EXERCISE PHYSIOLOGY Flashcards
Define homeostasis
The condition of equilibrium in the bodys internal environment
What does AFFerent mean
AWay from control centre
What does EFFerent mean
Towards control centre
Describe the pathway of homeostasis
Regulated variable
Sensor
Control centre
Effector
What happens to regulated variables when you get ill
They can get reset
eg temp gets reset and you get a fever
What is negative feedback
Acts to reduce an effect
Give an example of negative feedback when your cold
Feel cold
Shiver to trigger heat production
Return to normal level
What is positive feedback
Acts to increase an effect
Give an example of positive feedback in ovulation
Ovulation between days 12-14
Oestrogen provides positive feedback to the hypothalamus and pituitary gland
causing rise in oestrogen production in ovaries
Leads to ovulation
What are feedforward loops
Are physiological responses in anticipation of a change in a variable
Give an example of a feedforward loop
Heart rate increases prior to a running race
What is a reflex
Requires knowledge from an integrating centre and a circuitry that connects the receptor and the effector
What are local homeostatic controls
Are highly significant because they allow individual parts of the body to self regulate their responses
How do cells communicate
Direct contact
Neighbouring cells through gap functions
Cell surface proteins trigger a response
Short distance release of chemicals (paracrine signalling)
Long distance release of chemicals (endocrine signalling)
How much does the brain weigh
1.5kg
What can primates do with neurones
Pack them
The neurones don’t increase in size when the brain does allowing you to pack neurones
What happens to the brain as your body size increases
The brain also increases
how many neurones in the brain
86 billion
how much % of cardiac output is directed to the brain
15-20%
How much of total energy does brain consume
20%
What makes up the nervous system
Central nervous system (CNS)
Peripheral nervous system (PNS)
What makes up the CNS
Brain
Spinal cord
What makes up the PNS
Nerves
Ganglion
What happens if you damage the CNS
It doesn’t regrow as encased in a bone structure
What happens if you damage the PNS
It can regrow as its plastic
What is somatic
CONTROLS VOLUNATRY MOVEMENT
Eg- Peripheral nerves exit spinal cord and contacts muscles
Stimulation of nerves cause contraction of muscle and moves body therefore voluntary
What is autonomic
CONTROLS INVOLUNTARY MOVEMENT
Controls lungs, heart, smooth muscle, endocrine & exocrine glands
What are the 2 sections to the autonomic nervous system
Sympathetic
Parasympathetic
What are 2 options in sympathetic
fight or flight
what are 2 options in parasympathetic
Rest and digest
What is the technical term for the forebrain
Prosencephalon
what is the technical term for the mid brain
Mesencephalon
what is the technical term for the hindbrain
Rhombencephalon
What are input senses
Visual
Auditory
Olfactory (smell)
Gustatory (taste)
Tactile (touch)
Vestibular (sense of head movement in space)
Proprioreceptive (sensations from muscles and joints of body)
What is vestibular sense
Sense of head movement in space
3 steps to making a decision
Sensory input
Integration
Motor output
What are the 2 major cell types in the brain
Neurones
Glial cells
Describe neurones
Electrically exciteable
Communicate with other cells via synapses
Make up majority of nervous tissue
Describe glial cells
Non neuronal cells that maintain homeostasis
Form myelin
Provide support and protection for neurones
NEURONES
how is info passed down a neurone?
Signal arrives at dendrite
Change electrical charge of cell up & down
If charge reaches threshold action potential occurs and travels down axon
When action potential reaches axon terminal it causes calcium to enter terminaL
Causes synaptic vesicles containing neurotransmitters to bind to the cell membrane and release contents into synaptic cleft
Neurotrasnmitter binds to specific receptors on dendrites of next neurone
NEURONES
If neurotransmitteris inhibitory what happens
Lowers charge in receiving neurone
NEURONES
If neurotransmitteris excitatory what happens
Increases charge in receiving neurone
NEURONES
what does myelin do
Speed up transmission by up to 10x
What are the 5 types of glial cell found in the CNS
Astrocytes Oligodendrocytes Schwann cells Microglia Ependymal cells
GLIAL CELLS
what are astrocytes
Regulate chemicals around neurones - glucose, iron
Regulate blood flow around brain (vasomodulation)
Nervous system repair (following injury to astrocytes)
GLIAL CELLS
what are Oligiodendrocytes
Form myelin sheath on axons in CNS
Each oligiodendrocyte can myelinate up to 50 axons
GLIAL CELLS
what are Schwann cells
Form myelin in PNS, assist with regrowth of axons
GLIAL CELLS
what are microglia
Creates brains immune system
Hunt CNS for damaged cells/ infectious agents
GLIAL CELLS
what are ependymal cells
Make up membrane called ependyma found in central canal of spinal cord
Producing cerebrospinal fluid
Build barriers between compartments
What are the 2 sections of the forebrain/ prosencephalon
Diencephalon
Telencephalon
What makes up the telencephalon
Cerebrum
what makes up the diencephalon
Thalamus
Hypothalamus
Epithalamus
What 3 things make up the brainstem
Medulla
Pons
Cerebellum
Where is the medulla located
Lower half of brainstem,
On top of spinal cord
What does the medulla control
Cardiac functions
Respiration
Reflexes
What is the function of the pons
Contains nuclei that relay signals from forebrain to cerebellum
Nuclei deal with sleep, respiration, swallowing, bladder control, hearing, taste, eye movement, facial expressions & posture
What is the functon of the cerebellum
Maintenance of balance and posture
Coordination of movement
Motor learning
What happens if the cerebellum is damaged
Movements still occur just less coordinated
What does the midbrain control
Tectum controls rapid orientation of head and neck
What does the diencephalon control
Thalamus acts as a switchboard
Takes info from periphery and passes it to the cortex
What is the basal ganglia
Series of interconnected nuclei
Needed for movement regulation, skill learning, addiction, selection of behaviours & movement
What are the 2 pathways through the basal ganglia
Direct
Indirect
Where does the direct path through basal ganglia go
runs directly through basal ganglia, excitory effect on cortex, net effect is pro movement
Where does the indirect path through basal ganglia go
takes a longer loop through basal ganglia, has inhibitory effect on cortex, net effect is antimovement
What happens if basal ganglia is damaged
Body produces too much or too little movement
What is the function of the cerebral cortex
Plays key role in movement, attention, perception, memory, language, conciousness
What are the folds in the cerebral cortex called
Gyri
what are the grooves in the cerebral cortex called
Sulci
What is FMRI
Functional magnetic resonance imaging
Measures blood flow
Shows active areas of the brain that require glucose which is transported in the blood
Oxygenated & de-oxygenated blood have different levels of megneticity
What is DBS
Deep brain stimulation
Therapy that delivers high frequency electrical pulses directly deep onto the brain
For Parkinson’s it targets nuclei in basal ganglia
What is the middle of the spinal cord made up of
Neurones
& other cells (grey matter)
What is the outside of the spinal cord made up of
Fibres (White matter)
What are the 3 horns
Dorsal (back)
Ventral (front)
Lateral (side)
function of the dorsal horn
Contains sensory neruones
Receive sensory info and send it to brain
Function of ventral horn
Contains neurones that send messages directly to muscles
Function of intermediate zone
Contain interneurons, these integrate info from sensory neurones and contact motor neurones (inhibition)
Which horn is sensory info collected in
Dorsal horn
Which horn are motor neurones located in
Ventral horn
What is spinal white matter
Fibre tracts that carry info to and from the brain
What do corticospinal fibres influence
The movement of every part of the body but ESPECIALLY individual finger use
What 2 tracts make up the lateral descending system
Corticospinal tract
Rubrospinal tract
What 2 tracts make up the medial descending system
Vestibulospinal tract
Retriculospinal tract
What is the medial descending system involved in the control of
Control of balance & posture
The medial lemniscus/ dorsal column pathway carries sensory info from joint to skin about what
Fine touch
Vibration
2 point discrimination
Proprioreception
What does the spinothalamic tract do
Conveys crude touch (sense of being touched but without knowledge of where)
Pain
Temperature
What does the vestibulospinal tract do
Sensory system that provides sense of balance and spatial orientation for purpose of coordinating movement with balance
Send most of output to spinal cord and muscles that move eyes
What does the reticulospinal tract do
Reticular formation is a set of interconnected nuclei located throughout brainstem
Maintain tone, balance & posture
What does the rubrospinal tract contain
Contains red nucleus’
What are dermatones
An area of skin supplied by nerves from a SINGLE spinal root
What does a single action potential cause
A single twitch
What do multiple action potentials in quick succession cause
Maximal contraction called tetanic
What is a tetanic contraction
maximal contraction
Muscles cannot relax between action potentials
What is the primary motor cortex
The neurones have simple relationship to movement
Fire before movement onset
Code for basic parameters for movement, force, direction, extent, speed
What is the non primary motor cortex
Neurones in the non-primary motor cortex have a more complex relationship to movement
They code for more complex aspects of movement
What are the 2 cortexs found in the non primary motor cortex
Pre motor cortex
Supplementary motor cortex
What does the pre motor cortex do
planning movement, spatial guidance, sensory guidance
What does the supplementary motor cortex do
connected to basal ganglia – coordinating temporal sequences of actions, bimanual coordination
What does the primary sensory cortex do
Code for touch, vibration, heat, pain, pressure, proprioreception
What is proprioreception split into
A. Joint position sense- ability to recognise joint position in space
B. Kinaesthesia – ability to appreciate and recognise joint movement or motion
C. Sensation of resistance – ability to appreciate and recognise force generated within a joint
What is the posterior parietal cortex for
Reaching movements
SLIDING FILAMENT MODEL
What are binding sites
positions on actin filaments where myosin heads can attach
What are cross bridges
temporarily formed mechanical bridges between actin binding sites and myosin heads
SLIDING FILAMENT MODEL
What is a power stroke
a ‘nod’ of the myosin head that applies force to the actin filament via the cross bridge, causes the slide
What are the 3 types of muscle
Skeletal
Cardiac
Smooth
Which muscle types are striated
Skeletal
Cardiac
What is the cardiac muscle controlled by
sub-conscious autonomic nervous system
What is the smooth muscle controlled by
sub-conscious autonomic nervous system
Is skeletal muscle uni or multi nuclei
Multinuclei
What is a muscle surrounded by
fascia
Are A bands light or dark
DArk
Are I bands light or dark
LIght
Are A bands actin or myosin
Thick myosin filaments
Are I bands actin or myosin
Thin actin filaments
What are troponin and tropomyosin useful for
Important in regulation of muscle contraction
Define contraction
Activating of force generating sites within muscle fibres (cross bridges)
What is a motor unit
Group of muscle fibres that is innervated by a single motor neurone
Describe what happens to the action potential at a neuromuscular junction
Motor neurons action potential arrives at axon terminal
Depolarises plasma membrane
Ca2+ channels open
Ca2+ ions diffuse into axon terminal
Ca2+ binds to proteins
Synaptic vesicles release acetylcholine (Ach)
Ach diffuses from axon terminal to motor end plate, binding to nicotinic receptors
Binding of Ach opens ion channel
Na and K can pass through these channels (electrochemical gradient – Na moves in K moves out)
Local depolarisation of motor end plate
Muscle fibre action potential initiated
Propagation
What happens with cross bridges in a relaxed muscle
Low Ca2+
Cross bridge cannot bind with actin because tropomyosin is covering the binding site (troponin holds tropomyosin over binding site)
What happens with cross bridges in an active muscle
High Ca2+
Ca2+ binds to troponin
Tropomyosin moves away from cross-bridge binding site
Actin binds to cross bridge
What are the 2 proteins responsible for linking membrane action potential with calcium release in the cell
Dihydropyridine (DHP) receptor - found on membrane
Ryanodine receptor - found in sarcoplasmic reticulum
When the muscle shortens what happens to actin
Actin slides over myosin
What are the 4 stages of a cross bridge cycle
- Energised myosin cross bridges on thick filaments bind to actin
- Cross bridge binding triggers release of ATP hydrolysis products from myosin, producing angular movement
- ATP bound to myosin, breaking link between actin and myosin causing cross bridge to dissociate
- ATP bound to myosin, is split energising myosin cross bridge
What are the 2 factors affecting muscle force
Tension
Load
Define tension
The force that muscle exerts on object when it is contracting is called the tension of the muscle
Define load
The force that is exerted on a muscle by an object
In regards to tension and load what must happen for a muscle to shorten
Tension must EXCEED load
In regards to tension and load what must happen for a muscle to lengthen
Load must EXCEED tension
remember - Lengthen Load
Define summation
The increase of muscle tension from successive action potenials
Define tetanus
When successive stimulations result in a sustained contraction
What are the 2 types of tetanus
Fused
Unfused
What is unfused tetanus
muscle fibre has time to PARTIALLY relax before next stimulation. The development of tension oscilliates
What is fused tetanus
muscle fibre has NO TIME to relax between stimulations
The development of tension is continuous and smooth
What does CP stand for
Creatine phosphate
What does CP do
Provides energy very fast
Forms ATP from ADP
Only lasts 1-2s
Define glycolysis
Energy from glucose in absence of oxygen (anaerobic metabolism)
10 step process
Describe oxidative phosphorylation
Energy from glucose or fat in presence of oxygen (aerobic metabolism)
What is oxygen debt
To replenish glucose and creatine stores and remove lactic acid we require energy. To do this we use more oxygen to produce the energy needed after exercise has finished
What are the 5 mechanisms involved in muscle fatigue
Conduction failure Lactic acid build up Inhibition of cross bridge cycling Fuel substrates Central command fatigue
What is conduction failure
caused by potassium accumulation in the T tubules Fast recovery
What is lactic acid build up
acidic environment in muscle effects physiological functioning of proteins and the mechanisms involved in calcium release and re-uptake
What is inhibition of cross bridge cycling
accumulation of ADP and Pi in muscle fibres slows down in the cross-bridge cycling by preventing the release of cross bridges from actin molecules.
What are fuel substrates
muscle glycogen, blood glucose, dehydration
What is central command fatigue
failure to propagate signals from the brain to the motor neurons
what are the 3 types of muscle fibres
Type 1 slow oxidative
Type 2a fast oxidative
Type 2x fast glycolytic
Describe type 1 muscle fibres
SMALLEST Slow contractile speed High resistance to fatigue Small diameter low ATPase activity Highly oxidative Dark in colour due to lots of myoglobin & oxygen
Describe type 2a muscle fibres
small diameter high ATPase activity highly oxidative moderately glycolic white in colour
describe type 2x muscle fibres
BIGGEST Fast contractile speed Little resistance to fatigue large diameter high ATPase activity Highly glycolic White in colour Most fibres in motor unit
define autocrine
can be signalled by the same cell
define paracrine
signalled by nearby cells
what does paracrine signalling use
cytokines
define endocrine
signal via distant multi cellular
what does endocrine signalling use
hormones
secreted into blood from endocrine gland
What is the difference between endocrine and exocrine glands
EXOcrine secrete their products INTO DUCT
ENDOcrine are DUCTLESS and release HORMONES into blood
Define a hormone
chemical messengers carried by the blood to target cells
what are the 4 functions of hormones
1. help regulate... metabolism contraction of smooth & cardiac muscle some immune system activities glandular secretions 2. control growth and development 3. regulate operation of reproductive system 3. help establish circadian rhythm
how fast does the endocrine system work
relatively slowly but has long lasting effects
Give an example of some amines
thyroid hormones
dopamine
catecholamines
Give an example of peptides and proteins
insulin
any hormone
Give an example of steroids
alderosterone
cortisol
androgens (testosterone)
Can steroids dissolve in plasma
often lipid based so can’t dissolve
What does the responsiveness of a target cell to a hormone depend on…
- the hormones conc in blood
- abundance of target cells hormone receptor
- influences exerted by other hormones
What are the 3 types of effects hormonal interactions can have
permissive
synergistic
antagonistic
Name some things the anterior pituitary gland secretes
Growth hormone (GH) Thyroid stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Prolactin Follicle stimulating hormone (FSH) Luteinizing hormone (LH)
What 2 hormones does the thyroid gland secrete
T3 (thyroxine)
T4 (triiodothyronine)
what is T3 hormone required for
production of growth hormone from anterior pituitary gland
Physiological functions of cortisol during NON stressful situations
Affects responsiveness of smooth muscle cells to epinephrine & norepinephrine helping maintain normal blood pressure
required to maintain certain enzyme concs involved in metabolic homeostasis preventing blood glucose dropping too low
has anti-inflammatory and anti immune functions
Physiological functions of cortisol during STRESSFUL situations
Maintenance of plasma glucose conc
Enhanced vascular reactivity improving CV performance
Inhibition of inflammation and specific immune responses
Inhibition of nonessential functions - reproduction
What happens when the stress response is triggered
sympathetic nervous system is activated triggering release of epinephrine
At same time endocrine system releases cortisol from adrenal glands
What is growth hormone (GH) stimulated by
Growth hormone releasing hormone (GHRH)
What is growth hormone (GH) inhibited by
Somatostatin (SST)
What are the 3 sex hormones
Oestrogen
Progestogen
Testosterone
What is the function of the cardiovascular system
Transport oxygen, nutrients, metabolites to tissues
Removal of waste products
involved in body temp regulation
distribution and secretion of hormones
What is systemic circulation
Connected to heart in parallel
Choice of which part of body receives more or less of available blood
BOTTOM HALF OF DIAGRAM
What is pulmonary circulation
Connected to heart in series
Entire blood volume has to pass through it every time it circulates the body
TOP HALF OF DIAGRAM
What is the total blood volume roughly
approx 5 litres
What is driving pressure
Flow is created by the pressure difference between 2 points
FLOW REQUIRES A PRESSURE DIFFERENCE
what is darcys law equation
flow = pressure difference / resistance
What is poiseuilles law and equation
determines resistance to flow
flow = pressure difference x r to power of 4
What happens to resistance to flow if you double vessel radius
Resistance reduces by a lot
What happens to resistance to flow if you halve vessel radius
Increases resistance by a lot
To get fastest flow do u want a wide vessel or a narrow vessel
narrower the vessel = faster the flow
what is the equation linking velocity, flow rate & cross sectional area
velocity = flow rate/ cross sectional area
What is the pericardium
protects the heart by providing lubrication during its constant movement
Also anchors heart against diaphragm & spine
Describe flow of blood
Arrives from superior & inferior vena cava Right atrium Tricuspid valve Right ventricle Pulmonary valve Pulmonary arteries To lungs to be oxygenated Back through pulmonary veins Left atrium Mitral/ bicuspid valve Left ventricle Aortic valve Aorta to body
What do pulmonary arteries do
take blood AWAY from heart to lungs to be oxygenated
What do pulmonary veins do
Bring oxygenated blood BACK TO heart
Can tetanic contractions occur in skeletal muscles
YES
Can tetanic contractions occur in cardiac muscles
NO
If heart was always contracting there would be no relaxation period and the heart could not fill
Rate of firing in the SA node depends on…
Initial value of membrane potential
The slope of the drift towards threshold
Explain cardiac conduction
SA node fires action potentials
Stimulus spreads through muscle fibres & stimulates both atria simultaneously
Stimulation in atria spreads from fibre to fibre through gap junctions
Reaches AV node, signal delayed to enable atria to empty before ventricular contraction begins
Bundle of HiS
Signal travels down the interventricular septum via 2 bundle branches
Ventricles begin to contract as stimulus spreads upwards depolarising muscle fibres via purkinje fibres
What does a P wave on an ECG represent
atrial contraction
What does a Q wave on an ECG represent
ventricular contraction
What does a R wave on an ECG represent
Ventricular contraction
What does a S wave on an ECG represent
Ventricular contraction
What does QRS on ECG form
QRS complex
Ventricular contraction
What does a T wave on an ECG represent
relaxation of ventricles
When does the tricuspid valve open
when right atrial pressure BIGGER than right ventricle pressure
When does the tricuspid valve close
when right atrial pressure LOWER than right ventricular pressure
When does the bicuspid valve open
when left atrial pressure BIGGER than left ventricle pressure
when does the bicuspid valve close
when left atrial pressure LOWER than left ventricular pressure
When does the pulmonary valve open
when right ventricular pressure BIGGER than pulmonary artery pressure
When does the pulmonary valve close
when right ventricular pressure LOWER than pulmonary artery pressure
When does the aortic valve open
when left ventricular pressure BIGGER than aortic pressure
When does the aortic valve close
when left ventricular pressure LOWER than aortic pressure
what is systole
ventricular contraction
what is diastole
ventricular relaxation
Whta is cardiac output
Volume of blood pumped out by heart EVERY MIN
what are units for CO
ml per min
What is the equation for CO
CO = HR x SV
What symbol is CO sometimes given
Q
Describe parasympatehtic nerve activity
Takes place via vagus nerve
Releases the neurotransmitter acetylcholine which slows HR
Describe sympathetic nerve activity
sympathetic fibres (cardiac nerves) increase HR by releasing norepinephrine
What is stroke volume regulated by
- The force by which the muscle cells contract
2. The arterial pressure against which they have to eject the blood
define blood pressure
the driving force for flow in the cardiovascular system (pressure gradient between arteries and veins) and it must be maintained at all times
Where is blood pressure highest and lowest
Blood pressure highest close to heart and it declines as blood moves further away from it
What is mean arterial pressure (MAP)
is calculated from the values of systolic and diastolic blood pressure, NOT AN AVERAGE OF THE 2
What is the equation for MAP
diastolic + ((systolic - diastolic) / 3)
What is normal blood pressure
120/80
what factors effect blood pressure
Age - arteries become stiffer with age
Gender - women have lower blood pressure than men
Pressure higher in foot and lower in head due to hydrostatic pressure
What happens to BP in dynamic exercise (walking running etc)
remains relatively stable
What happens to BP in static exercise (lifting weights)
rises dramatically
What is the MAP blood pressure equation
MAP = CO x TPR (total peripheral resistance)
If TPR decreases what happens to MAP
Map decreases too
What is the sequence of events initating a muscle contraction
An action potential propagates along the length of the fibre depolarizing the t-tubule membrane, causing a release of calcium from the sarcoplasmic reticulum. This binds to troponin making the actin binding sites available for the attachment of an energised myosin head to form a cross bridge and subsequently generate tension in the muscle.
Damage to the basal ganglia can lead to what
unwanted spontaneous movements
All the motor neurones that innervate a single muscle are called a?
motor pool
A normal range for blood glucose concentration is?
70-110 mg/Dl
Motor neurones that control the lower limbs are found in which part of the spinal cord?
lumbar englargement
Length wise what is the difference between diastole and systole
diastole lasts twice as long as systole
In arteries what are adventitia
Provides structural strength and tethers the vessels in place
In large vessels the adventitia contains small blood vessels - the vasa vasorum (the vessels of the vessels)
In arteries what is elastin for
Gives vessels mechanical strength and their elastic properties (expend and recoil)
In arteries what does the endothelium do
filtering interface between blood and body
Secretes various vasoactive products
In arteries what does smooth muscle do
supplies vessels with contractile power and regulates the diameter of the lumen
In arteries what are the pre capillary sphincters
controls blood flow to specific capillary beds selectively
What do arterioles do
responsible with altering levels of resistance to blood flow in order to distribute the valuable amount of blood to where it is needed without disturbing the control of mean arterial pressure
What is active hyperaemia
the increase in blood flow via local vessels dilating to increase blood flow to the tissue working hard according to the metabolic needs
What is flow autoregulation
concerned with the maintenance of blood flow rather than changing it. When the driving pressure drops the vessels dilate, and when it increases the vessels constrict
What does a tonic state mean when referring to muscles
partially contracted
what state is arterial smooth muscle constantly in
tonic state
what controls contraction of smooth muscles
autonomic nervous system
where is smooth muscle found
in organs
contraction time of smooth muscle
contract slowly but can sustain contractions for long periods of time without fatigue
do smooth muscles have striations
no
do smooth muscle have sarcomere
no
does smooth muscle have a neuromuscular junction
no
is there troponin in smooth muscle
no
therefore actin binding sites always available
which filaments does calcium act on
thick or thin
thick
What is moved in vesicle transport
larger molecules like proteins
what is moved in bulk flow
water and solutes
define filtration
fluid movement from the capillaries to the interstitial fluid
takes place when hydrostatic pressure exceeds colloid osmotic pressure
define absorption
fluid movement from the interstitial fluid to the capillaries
takes place when colloid osmotic pressure exceeds hydrostatic pressure
does hydrostatic pressure favour filtration or absorption
favours filtration
does osmotic pressure favour filtration or absorption
favours absorption
what happens when filtration exceeds absorption
the net accumulation of fluid in tissues is
dealt with by the lymphatic system.
what are the 3 ways to change compliance of a vein
neural - Sympathetic stimulation releases norepinephrine to the smooth muscle of veins in the gastrointestinal (stomach & intestines), renal (kidneys), hepatic (liver), and cutaneous (skin) circulations causing vasoconstriction.
This reduces their capacitance and displaces blood towards the heart.
hormonal - The diameter of veins is affected by the presence of blood circulating epinephrine
endothelial - Paracrine vasoconstrictors and vasodilators (nitric oxide, endothelin -1) also operate in veins
during inspiration what happens to flow to the heart
flow to heart increases
during expiration what happens to flow to the heart
flow to heart impeded
what do lymph vessels do
collect filtered fluid from the interstitial space and return it to the circulating blood volume
what is ODEMA
Failure of lymphatic system leads to Oedema
Accumulation of excess fluid in the interstitial spaces (subcutaneous, abdomen, lungs)
Filtration exceeds lymphatic drainage
what is an endotherm
they generate their own internal body heat and do not rely on the energy of sunlight to warm the body
what is a homeotherm
Maintain their body temperature within very narrow limits despite wide fluctuations in ambient temperature
when is body temp highest
DAY OR NIGHT
during day
when is body temp lowest
DAY OR NIGHT
during night
what causes body temp to fluctuate
eating
exercise
circadian rhythm
give some examples of heat conservation/ production
Shivering thermogenesis
Voluntary muscular activity
Non shivering thermogenesis
Give some examples of heat loss
Sweating
Blood reaching the skin
what is shivering thermogenesis
creating heat
what is non shivering thermogenesis
from tissue called brown adipose tissue
what is the therm-neutral zone
not having to activate heat loss NOR heat conservation/ production mechanisms
describe the physiological control of heat loss
- Body temp increases
- Thermosensors (in skin & brain and hypothalamus) detect change
- Sends signal to brain then to hypothalamus
- Send efferent signal to adrenal medulla which activates release of epinephrine/ adrenaline
- Help blood vessels dilate
- Sweat glands secrete fluid and heat is lost
why does vasodilation happen
Vasodilation happens due to a reduction of sympathetic stimulation
It also happens due to the release of acetylcholine from specialised sympathetic neurons
what are the 2 types of sweat gland
eccrine (all over body)
Apocrine (head or hair)
why does vasoconstriction happen
happens as a result of norepinephrine acting on adrenergic receptors
how does shivering work/ what’s so special
Shivering is a specialised form of muscular contraction in which muscles perform no external work and virtually all energy of contraction is converted into heat
Shivering is a result of stimulation by somatic motor neurons
what is cardiac arrhythmias
rhythm of heart becomes out of sync
define heatstroke
failure of thermoregulation with a body temp of >40.6
what are the signs of heatstroke
- Dizziness
- Disorientation
- Dry skin
- Increased HR
- Collapsing
what is hyPOthermia
too cold
What is hyPERthermia
too hot
what happens to body temp at exercise
it is maintained but higher than at rest
what is acclimatisation
Acclimating to heat means that an individual can regulate body temperature more efficiently
Crucial for exercise in hot places
how does acclimatisation work
Involves the repeated exposure to heat either by habitation in a hot climate or use of environmental chambers
Acclimatisation begins after 5-10 days of prolonged exercise in heat, happens via adjustments in blood flow and sweating
what effects does an acclimatised individual have
Sweat more and sooner Increased blood flow to skin More dilute sweat Increased blood volume and SV Lower core body temp Lower HR Less fatigue
define basal metabolic rate
the amount of energy expended while at complete rest
what is the thermic effect of food
the energy required to digest and absorb food
define oxygen consumption/ VO2
the volume of oxygen used by your body to convert energy from the food into work
what is VO2 measured in
L/min
what is the most dense nutrient
fat
what is the least dense nutrient
carbs
what is the energy expenditure equation
energy expenditure = base metabolic rate (BMR) + physical activity level
define base metabolic rate (BMR)
rate at which person uses energy to maintain the basic functions at rest; breathing, keeping warm, keep heart beating
what are the factors that decrease metabolism
- Sleep (decreased during sleep)
- Age (decreased with increasing age)
- Gender (women typically lower rate than men at any given size)
- Fasting (BMR decreases, which conserves energy stores)
what are the factors that increase metabolism
- Growth
- Pregnancy
- Infection
- Body temp
- Recent ingestion of food
- Muscular activity
- Emotional stress
- Environmental temperature
how many kcal do men need to maintain weight
2500
how many kcal do women need to maintain weight
2000
what do baroreceptors detect
detect blood pressure
what happens to action potentials as MAP increases
firing rate of action potentials increase
what happens to action potentials as MAP decreases
firing rate of action potentials decrease
where is the medullary cardiovascular centre located
in the medulla oblongata
how does blood pressure increase through baroreceptors
A fall in BP causes carotid and aortic baroreceptors to detect a hypotensive stimulus
Leading to decreases in afferent baroreceptor nerve firing
This reduction in neural input to the brainstem causes a decrease in parasympathetic nerve activity to heart
Increases in sympathetic outflow to heart and vasculature
how quick are cardiovascular responses
within seconds
how quick are kidney responses
within hours
describe redistribution of CO during exercise
Blood flow decreases in kidneys, digestive tract & all other parts of body not directly involved in exercise
Blood flow through the brain remains fairly constant due to autoregulation
The fixed volume of the cranial cavity cannot accommodate large increases in blood flow
does vasoDILATION increase/ decrease peripheral resistance
Dilation Decrease peripheral resistance
does vasoCONSTRICTION increase/ decrease peripheral resistance
Constriction increases peripheral resistance
the net effect of vasoconstriction and vasodilation does what to peripheral resistance
reduction in TOTAL peripheral resistance
what happens to CO in trained/ untrained performers
CO is larger in trained performers
what happens to max HR in trained/ untrained performers
Max HR can not be increased by training therefore same
what happens to general HR in trained/ untrained performers
Trained have a lower HR for a given workload
what happens to SV in trained/ untrained performers
Higher in trained people
what does VO2 max test show
assessment of aerobic endurance or power
what do sub maximal exercise test show
used to asses physiological responses to a standardised workload
what is steady state exercise
the level of exercise at which the physiological responses remain relatively stable for an extended period of time
factors affecting steady state exercise
- Delivery of adequate oxygen to exercising muscles
- Ability of cells to utilise oxygen in the aerobic process of energy metabolism
- The ability to eliminate heat
how long does it take to reach steady state exercise
3-5 mins
what are the 4 states to steady state exercise
- Initial rapid rise occurs within 1st min
- A more gradual rise occurs between 1-3mins
- A plateau is reached between 3-5mins and maintained
- Finally, extended exercise (1-4 hours) there may be a small continuous increase due to factors such as increase in core body temp
This is called drift
what are the mechanisms for the control of ventilation
- The initial rapid rise in ventilation is explained by central command (that is, the motor cortex signals the respiratory control centre to increase ventilation). Mechanoreceptors in the muscles and limbs detect limb movement and physical deformation, and further supplement central command.
- The subsequent gradual rise in ventilation may be explained by a fine-tuning of respiratory neurons in response to central command and feedback control from arterial chemoreceptors positioned in the carotid and aortic bodies.
mechanisms of control for CO
Initial rapid rise explained by central command & starlings law
Input from mechanoreceptors in muscles contribute to central command by feedback control
Chemoreceptors in muscle responsible for gradual rise to steady state exercise
what is the starling effect
when venous return of blood to heart increases, the my-filaments (actin & myosin) in cardiac muscle are stretched to a more optimal overlap
As a result the strength of contraction = greater & increased
what relationship do HR and vO2 have
a strong linear relationship
functions of respiratory system
- Gas exchange between environment and blood
- Control of acidity of body
- Filtering of inhaled air
- Vocalisation
how many lobes in right lung
3 lobes
how many lobes in left lung
2 lobes
what is the pleural sac
Double walled enclosure of lungs filled with pleural fluid
Reduces friction from movement on surface of lungs
Fixes lungs firmly on thoracic wall without any physical attachments
what is the function of rib cage and spine when talking about lungs
offer rigid protection to sensitive organs - heart and lungs
what are the functions of the airways
- Warming up inspired air
- Humidification of dry inspired air
- Filtrated of inhaled foreign materials
what are the 2 types of airways
conducting zone
exchange zone
what is the conducting zone in the airways
no gas exchange takes place
what is the exchange zone in the airways
where diffusion/ gas exchange takes place
what are the turbinates (conchae) in the nasal cavity
bony dividers that increase surface area of nasal cavity
what is airflow directly proportional to
Airflow is directly proportional to pressure difference between 2 points
what is airflow inversely proportional to
Airflow is inversely proportional to the resistance created by the airways
what is the main factor affecting resistance in the respiratory system
airway radius
what things affect viscosity
humidity
concentration of air (high altitude)
What is boils law
P1 x V1 = P2 x V2
P is presure
V is volume
what type of process is normal expiration
passive process
no muscle contaction required
how could you describe intrapleural pressure
negative and subatmospheric
what type of process is forced expiration/ heavy breathing
active
requires contraction of muscles
what does surfactant do
Surfactant; promotes diffusion, increase lung compliance & prevents the collapse of smaller alveoli.
what does reduced surface tension of lungs mean
Alveolar spaces are less prone to collapsing
The lung is more compliant and is inflated easier
can residual volume be measured with a spirometer trace?
no
can functional residual capacity be measured with a spirometer trace?
no
define tidal volume
The amount of air that is moved in and out of the lungs with EVERY BREATH during normal breathing
define reserve volume
The amount of ADDITIONAL air that can be moved in and out of the lungs during heavier breathing
define vital capacity
The TOTAL amount of air that can be moved in and out of the lungs during MAXIMAL respiratory effort
define functional residual capacity
The amount of air that is LEFT in the LUNGS at the END of a normal EXPIRATION
define residual volume
The amount of air that is LEFT in the LUNGS at the end of MAXIMAL EXPIRATION
what is anatomical dead space
refers to the part of the airways where gas exchange does not take place and is a fixed volume
what is alveolar dead space
refers to areas of lungs where gas exchange can take place but that are not properly perfused with blood
define minute ventilation
is the amount of air that is moved by the lungs in ONE MINUTE
What is the minute ventilation equation
minute ventilation = tidal volume x breathing frequency
what does hyperpnoea do to minute ventilation
minute ventilation increases in proportion to metabolic rate
what does hyperventilation do to minute ventilation
minute ventilation increases more than metabolic rate does
what is daltons law
= the pressure of a gas mixture is equal to the sum of the pressures of the individual gases
how much % of nitrogen is in the air
78.1%
how much % of oxygen is in the air
20.9%
how much % of carbon dioxide is in the air
0.033%
how to find the partial pressure of a gas
times the air% of the gas (eg 20.9% for oxygen) by atmospheric pressure (760mmHg)
760mmHg x 20.9% = 159 mmHg
what is atmospheric pressure
760 mmHg
what does ficks law mean
From Ficks law it is obvious that greater solubility for a particular gas means a greater rate of diffusion for that gas.
(CO2 is a lot more soluble than O2, and it diffuses across the membrane easier)
What is more soluble CO2 or O2
CO2 is more soluble than O2
what does movement if molecules depend on
temperature
pressure difference
solubility
what is how many polypeptide chains in Hb
4 polypeptide chains
how many haem groups in Hb
4 haem groups
what is in the middle of each haem group
an Iron molecule that binds to oxygen
does oxygen that is bound to Hb contribute to partial pressure
no does not contribute
What is the shape of the dissociation curve
sigmoidal shape
what does a shift to the left mean for the oxygen dissociation curve
increased affinity for oxygen
what does a shift to the right mean for the oxygen dissociation curve
decreased affinity for oxygen (BOHR SHIFT)
what affects oxygens binding to haemoglobin
acidity
DPG concentration
CO2
Temperature
how much co2 is carried as bicarbonate ions (HCO3-)
70%
what is it called when carbon dioxide is bound to haemoglobin
carbaminohaemoglobin
how much of co2 is carried bound to haemoglobin
23%
when does haemoglobin carry co2
when the binding sites aren’t occupied with oxygen they occupy them with co2
what is the role of H+ ions in the blood
act as a buffer by binding to empty binding sites
can ventilation be voluntary
yes
how can ventilation be made voluntary
hyperventilation
holding your breath
speaking
swallowing
what does the Hiring-Breuer reflex do
protects the lungs by initiating a signal that inhibits inspiration (the switch-off point).
describe slowly adapting pulmonary stretch receptors
These receptors are located within airway smooth muscle
and they are active only when tidal volume approaches
the physical limitations of the lung tissue for expansion.
describe rapidly adapting pulmonary stretch receptors
These receptors are dense in the trachea and large airways.
They respond to stimuli such as cigarette smoke, inhaled
particles and cold air, by initiating reflexes such as coughing and sneezing and by causing bronchoconstriction.
what creates the ventilatory drive
carotid chemoreceptors (carotid bodies) aortic chemoreceptors (aortic arch)
control of ventilation in steady state exercise
phase 1
Ventilation increases abruptly and as early as in the first breath after exercise has commenced. It is thought to be controlled by neural mechanisms.
control of ventilation in steady state exercise
phase 2&3
Ventilation increases gradually until steady state exercise is achieved. Chemical stimuli are more likely to contribute to this part of the response
what drives phase 1 of control of ventilation
neural mechanisms
Muscle afferents
Central command
Learnt response
what drives phase 2 of control of ventilation
chemical mechanisms
Temperature
PCO2 and pH oscillations
Plamsa K+, catecholamines
Hypoglycaemia, metabolic rate
what is the Haldane transformation correction factor
1.5
how to calculate volume of inspired oxygen
volume of inspired air x percentage of inspired O2
how to calculate volume of expired oxygen
volume of expired air x percentage of expired O2
how to calculate oxygen consumption
volume of inspired oxygen - volume of expired oxygen
what does RQ stand for
respiratory quotient
define RQ
The ratio between the rate by which O2 is consumed and CO2 is produced depends on the fuel that is used to provide the energy needed for metabolic functions
with RQ when does the rate of CO2 production vary
it is different when carbs, fats & proteins are used as fuels
what is the RQ equation
CO2 production/ O2 consumption
what are the functions of the renal system
- Regulation of water, ions balance
- Removal of metabolic waste products from blood and excretion
- Removal of foreign chemicals from blood
- Gluconeogenesis
- Production of hormones/ enzymes (EPO, Renin)
what generates the high pressure in the glomerulus
afferent and efferent arterial blood flow causes high pressure
what’s the benefit of glomerulus having lots of pores
lots of pores so you can squeeze fluid & other small molecules out of blood
what cells allow filtration
podocytes
which are found on capillary wall
where is the bowmans space
between glomerulus and bowmans capsules
what stays in glomerulus and what gets filtered
Amino acids, RBC and large proteins stay as they’re too large
Na+ & glucose get filtered
describe the route through kidneys
glomerulus bowmans capsule PCT (proximal convoluted tubule) Loop of henle DCT (distal convoluted tubule) Collecting duct
what happens in PCT
selective reabsorption
Is selective reabsorption active or passive
active process (uses ATP)
what happens during selective reabsorption
Na+, glucose & H2O being reabsorbed back into body
what are the 2 sides in the loop of henle
descending
ascending
what happens in the descending loop of henle
water moves out nephron back into body
what happens in the ascending loop of henle
Na+ & Cl- pumped out
what happens to nephron in loop of henle
crosses from cortex to medulla
is medulla hyPERtonic or hyPOtonic
hyPERtonic
what happens in DCT
more reabsorption
what hormone acts in collecting duct
ADH
what does each nephron consist of
renal corpuscle which contains the glomerulus (tuft of capillaries) and a renal tubule (bowmans capsule)
in the kidney what are juxtaglomerular cells
Mechanoreceptors
They sense blood pressure in the afferent arteriole
in the kidney what are macula dense cells
chemoreceptors that respond to the changes in the NaCl (salt) content of the fitrate
what makes up the juxtaglomerular apparatus
juxtaglomerular cells
macula dense cells
define GFR
GFR is the amount of blood filtered by the glomeruli EACH MINUTE
What affects GFR
Capillary permeability
Surface area of capillary bed
Hydrostatic pressure that drives fluid out of capillaries
Osmotic forces within capillaries which oppose the exit of fluid
what happens if there are proteins in urine and what is it called
Proteinuria
indicates a problem with filtration membrane
what are tubular secretion mechanisms important for
- Disposing of drugs and drug metabolites
- Eliminating undesired substances or end products that have reabsorbed by passive processes (urea & uric acid)
- Removing excess K+
- Controlling blood pH
in the kidneys what is RC
Renal clearance
Define renal clearance (RC)
the amount of a substance filtered per minute, divided by its plasma concentration
measured in mL/min
what is inulin
Neither reabsorbed nor secreted, not harmful to body, small enough to get filtered out by glomerulus
what is a healthy GFR
approx 120ml/min
Define the filtration fraction
the proportion of plasma that enters the kidneys that is subsequently filtered at the glomerulus and passes into the renal tubules
what is the typical filtration fraction?/ % of blood filtered
filtration fraction 0.16-0.20
therefore 20% of blood entering kidney is filtered
how much of our lean body weight is water in %
60%
how many thirds of our total body water is located within cells (intracellular fluid)
2/3
how many thirds of our total body water is located outside cells (extracellular fluid)
1/3
KIDNEYS
where does sodium reabsorption happen
all tubular segments except descending limb of loop of henle & medullary collecting duct
KIDNEYS
is sodium reabsorption an active or passive process
active process
KIDNEYS
where are majority of aquaporins clustered
proximal nephron
kidneys
What is water reabsorption dependant on
sodium reabsorption
KIDNEY
active sodium reabsorption key points
-Active transport out of cells into interstitial fluid
-Transport achieved by Na+/K+/ ATPase pump
Keeps intracellular conc of Na + low to allow movement of Na+ from lumen
-PCT has co transport/ counter transport of organic molecules (glucose & amino acids)
-Cortical collecting ducts via Na+ channels
what is the function of aquaporins
Function of aquaporins in medullary collecting duct cells is to increase water reabsorption
what is ADH also known as
vasopressin
factors determining rate of tubular Na+ reabsorption
- Aldosterone (Most major)
- Atrial natriuretic peptide (ANP)
- Local effect of blood pressure on tubules
what inhibits Na+ reabsorption
High pressure also inhibits Na+ reabsorption (as well as reducing renin release)
How does renin increase Na+ reabsorption
- Release of Renin converts the peptide angiotensinogen to angiotensin 1
- Angiotensin 1 then converted to angiotensin 2 by ACE enzyme
- Angiotension 2 acts on angiotensin receptors located around body
- Activation of these receptors in adrenal gland stimulates aldosterone release, increasing Na+ reabsorption
How does ANP increase Na+ reabsorption
- ANP is synthesised and sorted in atrial myocytes
- ANP is released in response to stretching of the atria
- This occurs when circulating blood volume increases
- An increase in circulating levels of ANP causes an increase of Na+ excretion
what do diuretics do
promote the loss of Na+ and H2O
How does alcohol act as a diuretic
inhibits the release of vasopressin/ adrenaline from pituitary gland
What is the function of the glomerulus/ bowmans capsule
forms ultra filtrate of plasma
what is function of PCT
bulk reabsorption of solutes and water
secretion of solutes and organic acids and bases (except K+)
what is the overall function of loop of henle
establishes medullary osmotic gradient
secretion of urea
what is the overall function of descending limb
bulk reabsorption of water
what is the overall function of ascending limb
reabsorption of NaCl
what is the function of DCT
Fine tuning of reabosprtion/ secretion of small quantity of solute remaining
what is the function of cortical and medullary and collecting ducts
fine tuning of water reabsorption
Reabsorption of urea
what is normal blood pH specifically
ranges from 7.35-7.45
What range of pH is acidosis
7-7.35
What range of pH is alkalosis
7.45-7.8
What does excretion of HCO3- do to H+ ions
increases plasma H+ ion
What does addition of HCO3- do to H+ ions
decreases plasma H+ ion
describe metabolic acidosis
Rate and depth of breathing are elevated
As CO2 is eliminated by respiratory system, PCO2 falls below normal
Kidneys secrete H+ and retain/ generate bicarbonate to offset the acidosis
describe metabolic alkalosis
Pulmonary ventilation is slow and shallow allowing carbon dioxide to accumulate in blood
Kidneys generate H+ and eliminate bicarbonate from the body by secretion
what do the kidneys do during exercise
1.Conserve body water
Excrete metabolites such as
- H+
- Creatine (excess created from muscle breakdown)
- Other proteins
what is rhabdomyolis
condition where skeletal muscle cell damage can cause acute renal failure & sometimes death
what sport is linked with rhabdomyolis
cross fit in unfit athletes
what is autocrine signalling
signalled by the same cell
what is paracrine signalling and what does it use
signalled by a nearby cell
Using cytokines
what is endocrine signalling and what does it use
signalled by distant multicellular organisms
Uses hormones
what does the parasympathetic nervous system release to slow HR
Acetlycholine
what does the sympathetic nervous system release to increase HR
norepinephrine
what is starlings law/ frank starling mechanisms
as SV increases so does venous return
talk about the ability to sustain a contraction for smooth muscle, skeletal muscle & cardiac muscle
skeletal = shortest duration cardiac = middle duration smooth = longest, can sustain contraction for long periods of time without fatigue
does smooth muscle have troponin
no therefore actin binding sites always available