Human Physiology Flashcards
Temperature homeostasis?
Body temp falls:
Blood vessels constrict
Sweat glands don’t secrete fluid
Shivering occurs
Body temps increase:
Blood vessels dilate
Sweat glands secrete fluid
Shivering doesn’t occur
What is glucose homeostasis?
High blood glucose:
Pancreases releases insulin
Low blood glucose:
Pancrease releases glucagon
What is respiration in pulmonary level and cellular level?
Process of ventilation
Exchange of O2 and CO2 in the lungs
O2 utilisation and CO2 production
Main purposes of respiratory system?
Gas exchange
Acid-base regulation
Homeostatic regulation of body pH
Vocalisation
Protection from inhaled pathogens and irritating substances
What’s pulmonary ventilation?
Moving air in and out of lungs
What’s external respiration?
Gas exchange between lungs and blood
What’s internal respiration?
Gas exchange between systemic blood vessels and tissue
What’s in conducting zone and what does it do?
Moves air into respiratory zone
Humidifies, warms and filters
Trachea
Bronchial tree
Terminal bronchioles
What does the respiratory zone do and what’s in it?
Exchange of gases
Respiratory bronchioles
Alveolar ducts
Aveolar sacs
What cleans alveolus?
Alveolar macrophage
What do type 1 and type 11 alveolar cells do?
Type 1 aids permeability
Type 11 makes surfactant to stop them sticking together
What Boyle’s law?
Pressure of a gas in a closed container is inversely proportional to the volume of the container at a constant temperature
What is atmospheric pressure?
760 mmHg or 1 ATM
Process of breathing in (exact opposite occurs for exhalation)?
Increase size of lungs
Volume increases
Decreased alveoli pressure
Air rushes into lungs
What does diaphragm and external intercostals do in active inhalation?
Diaphragm:
Flattens
Due to phrenic nerves
Lowers dome when contracted
External intercostals:
Contraction elevates ribs
Up and outwards
Accessory muscles aid for deep forceful inhalation
What occurs in exhalation at rest?
Pressure lungs greater than atmospheric
Passive process due to elastic recoil and relaxation of diaphragm and external intercostals
Thoracic cavity reduces
External intercostal muscles relax
What is minute ventilation?
Amount per minute
What is tidal volume?
Amount per breath
Breathing frequency?
Number of breaths
How to work out alveolar ventilation?
0.7 x tidal volume
How to work out dead space ventilation?
0.3 x tidal volume
What is inspiratory reserve volume?
Maximum volume of air that can be inhaled (from top of tidal volume on graph)
What is Expiratory reserve capacity?
Maximum volume of air that can be voluntarily exhaled (from bottom of tidal volume on graph)
What is residual volume?
Volume of air remaining in the lungs after maximal exhalation
What is vital capacity?
Maximum volume that can be inhaled and exhaled (IRV + Tidal volume + ERV)
What is FRC functional residual capacity?
Volume of air present in the lungs at the end of passive expiration (ERV + RV)
What is total lung capacity?
Around 6 litres
How do we breathe?
Respiratory control centres within our brain
Medulla oblongata:
Rhythmicity area-
Ventral group
Dorsal group
Pons:
Pneumotaxic
Apneustic area
What does pneumotaxic exactly do?
Superior portion of pons
Teams with MRA to set rhythm of breathing
Inhibitory pulses prevent lungs from becoming to full with air
What does Apneustic area do?
Coordinates transition between inspiration and expiration
Stimulates inspiratory area to prolong inspiration and slow rate of breathing
Only occur when pneumotaxic area is inactive
What dictates how we breath?
Voluntary control:
Motor cortex
Involuntary control:
Feedback
Ventilation loops?
Sensors, to central controller to effectors back to sensors
What do central chemoreceptors do?
Elevated PCO2 or pH results in hyperventilation
What are the peripheral chemoreceptors?
Cartoid body
(CN9)
Aortic body
(CN10)
What are the respiratory stretch receptors?
Activated by overinflation of the lungs
Inhibitory discharge sent to inspiratory area
Reduced discharge from RSR
2 other types of receptors?
Irritant receptors (mechanoreceptors) and peripheral proprioceptors (muscles tendons joints)
How do gases move into blood from alveoli?
Diffusion
Pressure gradient, not a concentration gradient
What is Dalton’s law?
Total pressure of a mixture is equal to the sum of the partial pressures of the individual gases in a mixture
So partial pressure = % concentration ( as decimal) x total pressure of mixture
What gas is most abundant and second most in the atmosphere?
Nitrogen, second is Oxygen
Henry’s law?
When a mixture of gas is in contact with a liquid each gas dissolves in the liquid in proportion to it’s partial pressure and solubility until equilibrium is achieved and the gas partial pressures are equal in both locations
Solubility is constant
Pressure gradient is critical, gases diffuse from high pressures to low pressures
So more gas molecules are soluble at a higher pressure
Fick’s law of diffusion?
V Gas = A x D x (P1 -P2) / T
V gas = rate of diffusion A = tissue area D = Diffusion coefficient of gas P1 - P2 = Difference in partial pressures T = Tissue thickness
What damages alveoli?
COPD (Chronic Obstructive Pulmonary Disease) and smoking
Features of capillaries?
Single cell layer so very thin
Slower blood flow in capillary bed providing more time for diffusion
Largest surface area
Types of blood samples?
Capillary:
Fingertip
Ear
Venous:
Venipuncture
Cannula
What do you need for capillary blood collection?
Disinfectant, steile swabs, sterile gloves, a safety lancet, appropriate sample container, plasters, waste container
Capillaries should be horizontal or slightly inclined
Sample container needs to be inverted after blood collected
Components of blood?
Plasma:
Mainly water
Some protein
Little nutrients and hormones
Buffy coat:
White blood cells and platelets
Red blood cels
Haematocrit
Females 37-47%
Males 42-52%
Typres of oxygen transport?
1% dissolved in plasma:
Dissolved O2 establishes the pressure of oxygen in blood which regulates breathing and determines loading of haemoglobin
99% combined with haemoglobin = oxyhaemoglobin
Features of a RBC and Haemoglobin?
Bioconcave shape
4 iron molecules per haemoglobin, 1 molecule per iron group
High affinity for O2
Describe the oxyhemoglobin dissociation curve?
Higher Po2 = Higher % O2 saturation
Acidity
Pco2
2,3-BPG (2,3-DPG) Temperature
All affect unloading
Acidosis occurs when acidity increases, affinity of Hb decreases, more O2 delivered to acidic sites
When Pco2 increases, affinity of Hb decreases, the harder the tissue is working more O2 is released
BPG is formed during glycolysis and helps to unload O2 by binding with Hb
As temperature increases, there is higher unloading
Affinity of Hb decreases, so more O2 delivered to warmed up muscles
Features of myoglobin?
Iron-containing globular protein in skeletal and cardiac muscle
1 iron atom
Even higher affinity than Hb, even at low Po2
Transfers O2 from cell membrane to mitochondria/muscles
Features of Cytochrome C Oxidase?
O2 binds to harm a3 group
Higher affinity than myoglobin
O2 is then the final acceptor in the ETC
CO2 combines with? forming what equation? What does chloride shift do?
CO2 + H2O (catalysed by carbonic enzyme) = H2CO3 = H+. + HCO3-
Replace HCO3- with Cl-, maintains balance of charge
How is CO2 transported in blood?
Dissolved
Carbamino compounds
Bicarbonate ions
Decreases in O2 carrying capacity?
Hypobaric environment
Concentration of gases in mixture stays the same
But there is Reduction in total pressure decreases the partial pressure of O2
Less molecules of Oxygen
Anaemia:
Reduces RBC’s and iron and therefore O2 carrying capacity
Illegal ways of increasing O2 in blood?
Withdraw blood and store in fridge, training recovers RBC mass, inject own blood back in overall RBC mass increases
Inject EPO
Purpose of the cardiovascular system?
Controls blood transport around the body:
O2 and nutrients to tissues
Removal of CO2 and wastes from tissues
Transport of hormones
Regulation of body temp
Immune function
What is the CV system composed of?
Heart
Arteries and arterioles
Capillaries
Veins and venules
Describe the cardiac cycle?
Diastole:
Relaxation phase
Filling
Pressure in ventricles is low
Atria fills with blood
Atria pressure > ventricular pressure
AV valves open
Systole:
Contraction phase
Ejection of blood
Pressure in ventricles rises
Blood will be ejected in pulmonary and systemic circulation once ventricular pressure is larger than aortic pressure as semi lunar valves open
What does an electrocardiogram do?
Composite record of electrical events
12 leads
Electrical components of the heart?
Sinoatrial node: Anterior internal tract Middle internal tract Posterior internal tract Bachmann's bundle
Atrioventricular node:
Bundle brunch
Conduction pathways
3 recognisable waves in an ECG?
P wave- small bump before QRS complex, atrial depolarisation
QRS complex - down, up, down, ventricular depolarisation
T wave - small bump after QRS complex = ventricular repolarisation
Abnormalities indicate disease
What is Lub dub sound created from?
Mitral valve closes
Aortic valve closes
Resting values of BPM in trained and untrained, and in Bradycardia and Tachycardia?
70 BPM males and females untrained
50 BPM trained males
55 BPM trained females
Bradycardia is smaller than 60 BPM
Tachycardia resting is larger than 100 BPM
2 important factors of vessel radius?
Vasconstriction:
Radius decrease
Resistance to flow increases
Vasodilation:
Radius increases
Resistance to flow decreases
What location of the brain can influence breathing?
Medulla oblongata
Features of the parasympathetic nervous system?
Activates vagus nerve
Parasympathtic neurones release acetylcholine
Inhibits SA and AV discharge delaying the rate of sinus discharge
So heart rate decreases
What does the sympathetic nervous system do?
Actiaves sympathetic cardiac accelerator
CA nerves release adrenaline and noradrenaline from adrenergic fibres
Positive chrontropic and inotropic effects though beta-adrenergic receptors
Heart rate increases
Ventricular contractility increases
Who discovered the cell?
Robert Hooke, looking at thin slice of cork, witnessed cells
Differences of prokaryote cell to a eukaryote?
Pro:
Lack a distinct nucleus bound by a membrane
lack membrane bound organelles such as mitochondria and chloroplasts
Single circular DNA and some small DNA called plasmids in cytoplasm
Eu:
Have a nucleus
Contain membrane bound organelles
Mitochondria for respiration
What is the cytosol?
The cytoplasm but if the organelles were removed
Location of chemical reactions
What is the nucleus?
Contains DNA, condensed and orgaisned with proteins as chromatin
Surrounded by nuclear envelope
Contains nuclear pores, regulated by a protein structure - the nuclear pore complex
What is the nucleolus?
Spherical body of the nucleus that becomes enlarged during protein synthesis
Contains DNA templates for rRNA transcribed by RNA polymerase 1
Central dogma?
DNA to RNA to Protein
Features of mitochondria?
Allow oxidative phosphorylation:
Occurs in a membrane bound electron transport system
Creates ATP using a H+ gradient
What is endosymbiotic theory?
Mitochondria were primitive bacterial cells
Over millions of years mitochondria and eukaryotes become mutually beneficial
This is now a permanent dependent relationship
Features of mitochondrial DNA?
They have their own DNA
Circular
Zygote derives from mtDNA from the ovum - passed on through mother
Encodes for 37 genes
Features of the endoplasmic reticulum>
Forms an interconnected network of tubules, vesicles and cistern within cells
Site of protein synthesis and packaging of cell chemicals into transport vesicles
Smooth:
Takes part in synthesis of membrane and lipid steroids
Small portion of ER
Rough:
Studded with ribosomes
Where protein synthesis occurs
What does Golgi apparatus do?
Stacks of membrane bound cistern located between the ER and cell surface
Mainly devoted to processing the proteins synthesised in the RER
Vesicular enzymes modify and transports molecules in cells
Features of ribosomes?
Made up of protein and rRNA
The ribosomes clamps over the tRNAs and mRNAs to make new protein
A site receives new tRNA
P site receives peptide bearing tRNA after peptide bond forms
E site is where tRNAs exit
4 major proteolytic systems?
Lysosomes
ATP - dependent ubiquitin proteasome - protein breakdown
Calpains
Caspases
What are lysosomes?
Created by the addition of hydrolytic enzymes to early endoscopes from the Golgi appartus
Work best at low pH - so they pump H+ ions into themselves from cytosol
They create a space where the cell can digest molecules
features of ATP - dependent ubiquitin proteasome - protein breakdown ?
Breakdown tagged cellular proteins
Essential part of normal cell turnover
Features of calpains and caspases?
More specific protein degradation - for fine tuning
What are peroxisomes?
membrane bound organelle sacs
Oxidation reactions produce Hydrogen peroxide, they contain catalase converting it to H2O or use it to oxidise another organic compound
Uric acid, amino acids and fatty acids are all broken down via these oxidation reactions
Features of the cytoskeleton?
Extensive network of protein fibres
Functions in: Providing mechanical strength Locomotion, remodelling Chromosome seperation in mitosis and meiosis Intracellular transport of organelles Cellular signalling
Microfilaments - Linear polymers of actin subunits which resist compressive and tensile forces
Microtubules - conveyer belts inside the cells, they move vesicles, granules, organelles like mitochondria and chromosomes via special attachment proteins. Made up of linear polymers of tubular
Intermediate filaments - withstand mechanical stress
What are focal adhesions?
Attachment complexes anchor contractile filaments to cell membrane
What is part of the extracellular matrix?
Proteins exocytosed in to the extracellular space - often referred to as connective tissue
What is endocytosis?
Take up
Cell membrane invaginate, pinches in, creates vesicle enclosing contents
What is exocytosis?
Release
Membrane vesicle fuses with cell membrane, releases enclosed material to extracellular space
Example of exocytosis?
Collagen synthesis
Features of cell membrane (fluid mosaic model)?
Hydrophilic (polar) heads on outside, Hydrophobic (non-polar) fatty acid tails on inside
Features of crossing the membrane?
Osmosis- aquaporins
Simple diffusion - no channels
Facilitated diffusion - assisted via protein channels
Active transport pumps and carriers - requires energy, primary and secondary transport
What is a solvent?
The liquid which contains a solute
Solute?
Substance that is put into the solvent
Hypertonic fluid?
High concentration of solutes , so water moves from inside to outside of cell
Isotonic fluid?
Equal solute concentrator. inside and out so no mocement
Feature of hypotonic?
Lower concentration of solutes, so water moves from outside to inside cell
Which molecules can simply diffuse?
Small non polar molecules such as oxygen
Molecules that are transpired in facilitated diffusion?
Polar molecules and charged ions, as can’t get past polar fatty acid tails
What is secondary active transport (coupled transport)?
Ions are moved across the membrane against the concentration gradient due to pumps
Then another molecule can join with the ion which will return down the electrochemical gradient
What creates the resting membrane potential?
SOPI pumps
What is a signal transduction pathway?
Series of molecular steps that describe the signal being transmitted through the cell
What is thermoregulation?
The ability of an organism to keep its body temperature within certain boundaries
What does humans being homeotherms mean?
Constant internal body temperature regardless of external stimuli
What are endotherms?
Generate heat internally
Maintain high basal heart production
eg. mouse
What are ectotherms?
Depend on external heat sources
Temperature changes with the environment
How hot are humans?
Internal core body temp = 36.6-37.5 degrees
Optimal function = 36.5-40.0 degrees
When does hypothermia occur and symptoms?
When internal core temperature drops bellow 35 degrees
When does hyperthermia occur?
Internal core temperature above 38 degrees
Results in heat exhaustion (lots of sweating) or heat stroke (no sweating)
Above 42 will cause damage to cells
Which part of the brain controls body temperature?
Hypothalamus
Sites in which core body temperature can be measured?
Hypothalamus Oesophagus Rectum Intestinal Oral under tongue Ear drum
What does the body priorities in having the correct optimal temperature in cold or hot conditions?
Areas near your internal organs and brain
What is specific heat capacity?
Amount of energy required to raise the temperature of a given substance by 1 degree
Different substances have different values
Water = 4.186
Human body tissue = change in temperature
The law of conservation of energy?
Energy can neither be created nor destroyed - it can only be transformed from one state to another
How can heat be generated?
Liberate chemical energy in food we eat
Resynthesize ATP, process inefficient as energy is not equal to ATP resynthesis
Difference between voluntary and involuntary heat production?
Voluntary:
Exercise
70-80% EE appears as heat
Involuntary: Shivering Action of hormones Thyroxine Catecholamines
Examples of external heat gain?
Sky thermal radiation Solar radiation Reflected Air température and humidity Ground thermal radiation
Examples of heat loss?
Conduction
Convection
Radiation
Swear evaporation
Heat transfer is always from?
Higher to lower temperatures
What is heat transferred through?
Electromagnetic waves
What is conduction?
Heat transfer from the body of an object with direct contact
What is convection?
Heat transfer to or from air or water
What is evaporation?
Vaporisation of sweat from water to vapour
Features of sweating?
Released from sweat glands
Stimulated by sympathetic nervous system
Increased SNS when exercising, or nervous
Factors influencing evaporation?
Temperature
Convection currents
Skin exposure
Equation for sweat loss?
= Change in mass + fluid intake - urine
Sweat rate depends on?
Body size Absolute VO2 Aerobic fitness Heat acclimatisation Environment
Areas of the body with greater heat loss?
The skull
The groin
The armpits
Extremities
How does hyperthermia improve sprint/power performance?
Decreased resistance of muscles/joints
Faster nerve conduction velocity
Improvement in muscle contractile elements
Faster metabolic rate
Q10 effect
Increased SNS activity
However it impairs endurance performance
What is central fatigue?
Brain stops sending out the neural impulses to contract the muscles
Importance of hydration?
Cool drinks can lower temperature
Cool drinks are absorbed faster in the GI tract
Total body water definition?
Fluid that occupies intra-cellular and extra-cellular spaces = 0.6 L/Kg = 60% of body mass
Intra-Cellular volume?
Fluid within tissue cells = 0.3L/kg = 40% of body mass
Extra-cellular volume?
All fluids outside of cells = 0.2L/Kg (20%) of body mass
What is interstitial fluid volume?
Located in spaces between tissue cells = 16% of body mass
What is plasma volume?
Liquid portion of blood = 4% of body mass
Describe the 2 semi-permeable membranes that separate, ICF, interstitial fluid and plasma?
Plasma membrane separates ICF from surrounding interstitial fluid
Blood vessel wall (capillaries) divide interstitial fluid from plasma
WHat’s a solvent?
Substance that dissolves a solute
What’s a solute?
A substance dissolved in a solvent
Describe measuring body water status?
Measures body’s electrolyte-water balance
Osmolality - number of osmoses of solute per kg of solution
Osmolarity - number of osmoses of solute per litre of solution
Determined on a plasma, saliva or urine sample
What is euhydration?
State of normal body water level
What’s hypohydration?
State of reduced body water level
What is hyper hydration?
State of elevated body water level
Electrolyte functions?
Control osmosis of water between body fluid compartments
Helps maintain the acid-base balance
Carry electrical current]]
Serve as cofactors
In the extra cellular fluid which is most abundant cation and anion?
Na+ - Muscle contraction Impulse transmission Fluid and electrolyte balance Main electrolyte lost in sweat
Cl -
Regulates osmotic pressure
Forms HCl
In the intra cellular fluid which is most abundant cation and anion?
K+ Resting membrane potential Action potentials Maintains intracellular volume Regulation of pH
Anions are proteins and phosphates
Describe how sodium interaction with body water regulation?
Sodium is the only cation to exert significant osmotic pressure
Sodium ions leaking into cells and being pumped out against their electrochemical gradient
Osmoreceptors stimulated, then either increased ADH released, increased thirst, decreased urinary water loss
Or reduced ADH released, decreased thirst, increased urinary water loss
Features of ADH?
Hypothalamus tells the posterior gland to release it
This is stimulated by haemoconcentration during exercise, increase in plasma osmolality, or decrease in plasma volume
ADH promotes water retention in the kidney in an effort to dilute plasma electrolyte concentrations
Features of aldosterone?
Mineralcorticoid hormone
Released from adrenal cortex
Secretion is stimulated by (renin-angiotensin mechanism) : Decreased plasma sodium Decreased blood volume Decreased pressure Increased plasma potassium concentration
Promotes renal reabsorption of sodium, causing the body to retain sodium
Systemic aldosterone release reaches kidney, increased sodium reabsorption in distal convoluted tubule and the collecting duct
Net effect is increased fluid retention
Look at past papers to see if long question on renin-angiotensin mechanism)
if so add all steps from water lecture
Features of Hyponatremia?
When Na+ concentrations fall bellow normal range due to excessive fluid intake, or lots of blood loss
lots of negative symptoms
Cellular consequences of dehydration?
Loss of solutes / reduced blood volume
Causes changes in osmotic pressure
Cells lose water and shrink due to osmosis
Advantages of isotonic (balanced), hypotonic (low concentration of solutes), and hypertonic solutions (high concentration of solutes)?
Isotonic:
Easily absorbed and quickly leaves the stomach
Hypotonic:
Less easily absorbed, more useful in hot weather
hypertonic:
Take too long to leave stomach, digestion problems, cause dehydration
Effects of alcohol?
Increased rate of urination
Lower fluid retention
Reduced plasma volume
What’s successful compensation?
When Homeostasis has been re-established
What is failure to compensate?
Negative effects occurring due to failure to re-establish homeostasis
What’s the endocrine system?
Glands that release hormones into the blood to be carried to distant organs
Example is skeletal muscle
4 keys way hormones can communicate?
Endocrine - blood to distant site
Autocrine - acts back on the cell that produced it
Paracrine - acts directly on a nearby cell
Juxtacrine - communication between 2 connecting cells which requires physical contact between them
3 ways endocrine glands are stimulated to release hormones?
Humoral stimuli - changes in composition of blood
Hormonal - due to other hormones
neural stimuli - nerve fibres stimulate the release
Do hormones affect all cells?
No only target cells, which has the specific receptors
What does the magnitude of hormone effect depend on?
Number of target receptors (they are continuously synthesised and degraded, so number can vary over short time periods)
Concentration of hormone
Affinity of receptor for hormone
Influence of other hormones
2 main catergories of hormones?
Steroid:
Lipid soluble - synthesized from cholesterol
Circulate in blood with bound protein (classifying them as inactive at the point)
Diffuse into the cell
Non steroid:
Water soluble
high molecular weight so can’t diffuse across cell membrane
So act via binding to receptors on plasma membrane = first messenger
What is signal transduction?
the process by which extracellular signals are communicated into a cell to affect function
first messenger followed by a second messenger, series of enzymes altered, altering cell function
Positive and negative feedback loop?
Positive - effect is amplified
Negative - effect is nullified
Features of the pituraity gland?
In brain and has posterior and anterior lobes both under control from hypothalamic hormones
Anterior:
Receives hypothalamic hormones via vessels, which stimulates further hormone release by pituitary
Posterior:
Stores hormones made by hypothalamic neutrons and releases into circulation (so does not synthesise hormones)
Main ones are ADH and oxytocin (uterus contraction and milk ejection during lactation)
Difference between the nervous system and the endocrine system?
Nervous system is more short term and very specific and uses neurotransmitters
Endocrins system is more long term, more general and uses hormones
Describe the action of a steroid hormone?
Diffuse into the cell
Bind to specific receptor located in either the cytoplasm or nucleus
Hormone - receptor complex activates gene expression
Protein synthesis is induced
Features of the pineal gland?
Produces melatonin, which is suppressed by light and stimulated by dark so most active at night time
Modulates sleep patterns in circadian rhythms
Features of the thyroid gland?
Butterfly shaped and located in the neck, inferior to the larynx
Secretes the hormones Triiodothyronine and Thyroxine
Involved primarily in tissue development and growth as well as macronutrient metabolism
Hormone production is stimulated by anterior pituitary releasing thyroid stimulating hormone
Features of the parathyroid gland?
4 glands located at posterior of thyroid gland, which produce PTH
PTH is most important regulator of serum Ca(2+) levels, as stimulates reabsorption at kidneys, and in bone
2 functions of the pancreas?
Exocrine function:
Secretes enzymes to digest carbohydrates
Endocrine function:
Secretes substances to regulate blood glucose levels
Describe the islets of langerhans in the pancreas?
Alpha cells produce glucagon that increases blood glucose
Beta cells produce insulin that decreases blood glucose
Deta cells - produce gastrin and somatostatin that regulates alpha and beta cells
F cells - produce pancreatic polypeptide that regulates metabolism
Features of the adrenal glands?
Pair of glands that sit on the top of the kidneys
Each gland has an outer adrenal cortex and an inner adrenal medulla
Outer adrenal cortex:
produces steroid hormones
Inner adrenal medulla:
Acts as part of sympathetic nervous system and releases epinephrine (adrenaline) and norepinephrine in fight or flight response
Describe the 3 main dysfunctions that can occur to the hormonal system?
Abnormal hormone receptor function / levels
Altered intracellular response to the hormone receptor complex
Hyper or hypo secretion of hormones by glands
Where are alpha receptors found and what are they stimulated by?
Mostly found in sympathetic organs / tissues
Norepinephrine and epinephrine
Where are beta receptors found?
Located on membranes of many organs such as muscles lungs heart and liver
just epinephrine
4 hormones that work to increase the amount of circulating glucose?
Glucagon, epinephrine, norepinephrine and cortisol
Epinephrine and norepinephrine stimulate more glucagon to be released and less insulin
Difference between type 1 diabetes and type 2?
Type 1:
Results from the body’s failure to produce insulin
Onset typically in early childhood
Type 11:
Insulin resistance - cells fail to use insulin properly
Onset typically in adulthood
Symptoms of type 1 diabetes?
Weight loss as loss CHO causes excess use of fat for weight loss, and the inhibitory effects of insulin on breakdown is lost
Ketoacidosis occurs so ketones are released into blood by the liver due to lots of fats being used as an energy source, lots of dehydration as kidneys try to remove them in urine and by vomitting as well. Can go in coma
Symtoms of type 2 diabetes?
Vascular complications
Nerve damage
What does the CNS include?
Brain and spinal cord
What odoes the peripheral nervous system contain?
Cranial nerves, 12 pairs
Spinal nerves, 31 pairs
4 lobes of the cerebrum?
Frontal
Parietal
Temporal
Occipital
google function and location
What is the cerebellum?
Coordinates movement by cerebral cortex
Parts of the brain in sensory integration and homeostasis regulation?
Diencephalon - thalamus, hypothalamus, pituitary gland
What is the brain stem?
Connects brain to spinal cord
CV and respiratory control
What the device called that can stimulate different part of the brain?
TMS (transcranial magnetic stimulation)
What are afferent nerves?
Sensory neurons
Impulses from receptors to CNS
Features of efferent nerves?
Motor neurons
Impulses from CNS to effectors
What are baroreceptor?
Stretch receptors, sensitive to changes in blood pressure
What are chemorecptors?
chemical receptors
What are mechanoreceptors?
Detect muscle tension and length
What are metaboreceptors?
Skeletal muscle metabolites
What are nociceptors?
Pain receptors
What are interneurons?
When a shortcut is needed, for example pain
Pass afferent transmission to efferent transmission without need to involve brain, so it’s just spinal cord
So Spinal cord can control simple motor reflexes
Where brain controls more complex and sometimes subconscious motor reactions
Describe what the interneuron does in the myotatic/stretch reflex (hammer on knee)?
Stimulate muscles to make knee flex as well as stopping other muscles preventing this
so they analyse the sensory information, store some aspects and make decisions
What’s in the autonomic nervous system?
Involunatry responses
SNS and PNS
What’s in the somatic nervous system?
Motor nuerons
Skeletal muscle function
Tissues of the nervous system?
Neurones
Neuroglia - protective and supporting, don’t conduct nerve impulses
Oligodendrocytes - support cells in CNS
Astrocytes - regulate electrical transmission in the brain
Features of motor units?
2 components - alpha motor neurones and muscle fibres stimulated by them
3 types are slow (type 1), fatigue resistant (type 11a), fast fatiguing (type 11x)
One muscle neurones innervates each single muscle cell
Anatomy of a neurone?
Dendrites- pick up signals
Axon hillock - nerve impulse generated
Axon carries nerve impulse away from cell body
Synapses = contact point
Myelinated means they have a myelin sheath which are fatty and insulating
Nodes of ranvier are breaks in the myelin sheath - increases the transmission of impulses, as they jump between them
3 nerve fibre groups?
A - (Alpha, bet, gamma) all are myelinated
B - moderate myelination
C - unmylinated
How to increase velocity of an action potential?
Amount of myelination, more = faster
Axon diameter - faster as diameter increases
Temperature, faster as temperature increases
3 structural classifications of neurones?
Multipolar - cell body in dendrites
Unipolar - cell body at the side
Bipolar - cell body in the middle
Action potential definition?
A sequence of rapidly occurring events that reverse the membrane potential and then restore to a resting state
What is the membrane potential?
Difference in amount of electrical charge inside and outside the cell.
What creates the resting membrane potential in cells?
SOPI pumps create a -70mV inside the cell
Describe the steps of an action potential?
Depolarisation occurs when sufficient stimulus depolarises the cell, voltage gated Na+ open and sodium floods in at-55mv
Repolarisation - returning to resting membrane potential, Na+ channels close, K+ leaves the cell due to voltage hated K+ channels
Hyperpolarisation - caused by delay in closing of voltage gated K+ channels
What does graded potential mean?
That an action does happen or doesn’t, no in-between
What are synapses?
Gaps between neurones so they have to communicate via electricity or chemicals via the synaptic cleft
2 types of postsynaptic potentials?
EPSP - excitatory postsynaptic potential
IPSP - inhibitory postsynaptic potential
What’s spatial summation?
Summation of effectors of neurotransmitters released from several end bulbs onto one neuron
What’s temporal summation?
Summation of effect of neurotransmitters released from 2 more in rapid succession
What’s the refractory period?
Excitable membrane needs recovery, during this period it can’t be excited again
there is absolute period where nothing can stimulate it, and a relative period where only a large stimulus could evoke an action potential
3 types of muscle?
Smooth
Cardiac
Skeletal
Features of smooth muscle?
Fusiform shaped (tapering at both ends) Involuntary contractions (slow wave motions) Not striated with only one, centrally located nucleus
Primary functions - digestion, Breathing and circulation
Features of cardiac muscle?
Has cardiomyocytes
Narrow and shorter than skeletal
One nucleus, many mitochondria
Intercalated discs support synchronised contraction of cardiac tissue
Features of skeletal muscle?
Elongated muscle cells
Myocytes (long structures)
Multi-nucleated
Striated
Banded pattern (proteins)
Describe the thick filament and thin filament in a myofibril (muscle cell)?
Thick: Mainly Myosin (bit of titin)
Thin:
Actin
Troponin
Tropomyosin
What does Titin do?
Inside the thick filament
Keep thick and thin filaments aligned
Resist muscle from overstitching
Recoil muscle to resting length after stretching
What’s in the toponym complex?
Tropomyosin
Calcium
Actin
What does Nebulin do?
Achors Actin to Z disk
What does dystrophin do?
Anchors actin to sarcolemma via a protein complex
What’s muscular dystrophy?
Weakening and breakdown of skeletal muscle
Does the I band contain myosin?
NO
What happens to bands during contraction?
H band dissapears
I band narrows
A band stays the same
Z line move closer together
What’s Henneman’s size principle?
Motor units are activated in a preset sequence depending on motor neurone size
1 then 11a then 11x
Recruitment is based on force not on velocity
More features of type 1 fibres?
Slow contraction sped
Adaped for aerobic respiration by having high capillary density, and high myoglobin content
High mitochondrial density and content of oxidative enzymes
More features of type 11 fibres?
Fast contraction speed
Adapted for anaerobic respiration
Less blood supply myoglobin and mitchdondria
High content of glycogen and glycolytic enzymes
Features of transverse tubules and steps after?
Dihydropyridine receptor - voltage gated calcium channel
Ryanodine receptor - responsible for release of Ca2+ from sarcoplasmic reticulum
Then Ca2+ are mechanically coupled to Actin, by binding to troponin on the thin filament, shifts tropomyosin off myosin dining sites, enables myosin to bind to actin
Features of Calsequestrin?
Glycoprotein
Moderate affinity and high capacity for Ca2+
Allows large quantities of Ca2+ to be stored in sarcoplasmic reticulum
