Unit 2 - Anatomical Organization, Histology, and Maintenance of Homeostasis

Cells

basic unit structure/function

Cellular organization

cell, tissue, organ, organ system, organism

Tissues

group of specialized cells which perform a specific function

Epithelial Tissue

lining and covering

Basement membrane

forms between the epithelial and connective tissue

Avascular

lacks its own blood supply; nutrients diffuse from neighboring connective tissue

Mitosis

very high rate; renews/repairs itself rapidly

Simple Squamous

Commonly found in alveoli and lining of blood vessels; nucleus is centrally located

Simple Cuboidal

Commonly found in kidney tubules; simple (single layer of cells)

Ciliated Simple Columnar

Commonly found in oviducts/upper respiratory tract

Nonciliated Simple Columnar

Commonly found in ileum, gallbladder, and urinary tract; may contain goblet cells (secrete mucus)

Simple Columnar with microvilli brush border

Commonly found in duodenum; microvilli found at apical surface to increase surface area/absorption

Keratinized Stratified Squamous

Commonly found in superficial skin layer; contains filaments of the protein keratin

Non-keratinized Stratified Squamous

Commonly found in esophagus, oral cavity, vagina, anal canal; no keratin, must be kept moist

Stratified Cuboidal

Commonly found in ducts of mammary, sweat, and salivary glands; rare

Stratified Columnar

Commonly found in lining of developing ovarian follicles and respiratory passages; only a single layer, but nuclei are at different levels

Pseudostratified

appears layered, but is not; nuclei don't line up

Ciliated Pseudostratified Columnar

Cilia = movement of materials

Nonciliated Pseudostratified Columnar Epithelium

No mucus or cilia

Transitional

Commonly found in urinary bladder; cells change shape (from squamous to columnar) as body parts stretch and move

Endocrine Glands

secretions enter the extracellular fluid and diffuse into the bloodstream; no ducts; secretions are called hormones

Exocrine Glands

secrete products into a duct that leads to the surface of the skin or into the lumen of a hollow organ

Merocrine secretion

Cells secrete their substances by exocytosis.

Common locations for Merocrine glands

Salivary and Sudoriferous (sweat) Glands.

Apocrine secretion

A portion of the cell membrane that contains the secretion buds off.

Common location for Apocrine glands

Sebaceous (oil) Glands.

Holocrine secretion

The entire cell disintegrates to excrete its substance.

Connective Tissue

Most abundant tissue used for binding and supporting.

Characteristics of Connective Tissue

Supports/strengthens/protects/insulates and is the major transport tissue (blood).

Stored energy in Connective Tissue

Adipose tissue.

Extracellular Matrix

Material found in space between tissue cells, containing ground substance and fibers.

Ground Substance

Can be fluid/semi-fluid/gelatinous/calcified.

Mesenchymal Connective Tissue

First connective tissue to develop in the embryo from which all connective tissues are later derived.

Mesenchymal stem cells

Clusters scattered throughout adult tissue that supply cells needed for replacement and repair after injury.

Composition of Extracellular Matrix

Composed of ground substance + protein fibers.

Rich nerve and blood supply

Characteristic of connective tissue, except for cartilage.

Collagen Fibers

Very strong and flexible; contain collagen protein

Elastic Fibers

Stretch and recoil; elastin protein

Reticular Fibers

Support and strength; collagen protein with glycoprotein coating

Immature Fibroblasts

Secrete the matrix and produce new cells in loose/dense connective tissue

Chondroblasts

Secrete gelatinous matrix in cartilage

Osteoblasts

Bone formation, secretion of organic fibers and inorganic salts to create crystalline matrix

Mature Fibroblasts

Secrete fibers and ground substance of matrix in loose and dense connective tissue, lots of collagen

Red Blood Cells (Erythrocytes)

Transport oxygen

White Blood Cells (Leukocytes)

Immune response; i.e. plasma cells - secrete antibodies/immune system

Platelets (Thrombocytes)

Blood clotting

Mast Cells

Produce histamine, a chemical that triggers inflammatory response which increases vascular permeability and attracts more phagocytic cells to the site

Adipocytes

Fat cells that store triglycerides, found below skin and around organs

Osteocytes

Mature bone cells

Chondrocytes

Mature cartilage cells

Macrophages

Develop from WBC's; move about in connective tissue as scavengers clearing foreign particles

Loose Connective Tissue

Includes areolar, reticular, and adipose; contains fibroblasts, adipocytes, mast cells, macrophages

Dense Connective Tissue

Mainly fibers; little else; includes regular and irregular types

Cartilage

Provides support and flexibility; minimizes friction; forms features and found in joints

Bone

Provides framework; protects organs; supports body

Blood and Lymph

Plays role in immune defenses; found in spleen and lymph nodes

Hemopoietic Blood

Provides transportation, regulation and protection; carries oxygen and nutrients to cells; carries away wastes and carbon dioxide

Muscle Tissue

Types include skeletal, cardiac, and smooth; contract to produce voluntary or involuntary movements.

Skeletal Muscle

Striated and voluntary; attached to bones of the skeleton.

Smooth Muscle

Non-striated and involuntary; located in walls of hollow organs such as blood vessels, intestines, and urinary tract.

Cardiac Muscle

Striated with intercalated discs; involuntary; walls of the heart pump blood.

Nervous Tissue

Initiates and transmits nerve impulses to coordinate activities of the body.

Neurons

Specialized to transmit electrical (nerve) impulses; sense stimuli and convert them into nerve impulses.

Neuroglia

Do not generate or conduct nerve impulses; smaller than neurons and many times more numerous.

Astrocytes

Help provide proper environment for the generation of nerve impulses; provide nutrients to neurons.

Microglial Cells

Engulf invading microbes and clear debris of dead cells.

Oligodendrocytes

Provide support for surrounding neurons; produce myelin sheaths around adjacent neuron axons.

Ependymal Cells

Line cavities of the brain filled with CSF; form CSF and aid with its circulation.

Schwann Cells

Produce myelin sheath around axons of PNS neurons.

Satellite Cells

Form a protective layer around neuron cell bodies in PNS providing nutritional and metabolic support.

Organ

Two or more tissues that work together to perform a specific function.

Organ System

A group of related organs that have a common function.

Integumentary System

The skin and structures derived from it such as hair, nails, and sweat and oil glands; regulates body temperature and protects.

Skeletal System

All the bones and joints of the body and their associated cartilages; supports and protects the body.

Muscular System

Specifically skeletal muscle tissue; powers movements of the body and generates heat.

Cardiovascular System

Blood, heart, and blood vessels; pumps blood carrying oxygen/nutrients to cells and removes carbon dioxide/wastes.

Lymphatic or Immune System

Lymph, lymphatic vessels, and structures containing lymphatic tissue; returns proteins and plasma to the cardiovascular system.

Transport of fats

Transport of fats from gastrointestinal tract to the cardiovascular system.

Nervous system

Brain, spinal cord, nerves, and sense organs. Regulates body activities in response to internal and external stimuli. Interprets stimuli and responds through muscular contractions or glandular secretions.

Endocrine system

Hormone producing glands such as the pituitary, thyroid, and pancreas. Regulates body activities through hormones, chemicals transported in the blood to target cells.

Respiratory system

Lungs and the airways leading into and out of them. Transfers oxygen from inhaled air to blood and carbon dioxide from blood to exhaled air. Helps regulate pH balance of body fluids.

Digestive system

Physical and chemical breakdown of foods, absorbs nutrients, eliminates solid wastes. Organs of the gastrointestinal tract (mouth, esophagus, stomach, intestines) and accessory organs (salivary glands, pancreas, liver and gallbladder).

Urinary system

Kidneys, ureter, urinary bladder, urethra. Regulates volume and chemical composition of blood. Eliminates metabolic wastes. Regulates fluid and electrolyte balance. Helps maintain pH of body fluids and calcium balance of the body. Secretes hormone that regulate red blood cell production.

Reproductive system

Gonads (testes/ovaries), uterus, vagina, ductus deferens, epididymis, and penis. Produce gametes and release hormones that regulate reproduction. Transport and store gametes.

Homeostasis

Maintenance of a stable internal environment (optimal conditions). Necessary for normal body functioning, to sustain life.

Homeostatic imbalance

A disturbance in homeostasis resulting in disease/breakdown.

Feedback Mechanisms

Mechanisms by which the body senses and responds to internal and/or external stimuli in order to maintain homeostasis.

Negative feedback

Includes most homeostatic control mechanisms. Ex: body temperature, glucose levels. Shuts off the original stimulus, or reduces its intensity.

Positive feedback

The response amplifies the initial stimulus. Not common - only blood clotting and childbirth.

Positive Feedback Example

Alarm or panic can spread by positive feedback among a herd of animals to cause a stampede.

Simple Squamous Epithelium Tissue

Simple Cuboidal Epithelium Tissue

Simple Columnar Epithelium Tissue

Nonkeratinized Stratified Squamous epithelial Tissue

Keratinized Stratified Squamous epithelial tissue

Pseudostratified Columnar epithelial tissue

Loose Connective Tissue

Adipose connective tissue

Dense Regular Connective Tissue

Dense Irregular Connective Tissue