Midterm 1 Flashcards
What is anatomy
things you can see, structure, memorisable
What is physiology
function of the body, and how these functions are preformed, need to understand
Reductionism?
theory that reduces complex phenomena to the most basic parts
3 main points of cell theory
1- Cells can only come from other cells
2- Cells are the smallest unit of life
3- All living organisms are made from cells
What are the requirements for life?
- The ability to maintain homeostasis
- To grow, breathe, etc.
- Reproduction
Plasma membrane
Made of double layer of phospholipids, serves as external cell barrier and maintains resting potential/ homeostasis
Mitochondria
Site of ATP synthesis, the powerhouse of the cell
Ribosomes
Dense particles, site of protein synthesis
Rough endoplasmic reticulum
A membranous system with ribosomes synthesizes phospholipids
Smooth endoplasmic reticulum
Membranous system without ribosomes, lipid and steroids synthesis
Golgi apparatus
Flattened membranes, packages and segregates proteins
Peroxisomes/ lysosomes
Membrane sacs containing enzymes, help to break down and detoxify toxic substances, the sight of intracellular digestion
Microtubules
Cylindrical structure, supports and shapes the cell
Intermediate filaments, microfilaments
Protein fibers, stabilize cytoskeletal element, fine filaments involved in muscle contraction
Centrioles
Paired cylindrical bodies, during mitosis form spindles and asters
Cilla, flagellum
Short cell surface projections that create a current to propel substances, Like a cillum but longer, propels the cell
Microvilli
Tubular extensions of plasma membrane, increase surface area for absorption
Nucleus/ Nuclear envelope
Largest organelle, control center of the cell, Double membrane structure with pores, separates nucleoplasm from cytoplasm
Nucleolus
Dense spherical bodies, site of ribosome manufacturing
Chromatin
Threadlike material composed of DNA and proteins, DNA constitutes the genes
4 Basic kinds of tissue
Connective, Epithelial, Nervous, Muscle
Epithelial Tissue
Found along the lumen or skin, sits along the basement membrane
Functions to protect, absorb, filter, excrete, secrete, and has sensory reception
2 kinds of epithelia?
Covering and lining epithelia, Glandular epithelia
Epithelia is what kind of barrier?
Selective barrier (allows nutrients but not toxins)
5 Features of epithelial tissue
- Polarity
- Specialized intercellular contacts
- Supported by connective tissues
- Avascular but inverrated
- Regeneration
Polarity?
Apical surface (faces lumen)
Basal surface (towards the body, connects to the basal lamina)
Loss of cell polarity is a hallmark of cancer
Specialized intercellular contacts
Form juctions/ barriers
1. Tight junctions
2. Adherens Junctions
3. Desmosones
4. Gap junctions
Supported by connective tissues
Sits on connective tissue (basement tissue)
Basal lamina and Reticular lamina
Avascular but inverrated
No blood vessels, nutrients and O2 from connective tissues
Regeneration
High regenerative capacities, requires nutrients and cell division for healing
How are epithelia classified
Number of cell layers and shape of cell
Simple squamous, 2 categories
Single layer of flattened cells, sparse cytoplasm, allows materials to pass by diffusion and filtration (blood vessels, lining of heart)
1. Endothelium
2. Mesothelium
Simple columnar
Single layer of tall closely packed cells, can have microvilli or cilla
(digestive tract, stomach to rectum, etc.)
Simple cuboidal
Centrally located, round nuclei, can have cilia
(kidney tubules, ducts)
Pseudostratified Columnar
Single layer of differing heights, nuclei seen at different levels, Secrete substances, ciliated can be found in trachea and upper respiratory system
What is stratified epithelia?
Two or more layers, durable
Stratified Squamous Epithelium
Most widespread, external part of the skin, entends a small amount into external ducts
Protects underlying tissue subject to abrasion
Can be keratinized or non
Stratified Cuboidal Epithelium:
Quite rare, mostly found in ducts of larger glands, functions to protect and secrete
Stratified Columnar Epithelium:
Also a very limited distribution in body, found only pharynx, male urethra, glandular ducts
Usually occurs at transition areas
Transitional Epithelium
Can be stratified squamous/ cuboidal, basal cells cuboidal or columnar
Covered in “plaques”
Stretches/ expands readily and permits distension of urinary organ
Glandular Epithelia
One or more cells that make and secrete an aqueous fluid called secretion
What is Glandular Epithelia classified by?
- Site of product release:
Endocrine: internally secreting (hormones)
Exocrine: externally secreting (sweat) - Relative # of cells forming the gland
Unicellular (goblet cells ) or multicellular (salivary)
Endocrine glands?
Ductless, release hormones into the blood to repsond in a characteristic way
(ex: thyroid, pancreas, ovaries)
Exocrine glands?
Secretions onto body surfaces or into body cavities, through the use of ducts
(ex: sweat, mammary, prostate)
Unicellular glands?
Made of mucous or goblet cells, Found in linings of intestinal and respiratory tract, all produce mucin
Multicellular glands?
Composed of a duct (acinus) and secretory unit
Classified by structure and mode of secretion
3 Mechanisms of secretion in glands?
- Merocrine (eccrine) glands secrete by exocytosis
- Apocrine glands accumulate product, only apex of cell breaks off
- Holocrine glands entire secretory cell ruptures
What is connective tissue/ main functions?
Major functions of tissues include binding and support, insulation, storing nutrients, transporting substances
What are the 2 features of connective tissues?
Common origin: derived from mesoderm
Sparse cells embedded in extracellular matrix (ECM
4 Classes?
CT Proper, Bone, blood, Cartilage
What is bone tissue? What does it do?
Hard calcified matrix containing many collagen fibers, very well vasculairzed
Supports and protects, provides levers for muscles to act on, stores calcium and other minerals, marrow inside site for blood cell formation
What is blood tissue? What does it do?
Red and white blood cells in fluid matrix (plasma and platelets)
Transports gases, waste, nutrients, other substances
6 kinds of connective tissue?
Loose: Areolar, Adipose, Reticular
Dense: Regular, Irregular, Elastic
What is Cartilage? what does it do?
80% water, packed collagen fibers and sugar proteins, made of tough flexible fiber, but lacks nerve fibers
Matrix secreted from chondroblasts (during growth), and chondrocytes (adults)
Avascular
3 Kinds of cartilage?
Hyaline, Elastic, Fibrocartilage
Plasma membrane lipids?
Lipid bilayer is 75% phosopolipids, 5% glycolipids, 20% cholesterol
Phospolipids
Amphipathic (hyrdo phobic/phyllic), Prevented charged species from crossing plasma membrane, impermiable to water and ions and molecules
What are plasma membrane proteins?
Specialized proteins float in plasma membrane, constantly changing patterns
Referred to as fluid mosaic model
2 Classes of membrane proteins?
Integral membrane proteins (function as transport proteins)
Peripheral membrane proteins (function as enzymes, signal transduction, scaffold proteins)
3 Functions of membrane proteins?
- Physical barrier
- Determines which substances cross
- Communication
Function of Glycocalyx?
Carbs on glycolipids/proteins protrude from cell surface
Every cell has different patterns of sugar coating, functions as bio. marker and allows immune cells to recognize ‘self” from “nonself”
Gap junctions?
Transmembrane proteins (connexons) form tunnels or gaps between cells that allow small molecules to pass
Used to spread ions, simple sugars, and allow electrical signals to be passed quickly
What is diffusion? What factors affect it?
Movement results in collisions, and when molec. In high concentration hit they scatter to lower concentration areas
1. Molecular size
2. Temp.
3. Concentration
Simple diffusion vs. facilitated diffusion?
Simple: Non polar lipid-soluble substances diffuse directly (oxygen, fatty acids, etc.), area of high conc. to low
Facilitated: Larger non-lipid soluble or polar molecules can cross membrane only with assistance of carrier molecules
Can be carrier meditated or channel meditated
Carrier vs. Channel mediated diffusion?
Carrier: Certain hydrophilic molecules (glucose, amino acids) are transported passively down the concentration gradient by carriers
Channel: Some integral membrane proteins form channels that allow ions to diffuse across the membrane. Ion channels show selectivity based on channel diameter, charged residues, and hydration
What is osmosis?
Osmosis is name for movement of water, moves from high to low
The more solutes inside a cell, the bigger the pull on water
Hydrostatic vs. osmotic pressure.
Hydrostatic pressure: outward pressure exerted on cell side of membrane caused by increases in volume of cell due to osmosis
Osmotic pressure: inward pressure due to tendency of water to be “pulled” into a cell with higher osmolarities
When 2 pressures are equal…
no further net movement of water occurs
What is osmolarity? What is tonicity?
Osmolarity is a measure of the osmotic pressure of a given solution.
Tonicity is a measure of the osmotic pressure gradient between two solutions separated by a permeable membrane
Hyper, osmo, iso
Hyper-osmostic, iso-osmotic, and hypo-osmotic, refer to concentration of all solutes, penetrating (p) and non-penetrating (np)
Hypertonic, isotonic, and hypotonic refer to the concentration of non-penetrating solutes
What is mOsm for cell at rest?
300 mosm
What is carrier-mediated transport? What 3 factors affect it?
Integral membrane transport proteins move solutes via changes in their shape
1. Extent to which binding sites are “saturated” (how full they are)
2. # of transporters in the membrane
3. Rate which conformational change occurs
2 Types of mediated transport?
Facilitated diffusion
Active transport
Primary active transport?
ATP hydrolisis provides energy for primary active transport
Transporters are ATPases (enzymes that hydrolyze)
How does ATP pump work? (5 steps)
- transporter (with bound ATP) binds 3 Na+ on inside of cell (low affinity for K+).
- ATPase activated. Auto-phosphorylation.
- Conformational change and release of Na+ to outside.
- Increased affinity for K+ allows two K+ to binds
- Dephosphorylation, Release of K+ to inside
Chemical and Electrical Gradient:
Na/K ATP establishes a electrochemical gradient:
Can be used to do work (transport of solutes)
Basis for electrical impulses in neurons
Secondary Active transport:
Uses stored energy of electrochemical gradient to move ion
Movement of ion down its electrochemical gradient
Symporter and antiporters
Cotransport (symport) : ion and second solute cross membrane in same direction
Countertransport (antiport): ion and second solute move in opposite directions
Phagocytosis vs. Pinocytosis?
Phago- cell eating, Pseudoppodia surrounding particles with vesicle nd pull into cell
Pino- Fluid phase endocytosis, pm infolding brings in ecf
Receptor mediated Endocytosis
Endocytosis of specific ligands, Ligands become concentrated in clathrin coated pits
Signal Transduction (cell signaling)
Receptors bind ligands (neurotransmittsers, hormones, etc.) which will cause a cascade, One ligand can cause different actions depending on where it binds to
G protein-coupled receptors:
G proteins affect ion channels, activate enzymes, or cause release of 2nd messengers
Receptors interact with G proteins, which bind GDP and GTP
Divisions of the nervous system
CNS (brain, spinal cord)
PNS ( everything else)
Somatic/ sensory (12 cranial, 31 spinal)
Autonomic (sympathetic [fight or flight], parasympathetic [rest and digest])
4 Characteristics of a neuron?
Excitable cells (conduct electrical impulses)
Extreme longevity
Postmitotic, do not undergo mitosis
High metabolic rate, require oxygen and glucose
Cell body?
Spherical nucleolus, most cell bodies in CNS, some in PNS
Nuclei: neuron cell body in CNS
Ganglia: clusters of neuron cell bodies in PNS
Dendrite and axon?
Receptive region of neuron, convey incoming messages to soma, CNS neurons have dendritic spines
Starts at axon hillock, and occasionally branches off into axon collaterals. Distal ends called axon terminals or terminal boutons
3 Classes of neurons?
Afferent- Towards CNS from receptors
Efferent- From CNS to effector
Interneuron- receive impulses and split towards CNS and effector
Glial Cells?
Supporting cells CNS and PNS, 90% of cells in CNS
Surround the soma, axon, dendrites, provide physical and metabolic support
Astrocytes
Spacial buffering of extracellular K, neurotransmitter uptake and release, provide metabolic support
Mediate neurovascular coupling, nervous system repair
Oligodendrocytes
Myleinate multiple CNS axons, composed of highly compacted layers
Speeds up conduction
Schwann cells
Myelinte PNS Axons, nuclei closely opposed to axon
Pain and temp. fibers are unmyelinated
Microglia
Macrohpage like cells that reside in CNS, proliferate and activate in response to injury
Na/K pump summary?
High Na outside cell, high K inside
Pump uses 40% of ATP produced by cell
At steady state ions flux through “leak” channels
Na,K,Cl present highest concentrauins, NA &Cl out, K in
What is the nerst equations?
Describes the equilibrium potential for ion species, Eion = 61/Zlog (Co/Ci)
Charges of membrane surfaces?
- inner, + outer
3 types of gated ion channels?
- Chemically gated (ligand-gated)
Open only with binding of specific chemical - Voltage gated channels
Open and close to response to changes in membrane potential - Mechanically gated
Open/ close in response to physical deformation of receptors, as sensory receptors
Depolarization and hyperpolarization?
decrease in mebrane potential (towards zero), Inside becomes less negative, Allows Na to come in
increase in membrane potential (away from zero)
Inside of membrane becomes more negative
Cl comes in, K goes out
What is a graded potential?
Short lived local changes, generated in response to opening some kind of gated channel
A weak stimulus will give smaller response, stronger will give larger
What is an action potential?
Principle way to send signals over long-distance communication, will not decay with distance
What is threshold potential?
Threshold when action potential is stimulated (~55 mv), all aps generated the same, Threshold indicates whether incoming stimuli are sufficient to generate action potential
Synaptic connections (3 types)
Axosomatic, axodentrtic, axoaxonic
Types of the synapse (2)
Chemical & electrical
Chemical synapse
Neurotransmitters, stored in vesicles, relay information to postsynaptic neuron across synaptic cleft
Electrical Synapse
Cytoplasm of adjacent neurons electrically coupled by gap junctions
Rapid communication (uni or bi directional)
What is the transmission delay
(0.3-0.5 msc)
5 steps at chemical synapse
- AP arrives at terminal
- Ca channels open, Ca influx causes synaptic vesicles to fuse with PM, release NT by excoytosis
- NT diffuses across synaptic cleft, binds to postsynaptic receptors
- NT Binding opens ion channels
- NT terminated by reuptake, diffusion, enzymatic degradation
2 Postsynaptic potentials
Excitatory, inhibtatory
Excitatory Synapses?
Na influx greater in K, resulting in depolarization
Glutamate main excitatory NT, can bind to AMPA,NMDA, Kainate
Inhibitory synapses?
IPSP moves membrane potential further away (more negative) from threshold
Glycine and Gaba are inhibitory NTs
Cloride will counteract the Na/K channels to hold cell at resting potential
What is synaptic integration?
Neurons undergo many ESPS and IPSP
Recive inhibatory/ excitatory input
Temporal vs. Spatial summation?
Temporal- converts a rapid series of weak pulses from a single source into one large signal
Spatial- several weak signals from different locations are converted into a single larger one
Developmental aspects of neurons
Neural tube: Becomes CNS
Neural crest: Forms PNS
Proliferation- mitosis to form neuroblasts
Migration- to final positions
Connection- axon outgrowth, pathfinding, synapse formation
Growth cone: allows axon to sense environment
What does skeletal muscle do?
Responsible for movements
Largest tissue by weight (40-50% body mass)
Stabilize position
Regulate organ volume
Move substances
Produce heat
4 key properties?
Excitability
Contractibilty
Extensibility
Elasticity
3 kinds of skeletal tissue?
Skeletal, cardiac, smooth
3 main internal structures?
Epimysium: surrounds whole muscle
Perimysium: surrounds fasucles, conduit for nerves
Endomysium: separates, insulates
transverse (T) tubules
Extend into cytoplasm, continuous with ECF, surround myofibrils
Function: Conduct APs from surface to interior
Sarcoplasmic reticulum?
Smooth ER around myofibrils
Initiates contraction by releasing Ca when prompted by T tubules
2 types of myofibrils?
Thin filament- actin
Thick filament- myosin
Cross bridge cycle 1
Atp is bound to myosin head
Myosin is its in low energy conformation (45 degree) and isnt attached actin
Cross bridge cycle 2
Myosin is ATPase
ADP and Pi remain in ATP binding site
Leaves mysoin head in HIgh E state (90 degree
Cross bridge cycle 3
Energized myosin binds to myosin binding sites on actin
Cross bridge cycle 4
Myosin head binding to thin filament causes change that releases ADP and P, and changes orientation of thick filament to low E state (45 degree)
Transition to E produces a force of filaments called Power Stroke
Myosin head rotates
Overview/Regulation of Contraction
Cross bridge movements mean thick and thin filaments sliding
Movements shorten sarcomere
Width of I-band decreases and thick filaments slide
Sliding filament model predicts the repetitive formation of cross bridges
Contraction driven by ATP hydrolysis but triggered by Ca release
Contraction requires Ca entry into cyoplasm, relaxation requires removal
Neuromuscular Junction
Skeletal muscles inervated by motor neurons
NMJ is point of contact between motor neuron and muscle fiber
Summary events at the neuromuscular junction
Ca entry releases acetylcholine, ACH binds to receptors, binding causes ion channels to open (depolarization)
3 phases of muscle twitch?
Latent phase, Contraction phase, relaxation phase
What is a motor unit?
A motor neuron and all the muscle cells it stimulates
2 types of muscle contraction?
Isotonic, tension exceeds load
Isometric, load exceeds tension
Excess atp used…
to synthesize creatine, used to build muscle and for energy, excess creatine is sign of muscle damage
