chem chap. 2 (tissues)

what is epithelial tissue?

the lining tissue that forms the boundary between our body and the external environment

epithelial tissue functions

protection, absorption, filtration, and secretion

what is the top surface of epithelial tissue called?

the free surface or apical surface

what is the bottom surface of epithelial tissue called?

basal surface

what is the membrane underneath the basal surface called?

basement membrane

what are all epithelial tissues?

avascular or have no blood cells (a- = without)

how are epithelial tissues classified?

by the number of layers and the shapes of the cells

what is the difference between simple and stratified epithelial tissues?

simple have only one layer of cells, while stratified tissue have more than one layer

simple squamous epithelium

this is a single, flat layer of cells that is thin and permeable

simple squamous epithelium function and location

function: rapid diffusion of materials

location: blood vessels and lung tissue

simple cuboidal epithelium

this is a single layer of cubed-shaped cells

simple cuboidal epithelium function and location

function: secretion and absorption of substances

location: in tissues of the kidney

simple columnar epithelium

this is a single layer of tall, closely packed cells. these cells may have cilia and goblet cells, which secrete mucus

simple columnar epithelium function and location

function: secretion of mucus for protection and absorption of substances

location: lining of digestive system

stratified squamous epithelium

these thick layers provide protection for the underlying layers

stratified squamous epithelium location

epidermal layer of skin

stratified cuboidal epithelium

more than one layer of cuboidal cells, rare in the body

stratified cuboidal epithelium location

salivary and mammary glands

stratified columnar epithelium

free surface is lined with columnar cells, rare in the body

stratified columnar epithelium location

your larynx and the male urethra

pseudo-stratified epithelium

in this, cell nuclei are found at different levels, so it appears stratified, though it is not

pseudo-stratified epithelium function and location

function: secretion and absorption

location: most of upper respiratory tract

how are the free surface cells of transitional epithelium?

they vary in appearance based on the stretching of the tissue

“transition” meaning

change shape with elasticity

“transition” location

lining of urinary bladder

what is a gland made of?

group of cells that secrete a fluid substance

two ways glands are classified

• complexity

• how substances are secreted (our focus)

  • exocrine

  • endocrine

how do exocrine glands secrete? add an example

outward through a duct (ex: sweat gland)

how do endocrine glands secrete?

they are ductless glands that secrete hormones through the bloodstream

what are the types of exocrine glands?

merocrine, apocrine, and holocrine

description of merocrine + example

cells excrete the products (substances) via exocytosis; mero = “part”

ex: sweat gland

description of apocrine + example

a portion of the cell pinches off with the secreted products; apo = “tip”

ex: mammary gland

description of holocrine + example

cells rupture and spill products into the duct; hol = “whole”

ex: sebaceous (oil) glands

what do endocrine glands do?

secrete hormones into the blood so they can be delivered over longer distances

describe endocrine cells + examples

packed tightly together with capillaries (really small blood vessels) running through the glandular tissue. they excrete products through exocytosis into the blood.

ex: thyroid, thymous, adrenal glands, pancreas

3 functions of connective tissue

• provide support and bind other tissues together

• they can provide insulation and protection for other tissues

• some are able to transport substances

what characteristics do all connective tissues share?

• all connective tissues are formed from one type of stem cell (mesenchyme)

• connective tissues vary in their degree of vascularity (presence of blood cells)

• all are mostly composed of extracellular matrix

extracellular matrix

ground substance: watery substance secreted by cells → extracellular matrix → fibers/threads: collagen, elastic

name 3 types of loose connective tissue

areolar, adipose, reticular

areolar

“thin branches”, mostly open space

adipose

(nucleus to the side), composed of fat cells (adipocytes), large vacuoles that contain fat/oil

function: insulates body and provides nutrients

reticular

“thick branches”, contains fiber which creates framework that supports cells

name 3 types of dense connective tissue

regular, irregular, elastic

regular

collagen fibers are arranged in one direction

function: provides “tensile strength” like a rope

location: found in tendons and ligaments

irregular

collagen fibers are arranged in many directions

function: provides strength in multiple directions

location: found in capsules around organs

elastic

function: provides flexible cushioning

location: found between vertebrae and in arteries

what does cartilage specifically not have? what do they have?

there is no nerves or blood vessels (avascular)

there is lacuna in all cartilage

3 types of cartilage

hyaline, fibrocartilage, and elastic

hyaline + location

• glassy looking

• firm around substance with lacuna (space for cells)

• few collagen fibers

location: found in larynx, bridge of nose, and ribs

fibrocartilage + location

• has lots of collagen fibers

• mostly runs parallel

location: found in intervertabrel spaces

elastic cartilage + location

• highly flexible = more elastic fibers

location: found in outer ear and tip of nose

what do osteocytes do? + location

secretes ground substances, fibers, collagen, and fluids

located in the bone

how does the ground substance eventually end up?

calcified and hard

2 types of osteocytes

spongy and compact

why is vascular/blood tissue “connective”?

it matches all the characteristics

ground substance: plasma (fluid)

“fibers”: platelets (thrombocytes) which clot the blood

3 types of vascular tissue (or blood tissue)

mast cells, macrophages, and blood cells

mast cells

• detects foreign substances

• contains granules that secrete inflammatory chemicals

macrophages

blob-like cells that engulf invading substances or organisms

blood cells (function for all three types)

red blood cells: (erythrocytes) carry oxygen

white blood cells: (leukocytes) provide immune response

platelets: (thrombocytes) “fibers” aid in clotting

what do all muscle tissues have in common?

movement

3 types of muscle tissue

smooth, cardiac, and skeletal

smooth muscle tissue + location

• contracts involuntarily

• non-striated (no stripes)

location: walls of stomach, uterus, intestines, bladder, arteries, veins, eyes

cardiac muscle tissue + location

• contracts involuntarily

• striated (striped appearance)

• activated by brain or hormones

• has intercalated discs (lines both ways)

location: heart muscles

skeletal muscle tissue + location

• contracts voluntarily

• striated

• controlled by somatic nervous system

location: connected to bones of skeleton

2 types of nervous tissue

neurons, neuroglia

neurons

• make up 10% of all nerve cells

• convert stimuli into nerve impulses

• pass impulses to other neurons, muscle fibers, or glands

• unable to regenerate

neuroglia

• make up 90% of all nerve cells

• supports and protects neurons

• do not generate nerve impulses

• able to regenerate after injury