ovaries & leads to formation of gametes. **[Mitosis]** -- Only last for roughly 1 hr on a 24 hour time span *[4 phases/stages]* - Prophase - Metaphase - Anaphase - Telophase Before and after it has divided, the cell enters a stage -- Interphase (G1, S and G2 sub-phase) - Extra organelles are manufactured by the replication of existing organelles, DNA also goes through replication. - Cell build-up of store energy that is required for cell division. **[Meiosis]** -- Has 8 stages = 2 cycles of cell division - *[Human cells]* = 23 pairs of chromosomes (22 pairs of autosomes + 1 set of sex chromosomes) - *[Reproduction]* = Ovum is penetrated by sperm, DNA copy from both parents is combined, ensuring that the resulting zygote has the correct amount of DNA. Egg and sperm undergo meiosis to ensure that they only contain one copy of chromosomes  **[Endoplasmic Reticulum]** -- found around the nucleus - Membranous network attached to Nuclear membrane - Site of protein synthesis, smooth and rough endoplasmic reticulum **[Ribosome]** -- site of protein synthesis - Made of RNA and protein - Produces proteins from genetic material - *[Free ribosomes]* -- Floating in the cytoplasm - *[Attached ribosomes]* -- Bound to the endoplasmic reticulum **[Golgi Apparatus]** - Network of flattened, smooth membranes - Packages proteins from the endoplasmic reticulum into secretory vesicles - Vesicles transport proteins to other organelles or releases them from the cell RNA carries DNA information. **[Lysosomes]** - Storage vesicles containing enzymes - Break down old organelles and digest foreign substance - Plays a role in [apoptosis] **[Peroxisomes]** - Similar structure to lysosomes, only smaller - Detoxification of harmful substances and neutralises dangerous free radicals. **Mitochondria** - Powerhouse of cell, surrounded by double lipid bilayer membrane - Participate in oxidative phosphorylation and ATP production - Contains own RNA, DNA and ribosomes - ATP = stores and transfers energy **[Cellular metabolism]** [Anabolism] -- energy using uses energy to construct. [Catabolism] -- energy releasing deconstructing, releases energy. [Cytoskeleton] -- Maintains cell's shape and internal organisation and permits movement of substances within the cell. **Cellular respiration** 1. Aerobic -- with oxygen. 2. Anaerobic -- lack of oxygen, unsustainable for a long period of time. **Types of Tissues** **Basic tissue types** 1. Connective tissue 2. Epithelial tissue 3. Muscle tissue 4. Nervous tissue **Epithelial** - Diverse group of tissue that include both surface epithelia and solid organs - Functions are: - Forming a protective barrier - Regulation of the exchange molecules between compartments (selective diffusion and absorption) - Synthesis and secretion of glandular products **Connective tissues** - Tissues that provide general structure, mechanical strength, space filling, physical and metabolic support for specialised tissues. - Three structural properties with corresponding construction materials: - Tensile strength - Elasticity - Volume i.e. bulk/substance **Specialised connective tissue: Bone & cartilage** - Bone is made up of collagen and a cellular matrix with cells that synthesise them. Provides a rigid protective and supporting framework resulting from the deposition of calcium salts within the collagen and matrix - Cartilage occurs in different forms and provides a smooth articular surface at bone ends as well as structural support in special area i.e. trachea and pinna. **Muscle** - Specialised contractile cells that generate force through contraction - Movement is generated by interaction of proteins actin and myosin. - Muscle cells can be divided into [3 types:] - Skeletal muscle -- Attached to bones, involved in movement of skeleton. Can be contracted voluntarily, controlled by somatic nervous system - Smooth muscle -- visceral muscle, found in internal viscera. Under controlled by autonomic nervous system. - Cardiac muscle -- found in the heart, striated muscle. **Nervous Tissues** - Provides rapid and precise communication between different parts of the body via the action of specialised nerve cells called neurons = they are interconnected and function together and process information and then generates appropriate response signals - Main parts of Nervous system: - Central Nervous system (CNS) -- Brain and spinal cord - Peripheral Nervous system (PNS) -- Nerves which run between the CNS and other tissues. \*Inflammation is the body's immediate reaction to tissue injury or damage, because when tissue injury or damage occurs, this stimulates the body's inflammatory and immune response spring into action to promote the healing process and to start immediately. \* **Homeostasis** - Ability of physiological systems to maintain conditions within the body in a constant state. Maintain the organism's internal environment within tolerance limits and to provide a stable environment for cells to carry out normal functions. - Goal of homeostasis is to maintain the internal environment at/or near a set point. **Vital Signs as a measure of homeostasis** - Resp rate, depth and rhythm, oxygen saturation, pulse rate and rhythm, blood volume and pressure, and temperature are regarded as essential part of monitoring patients. - Changes in vital signs = homeostatic imbalance.