Bith-eòlas (Lec 1)

Physiology: The study of how organs perform their vital functions. An example is the study of how a muscle contracts.
Human Body Organisation:
- Molecular Level: Atoms interact to form compounds.
- Cells: The smallest living units.
- Tissues: Groups of cells working together (e.g., muscle tissue, nervous tissue).
- Organs: Different types of tissues that perform specific functions (e.g., lungs, heart).
- Systems: Groups of organs working together to perform specific functions.
- Organism: The total of all systems working together.

Monosaccharides: Simple sugars:
- Glucose
- Fructose
- Galactose
Disaccharides: Two monosaccharides joined together:
- Maltose
- Sucrose
- Lactose
Polysaccharides: Many monosaccharides joined together:
- Starch
- Glycogen
- Cellulose

Composition: Made of carbon, hydrogen, oxygen, and nitrogen.
Functions:
- Source of energy
- Building material
- Components of structures like nails and skin
- Formation of enzymes and antibodies.
Structure: Chains of amino acids joined by peptide bonds.
Amino Acids:
- Essential: Must be obtained from food (e.g., alanine, arginine, cystine).
- Non-essential: Can be made by the body (e.g., lysine, methionine).

Composition: Fatty acids and glycerol joined by ester bonds.
Functions:
- Structural components of cell membranes
- Myelin sheath of neurons
- Sources of energy and hormones.

Vitamins:
- Fat-soluble: A, D, E, K
- Water-soluble: C, B vitamins (B1, B2, B6, etc.) and folic acid
Minerals: Inorganic substances; examples include sodium, potassium, magnesium, calcium.

Enzymes: Proteins that catalyze (speed up) metabolic reactions in cells, made of amino acids linked together.
Enzyme Function:
- Increase the rate of reactions.
- Catalyzing metabolic reactions of cells (e.g., respiration, photosynthesis, digestion).
- May act as transport proteins and receptors.
Enzymes Structure:
- Apoenzyme: The protein part of an enzyme.
- Holoenzyme: The complete enzyme with its cofactor.
- Active site: The region on an enzyme that binds to a substrate.
How enzymes work:
- Chemical reaction: Substrate binds to the active site.
- Geometric changes form an enzyme-substrate complex, the reaction happens and the products are released.

Temperature: Enzymes work best at a specific temperature (around 37°C for humans). Above or below this optimum, the rate of reactions decreases.
pH: Most enzymes function best in a specific pH range (around 7-8 for many). Extreme pH can denature (cause a change in shape) which can alter the enzyme and reduce activity.

Enzyme Concentration: Increasing the enzyme concentration increases the reaction rate.
Substrate Concentration: Increasing the substrate concentration increases the rate until all enzyme active sites are occupied.
Inhibitors: Substances that slow down or stop enzyme activity.
Specificity of Enzymes:
- Absolute specificity: Enzyme only catalyzes one specific reaction.
- Group specificity: Enzyme acts on molecules with specific functional groups.
- Linkage specificity: Enzymes acts on specific chemical bonds.
- Stereo Specificity: Enzymes act on specific isomers.

Main Organs:
- Mouth: Grinds and breaks down food
- Pharynx: Passageway for digestive and respiratory tracts.
- Oesophagus: Transports food and liquids to stomach via peristalsis (muscle contractions).
- Stomach: Mixes food with enzymes and acids.
- Small intestine: Major site of digestion and absorption of nutrients (carbohydrates, proteins, and lipids)
- Colon and rectum: Absorbing water and transporting waste.

Teeth: Grind and break down food
Tongue: Rolls food into a ball.
Salivary glands: Produce saliva.
Gallbladder: Stores bile.
Liver: Produces bile and is involved in metabolism.
Pancreas: Produces enzymes (e.g., insulin, glucagon) and other essential hormones.

Cells:
- Neurons: Transmit signals.
- Glial cells: Support neurons
Types of Nervous Systems:
- Central NS: Brain and spinal cord
- Peripheral NS: Nerves that carry information to and from the CNS.
  - Somatic NS: Controls voluntary movements
  - Autonomic NS: Controls involuntary functions
    - Parasympathetic NS: Rest and digestive system
    - Sympathetic NS: Fight or flight response
Types of Neurons:
- Sensory neurons: Receive stimuli from tissues
- Motor neurons: Transmit signals from the CNS to organs and tissues
- Interneurons: Link between sensory and motor neurons.

Histology: Study of tissues and how they form organs.
Tissues: Groups of cells with a common function organized in a specific pattern.
Epithelial Tissue: Covers surfaces or lines cavities; composed of tightly packed cells, supports underlying structures and is avascular (not penetrated by blood vessels)
- Cells lying on a basement membrane.
- Not directly attached to other cells (in a layer).
- Nourished and supported by cells of the connective tissue.
- Rich in nerve supply.

Covering and lining epithelium: Types include:
- Simple squamous epithelium: Found in blood vessel walls, a single layer of flat cells with a central nucleus.
- Simple cuboidal epithelium: Forms tubules that secrete, absorb or excrete substances.
- Simple columnar epithelium: Found in the digestive tract with goblet cells to secrete mucus.
  - Ciliated: With hair-like structures.
- Stratified epithelium: Multiple layers of cells; includes squamous (with keratinized [hardened skin] and non-keratinized [soft, lining body cavities] ) varieties and others. Important for protection and secretion.

Glandular epithelium: Secretion and formation of specialized tissue structures.
- Unicellular glands: Single cell glands, like goblet cells (in digestive system).
- Multicellular glands: Groups of cells that produce secretions.
Types include:
- Exocrine: Secretion released through a duct.
- Endocrine: Secretion released directly into the bloodstream.
- Mixed: Secrete both internally and externally.
Specialized epithelial types: such as neuroepithelium and germinal epithelium.