module 6 Flashcards
Basic Cellular Functions
-Growth
-Repoduction
-Metabolism
Requirements for Cellular Function
-Bring in nutrients and expel wastes
-Create cellular energy
-Synthesize new proteins
-Respond to external signals
-Transport materials throughout the cell body
Epithelial Cells
-Form protective barriers in tissues and may be specialized to absorb or secrete specific compounds
-Line cavities and surfaces of organs
Muscle Cells
-Responsible for movement of skeleton, heart, and many internal organs (stomach)
-Have specialized structures and proteins that allow them to generate motion
Nervous tissue
-Conduct electrical signals to carry info
-Differences in ion concentrations across membrane create electrical potential
-composed of nerve cells and glial cells (ex.schwann cells)
Bone Cells
-Form bones and skeleton system that give strength and support to the body
-These cells include osteoclast cells that degrade bone and osteoblast cells that create new bone
Secretory Cells
-Form glands and, as their name implies, secrete substances (e.g., mucous, hormones, enzymes, etc.)
Adipose Cells
-Located throughout the body to store fat
-This fat is in the form of triglycerides which are released when the body is in a period of fasting
Red Blood Cells
-Formed primarily in the bone marrow and released into the circulation where they move and deliver oxygen throughout the body
-NO nuclei or mitochondria
-limited lifespans, must continuously be replaced
Cell Junctions
-Membrane proteins
-Faciliate cell-to-cell attachments (for communication)
What kind of cells require junction complexes (adhesion proteins)
-Endothelial Cells
-Epithelial Cells
Endothelial Cells
Line inside of blood vessels
What are the proteins in the junctional complex
-tight junctions
-adherens junctions
-desmosomes
Tight Junctions
Divide plasma membrane into 2 domains:
* The apical (top) surface of the cell
* The basal (bottom) surface of the cell
Regulate paracellular transport
Phospholipids cant move across it
Adherens Junctions
Use transmembrane receptors proteins called cadherins that bind to other cadherins on neighbouring cells
amount of overlap –> proportional to bond strngth
found in neural synapses and cardiac muscles
Desmosomes
“Provide structural integrity to cell, ““snap”” cytoskeleton of cell together
In cells that are exposed to physical stress”
What does 1/2 of the desmosome complex consist of?
Hemidesmosomes, tether to basement membrane of epithelial cells, attachign them to extracellular matrix ECM
Gap Junctions Structure & Function
-Built in 2 halves to connect intercellular gap
-Use channel gating to move ions, sugars, nucleotides and other molecules from one cell to another
-important for cardiac muscle contractions
Extracellular Matrix
Proteins in matrix provide structure and support
Special matrix: basement membrane
Basement Membrane
-Matrix found below epithelial cells and outside tissues
-Contains special collagen sheet the provides structure and barrier for epithelial cells
Types of proteins in the ECM
-collagen
-gibronectin
-elastin
-laminins
-proteoglycans
Collagen
Most common protein in the body
-Main structural protein in the ECM
-Exists as a triple helix –> crosslinks to form fibrils –> form collagen fibers.
-Body makes multiple types of collagen
Fibronectin
-Glycoproteins that connect cells to collagen matrices, functioning in cell adhesion
-Expressed as dimers, and bind to integrins
-Interactions with cytoskeleton causes fibronectin dimers to straighten and associate with other fibronectins –> fibrils @ cell surface
Elastin
-Responsible for giving elasticity to tissues, allowing them to return to their original shape after being distorted
-Has hydrophobic and hydrophilic regions that return to og shape
Laminins
-Provide adhesive substrate for cells
-Strengthens the ECM -Forms triple helical coils
-Forms cross-like structure and has multiple binding sites for ECM proteins
-Each end of “cross,” forms aconnection with a neighbouring molecule, helps it handle tension in multiple directions
Proteoglycans
-Hydrated gel that are resitatnt to compressive forces
-Critcal for structure like cartilage in our joints
-Consist of a portein polypeptide core and attached sugar residues
Types of Tissues of cells
Epithelial Tissues
Nervous Tissues
Muscle Tissues
Connective Tissues
Epithelial Tissues
-Anything that needs to enter the body must cross an
epithelial cell barrier (protects inside of body from environment) *exhange isnt the same for all epithelial tissues
-Epithelial cells and tissue can specialize
Epithelial Tissues in Digestive Tract
Specialized for absorption, secretion, and protection
-Line entire digestive system, from mouth to anus
Epithelial Tissues in Glands
Cells organize to form pocket-like structures which release secretions via ducts
2 types: Exocrine glands & Endocrine glands
Exocrine Glands
Release secretions to the outside of the body (ex. sweat glands)
*Endocrine glands have no ducts
What are the types of specialization of epithelial tissues
In skin
In glands
In digestive tract
Roles of Epithelial Tissues in Digestive Tract
- Produce & Excrete Proteins (via exocytosis)- proteins form layer of mucus to protect cel from itself and acidic enviroment
- Form Digestive Glands- (lumen) produce and release both digestive enzyme proteins and hydrochloric acid, which helps to break down food.
- Facilitated Transportation
hemidesomes
Tether to basement membrane attaching them to extracellular matrix ECM 1/2 of desmosomes consist of hemidesomes
5 main proteins in matrix
-collagen
-fibronectin
-elastin
-laminins
-proteoglycans
Muscle Tissues
-convert chemical and electrical signals into mechanical movement
-comprised of cells that specialize in contraction
-rich in actin-myoson networks
Skeletal Muscle
Responsible for moving the skeleton
Smooth Muscle
Lines digestive system, larger blood vessels, and anywhere else that requires contractile activity
Cardiac Muscle
-Found only in the heart -Pump blood throughout the body
Connective Tissues
fill spaces betwen cells (outside cell): provides mechanical strength and cushioning -make up large component of ECM
Types of epithelial tissue
-skin
-glands
-digestive tract
types of muscle tissues
-smooth
-skeletal
-cardiac
types of nervous tissue
-nerve cells
-glial cells
connective tissues examples
-elastin tissue
-bone ECM tissue
-cell: fibroblast
Stomach- Epithelial tissue
-inside of stomach lined with tissue
-protect underlying layers from digestive proteisn and acids released by epithelial glands
organs
structures where 2+ tissues types perform function together
Stomach- Muscle tissue
-under epithelial tissues, outside stomach
-contract to mix stomach contens and propel into intestine
Stomach- Nervous tissue
-Stomach wall contains nervous tissues
-control/coordiante muscle contractions & gland secretion
Body systems
2+ organs come together with purpose
Stomach- Connective tissue
-hold everything together
-provide shape to stomach
There are _ body systems total
11
Body system- cardiovascular system
Blood: carries nutrients/removes waste Heart: pump
Blood Vessels: Transport blood
Homeostasis
ability of a cell or organism to regulate and maintain its internal environment, regardless of the influences of the external environment
if external environment trys to alter internal enviroment, physiological mechanisms counter these changes
Homeostatic control system
Maintaining a set point via…
-sensor (detects environmental variable)
-integrator (comapres variables value to set point)
-effector (if variable is different from set point change is inititaed to restore it)
Homeostasis Example: Body Temperature
Sensor: Temperature-monitoring nerve cells always sensing temperature & sending info to thermoregulation centre
Integrator: Thermoregulation centre takes info from sensor and compares it to the set point. If sensed temperature is different from set point, thermoregulation centre sends signals to effector
Effector: Integrator signals two effectors: blood vessels in the skin to contract, minimizing heat loss, and skeletal muscles to rapidly contract, causing shivering, which generates heat.
Intrinsically Controlled System
-Sensor, integrator, and effector of a system are all located WITHIN a tissue
-Tissue can regulate its OWN internal environment
Extrinsically Controlled System
Regulatory mechanisms are OUTSIDE of the tissue or organ ex. body temperature regulation
*majority of homeostatic control systems rely on this system
Feedback loop
When an effector is causing a change that is sensed by the sensor, this is called feedback
Negative Feedback loop
-Change in environmental parameter causes corresponding effector to initiate response in opposite direction, restoring parameter to its set point
-Once set point’s achieved, the actions of the effector stop
Positive Feedback Loop
-Effector amplify the initial signal
-Not homeostatic
ex. child breastfeeding stimulates more milk production
