Homeostasis Flashcards
1
Q
Physiology
A
-how living organisms function, from molecules to human beings
2
Q
Homeostasis
A
- defining feature of physiology
- involves the maintenance of nearly constant conditions in the internal environment
- control of numerous Vital parameters- arterial pressure, blood volume, body temperature, nutrients
- dynamic constancy
3
Q
Steady state
A
- maintenance of nearly constant conditions over time
- not the same as equilibrium
- need to put in energy
4
Q
Equilibrium
A
- a system when its solute concentrations and other parameters are constant in time without requiring the input of energy from metabolism or other sources
- no energy
5
Q
Cell environment response to changes
A
- single cells maintain their internal environment in response to changes in the external environment
- semi-permeable cell membrane facilitated the process that provided nutrients to the cell using diffusion, endocytosis etc
- damage to plasma membrane= impair metabolic function, lead to cell death if cell can’t restore homeostasis
- human body contains 100 trillion
6
Q
Multicellular organisms adapt to changes
A
- in multicellular organisms the basic homeostatic mechanisms of single celled organisms are mirrored by integration of specialized organ systems that create a stable environment for cells
- allows for specialization of cellular functions and a layer of protection for the systems
ex: lungs exchange gases, digestive tract- uptake of nutrients and water
7
Q
Organs vs organ systems
A
-Organs- 2 or more kinds of tissues
-Organ systems- collection of organs that perform a general function
- 11:
Circulatory, Digestive, Endocrine, Immune, Integumentary, Lymphatic, Musculoskeletal, Nervous, Reproductive, Respiratory, Urinary
-the functions of organ systems are essential to survival of the body
8
Q
Concept of mass balance
A
- for a system at steady state for metabolism means that any substance taken in by the body is nearly equal to the amount leaving the body plus that removed by metabolism
- the central compartment (POOL) is usually extracellular fluid (which includes blood plasma)
- it receives substances from intake, synthesis, and release from cells
- it loses by excretion, metabolism, and upstake into cells
- in steady state it is in balance
9
Q
Basal metabolic rate (BMR)
A
- energy expenditure at rest (kcal/hr/sq meter body surface area)
- largest in daily energy useage (60%), thermic effect of food 8%, nonexercise activity (7%), purposeful physical activity (25%)
- all the chemical processes involved in energy production, energy release and growth- anabolic (formation) or catabolic (breakdown)
10
Q
Resting metabolic rate
A
- 70 kg man requires 2100 kcal/day
- BMR is less than RMR
- RMR increased in males because of increased muscle
- RMR declines with age (reduced muscle)
- Increased by thyroid hormone, growth hormone, testosterone, epi/norepi
- RMR is higher in people living in arctic vs tropical regions (10-20%)
- malnutrition decreases metabolic rate
- components of energy expenditure
11
Q
Homeostasis and maintaining body fluid balance and electrolytes
A
- net fluid balance- fluid input needs to match fluid output
- if intake (from food and beverages) exceeds output (urine, fluid in feces, insensible losses), the organism is in positive balance, and urine volume will increase to eliminate excess fluid
- negative fluid balance occurs when intake is less than output, in this case integrated responses will increase thirst and decrease additional fluid losses, until homeostasis is restored
12
Q
Elements in Extracellular fluid are tightly controlled
A
- need to maintain control over numerous vital parameters to survive and grow
- some elements are controlled within extremely narrow ranges (pH) whereas others fluctuate over broader ranges (plasma glucose)
- loss of control over one or more of these manifests as illness and requires medical attention.
- oxygen, carbon dioxide, sodium ion, potassium ion, calcium, chloride, bicarbonate ion, glucose, body temp, acid-base
13
Q
Homeostasis is a dynamic process
A
- external environmental conditions that can be far from constant, common physiological variables in healthy humans are maintained within a predictable range
- some variables undergo fairly dramatic swings over the course of a day, yet are still considered to be in balance
- after a typical meal blood glucose levels rise considerably
- hemostatic compensatory mechanisms (endocrine) quickly respond to restore blood glucose to pre-meal levels without overshooting to a significant degree in the opposite direction
14
Q
Negative feedback
A
- major process used to maintain a stable internal environment (homeostasis)
- it is the initation of responses that counter deviations of a controlled variable from a normal range
- negative feedback loops often operate as part of a larger network of control
15
Q
Feedforward control
A
- also regulates body systems, particularly when a change with time is desirable (heart rate and breathing increase in anticipation of exercise_
- feedforward and negative feedback also act in combination
