Tissue types - Intro to integument - Layers of the skin

get ready to memorize a bunch of random shit!

epithelial tissue

general meaning

large sheets of cells that cover interior and exterior surfaces

interior: blood vessels, external surfaces of internal organs

external: skin, respiratory tract, digestive tract, urinary system, reproductive system

epithelial tissue > internal surfaces

never gonna encounter something outside the body

blood vessels, external surfaces of internal organs

epithelial tissue > external surfaces

skin, respiratory tract (cilia), digestive tract, urinary system, reproductive system

epithelial tissue function

provide protection from wear and tear (e.g., skin, serous membranes)

protection from external threats (e.g., respiratory epithelium)

control of materials across barriers (e.g., absorption in digestive tract, alveolar tissue absorbs O2)

secretion of chemical compounds (e.g., digestive enzymes - acidic breaks things down)

simple squamous epithelium location and function

air sacs of lungs and the lining of the heart, blood vessels, and lymphatic vessels

THIN = Allow materials to pass thru by diffution and iltration, and secretes lubricating substance

simple cuboidal epithelium location and function

in ducts and secretory portions of small glands and in kidney tubules

secretes and absorbs

simple columnar epithelium location and function

ciliated tissues are in larger bronchioles, uterine tubes, and uterus;

smooth (non ciliated) are in the digestive tract, bladder

absorbs; it also secretes mucus and enzymes

Pseudostratified columnar epithelium location and function

ciliated tissue lines the bronchi, trachea, and much of the upper respiratory tract

secretes mucus; ciliated tissue moves mucus

stratified squamous epithelium location and function

lines the esophagus, mouth, and vagina

protects against abrasion 😏😏

stratified cuboidal epithelium location and function

sweat glands, salivary glands, and the mammary glands

protective tissue

stratified columnar epithelium location and function

the male & female urethra and the ducts of some glands

secretes and protects

transitional epithelium location and function

lines the bladder, urethra, and the ureters

allows the urinary organs to expands and stretch

what are glands

structure made of one or more cells that synthesize and secrete chemical substances

endocrine

secretes directly into surrounding tissues/fluids, picked up by whatever is nearby, usually blood

NO ducts

exocrine

secretes to the external environment via ducts (indirectly or directly)

merocrine secretion

apocrine secretion

holocrine secretion

merocrine secretion

secretions are enclosed in vesicles that move to the apical surface of the cell where the contents are released by exocytosis.

apocrine secretion

portion of the cell and its secretory contents pinch off from the cell and are released.

holocrine secretion

cell does not regrow (a new cell grows in its place)

faster release

connective tissue function

support and connect other tissues (bones, tendons)

protection (fibrous capsules around more delicate structures)

transport of materials (blood, lymph)

storage of energy (fat cells)

all connective tissues are ____ dispersed in ____

cells dispersed in a extracellular matrix

extracellular matrix is made of…

ground substance - major component, can be fluid or solid

protein fibers - rigid proteins that contribute structural strength to the tissue

ground substance

stuff in the ECM that is not protein fibers

rigid ground substance in bones

protein fibers

rigid proteins that contribute structural strength to the tissue

wtf is connective tissue proper

support, attachment and protection of structures; immune functions.

common cells:

fibroblasts - most common, produce the EC matrix

adipocytes - fatass cells for energy storage (store lipids)

macrophages - immune cells, help destroy infectious agents “big eater”

2 subtypes": loose and dense connective tissue

fibroblasts

fibroblasts - most common, produce the EC matrix

connective tissue proper → loose connective tissue

commonly found btwn organs,

absorb shock and bind tissues together

adipose tissue

reticular tissue

areolar tissue

loose connective tissue→adipose tissue

fatass storage cells, very little ECM

loose connective tissue→reticular tissue

mesh like framework for soft organs

(lymphatic tissue, spleen, liver)

require having stuff moved thru them.

supports developing blood cells

loose connective tissue→areolar tissue

broad group of tissues underlying most epithelia

between muscle fibers, surrounds blood and lymph vessels,

glue that holds epithelium to the organs

dense connective tissue

higher abundance of collagen fibers in the matrix than loose connective tissue. greater resistance to stretching

ex: ligaments and tendons - connections btwn structures that experience extreme strain

supportive connective tissue

maintains body posture/position, protects internal organs

2 types! cartilage and bone

cartilage

chondrocytes within matrix. they produce cartilage within lacunae.

cartilage matrix is avascular - nutrients must diffuse through matrix to reach chondrocytes = heal very slowly

types of cartilage:

hyaline - strong and flexible; most common (rib cage, nose, joints between bones)

fibrocartilage – strongest (meniscus in the knee, intervetrbral discs)

elastic – most flexible (ear)

hyaline cartilage

hyaline - strong and flexible; most common (rib cage, nose, joints between bones)

fibrocartilage

strongest (meniscus in the knee, intervetrbral discs)

elastic cartilage

most flexible (ear)

bone

osteocytes – bone cells within lacunae

bone matrix is vascular – blood carries nutrients to osteocytes – bone heals quickly

ridgid ECM contains collagen fibers (protein fibers for flexibility) within hydroxyapatite (ground substance for rigidity)

bone matrix has……

collagen fibers (protein fibers for flexibility)
within
hydroxyapatite (ground substance for rigidity)

fluid connective tissue

carry materials throughout the body

blood and lymph

blood contains…

erythrocytes - red blood cells, carry oxygen and carbon dioxide

leukocytes - white blood cells, immune response

muscle tissue

allows mobility of body parts.

excitation of myocytes (muscle cells) cause muscles to

contract or relax!

skeletal – voluntary movement, most common

cardiac – involuntary, forms the heart

smooth – involuntary movements of internal organs

three types of muscle tissue

skeletal – voluntary movement, most common

cardiac – involuntary, forms the heart

smooth – involuntary movements of internal organs

nervous tissue

allows transmission and processing of information about the internal and external environments AKA sends signals thruout the body

cell types: neurons and neuroglia

neurons

have 3 major components:

cell body – contains most organelles

dendrite(s) – receives signals from other cells

axon – sends signals to other cells

(in some neurons the dendrite and neuron have the same structure)

synapse

junction btwn 2 neurons

functions of the integumentary system

protection

sensation

thermoregulation

vitamin D synthesis

merkel cells

sensory touch sensor in the stratum basale of the epidermis.

only sensory cell in the epidermis

How does skin protecc

protect against:
physical damage

corrosive chemicals

UV radiation

How is vitamin D synth good

crucial to the formation of many types of white blood cells + essential for absorption of calcium and phosphorous

what is rickets

misshapen bones in children due to lack of calcium resulting from insufficient vitamin D

true skin is made of

epidermis + dermis

hypodermis

aka subcutaneous tissue

aka superficial fascia

thick skin layers and location

has five epidermal layers, only on palms of hands and soles of feet

thin skin layers and location

has four epidermal layers, everywhere else in the body

layers of the epidermis from top to bottom

Stratum corneum

lucidum !!

granulosum

spinosum

basale

(come lets get sun burned)

layers of the epidermis from top to bottom (minimal)

corneum

lucidum !!

granulosum

spinosum

basale

keratin

intracellular fibrous proteins that give structures hardness and water resistance

keratinocytes

cells that produce keratin