animal physiology - challenge 2 (Intracellular Communication) Flashcards
because animals are multicellular this proposes what challenge?
since cells all have special structure and function it is a challenge to coordinate all the functions in cells
how do cells communicate?
Cells can signal to each
other and interpret the
signals they receive from
other cells and the
environment
Signals are most often
chemicals
Animals will utilize two distinct types of signaling to organize the cells of the body, what are the two types?
- Electrical Signaling
2. Chemical Signaling
what is one type/example of electrical signaling ?
Action potentials
- Along an axon - Along the sarcolemma (plasma membrane of a muscle cell)
what are 3 types of chemical signaling?
- Neurotransmitters
- Such as acetylcholine
- Paracrine (localized)
- Endocrine(long distance)
- Hormones
In local signaling, animal cells may communicate by direct contact- what is direct contact?
Animal cells have cell junctions that directly connect the cytoplasm of adjacent cells and Signaling substances in the cytosol can pass freely between adjacent cells
what enables cells for direct contact?
cellular junctions and the structure of gap junctions
These structures enable cells in direct contact to communicate
This is one form of local signaling
In many other cases, animal cells communicate using secreted messenger molecules that travel only short distances, what are the two types of secreted messengers?
Synaptic signaling
Paracrine signaling
In both of these forms chemical signals will be secreted from the cell
where and when does Synaptic signaling occur?
Synaptic signaling occurs in the animal nervous system when a neurotransmitter is released in response to an electric signal
In long-distance signaling, animals use chemical messengers referred to as?
hormones
Hormonal signaling in animals is called ?
endocrine signaling;
specialized cells release hormones, which travel to target cells via the circulatory system
The ability of a cell to respond to a signal depends on what?
whether or not it has a receptor specific to that signal
what are Glands?
Specialized organ (or a group of cells) which manufacture and secrete chemical signals (hormones)
what does Production of these chemical messages (from glands) allows for
the coordination of activities in multiple areas of the body
Many of these glands (or cells) are associated with the integrating center (comparer) of negative feedback loops
Why?
because the physiological response is tied to negative feedback loops which send messages to other cells to maintain homeostasis.
it coordinates amount other cells for growth and development for bilateral symmetry
what are three types of glands?
- Exocrine glands
- Endocrine glands
- Mixed function glands
what do Exocrine glands do? give 2 examples.
secrete their products into ducts that carry these products to other organs or outside the body
- Salivary glands
- Sweat glands
what do Endocrine glands do? give 2 examples
secrete their products directly into the bloodstream
- Pituitary gland
- Thyroid gland
what do Mixed function glands do? give one example
capable of both exocrine and endocrine secretion
1. Pancreas
What are hormones?
Chemical signals that promote communication between cells, body parts, and even individuals
what does it mean that hormones are targeted?
they will only interact with a target cell
target cell will be carried in the extracellular fluid or blood of an animal
why must hormones exhibit complexity but yet be simple?
they have to be complex enough to avoid mixing up signals and they have to be simple enough to travel around the body
what are Hormone Receptors?
Proteins of target cells in which a hormone will bind -
Once binding occurs a response will occur
and Internal conditions of cell could change triggering a response
why is specificity of protein receptor to specific hormones
vital?
so that the hormone goes to the right place and coordinates the correct response.
what are the two main classes of hormone receptors?
- Internal receptors
2. External receptors
what are Internal hormone receptors?
receptors within the cell; hormone must cross plasma membrane (they are small, non polar, and highly regulated.
what are External hormone receptors?
protein receptors on the plasma membrane which bind hormones on extracellular face of the cell (polar, hydrophilic)
what are the characteristics of a “good” hormone? (3)
- complexity
- stability
- elicit a response
Two methods of categorizing hormones.. what are they ?
- Molecular: the type of molecule and its chemical nature
2. Behavior: specifically in regards to water, its hydrophobicity
what is Hydrophobicity? what are the three classes of it?
Chemical nature of the molecule will determine how the hormone is moved through the body (i.e. blood) and the type of receptor it will interact with.
- Hydrophobic or Lipophilic
- Hydrophilic or Polar Hormones
- Special Classes
what are special classes?
not truly hydrophobic or hydrophilic
what are Hydrophobic or Lipophilic hormones? give an example.
Non-polar molecules that hate water, are fat-soluble and love lipids
Examples:
All steroid hormones and some amine hormones
As Hydrophobic or Lipophilic hormones do not dissolve in water how do we move them?
Bind to carrier molecules
what are Hydrophilic or Polar Hormones? give at least one example
Water-soluble and Found in blood free and in active form
Examples:
All peptide hormones and many of the amine hormones
since Hydrophilic or Polar Hormones are not able to pass through plasma membrane they are?
Surface receptors
Hormones must be able to induce a response in the target– This process will vary between what two things?
- hydrophilic and 2. lipophilic hormones
what are the three Stages of Cell Signaling?
- Reception
- Transduction
- Response
what is Reception cell signaling?
In reception, the target cell detects a signaling molecule that binds to a receptor protein on the cell surface
what is Transduction cell signaling?
In transduction, the binding of the signaling molecule alters the receptor and initiates a signal transduction pathway; transduction often occurs in a series of steps
what is Response cell signaling?
In response, the transduced signal triggers a specific response in the target cell
what are the main two differences between Hydrophilic and Lipophilic?
Hydrophilic
-Much faster time from reception to response
-Relatively short lived response
Lipophilic
-Slower than hydrophilic responses
because it has a harder time getting into the blood- it has extra steps / longer time but a longer lived response
-Much longer lived response
