Anatomy: Homeostasis, Skeleton & Anatomical Terms

• Homeostasis refers to the process where living organisms maintain a stable internal environment.
• This stability represents the optimal condition for an organism to function efficiently.
• Positive feedback loops amplify changes, leading to the completion of a process.
• Negative feedback loops counteract changes, thereby maintaining homeostasis.

Anatomical Terms

• Superior: Above.
• Inferior: Below.
• Anterior: Front of the body.
• Posterior: Back of the body.
• Proximal: Closer to the point of attachment.
• Distal: Further from the point of attachment.

Skeletal Components

• Axial Skeleton: Composed of the skull, vertebrae, ribs, and sternum.
• Appendicular Skeleton: Includes the arms, legs, and hips.

Anatomical Planes

• Transverse planes divide the body into upper and lower halves.

Ribosomes

• Ribosomes function as micro-machines to create proteins.

Tissue Characteristics

• Skeletal tissue is found in the skeleton, is striated, voluntary, and multi-nucleated.
• Smooth tissue is found in hollow organ walls, is non-striated, involuntary, and has one nucleus.
• Cardiac tissue is found in the heart, is branched, involuntary, and has one nucleus

Connective Tissues

• Types include blood, cartilage, connective tissue proper, and bone.

Burns

• 1st-degree burns affect only the epidermis.
• 2nd-degree burns affect the epidermis and dermis.
• 3rd-degree burns affect all skin layers, including fat and muscle.

Skin Layers

• The epidermis is the only skin layer directly exposed to the environment.
• The dermis is the thickest skin layer and provides structural support.
• The hypodermis (subcutaneous layer) stores fat and provides insulation.

Bone Marrow

• Red bone marrow appears red due to its rich blood supply.
• Yellow bone marrow appears yellow due to its high fat concentration.
• Hematopoiesis (blood cell production) occurs in red bone marrow.

Bone Cells

• Osteoblasts form new bone and heal existing bone.
• Osteocytes maintain bone structure by regulating mineral concentration.
• Osteoclasts resorb or break down bone to increase calcium levels.

Bone Classification by Shape

• Long bones are long, thin, and cylindrical.
• Flat bones are flattened and broad, often curved.
• Short bones are squat, cubed, and have roughly equal dimensions.
• Irregular bones have complex shapes that don't fit other categories.
• The hyoid bone serves as an attachment structure for the tongue and muscles.

Cellular Processes

• Sodium ions enter a cell during depolarization.
• Repolarization involves closing sodium ion channels and opening potassium ion channels, causing potassium ions to exit the cell.
• Depolarization is when the opening of sodium ion channels causes a rapid rise in membrane potential.
• Hyperpolarization is when the membrane potential dips below the resting voltage.

Muscle Contraction

• Acetylcholine's primary role in muscle contraction occurs at the axon terminal of a motor neuron at the neuromuscular junction.
• The sarcoplasmic reticulum stores and releases calcium ions.
• Muscle contraction or relaxation occurs when calcium ions are released.

Muscle Fiber Components

• Sarcomere: The primary site of muscle contraction where the sliding filament mechanism occurs.
• Myofibril: A long, cylindrical organelle within a muscle fiber that generates force.
• Myofilaments: Protein filaments within a sarcomere that interact through cross-bridges to produce muscle contraction.
• Muscle fiber: A single muscle cell containing multiple myofibrils, surrounded by a sarcolemma (cell membrane).

Cell Structure

• Nucleus: The control center of the cell, contains DNA.
• Smooth ER: Interconnected membrane tubules lacking ribosomes.
• Mitochondria: The "powerhouse" of the cell, generates energy in the form of ATP through cellular respiration.

Levels of Organization

• Atom: The basic building block of matter.
• Molecule: A group of atoms bonded together.
• Organelle: A specialized structure within a cell with a specific function.
• Cell: The basic unit of life, made up of organelles.
• Tissue: A group of similar cells working together to perform a specific function.
• Organ: A structure composed of multiple tissues working together to perform a specific function.
• Organ System: A group of organs working together to perform a broader function in the body.
• Organism: A single living individual.
• Population: A group of individuals of the same species living in a particular area.
• Community: A collection of different populations interacting in a given area.
• Ecosystem: A community of living organisms interacting with their physical environment.
• Biosphere: The entire part of the Earth that supports life, including all ecosystems.

Skin Cells

• Melanocytes produce melanin, the pigment responsible for skin color and UV protection.
• Keratinocytes produce keratin, which forms the majority of the skin's structure.
• Epithelial cells line outer surfaces of the body, including the skin, and serve as a protective barrier.

Osmosis

• Osmosis is the movement of a solvent to equalize solute concentrations on both sides of a membrane.

Tissue Functions

• Epithelial tissue functions include protection, secretion, and absorption, and is typically found lining body cavities and covering external surfaces.
• Nervous tissue transmits electrical impulses and coordinates bodily functions.
• Muscle tissue is specialized for contraction, allowing movement.
• Connective tissue provides support and binds other tissues together.

Bones of the Skull

• Cranium: Includes the frontal bone, occipital bone, parietal bones, sphenoid bone, ethmoid bone, and temporal bones.
• Facial Bones: Include the mandible, maxilla, vomer, zygomatic, lacrimal, nasal, palatine, and inferior nasal concha.

Skin Cell Production

• The stratum basale is the skin layer primarily responsible for producing new skin cells .

Connective Tissue Coverings

• Epimysium covers the "whole muscle".
• Perimysium covers the "bundle".
• Endomysium covers the "fiber".

Explore homeostasis, the process of maintaining a stable internal environment in living organisms. Understand anatomical terms like superior/inferior and anterior/posterior. Learn about the axial and appendicular skeleton components, transverse planes, and the function of ribosomes in protein creation.