Wk 4 - Intro to Physiology Flashcards
What is physiology?
The study of how things work in a living organism
Define homeostasis
Holds the body at a constant level/magnitude even throughout external and internal disturbances
What is the function of homeostasis in the body
- Mechanisms to regulate control variables that are key to being kept “normalized” for homeostasis
- Stay in control using negative feedback loops – maintains dynamic constancy in normal functioning range
Overview of the respiratory system
- Take in O2 for respiration and release CO2
- Monitor partial pressures of gases and modify through ventilation
Overview of the urinary system
- Regulate extracellular fluid balance (and BP)
- Regulate blood plasma composition (pH, electrolytes, water, salts)
- Osmoreceptors in hypothalamus
… Secrete ADH
Increased ADH? Increase water reabsorption
Overview of gastrointestinal system
- Digest, absorb, secrete: enzymes, fluids, nutrients
- Motility/speed through system
- Regulation: parasympathetic from CNS (acetylcholine) –> comes from long reflexes
- Short reflexes from cephalic brain
Overview of reproductive system
- Produce gametes/support development of fetus and infant (lactation)
- Hormone production and control (mainly from hypothalamus – LH hormone)
Overview of endocrine system
- Regulation/coordination of growth, metabolism, reproduction, BP, electrolyte balances
Mechanistic effect
- Cause and effect
- Starts at beginning and looks at how events happen
Ex: body temperature drops below normal and so a reflex pathway causes involuntary oscillating skeletal muscle contractions to produce heat
Teleological effect
- Starts at the end
- Looks at why things happen and explains the purpose of an action
Ex: Shivering elevates a low body temperature
Body temperature negative feedback process
Sweating
- Dilation of blood vessels helps radiate heat
- Fluids become more concentrated
- Concentrated fluids detected by osmo-receptors in hypothalamus – leads to increase in thirst
- Drink more water!
Shivering
- Muscles contracting – requires energy – told to do so by the hypothalamus
- Heat is released from skeletal muscles
- Blood vessels constrict to make them go deeper into tissues and not release a lot of heat
Overview of cardiovascular system (example from powerpoint)
Flow = Pressure/Resistance
Blood pressure = cardiac output * total peripheral resistance
BP = CO * TPR
What is controlled variable? – BP!
How is cardiac flow determined?
CO = Heart rate * Stroke volume
What is the sensor? – Baroreceptors!
What transmits the efferent signal?
- Vasodilation
- Decrease HR (Decreases CO too)
- Decrease stroke volume (decreases CO too)
- NERVES: sympathetic response (norepinephrine)
What is the effect of an increase in blood pressure??
- Decrease in resistance and cardiac output
What’s the equation for controlling blood flow through a blood vessel?
FLOW = PRESSURE/RESISTANCE!!
What’s the primary controlled variable to make sure that the CV system meets its homeostatic role?
Blood pressure!
BP = CO * TPR
What are the 2 factors that control mean arterial pressure?
CARDIAC OUTPUT
TOTAL PERIPHERAL RESISTANCE
Increase either one and cause increase in pressure
