BIOL 273 - Unit 1 Flashcards
Physiology
Study of the normal functioning of a living organism and its component parts
Key concepts/themes important in understanding physiology
- Structure and function
- Biological energy
- Information flow
- Homeostasis
Organizational levels from smallest to largest
- Chemical - atoms and molecules
- Cellular - neuron, lymphocyte
- Tissue - collection of cells (connective)
- Organ -structural unit made of tissues (heart)
- Organ system - integrated group of organs
- Organism - individual form of life
Cells are held together by cell junctions…
anchoring junctions, gap junctions, tight junctions
There are four primary tissue types in the human body
Epithelial, connective, muscle and neural
Epithelial tissue
- protect the internal environment of the individual
- regulate exchange of material between environments
- epithelia consist of oneor more layers connected with basal lamina
Five types of epithelia
- Exchange - rapid exchange of material
- Ciliated - line airways and female reproductive tract
- Secretory - synthesize and release products into external
- Transporting - selective transport of material
- Protective - found on surface of the body
Connective tissue
provides structural supprot and barriers
- extensive ECM containing proteoglycans, collagen, elastin and fibronectin
Five types of connective tissue
- Loose (elastic tissue)
- Dense (strength the primary function)
- Adipose (contains adipocytes)
- Blood (watery matrix lacking insoluble protein fibers)
- Supporting (dense substances)
Muscle Tissue
Ability to contract to produce force and movement
Three types of muscle
- Skeletal (responsible for gross body movement)
- Smooth (Responsible for influencing the movement of substances into/out of/within the body)
- Cardiac (Found only in the heart, contraction moves blood through the body)
Neural connective tissue
Carry information from one part of the body to another
- Very little ECM in neural tissue
Two types of neural tissue
- Neurons (carry info as electrical or chemical signals)
- Gilal cells (supporting cells for neurons)
“Function” in physiology
the “why” - why does the system exist
“Mechanism” in physiology
the “how” - how does the system work
How do physiologists study mechanism to understand function
how cellular and molecular changes affect the organism as a whole
Homeostasis
a central organizing principle of physiology , the maintaenance of a relatively stable internal environment
How does homeostasis involve a series of automatic control mechanisms
- Maintains a similar condition for all the cells of the body
- Achieved through the effects of different organ systems working together
Acclimatization
Environmentally induced change in physiological function with no genetic change
What is the result of homeostatic control
oscillation around a set point (which can change with time)
Four Basic mechanisms of how cells communicate in the body
- Gap junctions
- Contact dependent signal
- Local communication
- Long-distance communication
Gap junction communication
(direct cell-to-cell communication)
- via protein channels between adjacent cells
- gap junctions are capable of opening and closing
Contact dependent signal communication
from the interaction between membrane molecules on two cells
- in immune cells
Local communication
communication with neighbouring cells
- occurs via paracrine and autocrine signals on the neighbouring cells
(can also be gap junctions and contact-dependant signals)
Autocrines
chemicals that act on the cell that produces them
Paracrine example
histamine
- paracrine signals are secreted by one cell and diffuse to adjacent cells
Long distance communication
- responsibility of the nervous and endocrine systems
- nervous system uses combinations of chemical and electrical signals (neurotransmitters)
- endocrine system uses chemical signals (hormones)
Why do some cells respond to a chemical signal and others do not
target cells have various receptor proteins , only respond to a chemical signal if they have right receptor
Receptors
- usually transmembrane proteins (glycoproteins)
- usually on plasma membrane but can be intracellular
Three domains of membrane spanning receptors
- Extracellular domain - involved in binding the ligand
- Trans - membrane domain - hydrophobic
- Intracellular (cytoplasmic domain) - involved in activating the cellular response
Two ways homeostasis may be maintained
- Local
- long-distance pathways
Local control of homeostasis
the effects are exerted on neighbouring cells, ex paracrine control of blood vessel diameter due to low O2
Reflex control/ long distance pathways
The reaction in one or more organs controlled from elsewhere in the body
- can be any long distance path of the nervous /endocrine system
Three types of feedback/control systems to regulate the response loops
- Negative feedback
- Positive feedback
- Feedforward control
Negative feedback
- results in a change that opposes or removes the signal thus returning the variable to its original value
- allows for homeostatic control
- keeps a system near or at set-point
- oscillation around the set point
ex. blood pressure
Positive Feedback
- response sends signal - reinforces stimulus sending the variable further from the set point until and external signal turns the response off
- NOT homeostatic (response reinforces the stimulus)
- sends system temporarily out of control
ex. labour
Feedforward Control
Anticipatory control: predicts that change is about to happen, starts the response loop -> prevent change
Lipophilic hormones
chemical messenger signals carried by the bloodstream until they diffuse from the blood into interstitial fluid.
- enter cells by simple diffusion through the phospholipid bilayer of the cell membrane [p. 134]. Once inside, they bind to cytosolic receptors or nuclear receptors
- generate long term effects
- intracellular receptors
Lipophobic
cannot cross membranes by simple diffusion. Instead, the vast majority of solutes cross membranes with the help of membrane proteins, a process we call mediated transport.
- cell membrane receptors
Describe the endocrine system (long distance communication)
Hormones are secreted by endocrine glands or cells into the blood. Only target cells with receptors for the hormone respond to the signal
Describe the nervous system
Neurotransmitters are chemicals secreted by
