Unit 5: Homeostasis Flashcards
Negative Feedback System
A response that involves the body stopping small changes from getting to large
(Thermostat)
Positive Feedback System
This response makes small changes larger to pull the body out of homeostasis.
(Childbirth)
What are the 3 stages of Urine formation?
- Filtration
- Reabsorption
- Secretion
Filtration
Water is filtered out and solutes dissolved when blood is forced through the GLOMERULUS and into BOWMANS CAPSULE
Filtration (Substances Transported)
Sodium & Chloride (active transport)
Water (passive transport)
Reabsorption:
When nutrients are reabsorbed from the filtrate back into blood via active AND passive transport.
Reabsorption (Substances Transported)
Bicarbonate, salt, water, potassium, hydrogen and ammonia.
Secretion:
Reabsorption of nutrients from the blood into the nephron transport. Distal tube regulates potassium and salt concentration.
Secretion (Substances transported)
Salt, Potassium, hydrogen, bicarbonate and ammonia.
Estrogen
Stimulates thickening of the endometrium
Growth Hormone
Regulates the growth of long bones
Epinephrine
Produced by stress
Insulin
Increase the bodies absorption of glucose
Thyroxine
Regulates cell metabolism
Testosterone
Stimulates the development of sperm
Explain a feedback loop that regulates blood sugar
- High blood sugar
- Insulin released from beta-cells of the pancreas
- Cells take in more glucose
- Lowers blood sugar levels.
Describe a reflex arc in 5 steps (e.g. hot stove)
- Initial stimulus: Hot stove burns hand.
- Sensory Neurons: Heat on skin triggers stimulus to the spinal cord
- Interneurons: send the signal to the motor neurons
- Motor Neuron: activate the appropriate effector (muscles)
- Effector Organ: Causes immediate response. (hand pulls back)
Describe the process of action potential
- Resting potential (-70)
- Stimulus (-40)
- De polarization (gates open)
- Repolarization (gates close)
- Refractory period
What is action potential?
The way nerves communicate with each other.
What is a reflex arc?
An action happening before the brain get the message.
This is possible because of the neural circuit that runs through the spinal cord.
Synaptic Transmission
The way nerves communicate with each other.
What are the steps of action potential?
- Depolarization
- Repolarization
- Refractory Period
Depolarization
How action potential is formed. K+ high on the outside Na+ high on the inside.
Na+ gate channels opens, K+ channel closes.
Repolarization
Polarity is restored.
Na+ channel closes. K+ channel opens again.
Refractory Period
1-10 milliseconds required for the cell to become repolarized.
How are Neurotransmitters related to Depolarization?
Neurotransmitter ACETYLCHOLINE opens the Na+ channel.
How are presynaptic neurons related to Depolarization?
Depolarization enables the presynaptic neuron to transmit a message.
How are postsynaptic neurons related to depolarization?
The postsynaptic neurons receive the message from the presynaptic neurons via neurotransmitters the cross the synaptic gap.
How do enzymes trigger Repolarization?
The enzyme CHINESTERASE is released after the message is sent. It EATS acetylcholine, closing the Na+ channel.
