Body system physiology Flashcards
What is systemic systolic arterial blood pressure?
The pressure exerted the blood on the walls of the aorta and systemic arteries when the heart contracts (
What is systemic diastolic arterial blood pressure?
The pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart relaxed (normally
What is Mean Arterial Blood Pressure (MAP)?
The average arterial blood pressure during a single cardiac cycle, which involves contraction and relaxation of the heart (70 - 105 mmHg)
Equations to calculate MAP?
MAP = (2 x diastolic) + systolic / 3
MAP = DBP + 0,5(SBP - DBP)
Where are baroreceptors?
Aortic arch
Carotid sinus
Which nerve takes the signal from the carotid receptors?
Glossolharyngeal nerve (CNIX)
Which nerve takes the signals from the aortic receptors?
Vagus nerve (CNX)
How does the cardiovascular control centre process the signal?
Recipes afferent information
NTS is site of first synapse for all CVS afferent in the medulla
NTS relays info to other areas of the brain
Generates vagal outflow to the heart
Regulates spinal sympathetic neurones
What is total peripheral resistance?
The sum of resistance of all peripheral vasculature in the systemic circulation
What 3 factors when regulated control BP?
Heart rate
Stroke volume
TPR
How is heart rate increased?
Noradrenaline acts on B1 receptors
How is heart rate slowed?
Acetylcholine acts on muscarinic receptors
How is stroke volume controlled?
Frank-Starling mechanism
What is the frank starling law?
The more the ventricle is filled with blood during diastole the greater the volume of ejected blood will be during the resulting systolic contraction
What is TPR regulated by?
Vascular smooth muscle
What is vasomotor tone?
Vascular smooth muscles are partially constricted at rest due to continuous release of noradrenaline
What nerves supply vascular smooth muscle?
Sympathetic nerve fibres
Neurotransmitter is noradrenaline
What 5 hormones are involved in controlling glucose?
Insulin (pancreas) Glucagon (pancreas) Adrenaline (adrenal gland) - in emergencies Cortisol (adrenal) Growth hormone (pituitary)
What cells are in the pancreas?
Exocrine (digestive & absorptive enzymes)
Endocrine (clustered into islets of Langerhans)
What do alpha cells in the pancreas release?
Glucagon
What do beta cells in the pancreas release?
Insulin
What do delta cells in the pancreas release?
Somatostatin
What does aldosterone do?
Regulates salt levels
What does cortisol do?
Stress hormone
What does insulin do?
Favours anabolism Stimulates conversion of - glucose to glycogen - fatty acids to triglycerides - amino acids to proteins
Hormone of the fed state
What does glucagon do?
Favours catabolism
Stimulates conversion of
- glycogen to glucose
- triglycerides to fatty acids
Hormone of the hungry state
What happens when glucose increase?
Insulin increases
Glucagon decreases
What happens when glucose decreases?
Insulin decreases
Glucagon increases
How does insulin promote glucose uptake into muscle and fat?
GLUT4 into plasma membrane
What causes diabetes mellitus?
Lack of insulin or impaired cellular responses to insulin
How is diabetes detected?
Oral glucose tolerance test
What is type 1 diabetes?
Childhood onset Little/no insulin secretion Defect in B cell function ketones develops (if untreated) Insulin injections for treatment Symptoms develop rapidly
What is type 2 diabetes?
Adult onset Insulin may be normal or exceed normal Defect in insulin sensitivity Ketones ramen Diet/exercise + oral drugs for treatment Symptoms develop slowly
How does glucagon increase glucose?
Increasing liver glycogenolysis
Inhibits liver glycogen synthesis
Promotes liver gluconeogenesis
Also promotors lipgloss in liver and adipose tissue
What rhythm does cortisol secrete in?
Diurnal
How does cortisol raise glucose?
Stimulates protein catabolism
Stimulates gluconeogenesis
Stimulates lipolysis
How does growth hormone increase glucose?
Mobilises glucose from livers
Promotes lipolysis in fat cells
How does the baroreceptor reflex work?
BP change Sensed by baroreceptors Sent to cardiovascular control centre in the medulla of the brain Heart rate & stroke volume change TPR changes BP normal
What damaging effects can increased body temperature cause?
Speeds up cellular metabolism Protein denaturation Nerve malfunction Convulsions Death
What harmful effects can decreased body temperature cause?
Slows down cellular reactions
May fatally slow down metabolism
Sites from monitoring body temperature
Ear drum
Rectal
Oral
How is heat gained in the body?
Metabolic heat
Radiation
Convection
Conduction
How is heat lost from the body?
Convection
Conduction
Radiation
Evaporation
What is BMR?
The minimum amount of energy required to sustain vital Boyd functions which leads to a basic level of heat production
How does the body know there is a change in heat?
Thermoreceptors (Central & peripheral)
Which part of the brain controls heat?
Hypothalamus
Posterior - cold
Anterior - hot
What is the effector responses to cold exposure?
Vasoconstriction
Increased muscle tone (shivering)
Postural changes
Warm clothing
Effector responses to heat exposure?
Vasodilation Sweating Decreased muscle tone Decreased voluntary movement Cool clothing
What is a pyrogen?
A substance which produces fever
Why do we get a fever?
Endogenous pyrogen (e.g. IL from white blood cells) stimulate the release of prostaglandins in the hypothalamus
Prostaglandins act to reset the thermostat at a higher temperature
The hypothalamus initiates cold response (shivering etc.)
Body temp increases to new set point = fever
