Main Final Exam Content Flashcards
6 Steps of Protein Synthesis
- Rough ER synthesises proteins to be secreted to exterior or to be incorporated into plasma membrane or other cell components
- Smooth ER packages protein into transport vesicle, which bud off and travel to Golgi complex
- Transport vesicle fuses with Golgi complex and empties contents into Golgi sac
- Proteins travel through layers of the Golgi complex
- Secretory vesicles containing finished protein bud off Golgi complex and remain in cytosol to store until signalled
- On appropriate stimulation, secretory vesicles fuse with plasma membrane, open and empty protein into cells exterior for use
Describe Desmosomes (Cell Junctions)
- join two cells together without touching
- bound by glycoprotein filaments attached to thickened cytoplasm
- prevents tearing of the tissue when stretched
- e.g. epidermis cells, cardiac cells
Describe Tight Junctions (Cell Junctions)
- membrane proteins from adjacent cells fuse together
- prevents passage of molecules between adjoining cells
- e.g. nephrons in kidney, intestine cells
Describe Gap Junctions (Cell Junctions)
- tunnels from one cell to another
- transport of ions and small molecules between cells
- e.g. some nervous system cells, cardiac cells
Describe Passive transport and list the 3 different types of passive transport
Passive transport = doesn’t require energy (ATP)
- simple diffusion
- osmosis
- facilitated diffusion (channels & carriers)
Describe Active transport and list the 3 different types of active transport
Active transport = requires energy (ATP)
- primary active transport
- secondary active transport
- vesicular transport (endocytosis & exocytosis)
Describe Diffusion
- movement of molecules from an area of high concentration to an area of low concentration
- molecules diffuse down a concentration gradient in order to reach equilibrium
Describe Osmosis
- diffusion of water across a selectively permeable membrane
- movement of water from an area of low solute concentration to an area of high solute concentration
- osmolarity = number of solute particles per litre of solution
- most body fluids are 300 mOsm/L
Describe Facilitated Diffusion
- down concentration gradient
- does not require ATP
- two types: channel or carrier
Describe Channels (Facilitated Diffusion)
- transport of small ions (Na, K, Ca, Cl) and water (aquaporins)
- can be open or closed
- open to both sides of membrane simultaneously
- allows rapid transport of molecules
Describe Carriers (Facilitated Diffusion)
- transport for larger hydrophilic molecules (glucose and amino acids)
- always open
- only open to one side of membrane
- allows slower movement of molecules
List and describe 5 things that affect Diffusion Rate
- The size of the concentration gradient
- bigger gradient = faster diffusion - Membrane surface area
- bigger surface area = faster diffusion - Size of the molecule
- small molecules diffuse more quickly than large molecules - Diffusion distance
- decreasing diffusion distance = increasing diffusion rate - Lipid solubility of the molecule
- whether the molecule can pass through the lipid part of the membrane
Describe Tonicity
Tonicity = the ability of a solution to change the shape of a cell
Isotonic = solution concentration is equal to ICF concentration = no cell change
Hypertonic = solution concentration is higher than ICF concentration = cell shrivels/shrinks
Hypotonic = solution concentration is lower than ICF concentration = cell bursts/swells
List the 6 Steps of Primary Active Transport: Na/K ATPase
- Binding of cytoplasmic Na to the pump protein stimulates phosphorylation of ATP
- Phosphorylation causes the protein to change its shape
- The shape change expels Na to outside and extracellular K binds
- K binding triggers release of the phosphate group
- Loss of phosphate restores the original conformation of the pump protein
- K is released and Na sites are ready to bind Na again,; the cycle repeats
List the 3 Steps of Secondary Active Transport: Sodium Glucose Transport
- Na/K pump creates ion gradient
- Na - glucose symport transporter loading glucose from ECF
- Na - glucose symport transporter releasing glucose to the cytoplasm
Describe Vesicular Transport
- transfer of materials between ECF and ICF within vesicles
- requires energy from ATP
- endocytosis = vesicular transport into cell
- exocytosis = vesicular transport out of cell
List the 7 Steps of Receptor - Mediated Endocytosis
- Target molecules (ligands) bind to receptors in plasma membrane
- Areas coated with ligands form deep pockets in plasma membrane surface
- Pockets pinch off, forming endosomes known as coated vesicles
- Coated vesicles fuse with primary lysosomes to form secondary lysosomes
- Ligands are removed and absorbed into the cytoplasm
- The lysosomal and endosomal membrane separate
- The endosome fuses with the plasma membrane and the receptors are again available for ligand binding
List the 3 Steps of Pinocytosis (Endocytosis)
- Solute molecules and water molecules are outside the plasma membrane
- Membrane pockets inward, enclosing solute molecules and water molecules
- Pocket pinches off as endocytic vesicle containing sample of ECF
List the 5 Steps of Phagocytosis (Endocytosis)
- Cell engulfs large solid particles (e.g. bacterium)
- The cell extends pseudopods (cytoplasmic extensions) around the object
- The resulting vesicle (phagosome) can fuse with a lysosome containing enzymes
- The enzymes break down the object
- The object is then killed and digested within the vesicles
Describe Exocytosis
- reverse of endocytosis
- secretory vesicles are released from the Golgi complex. They bind to the cell membrane, releasing their contents
Describe Membrane Potential
- difference in electric potential between the interior and the exterior of a biological cell
- separation of opposite charges across the membrane
- the resting membrane potential is negative because the Na/K ATPase pumps 3Na out and 2K in
- resting membrane potential is approximately -70mV in a human neuron
Describe the Effect of Na/K pump on membrane potential
- Na/K pump transports 3Na out for every 2K it transports in
- most of the membrane potential results from the passive diffusion of K and Na down concentration gradients
Describe an Action Potential
- occurs when the membrane potential of a specific cell location rapidly rises and falls: this depolarisation then causes adjacent locations to similarly depolarise
- action potentials assist in the propagation of signals along the axon
List the 5 Steps of an Action Potential
- Voltage gated ion channels closed
- Some Na channels open, Na in
- Many Na channels open, Na in
Depolarisation: decrease in potential; membrane less negative - K channels open, K out, Na inactivated
Repolarisation: return to resting potential after depolarisation - Na/K ATPase restore Na and K concentrations during this time it is more difficult to generate AP.
Hyperpolarisation: increase in potential; membrane more negative
Describe Graded Potential
- local changes in membrane potential that occur in varying grades or degrees of magnitude or strength
- vary in magnitude
- proportional relationship between graded potential and triggering event
List the 9 Steps of Synaptic Neurotransmission
- Nerve implies is propagated along the pre-synpatic neuron until it reaches the pre-synaptic membrane
- Depolarisation causes Ca to diffuse through channels in the membrane
- This causes vesicles containing neurotransmitter to fuse with the membrane
- Neurotransmitter is released into the synaptic cleft via exocytosis
- Neurotransmitters diffuse and bind to receptors on the post-synaptic membrane
- Binding of neurotransmitter to receptor open Na channels
- Na diffuses down the concentration gradient into the post-synaptic membrane, causing it to reach threshold potential (-50mV)
- An action potential is triggered in the post-synaptic membrane and propagated along
- Neurotransmitter is broken down
Describe the 2 types of Direct Intercellular Communication
- Gap Junctions
- specialised intercellular connection between a multitude of cell types
- they directly connect to the cytoplasm of two cells, which allows various molecules, ions and electrical impulses to directly pass through a regulated gate between cells - Transient Direct Linkup of Cells Surface Markers
- direct linkup of cells surface markers
- cells are not in constant contact with each other
Describe the 4 types of Indirect Intercellular Communication Via Extracellular Chemical Messengers
- Paracrine Secretion
- local chemical messengers
- effect is exerted only on neighbouring cells in the immediate environment of their site of secretion - Neurotransmitter Secretion
- short range chemical messengers
- in response to electrical signals (APs) - Hormonal Secretion
- long range chemical messengers specifically secreted into the blood by endocrine glands in response to an appropriate signal - Neurohormone Secretion
- hormones released into blood by neurosecretory neurons
- respond to and conduct electrical signals
- distributed through blood to distant target cells
Describe Skeletal Muscle
- striated muscle tissue
- under voluntary control of somatic nervous system
- most skeletal muscles are attached to bones by bundles of collagen fibres known as tendons
- abundance of mitochondria, as is expected with the high energy demands of a tissue as active as skeletal muscle
Describe A and I bands
- myofibril displays alternating dark bands (A bands) and light bands (I bands)
- parallel line up of A and I bands leads to striation
- contraction of A and I bands leads to muscle contraction
List the 7 Steps of Excitation - Contraction Coupling
- Acetylcholine released from the axon terminal binds to receptors on the muscle cell plasma membrane
- An AP is generated and travels down the T-tubule
- Ca is released from the sarcoplasmic reticulum in response to the change in voltage
- Ca binds to troponin; cross-bridges form between actin and myosin
- Acetylcholinesterase removes acetylcholine from the synaptic cleft
- Ca is transported back into the sarcoplasmic reticulum
- Tropomyosin binds active sites on actin causing the cross-bridge to detach
Describe Twitch Summation
- addition of a second twitch, resulting in greater tension and results from stimulating the muscle before it has a chance to relax completely
Describe Tetanus
- prolonged contraction without relaxation and results from repeating stimulation before the muscle has a chance to relax at all
Describe Smooth Muscle
- found in the walls of hollow organs and tubes
- contraction exerts pressure on and regulates forward movement of the contents of structures
- no striation
Describe Cardiac Muscle
- found only in heart
- striated
- has clear length-tension relationship
- many mitochondria and myoglobin
- have T-tubules
- slender and short
- displays pacemaker activity
- interconnected by gap junctions
- joined in a branching network
- cardiac APs last much longer before repolarising
Describe the 3 Steps of Receptor Potential in Specialised Afferent endings
- In sensory receptors that are specialised afferent neuron endings, stimulus open stimulus-sensitive channels, permitting net Na entry that produces receptor potential
- Local current flow between depolarised receptor ending and adjacent region opens voltage-gated Na channels
- Na entry initiates action potential in afferent fibre that self-propagates to CNS
Describe the 6 Steps of Receptor Potential in Separate Receptor Cell
- In sensory receptors that are separate cells, stimulus opens stimulus-sensitive channels, permitting net Na entry that produces receptor potential
- This local depolarisation opens voltage-gated Ca channels
- Ca entry triggers exocytosis of neurotransmitter
- Neurotransmitter binding opens chemically gated receptor-channels at afferent ending, permitting net Na entry
- Resultant depolarisation opens voltage-gated Na channels in adjacent region
- Na entry initiates action potential in afferent fibre that self-propagates to CNS
Describe Labelled Line Theory
= the CNS determines the type of stimulus based on receiving input from all sensory cells activated by that stimulus
i.e. the brain can decode the type and location of stimulus by determining which ascending pathway the information travelled up via
Describe Tonic Receptor
- do not adapt, or adapt slowly
- these receptors are useful when it is valuable to maintain information about a stimulus
- Examples: muscle stretch receptors and joint proprioceptors
Describe Phasic Receptor
- rapidly adapting receptors
- quickly adapts by no longer responding to a maintained stimulus
- these receptors are useful when it is important to signal a change in stimulus intensity rather than to relay status quo information
- Examples: Pacinian Corpuscle
Describe Tactile Receptors and list the 5 types
- sensory input from these receptors informs the CNS of the body’s contact with objects in the external environment
- types:
1. Hair receptors
2. Merkel’s disc
3. Pacinian Corpuscle
4. Ruffini Endings
5. Meissner’s Corpuscle
Describe Hair Receptors
- rapidly adapting
- senses hair movement and very gentle touch
Describe Merkel’s Disc
- slowly adapting
- detects light, sustained touch and texture
Describe Pacinian Corpuscle
- rapidly adapting
- responds to vibrations and deep pressure
Describe Ruffini Endings
- slowly adapting
- respond to deep, sustained pressure and stretch of skin
Describe Meissner’s Corpuscle
- rapidly adapting
- sensitive to light, fluttering touch
List the 4 Steps of Chemically Gated Receptor Channels
- Extracellular messenger binds to receptor
- Binding of messenger leads to opening of channel
- Ions enter
- Ion entry brings about desired response
List the 4 Steps of Receptor Enzymes
- Extracellular messenger binds to receptor
- Binding of messenger leads to activation of protein kinase enzyme site
- Protein kinase activates designated protein
- Active designated protein brings about desired response
List the 7 Steps of G-Protein Coupled Receptors
- Extracellular (first) messenger binds to receptor
- Receptor activates G-protein
- G-protein activates effector protein
- Effector protein produces second messenger
- Second messenger activates protein kinase
- Protein kinase activates designated protein
- Active designated protein brings about desired response
List the 9 Steps of Intracellular Receptors
- Free lipophilic hormone diffuses through plasma membrane
- Hormone binds with intracellular receptor specific for it
- Hormone receptor complex binds with DNAs hormone response element
- Binding activates gene
- Activated gene transcribes mRNA
- New mRNA leaves nucleus
- Ribosomes “read” mRNA to synthesis new proteins
- New protein is released from ribosome and processed into final folded form
- New protein brings about desired response
List and describe 7 points of comparison between the Nervous System and Endocrine System
- Wired or Wireless
NS= anatomically linked to target cells (wired)
ES= anatomically separated from target cells (wireless) - Type of Chemical Messenger
NS= neurotransmitter, neurohormone
ES= hormones - Distance of Action
NS= short distance (across the synaptic cleft)
ES= long distance (into blood) - Specificity
NS= specificity depends on the closeness of neurons and target cells
ES= specificity depends on the presence of the target receptor - Speed of Response
NS= rapid (ms)
ES= slow (mins to hours) - Duration of Action
NS= short (ms)
ES= long (mins, days or longer) - Major Function
NS= rapid, precise receptors
ES= activities that require a long duration
List the 5 Steps of the Cardiac Cycle
- Ventricular & Atrial Diastole
- blood entering atrium. Atrial pressure > ventricular pressure
- AV open (passive flow of blood into the ventricles) - Atrial Contraction
- atrial pressure increases and ventricular volume increases until EDV - Isovolumetric Ventricular Contraction
- ventricular pressure > atrial pressure = AV open (1st heart sound)
- ventricular pressure < aortic pressure = SL closed - Ventricular Ejection
- ventricular pressure > aortic pressure = SL open
- ventricular volume decreases until ESV - Isovolumetric Ventricular Relaxation
- ventricular pressure < aortic pressure = SL closes (2nd heart sound)
- ventricular pressure > atrial pressure = AV closes
Describe Heart Sounds
Closing of Valves
- lub dub (pause)
First Sound (S1)
- closure of the AV valve
- beginning of ventricular systole
Second Sound (S2)
- closure of SL valve
- ventricular diastole
Describe Cardiac Output and give the formula
- volume of blood pumped by each ventricle per minute
- indicates blood flow through peripheral tissues
Cardiac Output = Heart Rate (beats/min) x Stroke Volume (ml/beat)
where:
Heart rate = how fast the heart is beating
Stroke volume = volume of blood pumped out of ventricle during each contraction
Describe Stroke Volume and give the formula
- volume of blood pumped out of ventricle during contraction
- different between EDV and ESV
where:
EDV = End Diastolic Volume = volume of blood in the ventricle during relaxation
ESV = End Systolic Volume = volume of blood in the ventricle after systole
Stroke Volume = EDV - ESV
Describe Venous Return
- volume of blood returning back to the heart each minute
- increasing venous return will:
- increase EDV
- cause heart muscle to stretch
- as cardiac muscle stretches, the next contraction will be stronger
Describe the Frank Starling Law of the Heart
- the greater the EDV/venous return, the greater the force of contraction during systole (within limits)
- if increase in EDV, stroke volume also increases. At rest, heart muscle is not at optimal length to produce contraction. When increase EDV, muscle and cell stretches, creating more optimal overlap between actin and myosin, therefore, creating a stronger contraction
List the 4 factors affecting venous return
- Cardiac suction
- Skeletal muscle pump
- Venous valves
- Respiratory pump
- Sympathetic Nervous system
Describe Cardiac Suction and its affect on venous return
- heart acts as suction pump
- occurs in both systole and diastole
- contraction (systole) of ventricles: sucks blood from veins into atria
- relaxation (diastole) of ventricles: sucks blood from veins and atria into ventricles
Describe Skeletal muscle pump and its affect on venous return
- large veins lie between skeletal muscle/run through muscle
- muscle action compresses the vein and pushes blood through vein
Describe Venous valves and its affect on venous return
- valves control the direction of blood flow and prevent back flow
Describe Respiratory pump and its affect on venous return
Inspiration:
= expansion of thoracic cavity and decreased pressure in thoracic cavity
= increase venous return
Expiration:
= compression of thoracic cavity and increased pressure in thoracic cavity
= decrease venous return
Describe Sympathetic Stimulation and its affect on venous return
- causes vasoconstriction of veins and increases venous return
List the 6 Steps of fainting
- Standing at attention
- Decreased venous return
- Decreased cardiac output
- Decreased blood to brain
- Fainting - loss of consciousness
- Fall over - venous return and cardiac output return to normal
Describe Sphygmomanometry
- cuff is inflated
- cuff pressure > arterial pressure
- when the pressure in cuff is higher than in artery, the artery closes
- artery is completely blocked
- no sound due to no blood flow
- cuff pressure is reduced until first sound is heard
- systolic pressure
- blood passes through turbulently when arterial pressure transiently is greater than cuff pressure
- no sound heard when cuff pressure is less than diastolic pressure
- last sound heard is diastolic pressure
Describe Mean Arterial Pressure and give the formula
- average blood pressure in the arteries
- closer to diastole because heart spends longer in diastole
Mean Arterial Pressure = Diastolic Pressure + 1/3 Pulse Pressure
Describe Flow and resistance
- friction between blood and vessel causes resistance
- resistance to blood flow is controlled by:
- blood viscosity (constant)
- vessel length (constant)
- vessel diameter (only factor we can regulate)
- double the radius, increased blood flow by 16 times
Describe Flow and Pressure
- contraction of heart gives pressure to blood
- pressure in cardiovascular system decreases from arteries to veins
- blood flows from high pressure to low pressure
- blood flow is directly proportional to the pressure gradient
Describe Arteriolar Radius
- total peripheral resistance is controlled by blood
vessel radius
*radius of arterioles can be increased (dilated) or decreased (constricted)
*arterioles are the major resistance vessels - can be controlled by extrinsic and local factors
*local = changes at the level of muscle/vessel
*extrinsic = changes at level of nervous and endocrine systems
Describe Local Metabolic Changes
- local metabolic changes in a tissue control arteriolar diameter and allow blood flow to meet the needs of the tissue
- i.e. during exercise an increase in metabolism stimulates the dilated of local arterioles
List the 6 Steps of Local Metabolic Changes
- Exercise
- Increase in tissue metabolism
- Decrease in Oxygen, increase in Carbon dioxide and increase in hydrogen ions
- Arterioles dilate
- Decrease resistance = increase blood flow
- Increase oxygen and nutrients supplied to metabolising tissue
Describe Capillaries
- site of exchange between blood and tissue and gases (oxygen and carbon dioxide), nutrients and wastes
- exchange occurs primarily by diffusion