Lecture 1 Flashcards
Homeostasis
A dynamic range of conditions that is achieved via positive and negative feedback. Any wavering outside of these set range of conditions introduces the setting for disease.
Positive Feedback
Actions done to facilitate (continue in the same direction) the disturbance. Not seen very often. Usually pathologic if seen (Ex: Tumor producing increased sodium).
Negative Feedback
Actions done to inhibit any further changes, and ultimately reverse the direction of the disturbance.
Physiologic Examples of Positive Feedback
-Parturition (Childbirth)
-Lactation
-Coagulation
Parturition and Lactation result in increased oxytocin.
Example of Negative Feedback
When we are hypotensive due to dehydration, the kidney senses this and activates the RAAS. Aldosterone causes us to hold onto sodium, which holds onto water. This increases our blood volume to increase our BP.
Purpose of Homeostasis
To maintain constant ECF composition through positive and negative feedback. Involves nutrient delivery (ions, glucose levels, etc), removal of metabolic waste (such as BUN), protection, and regulation of body functions.
Cell
The smallest unit that is capable of all the functions of life and is therefore the primary location of all physiologic and pathological processes in humans.
Structure
determines function
Function
determines structure
Plasma Membrane
Made up of a phospholipid bilayer. Purpose of it is to separate fluid compartments (separate ICF from ECF).
Organelle and Cell Membrane
Within a cell, all organelles have the same membrane. This allows for trafficking of materials between cell membranes and organelle membranes.
Ex: Phagocytes eat toxins, and form a membrane around toxin. It can then fuse with lysosomes, which have the same membrane. this allows the toxin to be broken down.
Plasma Membrane Makeup
- Hydrophilic Heads
- Chains of hydrocarbons (Fatty Acids)
- Cholesterols
- Proteins
- Carbohydrates
Hydrophilic Heads
Composed of glycerol (3 carbon compound) and phosphate (PO4). Phosphate carries a charge, which allows the head of the phospholipid to interact with water.
Chains of Hydrocarbons (Fatty Acids)
A component of the plasma membrane. A hydrophobic area attached to the glycerol. Allows for separation of fluids.
Cholesterols
A component of the plasma membrane that allows for membranes to be flexible and allows cells to move in a fluid fashion. The less of this, the more rigid the cell.
Proteins
Ion Channels, Receptors, etc. that can go through the membrane. Also serve as a point of attachment for the cytoskeleton to the membrane (Anchoring site).
Carbohydrates
A component of the plasma membrane that can be attached to proteins or to the phospholipids. Used for cell signaling and for identification. Helps recognize our cells as “self”. Also, there are receptors that allow the cell to move and be mobile.
Cytoskeleton
Gives support and structure to cells. Composed of microfilaments (thin fibers composed of actin), intermediate filaments (composed of actin), and microtubules (composed of tubulin). Regulate cell movement (migration, contraction, division), movement of vesicles within cells, and act in cell signaling processes.
Microvilli
Cytoplasmic extensions containing microfilaments which increase cell surface area for absorption.
Cilia
Long, slender extensions of plasma membrane; composed of microtubules (9 groups of pairs surrounding a central pair) anchored to cell surface with basal body; beat rhythmically to move fluids or secretions across cell (respiratory and reproductive tracts)
Centrioles
Cylindrical structures composed of microtubules (9 groups of triplets); two in each centrosome; control movement of DNA strands during cell division
Ribosomes
Made of ribosomal RNA (rRNA) and proteins. Can be bound (Rough ER) or free in the cytoplasm. The site of polypeptide synthesis.
Ribosomes
Synthesize polypeptides (the primary structure of proteins). Made of small and large subunits that sandwich a strand of mRNA to read the codon, and then tRNA comes to bind a new Amino Acid to the chain.
Free Ribosomes
Free in cytoplasm that are synthesizing polypeptides that will be used BY the cell, WITHIN the cell.
Bound Ribosomes
Found in the rough Endoplasmic Reticulum. Usually are synthesizing proteins that are then shipped out (ex: Epinephrine, acetylcholine, etc.)
Mitochondria
Have a dual membrane (Outer and inner; inner is folded into Cristae folds). The site of aerobic respiration (Kreb’s Cycle/Tricarboxylic Acid Cycle). Along the folds are oxidative enzymes that transfer proteins, electrons across the membrane (the site of oxidative phosphorylation).
Requires oxygen.
Mitochondria DNA
mtDNA is unique DNA inherited from the mother. Responsible for developing metabolic enzymes/proteins. Potential site for epigenetic (gene silencing) and metabolic modifications.
Reactive Oxygen Species (ROS)
Used for regulating cell metabolism, cell signaling, and inflammatory mediators. Formed in the mitochondria. The primary target of anti-oxidant systems. Ex: hydrogen peroxide.
Rough Endoplasmic Reticulum
Contains ribosomes on its membrane and consists of continuous, flattened cisternae; continuous with nucleus. Responsible for the processing of proteins that are synthesized by bound ribosomes. Post-translational modifications to the proteins occur here.
Smooth Endoplasmic Reticulum
Consists of continuous tubular cisternae; continuous with the rER. Responsible for the:
- synthesis of phospholipids and cholesterols for membranes
- synthesis of steroid hormones in testes and ovaries
- Synthesis and storage of glycerides in liver and fat cells
- Synthesis and storage of glycogen in liver and muscle cells
Smooth Endoplasmic Reticulum
Dysfunction of this is theorized to lead to fat deposits, which lead to the development of Alzheimer’s Disease, Parkinson’s, ALS, etc.
Golgi Apparatus
Composed of flattened cisternae. Inside the cisternae are enzymes that modify proteins, lipids, or cholesterols that are received from the ER. These enzymes modify, store, and ship cellular products.
Golgi Apparatus
UPS or Fedex
- Renew membranes
- Form Excretory Vesicles (exocytosis) and vesicles for transport of products within cells
- Form complex carbohydrates
- Antigen presentation and histocompatibility
- Form lytic vesicles for detoxification, degradation, and digestion of cell products.
Lysosome
Lytic enzyme capable of metabolizing organic molecules (recycling, excising, or autolysis)
Peroxisome
Lytic enzyme capable of catabolizing fats and neutralizing toxins (PPAR).
Nucleus
Fluid nucleoplasm containing proteins, enzymes, nucleotides, and DNA surrounded by a double membrane.
Nucleolus
Nucleotides needed to synthesize RNAs or transcribe more DNA.
Nucleus
- Stores genes and gene-associated enzymes
- Regulates cell physiology both acutely (metabolically) and chronically (gene expression)
- Determines cell structure and function
- DNA is stored in a loosely condensed form called chromatin
- Epigenetic and Genetic modifications take place here
Intercellular Junctions
Cells have sides to them. They will face one side and anchor another side, stacked in tightly with each other. When cells are stacked in together (largely true for epithelium), they have junctions that bind them together.
Tight Junctions
Occur towards the apical membrane (top of the cell); have the highest strength.
Desmosome and Zona Adherens
Intercellular junctions that occur in the middle of the cell, and are largely for strength and holding things together. Not as strong as tight junctions.
Gap Junctions
A type of intercellular junction that contains pores made of proteins that allow for material to move from one cell to another. Allow small molecules passage. These are important for cell to cell communication. Ex: used in cardiac cells
Hemidesmosome
An intercellular junction that adheres cells to whatever their substrate is (basal lamina)
Apical Side
The side of the cell that is facing outward (to its environment, or facing the tube it’s in)
Basolateral
The side of the cell that is anchored to connective tissue.
Epithelial Tissue
Cover, protect, filter, absorb, and secrete. Has sides (apical and basolateral). Moves things across it.
Tissue
The level we “see” disease at. Dysfunction at the cellular level leads to changes in morphology of the tissue. Ex: Chronic GERD leads to Barrett’s esophagus. Esophageal tissue begins to resemble gastric epithelium.
Muscular Tissue
Extensible and elastic. Able to contract. Can produce heat. 3 Different types: Skeletal, cardiac, and smooth muscle.
Nervous Tissue
Can increase action potentials; sends electrical signals to control body functions
Connective Tissue
Extensible and elastic. Connects tissues together both physically and spatially. Important for support.
Ex: Blood
Epithelial Tissue
Found in the lining of tubes, ducts, and the outer surface of the body. Forms membranes and glands.
Cuboidal Epithelium
Found in the renal tubules. Important for taking things in/out of a cell layer. Ex: Kidneys filter out most of the Na and glucose, and what we need is reabsorbed in the proximal tubule.
Cilia
Found in the cells lining the trachea. Purpose is to move mucus up towards the oropharynx. An example of epithelial cells offering protection.
Muscular Tissue
Can be:
- extended (Stretched)
- elastic (returns to original state)
- excitable: action potentials or ion gradients cause them to do work
- contractile: Produce measurable force
Skeletal Muscle
Has multiple nuclei with extensive mitochondrial networks. Excited by a peripheral nerve motor neuron.
Cardiac Muscle
Has gap junctions that allow cells to be in sync. Excitable via ANS.
Smooth Muscle
Dependent on being close to each other, have to be touching to function as they communicate with each other about what’s going on in environment.
- Function: Maintaining tension. Ex: maintaining BP with changes in position such as sitting, standing, etc.
- Lines most of the hollow organs of the body
- Excitable via ANS
- Very susceptible to changes in environment.
Nervous Tissue
- Carry electrical impulses (Generate action potentials)
- Sensory or motor control
- Secrete Neurotransmitters
- Maintain their own internal environment
Neurotransmitters
Released from neurons to post-synaptic cell which has a receptor, tells cell what to do. Governs and regulates all body functions.
Glial Cells
A type of nervous tissue that maintains its internal environment. The protectors of the CNS. If something breaks the blood/brain barrier, these are activated and devour it.
Astrocytes
A type of nervous tissue that forms the blood/brain barrier and regulates glucose levels.
Swan Cells
A type of nervous tissue that is responsible for myelinating axons so that they can conduct impulses.
Connective Tissue
Matrix of semi-gelatinous fluid with fibers like collagen and elastin, and dissolved particles. Offers strength and rigidity to the tissues; supports the body. Connects and supports all body tissues.
Connective Tissue
- Cartilage: supportive and structural.
- Ligaments, tendons: Connects body tissues to other body tissues
- Loose connective tissue: fat, adipose, etc.
- Collagen: thick fibers.
- Blood
