The Human Body By: Sebastián Hernández Pérez
Levels of Organization
Tissue: Group of structurally and functionally similar cells and their intercellular material.
Organs: A group of tissues in a living organism that have been adapted to perform a specific function.
Systems: A group of tissues in a living organism that have been adapted to perform a specific function.
Cells: The basic unit of life.
Integumentary System Functions
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Covers and protects the body.
Temperature regulation / sensing
Vitamin production
Main Organ: Skin
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Epithelial tissue: Covers body surfaces.
Connective tissue: Provides support and protection.
Muscle tissue: Involved in body movement.
Nerve tissue: Forms the body's communication network.
Layer of the skin
Epidermis: Made up of epithelial cells (keratinocytes).
Contains keratin & melanin.
Dermis: Consists of connective tissue, nerve cells, muscle fibers, sweat glands, oil glands, and hair follicles.
Subcutaneous Layer: Layer of connective tissue that stores fat and helps the body retain heat.
The body would be subject to invasion by microbes through breaks in the skin.
Types of burns
First-degree: Cells in the epidermis injured.
Second-degree: Damage in epidermis and dermis
Third-degree: Nerve cells and muscle cells injured. Skin function lost.
Melanoma / Nonmelanoma
Cuts and scrapes
Effects of the Sun and burns
Skin cancer
Stages of Regenerative Process.
Hemostasis:Skin’s response to the lose of blood and to the fact that the epidermis barrier has been compromised.
Inflammation: In this stage the body sends special cells to fight any pathogens that may have gotten through.
Proliferative stage: Happens when fibroblast cells begin to enter the wound.
Remodeling: The wound matures as the newly deposited collagen is rearranged and converted into specific types.
Vasoconstriction
It is the process in which blood vessels tighten to minimize the bleeding
Phagocytosis
The process by which white blood cells devour bacteria and damage tissue.
Vasodilation
It is the process in which the previously constricted vessels expand.
Skin cells are connected by a process of collagen deposition.
ECM
Made of structural proteins like collagen secreted by specialized fibroblast cells.
Allows the transportation of nutrients, cell to cell communication and cell adhesion.
Skin Healing Process
The skin receives a cut that bleeds.
Blood flows out of the wound and a clot forms.
A scab forms on the skin to close the wound.
Cells beneath the scab multiply and fill the wound, and white blood cells move in to fight infection.
Fibrosis
The presence of excessive fibrous connective tissue in an organ.
Sunscreen
Its purpose is to shield our body against UV rays.
Types of sunscreens
Chemical: Chemical blockers absorb the sun’s rays.
UV Rays
Effects of UV Rays are: Sunburns, aging, and skin cancer promotion.
They are separated by their wavelengths as UVB and UVA.
SPF: Sunburn protection factor.
Muscle tissue:
Cardiac
Smooth
Skeletal
Muscle Fibers
Slow-twitch muscle fibers support long distance endurance activities like marathon running
Fast-twitch muscle fibers support quick, powerful movements such as sprinting or weightlifting.
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Smooth muscle: Muscle tissue in which the contractile fibrils are not highly ordered, occurring in the gut and other internal organs and not under voluntary control.
Involuntary muscle: Muscles that do not move or contract under the conscious control of a person.
Cardiac muscle: Is a specialized type of muscle tissue that forms the heart which performs highly coordinated actions that keep the heart pumping and blood circulating throughout the body.
Skeletal muscle: A muscle which is connected to the skeleton to form part of the mechanical system which moves the limbs and other parts of the body.
Voluntary muscle: muscle (such as most striated muscle) under voluntary control.
Tendon: connective tissues that transmit the mechanical force of muscle contraction to the bones.
Myofibril: Very fine contractile fibres, groups of which extend in parallel columns along the length of striated muscle fibres.
Involuntary muscle cannot be controlled consciously
Skeletal muscles are voluntary muscles that cause movement.
Tendon: Connects muscles to bones.
Sarcomere:
Basic contractile unit of muscle fiber. Each sarcomere is composed of two main protein filaments "actin and myosin"which are the active structures responsible for muscular contraction.
Skeletal System.
Bones are classified as long, short, flat or irregular.
Bone is a connective tissue.
Functions
Support
Protection
Formation of blood cells
Reservoir
Movement
Joints: where two or more bones meet. They are classified according to movement and shape.
Ligament: tough bands of connective tissue that attach one bone to another.
Formation of Bone
During fetal development, cells in fetal cartilage develop into bone-forming cells called osteoblasts.
The formation of bone from osteoblasts is called ossification.
Remodeling of Bone
Cells called osteoclasts break down bone cells, which are replaced by new bone tissue.
Osteoblasts form a callus made of spongy bone that surrounds the fracture.
Osteoclasts remove the spongy bone while osteoblasts produce stronger, compact bone.