Physiology of human cells 1 Flashcards
Define physiology
The branch of biology that aims to study and understand the mechanisms of living things from the ionic and molecular level to the integrated behaviour of the whole body and the influence of the external environment
What does this help us achieve
o Understand the basics of our bodily health
o How it responds to and adapts to everyday challenges
o The adverse effects of diseases which help us establish guidelines and develop treatments for human and animal health
o This combination of molecular, cellular systems is what sets physiology apart from other sciences
what tissues are covered in this course
o Muscle
o Nervous
o Epithelial
o Connective
what organs are covered in this course
o Lung
o Brain
o Heart
o Kidney
o Stomach
o Colon
what organ systems are covered in this course
o Nervous
o Endocrine
o Immune
o Circ
o Muscle/skeletal
o Integument (skin hair nails and exocrine)
o Respiraotry
o Urinary
o Digestive
o Reproductive
what is homeostasis
Homeostasis is the process by which the body reacts to changes in order to keep conditions inside the body like temperature at the same optimal level through cooperation and interdependance of cells body systems and organs to get to homeostatic range
what does homeostasis help us achieve
the state of steady internal, physical and chemical conditions maintained by living systems; It’s the condition of optimal functioning for organisms and includes body temp, fluid balance etc. being kept within pre-set limits called homeostatic range
what factors can homeostasis include
o Conc of nutrient molecules
o Conc of CO2 and O2
o Conc of waste products
o pH
o Conc of water, salt and other electrolytes
o Temperature
o Volume and Pressure
What is the homeostatic ocntrol system
the functionally interconnected network of body components that operate to maintain a given physical or chemical factor in the internal environment relatively constant around an optimal level
what are the two types of HCS
Intrinsic (local) controls are inherent compensatory responses of an organ to a change
Extrinsic controls are responses of an organ to factors outside like the nervous and endocrine systems
What are the two types of HCS responses
positive and negative feedback
what is positive feedback
Output is continually enhanced or amplified so that the controlled variable is moved in the direction of the initial change or a pathway in which the response reinforces the stimulus and only stops after a drastic change or change of state
What is negative feedback
Change in a homeostatic control factor triggers a response that seeks to restore the factor to normal by moving the factor in the opposite direction of its initial change; it is a pathway where the response opposes the signal
what are the key components of a feedback system
Sensor- specific to variable needing to be controlled
Set point- reference point for sensor to compare against
Effector- if sensor isn’t equal to set point, error signal produced to activate effectors to restore variable to desired level
define set point and dynamic range and how they relate
o Set point is the optimal point where our systems are at maximum efficiency
o Dynamic range is the margin of error above or below the set point where conditions allow us to still operate but not at maximum efficiency
this can be altered by training or exposure to environments and stimuli
what are the limitations of negative control
Feedback control is initiated after variable has been disturbed
Amount of correction is applied and assessed by magnitude of error signal causing incomplete correction
Overcorrection which is where an error signal causes inverse of stimulus to occur due to too much control application causing oscillations; These are overcome by multiple regulatory mechanisms
what is thermoregulation? how does it happen?
o The process in which the body achieves homeostasis by returning body temp to optimal levels
Too hot–>sweat
Too cold–>shiver
what are the two types of thermoregulatory responses
Voluntary like clothing changes, nutrition, resting
Involuntary like sweating and shivering and hair raising
how is positive feedback different from negative feedback in terms of the set point?
o Negative feedback means error signal results in reduced deviation from set/reference point
o Positive feedback means error signal increases deviation from set/reference point resulting in a vicious cycle
give examples of Positive feedback
Labour where oxytocin is released from hypothalamus increasing uterine contractions and baby’s head is pushed through stretching cervix and causing larger oxytocin release
Rising of action potential is when depolarisiation happens opening Na channels, the entrance of which cause further depolarization (positive feedback loop) which stops after a change of state where Na channels deactivate
what is a feedforward mechanism?
o Brings a compensatory response in anticipation of a change in a regulated variable like mouth watering and gastric secretions to the thought/smell of food
what is an anticipatory change
eg. Changes in renal function in preparation for changes brought on by food intake resulting in changes in concentration of ions in the plasma that will need to be controlled within physiological rang
