[Anatomy & Physiology] Chapter 4 TEST

Tissues

collections of cells and cell products that perform specific, limited functions

4 Basic Tissue Types

1) Epithelial Tissue: coveres exposed surfaces
2) Connective Tissue: fills internal spaces
3) Muscle Tissue: subdivided into 3, contraction
4) Neural Tissue: carries information

Epithelial tissue

covers exposed surfaces, lines internal passageways & chambers, + form glands

1) Epithelia: layer of cells that covers internal + external surfaces
- epithelium: single

2) Glands: structures that produce secretions

Connective tissue

fills internal spaces, provides structural support for other tissues, transports material within the body, & stores energy reserves - the "packing materials" of the body - supports other tissues, ie. body tissue + cartilage, etc - transports material (lymph + blood) - stores energy (fat )

Extracellular matrix

the non living, noncellular part of connective tissue

Muscle tissue

specialized for contraction

1) Skeletal muscle: voluntary; attached to bones
2) Smooth muscle: nonvoluntary; found in the wall of hollow organs
3) Cardiac muscle: only found in the heart

Skeletal muscle

voluntary; attached to bones

Smooth muscle

nonvoluntary; found in the wall of hollow organs

Cardiac muscle

only found in the heart

Nerval tissue (nerve, nervous tissue)

carries electrical signals from one body part to the another

Characteristics of Epithelia

1) Cellularity (cell junctions)
2) Polarity
3) Attachment
4) Avascularity
5) Regeneration

Cellularity (cell junctions)

cells are bound together by specialized structures -> many other tissue types have cells more widely spaced + seperated by extracellular material

Polarity

cells have a definete "top" + "bottom"

Attachment

epithelia are anchored to a layer of extracellular material called the basal lamina or basement membrane

Avascularity

unlike most cells, epithelia lack blood vessels -> attains O2 + nutrients from adjacent cells that do have blood vessels

Regeneration of Epithelia

the rate of cell division + regeneration is much higher than other tissue types

Functions of Epithelia

1) Physical Protection
2) Control Permeability
3) Provide Sensation
4) Produce Secretions

Physical Protection

from abrasion, microbes, dehydration and chemicals

Control Permeability

what's going in and out -> lining of intestines (ie. lungs, kidneys)

Provide Sensation

specialized epithelia -> tastebuds, olfactory epithelium, eyes, ears

Produce Secretions

glandular epithelial tissue

Specialization of Epithelial Cells

1) Movement of fluids over the epithelial surface
2) Absorption
3) Producing Secretions

Movement of fluids over the epithelial surface

Moving or pushing materials over the epithelial surface -> function of ciliated epithelia (cilia are hairlike structures, they wave or beat )

Absorption

absorbing nutrients from the intestine

Producing Secretions

aided by microilli (tiny bumps of cell membrane) -> increases surface area by atleast 20x compared to a normal cell
- eg. again lining of the small intestine -- food for absorbing nutrients

Intracellular Connections

connecting neighboring epithelial cells; gives strength to epithelial tissue and helps cells communicate with each other

1) In general, large areas of adjacent cell membranes may be conected by transmembrane proteins caled cell adhesion molecules (CAMs)
-> CAMs interlock to join the 2 cells + it's reinforced by intercellular cement.
2) Cell Junctions

Cell Junctions

1) Tight Junctions
2) Desmosomes
3) Gap Junctions

Tight Junctions

between the apical portions of 2 neighboring cells

- cells bound together tightly in a way that prevents water + other substances from leaking between the cells
- this is useful when an epithelium lines a tube (eg. intestine)
- tight junctions ensure that enzymes, acids, water, etc. stay inside the lumen

Gap Junctions

allows rapid communication between 2 connected cells

- the 2 neighboring cells are held together by channel proteins (any channel)
- allows ions + small molecules to pass cell to cell
- communication helps coordinated functions

x found in other tissue types where communication is important -> cardiac muscle

Desmosomes

very strong structures that can ensure stretching + twisting

- CAMs reinforced with intercellular cement -> CAMs are anchored firmly in the structure of the cell
- desmosomes are present in the superficial layers in the skin (eg. burnt skin comes off layers/strips/sheets)

Types of Desmosomes

a) regular kind between 2 cells
- spot desmosomes
- button desmosomes
b) hemiesmosomes: attaches 1 cell to the basement membrane

tissue membrane

epitheilial layer w/ connective tissue underneath

basement membrane (basal lamina)

made of layers of proteins that provide strength to epithelia + help form a barrier between the epithelium + underlying connective tissue

Roles for Proteins in the Body

- Enzymes
- Structural Proteins (collagen, keratin)
- Antibodies

Classifying cell shapes

1) Squamous
2) Cubodial
3) Columnar

Classifying # of layers

1) Simple
2) Stratified

Simple

a single line of cells

Stratified

multiple layers of cells

Simple epithelia

good for areas where substaces need to be absorbed through the epithelium but don't need a lot of protection

- eg. lining of the lungs, lining of the small intestine

Stratified epithelia

good for areas that need protection

Epithelia Maintenance and Repairs

new epithelial cells come from the division of stem cells -> called germinative cells

- located near the basement membrane

Glands

collection of epithelial cells that produce secretions

2 types
- endocrine glands
- exocrine glands

Endocrine Glands

"secrete inside", secretions are released into body fluids

Exocrine Glands

release secretions into ducts that open onto an epithelial surface (eg. perspiration on the skin, tears, mucus, milk, enzymes entering the digestive tract)

hormones

the secretions; chemical messengers that circulate around the body in the blood stream

Modes of Secretion

1) Merocrine Secretion
2) Apocrine Secretion
3) Holocrine Secretion

Merocrine Secretion

the most common form of secretion; the secretory product is packaged into secretory vesicles, vesicles fue to cell membrane and product is released into the duct via exocytosis

Apocrine Secretion

the product is released when the apical portion of the cell pinches off and breaks

- some cytoplasm is lost with secretory product
- the cell can generate a new apical portion + start over

(eg. the cells of mammary glands release milk using apocrine secretion)

Holocrine Secretion

secretion that destroys the whole gland cell

- entire gland cell becomes packed w/ secretory product + bursts
- product is released when the cell bursts which kills the gland cell
- cell gets replaced through the dividion of stem cells called germinative cells

(eg. sebaceous gland

Types of Secretions

1) Serous Secretions
2) Mucous Secretions
3) Mixed Exocrine Secretions

Serous Secretions

watery secretions that contain proteins -- enzymes usually

(eg. gastric chief chells -- secrete stomach acid)

Mucous Secretions

the glands secrete molecules called mucins which combine w/ water to form mucus

(eg. various difestive glands produce muscus to protect the digestive tract from harsh digestive juices)

Goblet Cells

the only unicellular exocrine glands which secrete mucins

Mixed Exocrine Secretions

Exocrine glands may have more than one type of gland cell + may produce both serous + mucous products (eg. saliavary glands produce saliva )

Connective Tissue

arises from an embryonic called mesenchyme; has three parts 1) Specialized cells 2) Extracellular protein fibers 3) Ground substance - compared to epithelial tissue, CT is never exposed to the outside environment - CT (excluding cartilage) is highly vascular vs ET which is highly avascular - there is a wide variety of CT tissue (blood, bone, lymph, reticular tissue , etc)

3 Basic Types of Connective Tissue

1) Connective Tissue Proper (CTP)
2) Supporting Connective Tissue
3) Fluid Connective Tissue

Connective Tissue Proper (CTP)

tissues that protect, and/or tissues that connect
- tendons + ligaments
- adipose tissue + others

Supporting Connective Tissue

bone and cartilage

Fluid Connective Tissue

blood and lymph

Some Cells of CTP

- Mast cells
- Adipocytes
- Lymphocytes
- Melanocytes
- Mesenchymal cells
- Fibroblasts
- Macrophages

Mast cells

trigger local inflammation by releasing chemicals, including histamines

Adipocytes

fat cells; stores energy in lipid molecules

Lymphocytes

white blood cells respomsibly for "specific defenses" (basis for immunity, vaccines, etc.)

Melanocytes

make melanin; brown pigment in skin

Mesenchymal cells

stem cells that can divide to make different types of cells

Fibroblasts

makes substance + produce fibers -> matrix

- most common cell type in CTP

Macrophages

large white blood cells tht engulf + destroy pathogens, dead tissues, debris, etc

fixed macrophages

stays in one place

free macrophages

can move; go to injured or infected areas "ameboid movement"

3 Protein Fiber Type in CTP

1) Collagen Fibers
2) Reticular Fibers
3) Elastic Fibers

Collagen Fibers

gives strength to many tissues in the body

- main component of tendons + ligaments

Reticular Fibers

thinner than collagen, with branching structure; forms a branched network to support the structure of organs

Elastic Fibers

similar to collagen, but made of the protein elastin; returns to original length after stretching

- relatively rare compared to collagen
- lots of them are found in the ligaments that connect the vertebrae together

2 Categories of CTP

1) Loose CT
2) Dense CT

Loose CT

more ground substance, fewer fibers

(eg. adipose tissue)

Dense CT

less groud substance, more fibers; packed with lost of collagen and/or elastic fibers

(eg. tendons + ligaments)

Types of Loose CT

1) Areolar Tissue
2) Adipose Tissue
3) Reticular Tissue

Areolar Tissue

least specialized more generic type of CT
- viscious (thick) ground substance
- has some elastic fibers, holds blood vessels and capillary beds

(eg. found under the skin in the subcutaneos layer)

Adipose Tissue

has a lot of adipocytes (fat cells), store fat (energy); absorbs shock, slows heat loss (insulation)

- adipose tissue cells, adipocytes don't divide in adults, expands to store, shrinks when fat gets broken down
- mesenchymal stem cells can divide + differentiate to produce more fat cells in times of plenty

Reticular Tissue

has lot of reticular fibers, support + maintains (helps) the structure of organs (eg. spleen, liver, lymph nodes, bone marrow)

Types of Dense CT

1) Dense Regular
2) Dense Irregular
3) Elastic Tissue

Dense Regular CT

tightly packed parallel collagen fibers

- fibers all run in the same direction -> the tissue has stength to withstand forces in that direction
- tendons + ligaments stresses come from predictable directions

Dense Irregular CT

interwoven networks of collagen fibers

- no organized pattern; runs in every direction -> has strength in every direction
(eg. in the dermis)
- forms capsules around many organs

Elastic Tissue

dense regular CT that's dominated by elastic fibers (instead of the usual collagen fibers)

(eg. elastic fibers that interconnect vertebrae)

Tendons

attach muscle to bone

Ligaments

attach bone to bone

Aponeuroses

different shaped tendon; a broad, flat, tendinous sheet

perichondrium

Dense irregular CT when wrapped around cartilages

periosteum

Dense irregular CT wrapped around bone

Fluid CT

blood + lymph

- have a watery matrix w/ extracellular proteins dissolved. the dissolved proteins in the fluid can be transformed into solid form for blood clotting

Plasma

the matrix of blood

- normally confined to blood vessels

Blood Cells

1) Red Blood Cells (RBCs)
2) White Blood Cells (WBCs)
3) Platelets

Red Blood Cells (RBCs)

erythrocytes

- make up ~1/2 of the blood volume, very small w/ no nucleus
- carry O2 + CO2

White Blood Cells (WBCs)

leukocytes

- ~20 different types; various immune functions

Platelets

technically not cells, they're cell fragments important for blood clotting

Lymph

collected from the interstitial space (between cells in body tissues) travels in lymphatic vessels and monitored by the immune system

- lymph is eventually returned to the cardiovascular system and becomes part of the blood

Bone

the matrix is calcified, made by minerals

Cartilage

ground substance is a very thick gel material
- good for protecting + shock protection // absorption

Chondrocytes

live in lacunaem small chambers withint the thick gel matrix -- cartilage is avascular, CT is usually highly vascular -

- heals poorly, the chondrocytes are isolated in the thick gel. they get nutrients through slow diffusion through the thick gel matrix

3 Types of Cartilage

1) Hyaline
2) Elastic
3) Fibrocartilage