Quiz 1 Flashcards
List the four intracellular junctions
Tight Junctions, Desmosomes, Gap Junctions and Adherence Junctions
Describe Tight Junctions
“Water tight” prevents extracellular fluid from traveling between cells. Usually on the apical surfaces of the cell.
Describe Desmosomes
Structural junction with exposed membrane on all sides. Think rebar and allows fluid to pass around it. (Muscles or Skin)
Describe Gap Junctions
Allows for fluid to pass quickly between cells. Great for electrical signals or second messenger from cell to cell. (Muscles)
Describe Adherence Junctions
holds EPITHELIAL cells together & help them resist separation during CONTRACTILE activities (passage of foods through intestine)
What is Homeostais
Homeostasis refers to the dynamic mechanisms that detect and respond to deviations in physiologic variables from their “set point” values by initiating effector responses that restore the variables to the optimal physiological range.
(Broadly) How does Homeostasis create a steady state?
Using water and other dissolved subtsances as transporters and communicators.
What are Body Fluids
the watery solution of dissolved substances (oxygen, nutrients, etc.) present in the body. Fluids can be divided into Intracellular Fluid (ICF) and Extracellular Fluid (ECF).
What is Extracellular Fluid (ECF)?
The fluid in the blood and surrounding the cells (i.e., outside the cell).
How is Extracellular Fluid (ECF) proportioned or distributed in the body?
About 25% of ECF is in the fluid portion of blood (plasma) and the remaining 75% of the ECF lies around and between cells and is known as the interstitial fluid.
So… EFC = Blood + interstial fluid
What is Endocytosis
A process where a section of a cell’s membrane enfolds subtances from outside, spearates from the membrane and moves inside the cell
What is Exocytosis?
Discharge or secretion of material from intracellular vesicles
why large organisms are multicellular?
To have a high surface-to-volume ratio. So cells in the human body are within a few cell layers of a capillary, and every cell is in contact with interstitial fluid.
What are the four main tissue types?
Connective Tissue (include blood)
Epithelial Tissue
Muscle Tissue
Nervous Tissue
Define Diffusion
Movement of a solute molecule from an area of greater concentration to an area of lesser concentration.
What are some things which can diffuse (passive) across a plasma membrane?
Hydrophobic molecules (O2, CO2, N2)
Small unchrged molecules ( H20, urea)
What is Hydrostatic pressure?
Mechanical force of water pushing against cellular membranes. (example in vascular system is blood pressure)
Describe Osmosis
The movement of water “down” a concentration gradient. Always from a higher concentration to a lower one.
Describe mediated transport (passive)
Comformational Change Model and Channel Model
Comformational Change doesnt require ATP but uses binding sites to shuttle molecules inside
Channel Mode is a channel which allows for faster diffusion of certain ions
What are the four ways cells communicate or signal?
Autocrine
Paracrine
Endocrine
Nervous
Describe how Autocrine signaling works
A cell’s receptor detects the molecule it has produced and exocytosed
Many cells use this as a method of negative feedback—
If there’s enough signaling molecule around to bind to the autocrine receptor, then the cell should save its energy and quit making it.
Describe the Paracrine system
Short distance signals
Messenger chemicals have a short lifespan
Messengers have high specificity to their receptors (no mistakes)
(Exampe NO)
Describe the Endocrine system (signaling)
Cells talking to other cells from near to far
- Lower specificity
- Goal is for one organ to give guidance across many cells or organ types
Describe Neuroendocrine (signaling)
When the nervous system talks directly to the endocrine system
-Usually a faster signal that lasts longer
Describe a “positive feedback” system
In a positive feedback system, the output enhances the original stimulus.
A good example of a positive feedback system is child birth. During labor, the hormone oxytocin is released that intensifies and speeds up contractions
Describe a “negitive feedback” system
A stimulus or “affect” casues a series of effects
Example: Body temperature rises (affect)
Sweat is produced (action)
Temp returns to normal (effect)
Negative feedback is more common for homeostais!!!!
Define Hormone
a chemical messenger secreted into the blood by cells of the endocrine system. Hormones may act on many different cells simultaneously because they circulate throughout the body, everywhere that blood goes.
Physiology vs Pathophysiology
When homeostasis is maintained, we refer to it as physiology; when it is not, we call it pathophysiology.
Describe Steady State
A system that is in a steady state remains constant over time, but that constant state requires continual work. (Requires energy)
Ionic compounds are maintained at constant concentrations in cells, but only through continually moving ions across the cell membrane.
For example, the potassium concentration in animal cells is maintained by active transport of ions up electrochemical gradients into the cell. Ecosystems may also exist in steady states.
Decribe Equilibrium
system at chemical equilibrium, or just equilibrium, is stable over time, but no energy or work is required to maintain that condition.
Define erythropoietin (EPO) and describe its role in red blood cell formation
Erythropoietin is a hormone scripted by the kidneys that increases the rate of production of red blood cells in response to falling levels of oxygen in tissues (Hypoxia).
