Week 1 Principles of physiology I Flashcards
How are organisms organised? (4 Levels)
- Cells (basic unit of life)
- Tissues = groups of cells with similar specialisation
- Organ = unit made up of several tissue types >2
- Body system = collection of related organs
Types of Tissues:
Epithelial = ____
Connective = ____
Muscle = ____
Nervous = ____
very diverse, all interconnected. (Integrated response)
Epithelial = protection, secretion, absorption
Connective = structural support
Muscle = movement
Nervous = communication, coordination, control
How many systems are there in the body?
11
What are the body systems?
- Nervous
- Immune
- Reproductive
- Circulatory
- Respiratory
- Muscular
- Skeletal
- Integumentary
- Urinary
- Endocrine
- Digestive
Body systems do NOT act in isolation Give an example.
Complex body processes - interplay
e.g. regulation of blood pressure
What is an External and Internal Environment?
External Environment = surrounding environment in which organism lives
Internal Environment = fluid that surrounds cells
Living organisms need to communicate with external environment. Why?
obtain nutrients & O2 & eliminate waste
- single-celled organism – communicates directly
- multi-cellular organism – communicates via internal environment
What is Intracellular and Extracellular Fluid ?
Intracellular Fluid = fluid contained within body cells
Extracellular Fluid = fluid outside cells > internal environment
- plasma (fluid portion of blood)
- interstitial fluid (surrounds & bathes cells)
What is the key to Homeostasis?
Internal Environment, fluid that surrounds cells –> interstitial fluid (surrounds & bathes cells)
What is homeostasis?
Why is it the foundation of physiology?
Homeostasis = maintenance of a stable internal environment
homeo ‘similar’
stasis ‘to stand or stay’
- cells make up body systems
- functions of each body system contribute to homeostasis
What is the dynamic steady-state in Homeostasis?
What factors are homeostatically maintained?
• nutrient molecules – energy production
- waste products – may be toxic
- O2 & CO2
- pH – nerve cells & enzymes
- water, salts, electrolytes
- cell volume, rhythmic beating of heart (K+)
- temperature - enzymes
- volume & pressure - plasma
Homeostatic control mechanisms may be intrinsic or extrinsic. What does this mean?
Intrinsic / local
intrinsic = within
•inherent in an organ
(e.g. exercising skeletal muscle – vasodilation of blood vessels)
Extrinsic / systemic
extrinsic = outside of
•initiated outside an organ to alter its activity (mediated by nervous & endocrine systems)
(e.g. blood pressure – nervous system acts on heart & blood vessels –> coordinated regulation to achieve common goal)
What do homeostatic control mechanisms operate on? How does this work?
principle of negative feedback
- change in controlled variable triggers response to oppose that change
- drives variable in opposite direction of initial change
- maintains level of specific variable within given range/set point
How does the negative feedback system function?
- Detects change away from set point
- Initiates mechanisms to correct situation
- Shuts itself off
What are the components of a negative feedback control system? (6 points)
What are the components of a negative feedback control system in terms of body temperature? (6 points)
What is positive feedback? How does it work?
Rare within the body (opposes homeostasis)
- control variable continues to move in the direction of initial change
- reinforce the change in same direction > moves away from set point
(e.g. release of oxytocin during end stages of pregnancy)
What is the posititive feedback loop in Parturition?
fetus changes position
- pressure on cervix
- stretch-sensitive cells stimulated
- impulse → brain
- oxytocin released
- uterus contracts
- ↑ pressure on cervix
- ↑ stimulus on stretch-sensitive cells
- ↑ oxytocin
- stronger uterine contractions
- POSITVE FEEDBACK LOOP
continues until fetus expelled & stimulus removed
What is the First law of thermodynamics?
- energy can neither be created or destroyed
- energy input = energy output
What is energy imput in terms of ingested food?
ingested food > energy harvested > used for biological work or stored
What is Energy output in terms of external work & internal work?
External work = energy expended by skeletal muscles (moving external objects)
- *Internal work** = all other forms of biological energy expenditure 1.Skeletal muscle activity (posture, shivering)
2. Energy-expending activities required to sustain life (pumping blood)
What is the #1 ATP consumer?
The Heart
- 6 KG ATP per day, 20-30 x its own weight
- 100,000 beats, 10 tons of blood/day
What process describes how energy is produced?
Oxidative Phosphorlyation
What is the overview of oxidative phosphorylation?
- ATP is formed as a result of what?
- Where does this take place?
- How much ATP does it generate? How?
- ATP is formed as a result of the transfer of electrons from NADH or FADH2 to O2 by a series of electron carriers.
- Takes place in mitochondria, is the major source of ATP in aerobic organisms
- Generates 26 of the 30 molecules of ATP that are formed when glucose is completely oxidized to CO2 and H2O.
What is Oxidative Phosphorlyation?
What process describes how fuel is produced from food?
Metabolic Substrate Utilization
What is Metabolic Substrate Utilization?
What is the ATP Transfer Mechanism?
Step process of thermodynamics in the body:
Define Metabolic Rate (MR).
rate at which energy expended by the body per unit of time
- most of body’s energy expenditure eventually appears as heat
- MR expressed as rate of heat production/hr (kcal/hr)
- 1kcal = 1000calories = 4187J = 4.18kJ
What are the factors that influence MR?
- Muscular activity
- Food intake
- Shivering
- Anxiety
- Fasting & malnutrition
- Fever
- Hormones - catecholamines, growth hormone, thyroid hormone
- Muscular activity (↑) (most strong influence)
- Food intake (↑)
- Shivering (↑)
- Anxiety (↑)
- Fasting & malnutrition (↓)
- Fever (↑)
- Hormones - catecholamines, growth hormone, thyroid hormone (↑)
Define Basal metabolic rate (BMR).
- index of metabolism under standardised conditions
- minimal waking rate of internal energy expenditure
What are the Standardised basal conditions?
- awake
- relaxed & rested (>30 min)
- physical & mental
- supine
- warm (TNZ 20-25oC)
- fasting (8-12hr)
BMR - 20-25 kcal/kg body weight/day
How is BMR Measured?
direct or indirect calorimetry
Indirect Calorimetry
- practical & less costly
- O2 uptake per unit of time is measured
- Food + O2 –> CO2 + H2O + energy (mostly heat)
- direct relationship between O2 consumed & heat produced
- depends on type of food being oxidised
- energy equivalent value for complete oxidation of food
- depends on type of food being oxidised
Which of the following will increase BMR?
- Sleep
- Chronic exposure to a cold environment
- Areductionin circulating thyroid hormone
- Low body weight
- Ageing beyond 20 years
- Sleep
- Chronic exposure to a cold environment
- Areductionin circulating thyroid hormone
- Low body weight
- Ageing beyond 20 years
What are the Factors that influence BMR?
- Age (BMR ↑ in children but ↓ with age)
- Gender ( ↓ in females)
- Genetic determinants (not well defined)
- Lean body mass (body fat %)
- Body weight ( ↑ in obesity)
- Body surface area (taller people have ↑ BMR)
- Environmental temperature
- Sleep (↓ 10-15%)
- Hormones – thyroid hormone, catecholamines
List 4 things that are homeostatically maintained by the body.
- O2 & CO2
- pH – nerve cells & enzymes
- temperature - enzymee
- volume & pressure - plasma
What 4 tissue types exist within the human body?
- Epithelial
- Connective
- Muscle
- Nervous
What 2 components make up the ECF (Extracellular fluid)?
- plasma (fluid portion of blood)
- interstitial fluid (surrounds & bathes cells)
Extrinsic control systems are mediated by which body systems?
mediated by nervous & endocrine systems
Does shivering increase or decrease MR?
increase
Positive feedback acts to maintain homeostasis. T/F?
False.
Positive feedback acts to oppose homeostasis
