Final Exam Flashcards
Break down the muscle starting from the muscle as a whole describe each if necessary
Muscle, Muscle fascicle, muscle fibers, myofibril, sarcomere (Z-disk to Z-disk), thick (m-line) and thin (Z-disk) filaments
Thick- myosin (myosin head, hinge region, myosin tail), titin (anchors)
Thin-actin (structure), troponin (calcium binding protein), tropomyosin (regulates interaction between actin and myosin)
Excitation-contraction Coupling steps
- Somatic motor neuron releases Acetylcholine at neuromuscular junction
- Net entry of Sodium through the Acetylcholine receptor channel initiates a muscle action potential
- Action potential in t-tubule alters conformation of the DHP receptor
- DHP receptor opens calcium release channels in the sarcoplasmic reticulum and Calcium (important signaling molecule) enters cytoplasm
- Calcium binds to troponin, allowing strong actin-myosin binding
- Myosin heads execute power strokes
- Actin filament slides towards center of sarcomere (shortening muscle)
Describe the length-tension relationship
Position of Sarcomeres
Optimal muscle length- ideal degree of overlap and ability to shorten. The peak
As you shorten- lots of overlap but no additional room for shortening
As you lengthen- lots of room for sliding but little to no overlap
What are the types of skeletal muscle fibers and their characteristics?
Fast glycolytic Fibers (Type IIB)- white fibers, rapid contraction, susceptible to fatigue, fast uptake of calcium, faster ATP splitting (running, lifting)
Slow-oxidative Fibers (Type 1)- red fibers, resistance to fatigue, long term activity, high amounts of myoglobin, dense capillaries
Fast-oxidative-glycolytic fibers (Type IIA)-pink fibers, can adapt to be red or white, intermediate speed
How does smooth muscle contraction differ from skeletal muscle?
- The initial source of calcium is extracellular and could later trigger the release of calcium form sarcoplasmic reticulum. NO tubules, no DHP
- Different calcium binding protein- CaM (calmodulin)
- The calcium CaM complex activates MLCK
- Myosin must be Phosphorylated before it will bind to actin.
- To relax myosin must be dephosphorylated
Endocrine vs Exocrine
Exo-Secretion enters duct/tubule
Endo- Enters blood stream
What are the 3 major types of hormones?
Peptide/Proteins, Steroids, Amines
Steps of Peptide hormone secretion and production
- mRNA binds amino acids together to form peptide chains (preprohormone) and taken into the ER lumen by a signal sequence
- Enzymes in ER take off signal sequence creating inactive prohormone
- Prohormone passes through ER into Golgi
- Vesicles containing enzymes and prohormone come out of Golgi and the prohormone is chopped into one or more active peptides and peptide fragments.
5.Vesicle releases contents by exocytosis - Hormone is moved into blood to be transported
Compare preprohormones, prohormones, and active hormones
Prepro- not active, contains signal sequence, can produce many difference hormones
Pro- no signal sequence still inactive (stored in this state)
Active- chopped prohormone, active hormone
Cholesterol
Steroid Homone
All other steroid hormones are made from this
Cytochrome P450s
Convert cholesterol to steroid hormone derivatives
Aromatase
A CYPs
Makes steroid hormones (testosterone) to estradiol (estrogens)
Females produce testosterone but it is converted using aromatase
Males make low levels
What are amine hormones derived from, describe them
Tyrosine- precursor for Catecholamines (dopamine, epinephrine) and Thyroid Hormones (T4, T3)
Tryptophan-precursor for serotonin and melatonin
Tropic Hormones
Hormones that control the release of other hormones
What 3 things control hormone secretion?
Ions/nutrients, Neurotransmitters, Hormones
Describe the structure the hypothalamus and pituitary gland
These are nervous tissues that produce hormones
They are connected by the infundibulum
The pituitary is made of two sections with different functions:
Posterior- neurons form hypothalamus go down infundibulum into this section
Anterior- contains a portal system that delivers hormones from the capillary bed in hypothalamus to the capillary bed in the pituitary gland. (HPA)
Steps of posterior pituitary release
- Hormone is made in the cell bodies in hypothalamus
- Vesicles are transported down the cell
- Vesicles containing hormone are stored in posterior pituitary
- Hormones are released into blood (Vasopressin and Oxytocin)
Releases 2 but produces none
Vasopressin (ADH)
Released form posterior pituitary
Causes kidneys to remove water from urine by stimulating more water channels to form on membrane
Important in water balance
Lack of ADH- Diabetes insipidus- excessive tasteless urine
Act in the nervous system to possible determine pair-bond behaviors in brain (divorce Gene?)
Oxytocin
Released form posterior Pituitary
In females: Stimulates uterine contractions of childbirth and milk ejection from the mammary glands
In males: transport sperm, sex behavior
Effect behavior (CNS)- trust, anxiety relieve, bonding, maternal behaviors, eye-contact
What hormones are released from the anterior pituitary?
Most are tropic
FSH, LH, Growth Hormone, TSH, Prolactin, ACTH
Growth Hormone
Also known as somatotropin
Released from Anterior Pituitary
Stimulates an increase in cell size and the rate of cell division directly or through IGF-1 produced in the liver
Protein synthesis, and metabolism
Growth Hormone disorders
Hypersecretion- gigantism
Hyposecretion- pituitary dwarfism
Acromegaly- thickens bones specifically in face and hands
Prolactin and problems
Anterior pituitary
Stimulates the mammary glands to produce milk and is produced during lactation.
Excess- infertility and lactation, maturation of sperm and overproduction leading to sterility
Thyroid-stimulating hormone (TSH)
Anterior pituitary
Stimulates thyroid gland to release thyroid hormones
ACTH
Anterior Pituitary
Controls synthesis and secretion of glucocorticoid (glucose homeostasis) hormones form the adrenal cortex
FSH
Anterior pituitary
promotes development of egg cells (ovum) and secretion of estrogen in females, acts on sperm in males
Occurs in the gonads
LH
Anterior Pituitary
Causes ovulation and the secretion of estrogen and progesterone and testosterone in males
Acts on gonads
How do LH and FSH work in females vs males?
Females- drives the ovarian cycle
LH surge triggering ovulation releasing egg
LH acts on Theca cells (Androgens are produced )
FSH acts on Granulosa Cells(androgens to estrogen)
Males- LH acts on Leydig cells to produce testosterone
FSH acts on sertoli cells for spermatogenesis
Receptive Field and how it relates to sensitivity
Area of the body that when stimulated leads to activity in an afferent neuron (sensory unit)
More sensitive areas have smaller receptive fields and more dense sensory units
Sensory adaptation
reduction in response to the continuous presence of a stimulus, preventing sensory overload
Lateral inhibition
Sharpens contrast in the pattern of action potentials received by the CNS, allowing a finer resolution of stimulus location
Referred Pain
The sensation of pain at a site other than the injured or diseases tissue caused by sensory convergence confusing the brain
What is the structure and function of the organ of corti?
Basilar Membrane- anchor and support
Hair cells-the sensory cells that move, opening/closing mechanically gated ion channels, triggering the flux of Potassium into the cell, triggering action potentials
Tectorial membrane-thick membrane structure that moves bends the hairs
Takes the sound waves and converts them into action potentials triggering a response in the brain
What are the semicircular canals
Posterior- tilt of head towards right or left shoulder
Superior canal- rotation of head front or back
Horizonal- rotation of head left or right
Cupula
Within Ampulla
Fluid in duct bends the cupula, bending stereocilia, opening channels to allow potassium to flow into the cells
Ampulla
Boney structure at the base of the semicircular canals
Utricle and Saccule
Involved with special awareness
Contain Macula (hair like cells) that are moved with otoliths (crystals) opening/closing ion channels
Vestibular system
Detects changes in the motion and position of the head by the use of fluid-filled tubes near each ear. This system is connected to the cochlear duct
Other half of the inner ear
What occurs in the rods and cones in the dark?
Retinal is bound to opsin
High levels of cGMP
Promotes opening of sodium channels causing sodium to enter and depolarize the cell
Cell is tonically active (constantly releasing neurotransmitter)
What occurs in rods and cones in the light? Recovery phase
Light causes photo bleaching which changes the shape of retinal causing opsin to release it
Activates transduction which lowers cGMP levels
Sodium ion channels close, reducing membrane potential
Less neurotransmitter is released
(Light suppresses electrical activity, hyper polarization)
Retinal is released into the pigmented epithelium and is slowly recombining with opsin (delayed night vision)
Purpose of Rods?
Cones?
photoreceptor that allows for monochromatic vision (black/grey/white)
more light sensitive than cones
photoreceptor that allows for colored vision and an abundance of light is needed to
Hypothalamic-Pituitary Portal System and function
Hypothalamus regulates the release of pituitary hormones
How the hypothalamic releasing hormones are delivered to the anterior pituitary, bind to cause secretion for pituitary hormones
What are the Hypothalamic hormones and what anterior pituitary hormones do they effect?
GnRH- regulate/stimulate FSH/LH
GHRH- stimulates GH
SS- inhibits GH
TRH- Stimulates TSH
Dopamine- inhibits Prolactin
CRH-stimulates ACTH
Tri-tropic Cascade
Relationship between hypothalamic, pituitary and third-gland hormones
How are Hormones autoregulated
Negative feedback or from input form sensory neurons
Short loop- hormone form anterior pituitary inhibits release form hypothalamus
Long loop- third their inhibits anterior on hypothalamus hormone
Steps to T4/T3 synthesis
- Iodine is Transported in with sodium
- Iodine diffuses to center of follicle to the core (colloid) that is full of thyroglobulin
- Thyroglobulin has tyrosine on it and iodine groups are added to form DIT or MIT
- Starting with DIT, MIT or DIT are added to form either T3 or T4 (95% T4 but the active form is T3)
- Stimulation brings the molecules into cell
- They are released and are either secreted or brought back into colloid
What are the function of the thyroid hormones
Growth, CNS, Cardiovascular, BMR and metabolism
Calorigenic Effect
Increase in metabolic rate and oxygen consumption because of Thyroid hormone
What is a goiter and what causes it?
Hypertrophy of the thyroid
A diet deficient in iodine prevents thyroid hormones form being produced, decreasing the negative feedback effect causing more hormones to be released from hypothalamus
Hyperthyroidism and its corresponding autoimmune disease
Elevated TH levels, general symptoms
Grave’s disease- stimulatory antibodies causing increase in T3/T4 therefore a decrease in TSH and TRH due to the inhibitory effects of negative feedback, can cause budging of the eyes
Hypothyroidism and corresponding autoimmune disease
Low TG levels, general symptoms but can have a lack of metabolic effects, Hashimoto’s disease, cells attack the follicle cells of thyroid reducing its ability to produce hormones (low T3/T4), due to the low levels negative feedback increases the production of TSH and TRH
Fluid-Mosaic Model
Used to describe our cell membranes.
Not ridged, dynamic in constant motion made up of different parts and pieces
Describe the Structure of a phospholipid
Polar, hydrophilic head and a nonpolar, hydrophobic tail (amphipathic)
Saturated vs unsaturated fats
Saturated are tightly packed, viscous with single bonds
Unsaturated can’t be packed as tightly allowing more motion (fluid) and has one or more double bonds
Membrane Fluidity
Measure of the ease with which phospholipids can move within the membrane
Indicated by the amount of saturated vs. Unsaturated fats
How are solutes transported across the cell membrane?
Simple diffusion, facilitated diffusion, active transport, endo and exocytosis
Simple Diffusion, and example
Passive process (no ATP), moves down concentration gradient (high to low), freely passing through lipid bilayer until equilibrium is reached (equal movement)
Must be small and lipid soluble
Ex: blood gases (oxygen), and steroids
Can be done through ligand-gated channels or through ion channels
Facilitated Diffusion and example
Movement from high to low concentration with the aid of membrane proteins by a physical binding, passive transport
Ex: Glucose, it binds, changes the shape, and it is let through
Active transport and example
Two types
from low to high concentration with the help of membrane proteins and ATP
ex: Na, K, H transporters
Primary-Directly consumes and uses ATP against the gradient. (sodium potassium pump)
Secondary-Does not directly consume ATP going from low to high concentration. Done by utilizing an established gradient of another molecule. Molecules entering/existing one with and the other against its gradient.
Endocytosis and example
Requires ATP, membrane folds in, forming small pocket that pinch off to produce intracellular, membrane-bound vesicle. Transports Large or bulk quantities in or out of the cell.
Receptor Mediated (proteins and cholesterol)
Exocytosis and example
Requires ATP, Intracellular vesicles fuse with membrane, releasing contents into extracellular space
Release of Neurotransmitter at the terminal neuron
Action potential cause vesicles to move towards membrane to release contents outside
Sodium Ion: Extra and Intra
140, 12 mM
Potassium ion: Extra and Intra
5, 150 mM
Calcium ion: Extra and Intra
1, 0.0001 mM
Chloride Ion: Extra and Intra
100, 7 mM
Osmolarity (osmotic concentration)
The total concentration of solutes (ions, sugars, protein) in a solution/cell
What is the typical osmolarity of Humans?
300 mOsm
Define:
Isosmotic
Hypoosmotic
Hyperosmotic
Same concentration as our cells
less than the solute concentration of our cells <300
More than the solute concentration of our cells >300
Tonicity
describes the effect of a solution on cell volume, need more information about the molecules to determine like if they are penetrating or non penetrating
Define:
Hypertonic
Isotonic
Hypotonic
Hypertonic- cell shrinks, water moves from inside to outside
Isotonic- no change in volume
Hypotonic- cells swell, water moves from outside to inside
Structure of the respiratory tree
Conducting zone: Trachea, left primary bronchus, Secondary Bronchus, Respiratory Zone: bronchiole, alveoli
What are the two types of alveolar cells and describe
Type 1- gas exchange, thin and flat (close to the capillary)
Type 2- Produce surfactant which lowers the surface tension of water, preventing the walls from sticking together during contraction, typical cell shape, no gas exchange
Ventilation and how it relates to Boyles Law
Air enters when Pressure alveoli is less than pressure atmosphere
Air exists when Pressure Alveoli is greater than pressure atmosphere
Under Boyle’s law pressure and volume are inversely related so changing the volume of the lungs changes the internal pressure
What occurs during inspiration?
Active process where the diaphragm (move down) and the external intercostals (move up and out) contract increasing volume and therefore decreasing the internal pressure, allowing air to flow in
What occurs during expiration?
Passive process where there is no contraction with reduced volume meaning increased pressure allowing air to flow out
Can be made active when you contract the abdominal muscles and internal intercostals further decreasing the volume
What is the typical partial pressures of oxygen in the alveoli, arterial blood, and tissues?
Alveoli- 100 mmHg
Arterial blood- 100 mmHg
Tissues- Less than our equal to 40 mmHg
Pulmonary- 40 mmHg
How is oxygen transported in blood?
Plasma and Hemoglobin
The partial pressure of oxygen in the tissues change, dictating the amount of oxygen leaving the hemoglobin
Supply and demand
How is CO2 transported in the blood?
Plasma, Hemoglobin, Bicarbonate
Bicarbonate is formed in the RBC and sent into the plasma to act as a buffer, when it leaves it causes Cl- to flux in (chloride shift)
Opposite effect occurs in the lungs
What is the typical partial pressure of carbon dioxide in the alveoli, arterial blood, and tissues?
Alveoli- 40 mmHg
Arterial- 40 mmHg
Tissues- Greater than or equal to 46 mmHg
Pulmonary- 46 mmHg
What does the oxygen-hemoglobin dissociation curve tell you?
The effect of partial pressure of oxygen on hemoglobin saturation. At higher oxygen concentrations the percentage of hemoglobin saturated with bound oxygen increases until all of the oxygen binding sites are occupied (100% saturation)
Hemoglobin Affinity
What is the most and least important stimulus to stimulate ventilation?
Oxygen is the least important, it requires a drastic change in oxygen levels to stimulate
CO2 and therefore acidity are the most important molecules in breathing rate. The slightest increase in CO2 concentrations dramatically changes the ventilation by the body in attempt to get rid of this waste product, when bicarbonate is produced during Co2 transport it increases the H+ concentration also increasing the rate of breathing
What is the challenge our bodies face when going up high altitudes (physiologically)?
Going up in elevation deceases Partial pressure of the atmosphere, reducing the gradient PO2 travels to fill and empty the lungs
How does the body acclimate to high altitude?
More ventilation
Erythrocyte synthesis (produce more RBC)
Increase in DPG (shifts curve to the right, but may cause less oxygen to be unloaded in the lungs)
Increase in capillaries (increase oxygen transfer)
Reduce plasma volume (increases the density of RBC to transport more oxygen)
Adrenal gland structure and function
Medulla- extension of sympathetic nervous system, fight or flight (epinephrine/norepinephrine)
Cortex: Zona Glomerulosa- Aldosterone- increase reabsorption of sodium and potassium
Zona Fasciculata/Zona Reticularis- Cortisol (stress hormone) and Androgens (stimulates skeletal muscle growth and sex drive in females)
Functions of Cortisol at rest vs time of stress
At rest- responsiveness of cells to nor/epinephrine, checks immune system, energy homeostasis, fetal development
Stress- increase energy production (Metabolic Fuel sources), Inhibits immune response, inhibits reproduction/growth, enhances actions of epinephrine
Short term stress response vs long term stress response
Short- increase heart rate and BP, stimulate epinephrine release, increase metabolic rate
Adaptive response- beneficial handling situation
Long-
Aldosterone- increase BP and blood volume, and water uptake
Cortisol- increase metabolism, increase blood glucose, suppression of immune system
Cause hypertension, maladaptive response (not beneficial)
Addison’s Disorders
Hypocortisolism
Autoimmune destruction
inadequate production of cortisol and aldosterone
With general symptoms other than the hyperpigmentation (increase production of MSH from negative feedback from lack of hormones produced)
Also can be caused by taken off of steroids abruptly (Addison crisis)
Cushing Diseases
Hypercortisolism
Caused by a tumor
excess cortisol causing the redistribution of fate to abdominal and face and none in legs and arms, inability to heal wounds
Physiology
Study of how living organisms work
Functions, processes, and integrations within living things
Claude Bernard
Father of modern Physiology
Milieu Interieur
Constancy of the internal environment is the condition for a free and independent life
Walter Cannon
Coined the term Homeostasis
Mechanisms that detect and respond to deviations in physiological variables form their set point values by initiating effector responses that restore the variables to the optimal physiological range
What are the components of homeostatic systems?
Sensors (receptors)- monitor detect variables
Integration center- place that processes the information (brain)
Effector- responds to bring back to set point
Afferent pathway
carry signals towards integrating center
Stimulus -> receptor -> integrating center
Efferent Pathways
integrating center -> Effector -> Response
Carry signals away from integrating center towards effector
Negative Feedback and examples
Brings closer to homeostasis.
Decrease function of pathways after then end goal has been reached
Diabetes (insulin and glucagon secretion) , body temperature regulation
Positive Feedback and example
response reinforces the stimulus sending the parameter farther form the setpoint
Continues until outside factor is present to turn it off
Factor -> sensor -> integrating center -> effector
Labor and delivery (release of oxytocin)
Parathyroid Glands
Glands are located on the back side of the thyroid gland and secrete PTH to decrease the concentration of calcium ions in the extracellular
Osteoblasts
Calcification and build bone
Osteoclasts
Break down bone and release calcium and phosphate, stimulated by parathyroid hormone
How does PTH regulate calcium homeostasis?
Low Calcium increases the secretion of PTH, stimulating osteoclasts
Acts on kidneys to increase retention of calcium (prevent it from being secreted)
Indirectly initiated the absorption of calcium in digestive tract
Calcitonin
Produced form the thyroid and plays a minor role in calcium homeostasis
It has the opposite effect of parathyroid hormone and favors osteoblasts (too much calcium)
1,2,5-(OH)2D3
Hormone secreted in kidneys due to the PTH
Acts on intestines to promote absorption of calcium.
Cholecalciferol is the precursor and can be produced due to UV light and diet
Osteoporosis
Decrease in bone density due to reabsorption exceeding deposition (more porous,), osteoclasts are more active
Due to: not enough calcium in diet, genes, smoking, alcohol, and sex hormones (block osteoclasts later in life until they are decreased due to Mesopause)
Melatonin
Amine based hormone, Secreted by the pineal gland, that is affected due to behavior (daily schedule) and light exposure (when the sun sets/rises)
Too much can lead to seasonal affective disorder
What maintains the biological clock in mammals and how does it do it?
Suprachiasmatic nucleus in the hypothalamus
UV light is processed here, where this is UV light this area of the brain blocks melatonin secretion
What are the parts of a neuron? Describe
Dendrites- receiving end
Cell body (soma)- contains nucleus and other organelles
Axon- sends signals away from cell
Axon terminals- where neurotransmitters are released and stored
Axon hillock- trigger zone, forms action potential
What glial cells form the myelin sheath and how?
Schwann cells in peripheral and Oligodendrocytes in the central nervous system
Wrap themselves around the axon
What is the membrane potential at rest of a neuron?
-70 mV
What are the two mechanisms of membrane potential and describe?
Sodium Potassium Pump- biggest factor, establishes a concentration gradient generating negative potential.
Leak channels- always open, allows Na+ to move back in and K+ to move back out, there is more K+ leaving than Na+ coming back in because there is more potassium channels
What are the two types of graded potentials and describe them
EPSP- excitatory, bring closer to threshold increasing the chance of an action potential, caused by the opening of ligand gated channels, depolarization
IPSP- hyperpolarization, suppresses the cell making it harder to get an action potential, caused by opening of K+ ligand channels causing K+ to leave the cell
What are the steps of an action potential
- Graded potential above threshold reaches trigger zone
- Voltage gates Na+ channels open and Na+ enters the axon, depolarizing the membrane, triggering release of more Na+ channels as it spreading into the negative parts of the cell.
- Voltage gated K+ channels open slowly, allowing K+ out as Na+ gates close, repolarizing the membrane
- K+ gates stay open hyperpolarizing the membrane
- K+ gates close but K+ can still exit through leak channels
- Cell returns to resting potential
What is the refractory period, What is its purpose?
Reduces the excitability of a neuron, reducing the tendency for an action potential and assures one way propagation of action potentials
Absolute refractory
Zero chance for an action potential, inactivation gates are closed, unresponsive to stimulus, the channels are already open
Relative refractory
reduced excitably but can get second action potential, would need a stronger graded potential to counteract the hyperpolarization
Saltatory Conduction
Action potentials jump from one node to the next as they propagate along a myelinated axon
What are the two types of synaptic transmission?
Electrical-uses gap junctions, very fast
Chemical- synaptic cleft, most common, slightly slower
Chemical synapse and steps
action potential reaches terminal triggering release of neurotransmitter form pre-synaptic neuron
1. Action potential depolarizes the axon terminal where neurotransmitters are stored in vesicles
2. Depolarization opens voltage gated Ca ion channel and Ca ions enters the cell (will always be calcium at the axon terminal)
3. Calcium entry triggers exocytosis of synaptic vesical contents by vesicles moving to membrane and anchoring at docking proteins (Synaptotagmin) and wrapped up b SNARE proteins.
4. Neurotransmitter diffuses across synaptic cleft and binds to receptors on postsynaptic cell
5. Neurotransmitter binding (ligand gated channel) initiates a response in post synaptic cell
Sympathetic vs parasympathetic
Both regulate involuntary bodily activates
Has two neurons- preganglionic (acetylcholine for both), postganglionic
Para- governs bodily activities during restful conditions, rest and digest, post: acetylcholine-short, released from cranial nerves or sacral region
Sym- fight or flight, prepares the body for stressful or emergency situations, post: norepinephrine/adrenaline -long, thoracic and lumbar.
Describe Parkinsons and its pathology
Degenerative disorder resulting from the death of dopamine producing neurons within the brain’s movement control center
Protein aggregation disorder
issues with alpha synuclein which may be associated with vesicles that haul dopamine in the axon terminals like a docking protein
What is known as the brain’s movement control center that is affected by Parkinsons?
Substantia Nigra
What is misfolded protein in Parkinsons? What is the protein aggregation?
alpha synuclein
Lewy body
Describe Alzheimer’s and pathology
Progressive, neurodegenerative disease caused by the death of acetylcholine-producing neurons in regions of the brain important in memory and intellectual function
Protein Aggregation disorder
Amyloid precursor protein gets chopped up to form Amyloid Reta. An accumulation of this protein occurs because it can’t be broken down as fast as it is being made. Extracellular plaques are formed form bunched up protein that kills the neurons
What are the misfolded proteins in Alzheimer’s?
What are the Protein aggregations?
Amyloid beta, Tau
Amyloid Beta plaques and neurofibrillary tangles
Water balance
Water intake (gains) must equal water loss
Intake- food, drink, metabolism
Loss- fecal loss, insensible loss (skin, respiratory), urine output
The path of filtrate through the nephron
Glomerulus- capillary network
Bowman’s Capsule- Wraps around capillary
PCT
Descending limb
Loop of Henle
Ascending limb
DCT
Collecting duct
Nephron
Functional unit of the kidney responsible for the formation of urine
What is the name of vascular system surrounding nephron?
Peritubular capillaries (vas recta) part of portal system
Steps of Urine formation
Brief description, where it occurs
Glomerular filtration- movement of fluid and solutes form the glomerular capillaries into bowman’s space (only takes place here)
Tubular reabsorption- the movement of materials form the filtrate in the tubules into the peritubular capillaries (throughout nephron)
Tubular secretion- secretion of solutes from the peritubular capillaries into the tubules (excess waste) (selective) (PCT,DCT, collecting duct)
What is the role of Podocytes?
In Glomerular filtration these foot cells are wrapped around the capillary and only allow filtrate through that can fit between the feet
What can get through the podocytes? And how much filtrate is produced?
Water, ions, glucose, amino acids, waste products
180 L/day
What gets reabsorbed during Tubular absorption
99% of water, sodium, chloride, potassium, nutrients, and 100% glucose
Nitrogen waste as low degree of reabsorption
Describe the countercurrent exchange that occurs in the loop of Henle
Counter-current exchange- direction of filtrate is opposite the direction of blood flow in capillaries.
Ascending limb- absorbs the ions in the filtrate, increasing the solute concentration of the blood
Descending limb- absorbs the water in the filtrate due to the osmotic gradient (why large amounts of water is recovered), increases the molarity of the filtrate decreases molarity of blood
Describe the spread of electrical activity generated by the heart
Depolarization of cells in the SA node that spread using gap junctions. (at same time)
the Atrioventricular node moves the electrical activity to the ventricles by depolarizing the bundle of hiss that carries it down the septum and branching at the apex
these branches are purkinje fibers that depolarize the pumping cells in the ventricle (at same time) using gap junctions
What does a ECG/EKG do and what are the waves that make it up?
Record electrical activity
1. P-waves- depolarization of the atria (small)
2. QRS- complex- depolarization of ventricles (large)
3. T-wave- repolarization of ventricles (small)
Describe the ion channels involved with an action potential in the myocardial pumping cell
Has a resting membrane potential
1. Depolarize opening voltage gates sodium channels that open when threshold is reached
2. voltage gated l-type calcium channels open causing a plateau of depolarization due to long lasting
3. Sodium and calcium channels close and voltage gated potassium channels open causing repolarization
Describe the ion channels involved with the action potential in the SA node
No resting membrane potential, myogenic part
1. Sodium ions leak in through F-type sodium channels and calcium move in through T-type Calcium channels causing a threshold graded potential
2. Opening of voltage gated (L-type) calcium channels causes repaid depolarization
3. Reopening of voltage gates potassium channels and the closing of the calcium channels is responsible for repolarization
Steps of the mechanical events of the heart, describe and the pressure involved
- Late diastole- both chambers relaxed, ventricles fill
- Atrial systole- atrial contractions forces small amounts of additional blood into ventricles (Atrial P> Ventricular P= AV valves open)
3.Isovolumic- ventricular contraction- no blood ejected, AV valves closed but semilunar not open (Ventricular P< Atrial P=AV closed) - Ventricular ejection- blood is ejected due to high ventricular pressure (ventricular P> Arterial P= semilunar open)
- Isovolumic Ventricular relaxation- ventricles relax blood is not refilling ventricles (Ventricular P< Arterial P= semi-lunar closed) ( Atrial P< Ventricular P= AV valve closed)
Cardiac Output definition and how it is calculated
Volume of blood pumped by one ventricle in a given period of time
CO=Heart Rate X Stroke volume
How do you speed up Heart rate to increase cardiac output?
Deliver sympathetic hormone (epinephrine), release more sympathetic neuron
Parasympathetic does the opposite
What is Starling’s Law of the heart and how stroke volume effects cardiac output
Is it near optimal?
By increasing end diastolic volume you increase Stroke volume, the more blood in ventricle increasing SV causing a better alignment of the sarcomere.
This is not near optimal so there is room for improvement when it is needed (exercise)
Describe each blood type in the ABO system, including their antigens, antibodies, and what blood they can receive
Type A- H and A antigens (N-acetylgalactosamine), Anti-B antibodies, can receive A and O blood
Type B- H and B antigens (galatose), Anti-A antibodies, can receive B and O blood
Type AB- H, A, B, antigens, No antibodies (universal receiver), can receive all blood types
Type O- Just H antigen, anti-A and anti-B antibodies (universal donor), can receive only type O blood
How do you classify Rh blood types
Positive- have D antigen
Negative- no D antigen
Those with positive can only receive positive blood, and vice versa
Atrial Systole
First step
Started by p-wave (atrium depolarization)
Atrial contraction builds up pressure opening AV valves, blood into ventricle increasing volume, QRS complex begins (ventricular depolarization)
Isovolumic Ventricular contraction
Second Step
Ventricle starts to contract.
Ventricular pressure rises above atrial (AV valves close SN1), semi-lunar valves are closed, blood is not ejected so ventricular volume is unchanged.
Ventricular Systole
Third Step
Ventricular pressure rises higher then Aortic pressure causing semi-lunar valves to open
Blood is ejected out of ventricles decreasing volume
Ventricles begin to repolarize (T-wave) causing ventricular pressure to decrease
Early Ventricular Diastole
Fourth Step
Ventricular pressure drops below aortic pressure causing the semi-lunar valves to close (SN2)
Volume remains constant
Ventricular relax causing a pressure decrease
Atrium fills with blood building up pressure, AV valves open when atrial pressure passes ventricular pressure
Ventricular Diastole
Fifth Step
Blood flows passively into ventricles
Ventricular blood volume increases
Process repeats
What are the 3 important hormones in Urine Formation?
ADH, Aldosterone, ANP
What is the role of ADH (vasopressin)
regulates the amount of water reabsorbed by the distal convoluted tubules and collecting duct
Increases the concentration of the urine by allowing the water to be reabsorbed
Mechanism of action for vasopressin
Produced in hypothalamus where it is released in posterior pituitary
1. Binds to membrane receptor in the collecting duct
2. Receptor activates cAMP second messenger system
3. Cell inserts water pores into apical membrane
4. Water is absorbed through osmosis into the blood
What factors affect ADH release?
Osmolarity receptors- monitor cerebral spinal fluid
Stretch receptors in atria- (less stretch=less blood volume=release ADH)
Baroreceptors- less BP=less h20= release of ADH
What is the role of Aldosterone?
Increase reabsorption of sodium by distal convoluted tubules, creating a passive gradient for water
Increased water reabsorption, decreasing water in urine
Structure of function of Juxtaglomerular apparatus
Distal tubule is close to Bowmans Capsule and blood supply from Glomerulus
Made of Granular Cells
Secretes the endocrine signal known as renin into the afferent arteriole
Describe the renin-angiotensin- aldosterone pathway
- Macula cells monitor the rate of filtration which is proportional to the amount of chloride ions and BP
- When BP is low signals are sent to Granular cells and singles to release renin
- Renin converts inactive Angiotensinogen to Angiotensin 1 (also inactive)
- On the surface of endothelial cells there is ACE enzyme that will convert Angiotensin 1 into Angiotensin 2 (active)
What effect does Angiotensin 2 have on the body and BP?
Act on arterioles for vasoconstriction= increasing BP
Act on medulla oblongata to simulate an increase in CO therefore increasing BP
Act on Hypothalamus to produce more ADH= increase in water= increase BP
Act on renal glad to produce aldosterone= Increaseing Sodium= increasing water= increasing BP
Aldosterone mechanism of action
- Combines with a cytoplasmic receptor
- Hormone recptor complex initiates transcription in nucleus
- New protein channels and pumps are made
- Aldosterone induced proteins modify existing proteins into sodium channels
- Increase in NA+ reabsorption and potassium secreation
Function of ANP
Released from the heart in response to increased blood volume and pressure relieving both these conditions with increased urine output and inhibiting ADH and renin
Decreases water reabsorption, increasing water release
What does increasing ANP do to blood pressure?
Increases stretch, increasing water, increasing BP
Opposite of ADH and Aldosterone
How is Ammonia produced in the body? Why is it dangerous?
Breaking down amino acids during Deamination
It is a cytotoxin that can cause cell death.
What are the ways of removing nitrogen form the body and what are their pros and cons
Aquatic animals- directly secrete from skin so no ATP loss but an abundance of water is required
Terrestrial animals- Convert to urea which is less toxic storage but it requires ATP and some water to produce Urine
Birds/Reptiles/insects- convert to uric acid, requires a lot of ATP but no water needed, can be released in a dry state
Clathrin
Protein that causes the membrane to round off and pinch during endocytosis.
Ligand binds to receptor, initiating clathrin to come to the surface to assist in the pinching of the cell membrane
What is the difference between lipid soluble and water soluble messengers?
Lipid soluble molecules- can pass through the membrane and are typically transcription factors that regulate gene expression, need carrier molecule while in plasma
water soluble- most common, have a hard time passing through the membrane so receptors are on the surface
First messenger vs second messenger
first- extracellular, water soluble triggers second messenger
Second messenger- intracellular, membrane to eventually trigger a response
Protein kinase vs Protein phosphatase
Kinase- enzyme that transfers a phosphate to another molecule, phosphorylates activating a molecule.
Phosphatase- removes phosphates form a molecule turning it off
G-proteins and its subunits
Membrane proteins that couple membrane recenters to ion channels or membrane enzymes, the receptor does nothing but bind
subunits- alpha, beta and gamma
Beta and gamma are anchors for alpha and alpha activates effector protein
Adenyl cyclase-cAMP pathway
- First messenger binds to GPCR activating G protein
- G protein turns on adenylyl cyclase
- Adenyl cyclase converts ATP to cyclic AMP
- cAMP activates protein kinase A (cAMP- dependent protein kinase)
- Protein kinase A phosphorylates other proteins eventually leading to a response
What is the most common second messenger and the one in Adenyl cyclase-cAMP pathway
cAMP
Phosphodiesterase
Family of enzymes that ends the cAMP pathway by degrading it, turns cAMP to AMP
Steps to the Phospholipase C system
- First messenger binds activating receptor and G protein
- G protein activates phospholipase C, amplifier enzyme
- PL-C converts membrane phospholipids into two second messengers: diacylglycerol (remain in membrane) and IP3 which goes into cytoplasm
- DAG activates protein kinase C which phosphorates proteins.
- IP3 causes a release of Ca form organelles creating a Ca signal
What is one of the most important signaling molecules and where can it be found?
Calcium
Intracellular- The endoplasmic reticulum
Extracellular- voltage gated channel (change in voltage), allowing the calcium in from ouside the cell
Describe the quantity and what happens when calcium enters the cell and why
Very little amounts (0.0001 mM) and it is quickly bound up by proteins to form a complex. This is done because it is a cytotoxin and can cause cell death (apoptosis)
