Unit 1.2 NURS Anatomy

Tissues

Tissue

A group of cells that have a similar shape and function. The simplest combination is called a membrane, which covers or lines the body surface or divides organs into parts

4 main types of basic tissues 

epithelial, connective, muscular, nervous

Epithelial tissue (basic)

Covers the body surface and forms the lining for most internal cavities. Major functions: protection, secretion, absorption, and filtration. Cells can be flat, thin to cubic, to elongated

Connective tissue

The most abundant and the most widely distributed of the tissues. They perform a variety of functions, including support and protection: ordinary loose … tissue, fat tissue, dense fibrous tissue, cartilage, bone, blood, and lymph

Muscular tissue

3 types: skeletal (voluntary) used in the contraction of skeletal parts, smooth (involuntary)  found in the walls of internal organs and blood vessels, and cardiac (involuntary) found only in the walls of the heart.

Nervous tissue

Composed of specialized cells which not only receive stimuli but also conduct impulses to and from all parts of the body.  Nerve cells or neurons are long and string-like.

Epithelia

Tissue made of cells arranged in a continuous sheet with one or more layers has apical & basal surfaces. Well innervated (nerv=nerves)
Covers all exposed surfaces, lines, internal passages, hollow organs, cavities and ducts.
Forms glands.

Two types of epithelial tissues:

Covering & lining epithelia and Glandular epithelium

Simple Epithelium

 one cell layer (absorption, secretion, filtration)

Stratified epithelium

 two or more cell layers

Pseudostratified Columnar Epithelium

When cells of an epithelial tissue are all anchored to the basement Membrane but not all cells reach the apical surface. Appears stratified, but is simple

Glandular Epithelium

Endocrine: releases hormones directly into the bloodstream 

Exocrine: secrete into ducts

Connective tissue

Contains many different cell types, including: fibroblasts, macrophages, mast cells, and adipocytes. The matrix is composed of two primary materials: ground substance, which includes proteins and polysaccharides, and fibre, which consists of reticular, collagen, and elastic fibres.

Loose Connective

Fibers & many cell types in gelatinous matrix, found in skin, & surrounding blood vessels, nerves, and organs

Dense Connective

Bundles of parallel collagen fibers & fibroblasts, found in tendons & ligaments

Cartilage

Made of collagen & elastin fibers embedded in a matrix glycoprotein & cells called chondrocytes, which was found in small spaces

Fibrous Cartilage

Strongest type, has dense collagen & little matrix, found in pelvis, skull & vertebral discs

Fixed cell

A relatively immotile macrophage found in connective tissue, lymph nodes, spleen, and bone marrow

Types of Fixed Cells

Fibroblasts, Macrophages, Adipocytes, Mesenchymal cells, Melanocytes

Wandering cell

A cell such as a leukocyte, having ameboid movements, with a power of locomotion

Characteristics of Epithelia

Polar Function, Tight Cellularity, Basal Attachment, Avascularity, Quick Regeneration

Membranes (mucosa)

A thin layer of tissue that covers a surface, lines a cavity, or divides a space or organ.
Consist of epithelial layer over a connective tissue layer

Mucous membrane (mucosa)

A membrane that lines cavities open to the outside. It consists of an epithelial layer for protection against pathogens and an underlying connective tissue layer that stabilizes the membrane.

Serous membrane (serosa)

A membrane that lines internal body cavities and covers organs within them. They have two layers: the parietal layer (lines the cavity) and the visceral layer (covers the organ), and secrete serous fluid to reduce friction between organs.

Cutaneous membrane

A membrane that covers the body and protects against microbes, light, heat, and injury. It’s the largest organ, storing fat, vitamin D, and water, containing sensory receptors, and regulating temperature through sweat

Synovial membrane 

A joint is where two bones meet. A membrane that surrounds movable joints and secretes synovial fluid to lubricate movement, nourish cartilage, and contain macrophages that remove debris and microbes.

Skeletal muscle tissue

• Long multinucleated cells

• Striated (actin and myosin in parallel so muscle appears to have bands across it)

• Large skeletal muscles under voluntary nervous system control (usually)

Cardiac muscle tissue

• Smaller cells with only one nucleus

• Also striated

• Not under nervous system control, heart has own pacemaker (involuntary muscle)

Smooth muscle tissue

• Small cells with one nucleus

• Not striated as actin and myosin are organized differently

• Generally not under voluntary control

• Surround hollow organs and passageways to exterior (resp tract, digestive tract, etc)

Neural Tissue

Made up of cells called neurons. Neurons are cells that convert stimuli into electrical impulses to the brain. Located throughout the whole body

Motor Neuron

Carry impulses from CNS to muscles and glands

Interneuron

Interpret input from sensory neurons and end responses to motor neurons

Sensory Neuron

Receive information from environment and transmit to CNS