CH6 Homeostasis and regulation Flashcards
what is homeostasis?
homeostasis is when Homeostatic mechanisms produce a
relatively stable internal environment by maintaining key variables within narrow limits
which systems control homeostasis?
the nervous system (by sending electrical messages through the brain, spinal chord and nerves) and the endocrine system (by sending chemical messages through the hormonal system)
what is the nervous system?
- The nervous system uses neurons to send quick, immediate messages.
- The message begins in the sensory cell, travels through the neurons to the Control Center (central nervous system), which then processes and responds to the signal in a matter of seconds.
- Electrical messages
what is the endocrine system?
- The endocrine system uses chemical signals instead of electrical signals to send messages.
- The messages are slower, as they rely on the bloodstream to deliver the chemicals to a specific target cell.
- The messaging chemicals are called HORMONES.
- Hormones are often produced in specialised Endocrine glands around the body.
what are the two types of hormones?
Water Soluble Hormones and Lipid-soluble hormones
what are water soluble hormones?
Polypeptides (which are simple proteins and hydrophilic)
Polypeptides require facilitated diffusion to enter a cell.
Their target proteins are therefore outside the cell, embedded in the cell membrane.
what are lipid soluble hormones?
Steroids (which are oils or fats and are Hydrophobic)
Steroids can diffuse naturally through the cell membrane. Their target proteins can therefore be on the inside of the cell.
what is the negative feedback system?
A negative feedback mechanism is taking away a stimulus.
what is stimulus?
a change in internal environment
what is a sensor?
a nerve or receptor that detects the change
what is a control center?
an organ that processes and controls the response to the stimulus
how does blood sugar increase
we eat a meal to increase blood glucose levels.
how do we decrease blood sugar
- pancreas releases insulin into the blood
- insulin stimulates the liver cells to convert glucose into glycogen, stored for later use
what is the body’s response to an increase in glucose levels?
- Glucose receptors in the pancreas detect the increase
- Pancreas releases insulin into the bloodstream
- Insulin stimulates the liver cells to convert glucose into glycogen
- Blood glucose levels return to normal and the pancreas stops releasing insulin
what is the bodys response to a decrease in glucose levels?
- Glucose receptors on the pancreas detect the decrease
- Pancreas releases glucagon into the blood
- The glucagon stimulates the liver cells to convert glycogen into glucose
- When blood glucose levels return to normal , the pancreas stops releasing glucagon.
how does water exit the body?
- sweating
- breathing
- urination
- defecation
how does water enter the body?
- eating
- drinking
- metabolic water ( as a waste product from cellular respiration)
what is ADH?
ADH stimulates the production of aquaporins in the wall of the collecting tubule.
this allows water to move out of the collecting tubule and be reabsorbed by the surrounding blood vessels
what are aquaporins?
channel proteins specific to water molecules
how is water balance maintained?
- the thirst centre in the hypothalamus
- ADH - a hormone secreted by the posterior pituitary - gland locted at the base of your brain
how does water regulation work?
- osmoreceptors in the hypothalamus detect the concentration of particles dissolved in your plasma (osmality)
- if there is an increase in osmality the thirst centre is activated, prompting you to drink more water, and ADH is reeased (which decreases the water lost in urine)
- these steps can also be triggered by the production of blood pressure
regulating water balance
- we cannot regulate our most water lost from our body, but we can control water concentration
- reabsoption of water int he kidneys is controlled by a peptide hormone called ADH.
anti-diuretic hormone
what is high osmality?
high concentration, less water in plasma
what is low osmality?
low concentration, more water in plasma
