Ch 1+4 Flashcards
What is Simple Squamous Epithelium?
Where can it be found?
Whats its function?
- What is it? One layer of flat, squamous cells resting on the basement membrane. Smooth apical surface; nuclei appear flattened.
- Function: rapid diffusion (of nutrients and waste in blood capillaries) through membranes, filtration (of blood in kidney glomeruli), reduction of friction (in blood and lymphatic vessels), secretion of lubricating serous fluid.
- Location: lining of heart, blood and lymphatic vessels (where is called endothelium), the surface of body cavities (including pericardial, pleural, peritoneal cavities where it is called mesothelium= the epithelium of the serosae), the alveoli of the lungs, kidney glomeruli.
What is SIMPLE CUBOIDAL EPITHELIUM?
Where can it be found?
Whats its function?
- What is it? One layer of cuboidal cells resting on the basement membrane. The cells are as tall as they are wide. Spherical nuclei are centrally located.
Apical surface can have long microvilli (in proximal tubules of kidneys) or few short microvilli (in distal and collecting tubules of kidney).
-Function: absorption, secretion (of respiratory mucus).
-Location: most of the tubules of the kidney, liver, thyroid, bronchioles, some excretory ducts of glands (mammary, salivary and others).
What is SIMPLE COLUMNAR EPITHELIUM?
Where can it be found?
What is its function?
- What is it? One layer of columnar, closely packed cells resting on the basement membrane.
The cell height is greater than the width. Ovoid nucleus located in the basal part of the cells. The apical surface can have microvilli. Some cells can have cilia. - Function: absorption and secretion (of mucus containing intestinal juice).
- Location: digestive tract (stomach to rectum), gallbladder, excretory ducts of some glands, fallopian tubes, testis, small bronchi.
What is PSEUDOSTRATIFIED COLUMNAR EPITHELIUM?
Where can it be found?
What is its function?
- What is it? One layer of cells that have different shape and height. They all rest on the basement membrane, but not all reach the free surface of the epithelium. It gives the false impression to be formed by two layers of cells, but it is instead a mono layer. Apical surface can have cilia (in respiratory tract).
- Function: secretion, propulsion of mucus and absorption of substances.
- Location: respiratory tract (nasal cavity, trachea and primary bronchi), portions of male urethra.
What is STRATIFIED SQUAMOUS EPITHELIUM?
Where can it be found?
What is its function?
- What is it? Several layers of cells. The superficial layer has flattened cells. Only the deepest layer rests on the basement membrane. It can be keratinized or non keratinized.
If keratinized, nuclei are visible in all the cell layers. If non keratinized, the upper layers of cells do not have nuclei, so the cells are dead. - Function: protection of underlining cell layers against injury, abrasion, infection, dehydration (the keratinized epithelium).
- Location: non keratinized - wet surfaces, oral cavity (soft palate, cheeks, floor of the mouth), esophagus, vagina, vocal cords; Keratinized – epidermis of skin.
What is STRATIFIED CUBOIDAL EPITHELIUM?
Where can it be found?
What is its function?
- What is it? Two or three layers of cuboidal cells.
- Function: secretion of sweat, ovarian hormones; production of sperm,
- Location: large ducts of exocrine glands (sweat glands, mammary glands).
What is STRATIFIED COLUMNAR EPITHELIUM?
Where can it be found?
What is its function?
- What is it? Two or three layers of cells. The top layer is columnar, the basal layer is cuboidal.
- Function: secretion
- Location: congiuntiva of the eye, large ducts of exocrine glands, pharynx, male urethra.
What is TRANSITIONAL EPITHELIUM?
Where can it be found?
What is its function?
- What is it? Several layers of cells: 4-6 in relaxed status, with surface cells dome-shaped.
In stretched bladder, the cells are extremely flattened. - Function: stretches to allow filling of urinary tract.
- Location: excretory channels (renal calyces, ureters, bladder, proximal segment of urethra).
Describe the process of the Homeostatic control mechanism.
Receptor: Some type of sensor that monitors the environment and responds to changes
Afferent pathway: the pathway that this information flows to the control center
Control Center: determines the set point which is the level or range at which the variable is to be maintained. Also determines the appropriate response
Efferent pathway: Information from the control center flood through this pathway to the effector
Effector: provides the means for the control centers response to the stimulus. This will either stop the process or continue at a higher rate if needed
Give an example of a positive feedback mechanism
This is where the result or response enhances the original stimulus so that the response is accelerated. It is considered positive because the change results in the same direction as the initial change causing the variable to further and further from its original value or range.
Example: Enhancement of labor contractions and blood clotting.
Give an example of Negative feedback mechanism
Regulation of body temperature, withdrawal reflex, and the control of blood sugar by insulin.
The goal for a negative feedback mechanism is to prevent severe changes within the body.
List the two body cavities and their sub divisions
Dorsal and Ventral body cavities.
Dorsal contains cranial and vertebral
Ventral contains thoracic and abdominopelvic
Subdivisions: Abdominopelvic contains abdominal and pelvic
Thoracic contains medial pleural cavities and mediastinum
mediastinum contains pericardial cavity
Describe the difference between the visceral and parietal serous membranes
Visceral serous membranes covers the organs within the cavity.
Pariteal serous membranes lines the cavity walls
Which type of membrane line cavities open to the outside of the body?
Mucous membranes.
Describe the differenced in endocrine and exocrine glands
Endocrine glands are often called ductless glands. They produce hormones secreted by exocytosis directly into the extracellular space. They are structurally diverse and vary in types of secretions.
Exocrine glands secrete their products onto body surfaces or into body cavities. The unicellular glands do so directly by exocytosis whereas multicellular glands do so via a duct.
