tissues Flashcards
what does the maintenance of life involve?
Maintaining boundaries
Movement
Responsiveness
Digestion
Metabolism
Excretion
Reproduction
Growth
what do we mean by “maintaining boundaries”?
Separation between internal and external environments must exist
Plasma membranes separates cells
Skin separates organism from environment
why do humans need movement?
Muscular system allows movement
1) of body parts via skeletal muscles
2) of substances via cardiac muscle (blood) and smooth muscle (digestion, urination)
what is contractility?
refers to movement at the cellular level
what is responsiveness? give a few examples
Ability to sense and respond to stimuli
ex: Withdrawal reflex prevents injury
Control of breathing rate, which must change in response to different activities
what is digestion?
Breakdown of ingested foodstuffs, followed by absorption of simple molecules into blood
what is metabolism?
All chemical reactions that occur in body cells
Sum of all catabolism (breakdown of molecules) and anabolism (synthesis of molecules)
what is catabolism?
(breakdown of molecules)
what is anabolism?
synthesis of molecules
what is excretion?
Removal of wastes from metabolism and digestion
do anabolic reactions require energy?
yes
do catabolic reactions require or release energy?
release
what are the different types of excretions?
Urea (from breakdown of proteins and nucleic acids), carbon dioxide (from metabolism), feces (unabsorbed foods)
what are the different types of reproduction?
At the cellular level, reproduction involves division of cells for growth or repair
At the organismal level, reproduction is the production of offspring
what is growth?
Increase in size of a body part or of organism
what are the 11 organ systems that work together to maintain life?
-respiratory
-integumentary
-skeletal
-muscular
-nervous system
-endocrine system
-cardiovascualr system
-lymphatic system
-digestive system
-urinary system
-male reproductive system
-female reproductive system
what is homeostasis?
Homeostasis is the maintenance of relatively stable internal conditions despite continuous changes in environment
what are variables in homeostasis?
Variables are factors that can change (blood sugar, body temperature, blood volume, etc.). A dynamic state of equilibrium, always readjusting as needed
what is interstitial fluid? what does it do?
The internal environment of vertebrates is called the interstitial fluid (ISF).
It exchanges nutrients and wastes with blood contained in microscopic vessels called capillaries.
what is the PH of blood/interstitial fluid in the body?
Our bodies control the pH of our blood and interstitial fluid to within a tenth of a pH unit of 7.4.
what are the processes of homeostasis?
1) stimulus (produces change in variable)
2) receptor (detects change)
3)input (information sent along afferent pathway to control center)
4) output (information sent along efferent pathway to effector)
5) responses (of effector feeds back to reduce the effect of stimulus and returns variable to homeostatic level
what is the most used feedback mechanism in the body?
negative feedback
what is negative feedback inhibition?
Response reduces or shuts off original stimulus
Variable changes in opposite direction of initial change
what does negative feedback inhibition allow for?
this prevents small changes from becoming too large
what are examples of negative feedback inhibition?
-regulation of body temperature
-regulation of blood glucose
How does sweating work
what is positive feedback?
Response enhances or exaggerates the original stimulus (not homeostasis)
How does insulin work
give two examples of positive feedback inhibition?
1) Enhancement of labor contractions by oxytocin
2) Platelet plug formation and blood clotting
explain positive feedback inhibition for childbirth
During childbirth, the pressure of the baby’s head against opening of the uterus stimulates uterine contractions.
These cause greater pressure against the uterine opening, heightening the contractions, which cause still greater pressure.
Positive feedback brings childbirth to completion (not maintenance of a steady state).
How does platelet formation work
what are some major changes, that are programmed to happen?
1) puberty and pregnancy.
2) hormone levels responsible for the menstrual cycle
3) the human body reacts to certain infections by raising the set point for temperature to a slightly higher level, and the resulting fevers helps fight infection.
what is the point to having body cavities?
Body contains internal cavities that are closed to environment
Cavities provide different degrees of protection to organs within them
what are the two sets of body cavities?
dorsal body cavity (back)
ventral body cavity (stomach)
what’s in the dorsal body cavity (two subdivisions)?
-cranial cavity
-vertebral cavity
what is the point of the dorsal body cavity?
Protects fragile nervous system
what are the subdivisons to the ventral body cavity?
-thoracic cavity
-abdominopelvic cavity
what’s in the thoracic cavity?
-plural (lungs)
-pericardial (heart)
what is the viscera?
internal organs in the ventral body cavity
what are organs in the ventral body cavity held by?
mesenteries
what are mesenteries
sheets of connective tissues called mesenteries in body cavities moistened or filled with fluid. attaches to body wall
what are tissues?
Tissues are groups of cell with a common structure and function.
how are tissues held together?
A tissue may be held together by a sticky extracellular matrix that coats the cells or weaves them together in a fabric of fibers.
what are the categories of tissues?
-epithelial
-connective
-nervous
-muscle tissue
what is epithelial tissue?
Epithelial tissue occurs in sheets of tightly packed cells, covers the outside of the body and lines organs and cavities.
how are epithelial cells so closely riveted together?
Cells of an epithelium are closely joined
- may be riveted together by tight junctions.
why doe epithelium need to be highly revised together?
if not tightly packed, since line organs, there could be fluid mix (ex: urine and blood)
what are the two main forms of epithelium?
Covering and lining epithelia: on external and internal surfaces (ex: skin)
Glandular epithelia: Secretory tissue in glands (ex: salivary glands)
can epithelium be both lining and glandular?
yes!
what does epithelial tissue do?
Epithelial tissue functions as a barrier protecting against:
mechanical injury
invasive microorganisms
fluid loss.
what are the two types of epithelial cell surfaces?
apical and basal
what is an apical surface?
upper free side, is exposed to surface or cavity (air or fluid)
true or false, all apical surfaces are smooth?
false. Most apical surfaces are smooth, but some have specialized fingerlike projections called microvilli
what is a basal surface?
lower attached side, faces inwards toward body
what does the basal surface attach to?
basal lamina
what is the basal lamina?
an adhesive sheet that holds basal surface of epithelial cells to underlying cells, is a thin layer of extracellular matrix that lies between epithelial cells and their underlying tissues.
what is the basal lamina composed of?
It is composed of collagen and other filaments embedded in proteoglycans.
what is another word for basal lamina?
basement membrane
how are epithelia classified?
Epithelia are classified by the number of cell layers and the shape of the cells on the free surface.
what is simple epithelium? what is it involved in?
has a single layer of cells
- involved in absorption, secretion, or filtration processes
what are the different types of shapes of epithelium cells?
-squamous
-cuboidal
-columnar
what does a squamous cell look like?
nucleus squished like cell
what does cuboidal cell look like?
cubelike shape, with round nucleus