Task 7 - Hunger, Thirst, Hormones Flashcards
Osmotic thirst
- desire to ingest fluids that are stimulated by a higher concentration of solute (like salt - NaCL) in the extracellular fluid, which is reducing intracellular fluid
- By sweating and urinating which makes us lose more
- By ingesting lots of salty food
Osmosensory neurons
located in Hypothalamus and detect concentration of extracellular fluid
- Balloon or shrink as concentration changes
- Opens/ closes special ion channels causing changes in membrane potential that track concentration
- Information passed on resulting in thirst through hormone release
Hypovolemic thirst
- desire to ingest fluids stimulated by a reduced volume of extracellular fluid that contain water and solutes
- By losing blood/ vomiting or diarrhea
- No change in solute concentration in neither intra- nor extracellular fluid so no osmotic pressure
- Blood vessels that would normally be full and stretched no longer contain full capacity -> blood pressure drops -> thirsty hungry for salty food
Baroreceptors
pressures receptors heart
-detects it in major blood vessels and heart
Baroreceptor reflex
change in blood pressure
signals the medulla
creators thirst and salt hunger
Ghrelin
- stomach
- hunger
- only hormone in peripheral system
CCK
released in response of fat
peptide yy (PYY)
release proportionate to the amount of calories you consume
Leptin
- fat cell
- more fat stored=more leptin, so body knows how fat it is
Leptin & fat people
fat ppl have a lot of leptin but they have become resistent to effects of leptin
Hormones cant cross blood brain area sooooo
part of hippocampus -> arcuate nucleus
-» hormones interact with nucleus/ interact with brain
vasopressin
from pituitary gland signals to kidney
-to reabsorb the water back to blood and not to bladder to make urine -» helps to conserve
ENERGY METABOLISM
cephalic phase
PREPATORY PHASE
- Begins with sight/smell/thought of food
- Ends with food starting to be absorbed into bloodstream
- High release of insulin in anticipation of glucose arrival in the blood, low glucagon
ENERGY METABOLISM
Digestive phase
food entering stomach causes release of gut hormones stimulates pancreas to release insulin
ENERGY METABOLISM
Absorptive phase
- low glucagon, high insulin levels in blood
- Period where energy absorbed into bloodstream meets body’s immediate energy needs
- Glucodetectors in liver detect glucose entering bloodstream, signal pancreas to release insulin
- Minimise increasing levels of bloodborne fuels by using, storing them
- When rapid weight gain: straight back to cephalic phase
Fasting phase
- All of unstored energy from previous meal has been used and body is withdrawing energy from its reserves to meet immediate energy requirements
- High glucagon, low insulin levels in blood
- Glucose can’t enter most body cells, stops being primary fuel -> glucose for brain
- Release of free fatty acids from adipose tissue and convert them to ketones -> used by muscles as source of energy
- Ends with next cephalic phase
Theories of Hunger and eating
Set point assumption
hunger (motivation to eat) in presence of energy deficit and eat to return to body’s optimal energy level (energy set point)
Problemo:
-Evolutionary: need to PREVENT energy deficit for survival, not react
-Fail to recognise factors such as taste, learning, social influences
Theories of Hunger and eating
Positive incentive perspective
driven to eat by anticipated pleasure of eating (positive-incentive value)
Theories of Hunger and eating
Settling points model of body weight/Leaky barrel model
body tends to drift around a natural settling point – the level at which the various factors that influence body weight achieve an equilibrium
Posterior Pituitary
release of Hormone Vasopressin
Basal Metabolism
consumption of energy by lifte-sustainable functions of body
Glucodetectors/Glucostats
sensors in liver that detect bloody glucose level
Fluid regulation
67% intracellular
33% extracellular (Blood plasma, cerebrospinal fluid, interstitiolfluid)
Osmotic pressure
the force that pushes or pulls water across the membrane
Isotonic solution
When cells are balanced = no osmotic pressure
Hypertonic solution
when cells are not balanced
