Download Life: The Science of Biology, 8e

Histology- Study of
Tissues
Physiological systems are made up of organs
that serve specific functions.
Organs are made up of tissues, which are
then made up of cells.
Four types of tissue:
► Epithelial
► Connective
► Muscle
► Nervous
Epithelial tissues are sheets of tightly
connected epithelial cells.
The tissues form skin and line hollow organs.
Function of Epithelial cells
Some epithelial cells can:
► Secrete substances, like hormones
► Move substances with cilia
► Act as chemical receptors
► Create boundaries
► Control filtration and transport
Cells in Epithelial Tissue
► Squamous
Cells- Simple /Stratified
► Columnar Cells- Simple/pseudostratified
► Cuboidal Cells- Simple/stratified
► Transitional Cells
Classification of Epithelial Tissue
Epithelial Tissue (A)
Stratified squamous epithelium, nonkeratinized, from
human mouth. LM, H&E stain.
Simple Cuboidal Epithelium
Simple Columar Epithelium
Simple columnar epithelium from human intrahepatic
bile duct. LM, trichrome stain.
Simple cuboidal epithelium lining follicles of human
thyroid gland. LM, H&E stain.
Pseudostratified columnar epithelium lining a human
bronchus; cilia on many cells. LM.
Pseudostratified Columnar
Epithelium
Transitional epithelium line the urethra of a male infant.
LM, H&E stain.
Pigmented epithelium from a person of African descent.
LM, H&E stain.
Keratinized Stratified Squamous
Epithelium
Non-Keratinized Stratified Squamous
Epithelium
Transitional Epithelium
Skin from human foot; note thick keratin layer. LM, H&E
stain.
Sweat glands in human skin. LM, H&E stain.
Epithelial Tissue (B)
► Simple
cuboidal epithelium is found in
glandular tissue and in the kidney
tubules.
Muscle tissues consist of elongated cells
that generate force and cause movement.
Three types of muscle tissues:
► Skeletal
► Cardiac
► Smooth
► Skeletal:
responsible for locomotion and
other body movements (e.g., breathing,
shivering).
► Cardiac: makes up the heart and is
responsible for the heartbeat and blood
flow.
► Smooth: involved in movement and
generation of forces in internal organs (e.g.,
gut, blood vessels).
Figure 40.4 Filaments in Skeletal Muscle Cells
Types of Muscle Tissue
Connective tissues are dispersed cells in an
extracellular matrix that they secrete.
The matrix contains protein fibers:
► Collagen: strong and resistant to stretch, supports
skin and connections between muscles and bones
► Elastin: can be stretched and then recoils; found
in tissues that stretch (e.g., lungs, arteries)
Diagram of Loose CT
Connective Tissue
Areolar connective tissue; elastic and collagenic fibers in
a rat. LM, silver stain.
Connective tissues:
► Cartilage provides structural support and is
flexible: has chondrocytes; cells that secrete
the extracellular matrix.
► Bone: provides support and is hardened by
calcium phosphate deposition in the matrix.
Bone cells are osteocytes.
Hyaline cartilage in cat larynx. LM, H&E stain.
Cartilage
Fibrocartilage in a mammalian intervertebral disc. LM,
H&E stain.
Elastic cartilage from a pig's ear.
Human compact bone, transverse section. LM, Schmorl's
stain.
More connective tissues:
► Adipose tissue: includes adipose cells that
form and store lipids. Cells are adipocytes.
► Blood: consists of cells in a very liquid
extracellular matrix, the blood plasma.
There are red blood cells (erythrocytes),
white blood cells (leukocytes), and platelets
(thrombocytes).
Blood cells from domestic chicken (Gallus gallus). LM,
Giemsa stain.
Normal human adipose cells. LM, H&E stain.
Nervous tissues contain two basic
cell types: neurons and glia.
Neurons encode information as
electrical impulses that travel over
axons to their targets.
Chemical signals from the neuron
stimulate a response in the target
cell, via receptors.
Glia provide support for neurons.
Neurons
Nervous Tissue Includes Neurons and Glia (A)
Organs consist of multiple tissues.
An organ system is a group of
organs that function together.
Different Tissues make up an organ
Example: The stomach wall is
arranged in layers:
► Epithelial cells
► Connective tissue
► Smooth muscle
► Neurons
► Connective tissue
Figure 40.7 Tissues Form Organs
Fig 40.7 whole figure except stomach