Bio Sem 1 Rev Flashcards
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Why is homeostasis important
To maintain a balanced level of temp/blood sugar level or the cells of the body to function
Define Homeostasis
The maintenance of a stable internal environment within the body despite changes in the external environment
Factors under homeostatic control
Temp - 36.5-37.5 C
pH - 7.35-7.45
Blood sugar levels
O2 CO2 concentration
Fluid balance
Stimulus
Change in the internal or external environment
Receptor
Structures that detect changes to the environment (usually cells)
Control Centre / Modulator
Cells / Organs (often the nervous system) that “decide” on a response
Effector
The molecule, cell or organ that produces a response
Response
Any change in the cell, organ or organism caused by the stimulus
Stimulus - Response Model (in order)
Stimulus –> Receptor –> Modulator –> Effector –> Response
Types of Receptors
Thermoreceptors
Nociceptors
Baroreceptors
Chemoreceptors
Photoreceptors
Define Thermoreceptors
Detects changes in Temperature
Define Nociceptors
Detects painful stimuli (skin)
Define Baroreceptors
Detects changes in pressure
Chemoreceptors
Detects changes in chemical concentration
Photoreceptors
Detects changes in light
Negative Feedback
The response acts to counteract the internal stimulus to return the body to the set point (homeostasis)
Positive Feedback
The response acts to increase the initial stimulus. (pushes the body away from a set point)
Hypothalamus
Structure deep in the brain responsible for monitoring and controlling your body temp
Thermoregulation - Two ways the body cools itself down
Sweating
Vasodilation
Vasodilation
Capillaries under the skin widen when you get hot, allowing more blood to circulate closer to the surface of the body
Thermoregulation - 3 things the body does to keep warm
Vasoconstriction
Piloerection
Shivering
Vasoconstriction
Capillaries under the skin shrink when you get cold, keeping the blood away from the surface of the body
Piloerection (Goosebumps)
Small muscles at the base of the hair follicles pull the hair so it stands up (traps heat)
How does SA:V affect heat loss and insulation?
Greater SA:V allows for easier heat loss
Lesser SA:V allows for insulation
Hypoglycemia
Low blood sugar level
Hyperglycemia
High blood sugar level
2 hormones from the pancreas that regulate blood glucose levels
Insulin
Glucagon
Glucose
Sugar molecule necessary for cellular resp and functioning of all cells
Glycogen
Stored form of glucose (cannot be used by cells)
Glucagon
A hormone that helps to raise glucose concentration in the blood
When is Glucagon released? And where is it released from?
Where: secreted from alpha cells
When: Secreted when blood sugar levels are low
How does glucagon help increase blood glucose levels?
Stimulates the liver to convert glycogen into glucose and release it into the blood
Insulin
Lowers blood glucose levels
When is insulin released and where is it released from?
Where: secreted from beta cells
When: secreted when blood sugar levels are high
How does insulin help lower blood glucose levels?
Stimulates liver to convert glucose from the blood into glycogen
Can target skeletal muscles and cells to take up more glucose
Islets of Langerhan
Pancreatic cell that produces hormones (Insulin and glucagon)
Type 1 diabetes
The immune system destroys the insulin-making cells in the pancreas
Type 2 diabetes
Body cells become resistant (no longer respond) to insulin
Phospholipid Structure
Hydrophilic head
Hydrophobic tails
Phospholipid Bilayer Structure
Heads point out tails hide in middle of the layer
Main components of the plasma membrane
- Phospholipids
- Cholesterol
- Proteins
Cholesterol
Scattered through phospholipid tails
Helps control the fluidity of the membrane