Exam I (2.1) Flashcards
Intro to Biology and Medicine
What is a biomaterial?
A nonviable material making up a medical device, participates in interactions with the body. (synthetics, biologics)
How do biomaterials interact with the body?
Via proteins that absorb onto the surface of the biomaterial, from serum (soluble) proteins to tissue (insoluble) proteins. This absorption process is rapid, competitve, and dynamic.
Proteins: structure
- Polymers of amino acids, connected by peptide bonds
- Defining differences in hydrophilicity/hydrophobicity
- Primary, secondary, tertiary, and quaternary structure (folding)
- Structural and functional, can be soluble or insoluble
Cell receptors
Those with specific affinities can recognize adsorbed proteins
Adsorption kinetics (phases)
1st Phase: Diffusion based, rapid, concentration-dependent/molecular weight-dependent
2nd Phase: Based on available surface, proteins adsorb in a monolayer
Vroman Effect
Protein adsorption is dynamic. Small proteins, due to faster diffusion, may attach in greater concentrations at first. However, later on, proteins with more surface affinity (even if larger/slower), dominate.
Protein Properties
Hydrophilicity, size, charge, and structural stability/rigidity (expand on each)
Surface Properties
Hydrophilicity, charge, topography, chemistry (expand on each)
Vivo vs. Vitro
In vivo, cells are constantly sensing and responding to the environment around them. By replicating the microenvironment in vitro, such as the pH levels, serum proteins, and temperature, can better study these interactions.
Microenvironmental factors
Soluble factors expressed/received, extracellular matrix, oxygen stress, cell-cell contact, mechanical environment
Mechanotransduction
- Cell adhesion allows for creation of a “bone structure” when integrin receptors bind to certain motifs in ECM proteins
- Actin cytoskeletal fiber can activate tensions within the cell, which leads to gene expression
Homeostasis in the body
- Continual balance of molecular synthesis and degradation
- All types of cells, tissues, and organs
Plasma membrane
Phospholipid bilayer! Expand on structure, and why it is protective and selective for the cell’s benefit.
Glycocalyx
A ‘hairy’ structure on the outer membrane, composed of sugar chains, that produce a negative net charge.
Active transport
- Specific receptors are needed, as well as ATP (energy)
- Often through vesicles
- Endocytosis, pinocytosis, transcytosis, phagocytosis, exocytosis
Signal Transduction
- Soluble factors
- Paracrine: growth factors, cytokines, etc. from other cells
- Endocrine: systemic factors in the blood
Synaptic: physical cell junctions
Cell differentiation
- Mediated through pluripotent stem cells
- Blastocyst is first formation of varying cell types
Blastocyst
- Endoderm, mesoderm, and ectoderm layers
- Leads to terminally differentiated cells that utilize different gene expression
Cell Differentiation terms
- Totipotent/pluripotent
- Multipotent
- Progenitor
- Precursor
- Terminally differentiated cells
How do tissues maintain homeostasis?
Old cells are regularly replaced
Liable tissues
- Contain multipotent stem cells that are constantly regenerating
- Ex: skin, blood, bone
Stable tissues
- Contain multipotent stem cells that can regenerate, but only if needed
- Ex: liver, pancreas
Permanent tissues
- Do contain stem cells, but have limited regeneration capacity
- Ex: nervous/cardiac tissue
Necrosis
- A cellular response to injury
- Occurs after trauma, chemical agent exposure, loss of blood, etc.
- Loses membrane integrity, ATP, then pH levels lower and acid builds up (swelling)
- No more protein production occurs, and the cell disintegrates
Apoptosis
- A cellular response to injury
- Triggered by cancerous activity, growth factor/cytokine changes, or immune system instruction
- Signaling cascades activate proteases that chew up cell into pieces, which are then phagocytosed by WBC’s
Tissue components
- Anisotropic!
- Arteries, arterioles, capillaries, venules, veins, lymphatic vessels
- Categories: epithelial, muscle, nerve bundle
Lymphatic system
Circulates fluid throughout the body
Extracellular Matrix (ECM)
- Deposited by cells during tissue development
- Fibroblasts, different proteins, basement membrane
- Fibrous structure via large adhesive proteins like collagen and fibronectin
- Has subunits, some of which can bind to integrins
- Elastin fibers allow for elasticity
Proteoglycans
- ECM component that is constructed of a protein core with sugar chains
- Can trap water into tissue and help distribute growth factors
ECM Functions
- Adhesion, mechanical support, cell orientation, cell differentiation and growth, work with soluble factors, and maintaining the microenvironment
Tissue Response to Injury
-Inflammation occurs first
- If stimulus is removed, then regeneration or repair can occur
- Regular repair involves clotting, then neutrophils, macrophages/lymphocytes accumulating, formation of a new capillary, and new deposited ECM
- Otherwise… fibrosis can occur (foreign body reaction)
Foreign Body Reaction
- After arrival/failure of neutrophils, giant cells form and attempt larger phagocytosis
- Upon failure, a fibrous capsule forms
- Essentially, this entails ECM very heavy in collagen to best ward off the foreign body
