Lecture 1 - Principles of Physiology Flashcards
- study of the biological functions of organs and their inter-relationships
- studies interplay of factors that affect growth
physiology
brings together everything known about an animal’s function to create an integral picture of how an animal operates in its environment
integrative science
what do physiologists do
- study (structure and function of various parts of animals and plants)
- design experiments
hallmark of physiology
diversity
what resulted in meeting the demands of survival
evolutionary variations
unifying themes of physiological processes
- obey physical and chemical laws
- regulate to maintain internal conditions and trigger appropriate response
- phyiological state of animal is part of its phenotype which arise from genotype, and its interaction with the environment
Subdisciplines of Physiology
- comparative physiology
- environmental physiology
- evolutionary physiology
- developmental physiology
- cell physiology
species are compared in order to discern physiological and environmental patterns
comparative physiology
examines organisms in the context of the environments they inhabit (evolutionary adaptations)
environmental physiology
techniques of evolutionary biology and systematics are used to understand the evolution of organisms from physiological viewpoint, focusing on physiological markers rather than anatomic markers
evolutionary physiology
how physiological processes unfold during the course of organism development from embryo through larva or fetus to adulthood
developmental physiology
vital information on the physiology of the cells themselves, which can be used to understand the physiological reponses of tissues, organs, and organ systems
cell physiology
Central Themes in Physiology
- structure/function relationships
- adaptation, acclimitization, and acclimation
- homeostasis
- feedback - control systems
- conformity and regulation
where is function based on
structure
form fits function at all the levels of life, from molecules to organisms
structure/function relationships
where is the structure-function relationship clear in terms of shape of bird wing
aerodynamic efficiency
where does the biological function at each level of organization depend on
structure of that level and the levels below
- four-chambered stomach with large rumen
- long small and large intestine
ruminant herbivore
- short intestine and colon
- small cecum
carnivore
where is the physiology of an organism well matched
environment it occupies, ensuring its survival
- evolution through natural selection leading to an organism whose physiology, anatomy, and behavior are matched to the demands of its environment
- generally irreversible
adaptation
how is a physiological process adaptive
- present at high frequency
- results in higher probability of survival and reproduction
present at high frequency in the population because it results in a higher probability of survival and reproduction than alternative processes
adaptive
genetically based, passed on from generation to generation (DNA) and constantly shaped and maintained by natural selection
physiological and anatomic adaptations
- physiological, biochemical, or anatomic change within an individual animal during its life that results from an animal’s chronic exposure in its native habitat to new, naturally occuring environemental condition
- animal in migrate to high altitude
acclimatization
example of acclimatization
animal migrates to high altitude
- refers to the same process as acclimatization when the changes are induced experimentally in the laboratory or in the wild by an investigator
- animal placed in hypobaric chamber
acclimation
the tendency of organisms to regulate and maintain relative internal stability
homeostasis
- “constancy of the interal environment is the condition of free life”
- the milieu interieur
- the ability of animals to survive in often stressful and varying environments directly reflects their ability to maintain a stable internal environment
Claude Bernard (1872)
the bodily fluids regarded as an internal environment in which the cells of the body are nourished and maintained in a state of equilibrium.
milieu interieur
- “homeostasis” - tendency towards internal stability
- extended notion of internal consistency to the organization and function of cells, tissues, and organs
Walter B. Cannon (1871-1945)
how is homeostasis maintained
negative feedback
homeostasis is the ability to __ _ __ __ __ __ in an ever-changing outside world
maintain a relatively stable internal environment
the internal environment of the body is in a __ __ __ __
dynamic state of equilibrium
interact to maintain homeostasis
- chemical
- thermal
- neural factors
the body functions within relatively __ __
narrow limits
Homeostatic Control Mechanisms
- receptor (sensor)
- control center
- effector
regulation of homeostasis is accomplished through what systems
- nervous system
- endocrine system
antagonistic hormones that help maintain glucose homeostasis
- insulin
- glucagon
has clusters of endocrine islets of Langerhans with alpha cells that produce glucagon and beta cells that produce insulin
pancreas
produce glucagon
alpha cells
produce insulin
beta cells
cell clusters in the pancreas that consist of different types of cells, including insulin-secreting β-cells, glucagon-secreting α-cells, and somatostatin-secreting δ-cells
Islets of Langerhans
deficiency of insulin due either to inadequate secretion of the hormone by the pancreas or to inadequate treatment of diabetes mellitus.
hypoinsulinism
two types of diabetes
- type I diabetes mellitus
- type II diabetes mellitus
- insulin-dependent diabetes
- autoimmune disorder
- usually appears in childhood
- treatment: insulin injections
Type I diabetes mellitus
- non-insulin-dependent diabetes
- usually due to target cells have a decreased responsiveness to insulin
- usually occurs after age 40 - risk increases with age
- accounts for over 90% of diabetes cases
Type II diabetes mellitus
example of effect of growth hormone
acromegaly
animals that can survive large fluctuations in external osmolarity
euryhaline
organisms can tolerate only a relatively-narrow range of salinity
stenohaline
ability of selected organisms to lose almost all water and enter a state of reversible ametabolism.
Anhydrobiosis
example of animals capable of anhydrobiosis
tardigrade
detects changes (stimuli) in the body
receptor
determines a set point fo a normal range
control center
causes the reponse determined by the control center
effector
where do regulatory processes that maintain homeostasis in the cells of a multicellular organisms depend on
feedback
return of information to a controller that regulates a controlled variable
feedback
Two types of feedback
- Negative feedback
- Positive feedback
regulatory mechanism in which a change in a controlled variable triggers a response that opposes the change
negative feedback
negative feedback mechanism __ the intensity of the stimulus or __ it
- decreases
- eliminates
ex. of negative feedback
cooling down when it is too hot
most homeostatic control mechanisms
negative feedback mechanisms
enhances or exaggerates the original stimulus so that activity is accelerated
positive feedback mechanism
why is positive feedback considered positive
change occur in same direction as original stimulus
what do positive feedback mechanisms usually control
infrequent events
ex. of positive feedback
- blood clotting
- childbirth
characteristic of positive feedback
- does not maintain homeostasis
- short in duration, and infrequent
what do most diseases cause
homeostatic imbalances
reduces our ability to maintain homeostasis
aging
what happens if a disturbance of homeostasis or the body’s equilibrium is not corrected
illness
Two ways an organism can respond when confronted with changes in its environment
- conformity
- regulation
- environmental challenges induce internal body changes that simply parallel the external conditions
- unable to maintain homeostasis
conformers
organisms that keep their internal fluids isotonic to their environment, that is, they maintain an internal salinity similar to their ambient conditions
Osmoconformers
example of osmoconformers
- shark
- starfish
organisms that cannot maintain their respiration independent of environmental oxygen concentration
oxyconformers
example of oxyconformers
annelid worms
- biochemical, physiological, behavioral, and other mechanisms to regulate their internal environment over a borad range of external environmental changes
- maintain homeostasis
regulators
maintain ion concentrations of body fluids above environmental levels when placed in dilute water vice versa
osmoregulators
zone where homeostasis is maintained
zone of stability
based largely on controlled movement of solutes between internal fluids and the external environment
osmoregulation
where do seagulls secrete excess salt
nostril
