MODULE 8 IQ1: Homeostasis Flashcards
homeostasis definition
process by which an organism can maintain a relatively stable internal environment despite external changes
stimulus response model
stimulus –> receptor –> control centre –> effector –> original state
set point definition
dictates what your range is until homeostasis mechanisms kick in
detecting temperature change
- thermoreceptors
peripheral: located over the body surface
central: located in the preoptic area of the hypothalamus
control centre for thermoregulation
hypothalamus
- set-point range: 36.3-37.7
above the setpoint in thermoregulation
- vasodilation –> blood moving near skin increases, increases heat loss from skin
- evaporative cooling –> sweat from the eccrine glands. endothermic process which allows energy coming from the body to dissipate through the change in state of sweat from liquid to gas
below the setpoint in thermoregulation
- vasoconstriction –> blood moving close to skin is reduced, decreases heat loss from the skin to the environment
- shivering thermogenesis: production of metabolic heat through involuntary movements of muscles stimulated by the autonomic nervous system
hyperglycaemia vs hypoglycaemia
hyper: BGL too high
hypo: BGL too low
role of insulin and glucagon in glucose regulation
insulin: glucose –> glycogen
glucagon: glycogen –> glucose
detecting change in glucose levels
cells in pancreas
control centre for glucose regulation
- pancreas (islets of langerhans)
above the setpoint in glucose regulation
beta cells of the islets of langerhans releases insulin –> takes glucose out of blood –> converts to glycogen –> stored in liver or muscle cells
below the setpoint in glucose regulation
alpha cells of the islets of langerhans releases glucagon –> breaks dow n glycogen from liver –> stimulates uptake of glucose from cells
behavioural adaptations
something an animal does in response to some type of external stimulus to survive
structural adaptation
physical features of an organism that helps them survive in their environment
physiological adaptation
internal functions of an organism that helps them survive in their environment
major glands of the endocrine system
hypothalamus, pituitary, parathyroid, adrenal, pineal gland, ovaries/testes
3 main classes of hormones
- steroid hormones that are hydrophobic
- non-steroid hormones which are hydrophilic
e.g. amino acid hormones and peptide hormones - tyrosine derived hormones which can act as both steroid and peptide hormones
hormones can exert their effect by
- directly passing through a cell membrane into the cell
- indirectly with a receptor on the surface of the cell
example 1: hypothalamic pituitary axis
- hypothalamus receives stimuli rom the body
- pituitary gland and hypothalamus are connected via a stalk that is the hypothalamic pituitary axis
- hypothalamus gives the order and the pituitary gland enforces it
e.g. oxytocin, gonadotropin releasing hormone (GnRH)
example 2: adrenal gland
- located above each kidney
- 3 layers:
1. zona glomerulosa: aldoesterone –> low blood pressure or increasing blood potassium to prevent water/sodium loss
2. zona fasciculata: cortisol
3. zona erticularis: sex hormone precursors & adrenaline - increase the activity of the sympathetic nervous system
what does the central nervous system (CNS) and the peripheral nervous system (PNS) control
CNS: brain and spinal cord
PNS: somatic & autonomic
autonomic –> parasympathetic or sympathetic
afferent pathway
receptor –> afferent nerve pathways –> CNS
- visual, auditory, chemoreceptors & somatosensory
efferent pathway
CNS –> efferent nerve pathways –> effectors
- motor information transmitted to the periphery from the CNS
