Detecting and Regulating Change Flashcards
what is a receptor?
a structure that is able to detect a change in a body’s internal or external environment
what are thermoreceptors and what is their role?
- able to respond to heat or cold
- in the skin: inform the brain to changes in temperature outside the body
wat are osmoreceptors and what is their role?
- osmotic pressure: determined by concentration of substances dissolve din water of blood plasma
- located in the hypothalamus, sensitive to osmotic pressure
- very precise receptors
what are chemoreceptors and what is their role?
- stimulted by particular chemicals
- present in the nose (odours), mouth (taste) and internally (composition of body fluids)
- some sentisitve to pH of blood and concentrations of carbon dioxide and oxygen
- involved in regulationo of heart beat
what are touch receptors and what is their role?
- mainly found in the skin
- occur in greater concentrations in areas of skin that are very sensitive (lips, fingertips, eyelids, external gential organs)
- base of hair follicle (respond to light touches that bend the hair)
what are pain receptors and what is their role?
- aka nociceptors
- stimulated by damage to tissues (cut or bump), poor blood flow to tissue, excessive stimulation (heat or chemicals)
- concentrated in skin and mucous membranes
- adapt very little
- prolonged stimulation may make pain worse
what is the definition of a reflex?
a rapid, automatic response to a change in external or internal environment, does not involve the tbrain
what are four important properties of reflexes?
- a stimulus is required to trigger a reflex (not spontaneous)
- involuntary - occurs without conscious thought
- rapid - only a small number of neurons are involved
- stereotyped - occurs the same way each time it happens
what is a basic reflex arc?
- stimulus triggers a reflex (no concious thought)
- receptor reacts to a change by initiating a nerve impulse from a receptor to CNS
- sensory impules enter dorsal (afferent) root of spinal cord
- relay neurons connect sensory neuron to motor neuron
- motor neuron leaves spinal cord through ventral (efferent root)
- effector receives nerve impulses and carries out appropriate response
- response - effector can be muscles or glands
what is an acquired reflex?
- a response to a stimulus that has been learned through practise
what is the defintion of homeostasis?
the process of keeping the environment inside the body fairly constant; helps a person remain independent from the external environment
what are important aspects of the internal environment that need to be regulated?
- core body temperature
- pH and concentrations of dissolved substances in body fluids
- blood pressure
- concentration of oxygen and carbon dioxide in the blood and other fluids
- concentration of metabolic wastes
what is a tolerance limit?
upper and lower limits to a range of factors
above or below these limits = impaired functioning
what is a feedback system?
a circular situation in which the body responds to a stimulus, with the response altering the original stimulus
what are the common features of a negative feedback system?
- stimulus = change in environment
- receptor = detects the change
- modulator = control centre responsible for processing the information
- effector = carries out a response to countact the effect of the stimulus
- feedback = achieved because the original stimulus have been changed by the repsonse
