Physiology Flashcards
what are the levels of organisation in physiology?
cells > tissues (a group of similar structure and specialised function) > body organs (made up of 2 or more types of primary tissue that function together to perform particular functions
what is a body system?
a group of organs that perform related functions and work together to achieve a common goal. systems work in harmony and are highly sophisticated
what must the body maintain to remain healthy?
highly regulated optimum physiological conditions
what is human physiology?
the study of normal functions of the human body and the integrative mechanisms that control them.
what is physiology essential for in a clinical setting?
understanding the body function in health and disease
understanding the patient presentations
planning and interpretation of patient investigation
planning patient management options
providing health promotion and disease prevention advice
in the cell where does a lot of physiological control occur?
the membrane
what is the change in membrane potential?
the voltage across the membrane between the inside and the outside of a cell
what is the membrane potential important for?
the functionality for nerve and muscle cells
what level do many pharmacological agents act at?
level of cell membrane to produce their therapeutic effect
what is homeostasis?
the maintenance for a stable internal environment by coordinated physiological mechanisms. several variables within the internal environment must be tightly regulated within a narrow niche
what are physiological control systems important for maintaining?
homeostasis
what are the two desired responses that physiological control systems produce?
intrinsic controls and extrinsic controls
what are intrinsic controls?
local controls that are inherent in an organ
what are extrinsic controls?
regulatory mechanisms initiated outside an organ
accomplished by nervous and endocrine systems
what is a feedforward response?
responses made in anticipation of a change
what is a feedback response?
responses made after change has been detected
what are the type of feedback systems?
positive: amplifies an initial change
negative: opposes an initial change (main type)
what is the primary type of homeostatic control mechanism?
negative feedback
what are core temperature and blood glucose regulated by?
negative feedback mechanisms
what must a negative feedback control system be able to do, to maintain homeostasis?
sense deviations (sensor) from desired range in a regulated variable that needs to be kept within a narrow range (set point) integrate information with other relevant information (control centre) make appropriate adjustment (effectors) in order to restore regulated variable to its desired range (set point)
what is blood pressure?
outwards (hydrostatic) pressure exerted by the blood on blood vessel walls. often measure the systemic arterial blood pressure and express it as systolic and diastolic blood pressures.
what is systemic systolic arterial blood pressure?
the pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart contracts
what is the systemic diastolic arterial blood pressure?
pressure exerted by the blood on the walls of the aorta and systematic arteries when the heart relaxes
what is the normal systemic arterial blood pressure?
between 120/80 and 90/60, this varies between individuals
what is hypertension?
high blood pressure, clinical blood pressure of 140/90 mmHg or higher, daytime blood pressure 135/85 mmHg or higher
which way round do the systolic and diastolic numbers go?
systolic = top diastolic = bottom
what is pulse pressure?
pulse pressure is the difference between the systolic and diastolic blood pressures. usually between 30 and 50 mmHg
what is the mean arterial blood pressure (MAP)?
the average arterial blood pressure during a single cardiac cycle which involves the contraction and relaxation on the heart.
True of false, the systolic portion is twice as long as the diastolic portion
false - the diastolic portion is twice as long as the systolic
what is the simplest way to estimate MAP?
[(2x diastolic) + systolic] / 3 or DBP +1/3 of pulse pressure
what value should MAP be in order to perfuse vital organs like brain, heart and kidneys?
at least 60mmHg. must be regulated within a narrow range to ensure pressure is high enough to perfuse vital organs but not too high to damage the blood vessels or place a strain on the heart and other organs
what are baroreceptors?
mechanoreceptors which are sensitive to stretch
what are two important baroreceptors?
carotid and aortic baroreceptors
what happens to the firing rate in baroreceptors afferent neutrons when the mean arterial blood pressure increases/decreases?
increases when MAP increases
decreases when MAP decreases
where do baroreceptors send afferent impulses to?
the cardiovascular control centre in the medulla of the brain stem
what are the sensors, control centre and effectors in the baroreceptor reflex?
sensor: baroreceptors
control centre: cardiovascular control centre (medulla)
effector: heart and blood vessels
what is the systemic vascular resistance?
sum of resistance of all vasculature in the systemic circulation
what is the cardiac output?
the volume of blood pumped by each ventricle of the heart per minute
what is the stroke volume?
the volume of blood pumped by each ventricle per heart beat
what can the mean arterial blood pressure be regulated by?
heart rate, stroke volume and systematic vascular resistance
how does the heart pump blood?
electrically controlled muscular pump which sucks and pumps blood
what is autorhythmicity?
when the heart beats rhythmically in the absence of external stimuli
how is heart rate modified?
by the autonomic (involuntary) nervous system (ANS)
what does sympathetic division stimulation do to heart rate?
increase heart rate (tachycardia)
what does parasympathetic division stimulation do to heart rate?
decrease heart rate (Brady cardia)
what happens to the stroke volume if the contractile strength of the heart increases?
increases
what regulates stroke volume?
autonomic system
what is SVR regulated by?
vascular smooth muscle
what happens when vascular smooth muscle contracts?
causes vasoconstriction and increases SVR and MAP
What happens when vascular smooth muscle relaxes?
causes vasodilation and decreases SVR and MAP
what is vasomotor tone?
when vascular smooth muscle are partially constricted at rest caused by discharge of sympathetic nerves resulting in continuous release of noradrenaline
what is noradrenaline?
acts on B1 receptors
what is acetylcholine?
acts on muscarinic receptors
what happens when sympathetic discharge increases?
vasomotor tone will increase, vasoconstriction will increase, SVP and MAP will increase
what do baroreceptors respond to?
acute changes in arterial blood pressure
what happens if high arterial blood pressure is sustained?
baroreceptors firing decreases
in the long term what is MAP controlled by?
blood volume via hormones
what are commonly assessed vital signs?
pulse , blood pressure, respiratory rate, oxygen saturation temperature
consciousness, capillary refill time
why is skin not a good site for monitoring temperature?
temperature varies more widely
what’s normothermia?
when the normal core body temperature is kept within a narrow range. optimum for cellular functions and metabolism
what does increasing body temperature to cellular metabolism?
increases it
how is temperature measured in clinical practice?
infrared tympanic thermometer
what is a very low temperature called?
hypothermia
what is diurnal variation in body temperature?
body temperature varies throughout the day, lowest temperature in early morning
what is basal metabolic rate (BMR)?
the minimum amount of energy required to sustain the vital body functions
how can your BMR be increased?
by hormones such as adrenaline
how does shivering increase heat production?
by increasing muscle activity
how much of the bodies heat is out through radiation?
around half
what does heat conduction mean for the body?
heat moves from warmer to cooler objects, heat conduction depends on temperature gradient and thermal conductivity
what does convection mean for the body?
transfer of heat energy by air (or water) currents that help to carry heat away from the body
what does evaporation mean for the body?
energy is required to convert water in the skin surface and lining of the respiratory airways into vapour, sweating is an active evaporative heat loss process controlled by the sympathetic nervous system
what are the sensors, control centre and effectors for the negative feedback in temperature control?
sensors: central thermoreceptors, peripheral thermal receptors
control centre: hypothalamus
effectors : skeletal muscles, skin arterioles, sweat glands
what is the body thermostat?
hypothalamus
what is the anterior/posterior hypothalamus activated by?
posterior - cold
anterior - warmth
what’s the difference between shortness of breath acute and chronic?
acute - comes on suddenly and unexpectedly
chronic - comes on gradually
why do we need to breath?
our body system is made of cells, the cells need a constant supply of oxygen to produce energy, the carbon dioxide produced by cellular reactions must be removed from the body
what are some causes of shortness of breath?
respiratory, cardiovascular, physiological, haematological, psychological, endocrine and metabolic causes
why with the diastolic arterial pressure not fall to zero during diastole?
elastic recoil of the aorta and large arteries and the intact aortic valve
what are the two main factors that affect extracellular fluid volume?
water recess or deficit and Na+ excess or deficit
what is the ECF volume?
the plasma fluid and the interstitial fluid, the fluid that the cells bathe in and acts as a go-between the blood and body cells
what happens if the plasma volume drops?
compensatory mechanisms shift fluid from the interstitial compartment to the plasma compartment
what regulates extracellular fluid volume?
hormones that act as effectors by regulation the water and salt balance in our bodies. water input should equal water output
what hormones regulated extracellular fluid volume?
the Renin-Angiotensin-Aldosterone System natriuretic peptides (NPs) antidiuretic hormones (arginine vasopressin)
