Friday, September 9, 2022

Cells - the most basic unit of life

Tissues - collection of like cells performing a similar task

Organs - multiple tissues working together

Organ system - a group of organs that serve a certain function

Organism - individual life form

Monday, September 12, 2022

The cell: the basic unit of life

• 4 regions: cell membrane, cytoplasm, cell inclusions, cell organelles

Cell disorders

Carcinoma: cancer cells

• Divide until large number of small non-functional cells

• Could be lethal

• Carcinogen: cancer causing agent

Benign tumor: abnormal growth; not cancerous; no metastasis; good tumor compared to mal…

Malignant tumor: cancerous; abnormal growth; undergoes metastasis(spreads); bad tumor

Wednesday, September 14, 2022

Cellular respiration

• Food is broken down to form energy in the form of ATP

• Everything we do requires energy

• Glucose + oxygen ---> carbon dioxide + water

Homeostasis: the maintenance of a stable internal environment

All body systems contribute to homeostasis, especially the endocrine and nervous system

Homeostatic control mechanism: causes an imbalance

1. Stimulus: produces change in variable

2. Receptor: change in variable is recognized or received by the receptor

3. Input: information sent along the afferent pathway to the control center

4. Output: information send along efferent pathway to effector

5. Response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis

Negative feedback mechanisms/loop: acting in opposition to become balance

• Shuts down reaction and counteracts the stimulus

Positive feedback mechanisms/loop: encourage or increase a reaction to become balances

• Speed up or enhances the reaction

Tissues: groups of cells that are similar in structure and function

4 types: epithelial, connective, muscle, and nervous

Tissue repair:

1. Inflammation - release of inflammatory chemicals which spark the blood/redness; capillaries dilate(bigger) which increases permeability(if it can pass through); blood clot begins to form(deep); scab forms(superficial)

2. Organization - clot replaced by granulation tissue(restore vascularity); collagen produced by fibroblasts(fibers); macrophages(large cells eat) clean dead/dying cells; surface epithelium regenerates

3. Regeneration - fibrous tissue reconnects: underlying tissue = scar tissue; epithelial tissue thickens: epithelium = fully regenerated

Factors affecting tissue repair: type of injury, immediate care, blood supply, health and age of organism

Thursday, September 15, 2022

Epithelial tissue: next to open space; “epi” meaning on top of/upon

Structure: closely joined cells; free exposed to air or fluid; attached to basement membrane; supported by underlying connective tissue; innervated but avascular(nerves but no blood in the epithelial tissue)

Function: covers body’s outside; lines organs and cavities; regenerate rapidly; barrier against microbes, injury and fluid loss

Categories of epithelial tissue: by shape or layer

• Squamous: very flat; circular; fried egg

• Cuboidal: cube shape; squares

• Columnar: tall and straight; rectangle

• Simple: 1 layer of cells

• Stratified: 2 or more layers of cells

• Pseudostratified: 1 layer with appearance of multiple; cells vary in length; “pseudo” means fake

Simple squamous: thin and leaky cause of circle and flat; cells function in the exchange of material by diffusion; found in line blood vessels and line air sacs of lungs to pass oxygen right through

Stratified squamous: regenerates rapidly near the basement membrane; new cells at the bottom of the tissue, not top so that newer cells are protected and old cells can be remove rather than newer ones; found in surfaces subject to abrasion or coming in contact with something like the out layer of skin

Simple cuboidal: specialized for secretion; found in kidney tubules, thyroid gland and salivary glands

Stratified cuboidal: rare in the body; found in the mammary glands in breast tissue

Simple columnar: like a water balloon filled with cytoplasm; found where secretion or active absorption is major function; found in intestines(small absorbs nutrients and large absorbs water)

Stratified columnar: protection; secretion; rare in the body; found in the male urethra and pharynx

Exceptions(two):

Transitional epithelium: several cell layers, basal cells are cuboidal, surface cells are dome shaped; stretched to permit the distention of; lines the bladder, ureters, and part of the urethra

Pseudostratified columnar: similar to stratified columnar; only 1 cell layer thick, but appears to be multiple layers; line nasal passages of many vertebrates

Monday/Tuesday, September 19/20, 2022

Connective tissue:

Structure: properties are determined by relative amounts of cells, extracellular matrix(ground substance/fluid and fibers), and vascularity varies(if there's blood present or not)

Function: connect/binding and support, protection, insulation(adipose), transportation(literal blood)

Structural elements: cells, fibers, and ground substances(every tissue does not have the same combination of all these)

• Cells: fibroblast/fibrocyte(fibrous material); osteoblast/osteocyte(bone); chondroblast/chondrocyte(cartilage); hemoblast/hemocyte(blood); macrophage/mast cell(white blood cells)

• Fibers: collagen(tough, strong fibers); elastic(long, thin stretchy fibers); reticular(branched delicate networks)

• Ground substance: interstitial(tissue) fluid; varying thickness

Loose areolar: fills all the spaces that seems empty; under any epithelial tissue; looks like lines

• Properties: gel-like matrix with all fiber types; cells include fibroblasts, macrophages, mast cells, white blood cells

• Functions: wraps and cushion organs; macrophages phagocytize bacteria and help with inflammation; holds tissue fluid

• Locations: under epithelia, lines mucus membrane; surrounds capillaries and organs

Adipose: hold onto fat; nucleus shoved to side due to fat taking up all the space

• Properties: sparse matrix; closely packed fat cells; nuclei pushed to side

• Functions: reserve fuel; insulation; support/protect organs

• Locations: under skin; around kidneys and eyeballs; within abdomen; forms breast tissue

Reticular: arms/branches out; branch-y networks

• Properties: network of fibers with cells; loose ground substance

• Functions: internal skeleton that supports other cell types(WBC, mast cells, macrophages)

• Locations: lymphoid organs; lymph nodes; bone marrow; spleen

Fibrous/Dense regular: looks like little waves of fibers

• Properties: parallel collagen fibers; few elastin fibers

• Functions: attach muscles to bone or other muscles; resistant to pulling

• Locations: tendons; ligaments; aponeuroses(what connects muscle to muscle)

Dense irregular: similar to regular but not in parallel lines

• Properties: irregular arranged collagen fibers; some elastic fibers

• Functions: withstand tension in many directions; structural strength

• Locations: dermis of skin; submucosa of digestive tract; capsules of organs and joints

Hyaline cartilage: tough; all over and around your bones; looks like swiss cheese

• Properties: no defined shape; firm matrix; collagen fiber network

• Functions: support, reinforce, cushions; resist compression

• Locations: embryonic skeleton; ends of bones; costal cartilage of ribs; nose, trachea

Elastic cartilage: hard-ish with lines; more “nasty” swiss cheese

• Properties: similar to hyaline but with more elastic fibers;

• Functions: maintains shape/structure; flexibility

• Locations: external; epiglottis

Fibrocartilage: somewhat parallel line with cells

• Properties: matrix like hyaline cartilage; mostly thick collagen

• Functions: resists tension; absorb compressive shock

• Locations: intervertebral discs; pubic symphysis; discs of knee joints

Bone: actually looks like swiss cheese; looks like tree trunks;

• Properties: hard calcified matrix; lost of collagen fibers; vascularized

• Functions: support and protect; hematopoiesis

• Locations: bones

Blood: only fluid tissue in the body; looks like vessels really zoomed out; purple dots are white blood cells and pink dots are red blood cells

• Properties: red and white blood cells; plasma(fluid matrix)

• Functions: transport gasses, nutrients, waste, and other substances

• Locations: blood vessels

Wednesday, September 21, 2022

Muscular tissue:

Structure: closely packed cells with contractile proteins; fed by many blood vessels; more tissue in you body is muscle than any other tissue; more muscle tissue in most animals than any other tissue

Functions: movement; temperature regulation

Skeletal muscle: long cylinder cells with multiple nuclei; long straight tube with stripes

• Properties: long, cylindrical multinucleate cells with obvious striations

• Functions: initiates and controls voluntary movement

• Locations: muscles that attach to bones or skin

Cardiac muscle: dark lines are the discs; branches; also striated/stripes

• Properties: branching, striated, uninucleate cells interlocking at intercalated discs

• Functions: propels blood into circulation; involuntary

• Locations: walls of the heart

Smooth muscle: not striated/striped; semi circle shape; thin lines that are pinched off at the end

• Properties: sheets of spindle-shaped cells with central nuclei that have no striations

• Functions: propels substances along internal passageways; involuntary

• Locations: walls of hollow organs

Nervous tissue: long strings spreading out from cytoplasm; looks like roots/ splat of paint

Structure: neurons and support cells; found in the brain, spinal cord, and peripheral nerves

Functions: sense stimuli; transmits electrical signals; regulates and controls body functions