Homeostasis and response Flashcards
What is HOMEOSTATIS?
Homeostasis is the maintenance of a constant internal environment. Regulating body temperature, blood glucose level and water content are all examples of homeostasis (REGULATION means controlling or keeping something at the right level.)
What does HOMEOSTATIS maintains optimal conditions of?
In the human body, these include control of:
-blood glucose concentration
-body temperature
-water levels.
What is the automatic control system?
Homeostasis consists of automatic control systems that make sure internal conditions stay constant without you thinking about it.
What do automatic control system feature?
- RECEPTOR CELLS- cells which detect stimuli (changes in the environment)
- CO-ORDINATION CENTRE- (such as the brain, spinal cord and pancreas) that receive and process information from receptors
- EFFECTOR- effectors, which is muscles or glands, which bring about responses which restore optimum levels.
What is the timeline for the automatic control system?
STIMULI -> RECEPTOR -> CO-ORDINATOR -> EFFECTOR -> RESPONSE
What is the structure for the CENTRAL NERVOUS SYSTEM?
1.STIMULUS
2.RECEPTOR CELLS
(ELECTRICAL IMPULSIES DOWN NEURONES)
3.CNS (CO-ORDINATION CENTRE)
** (ELECTRICAL IMPULSIES DOWN NEURONES)**
4.EFFECTOR
5.RESPONSE (IN MUSCLE {CONTRACTS}) (IN GLAND {SECRETES HORMONES})
What is the reflex arc?
- STIMULUS recognised by RECEPTORS
- ELECTRICAL IMPULES travel down sensory neurone to CNS
- at the end of the sensory neurone are synapses where a chemical is released
- that chemical diffuses into the RELAY NEURONE which is found in the CNS which triggers an electrical impulse
- electrical signal passes through the relay neurone to another synapse where a chemical is released
- this chemical triggers another electrical impulse into the MOTOR NEURONE
- Electrical impulse travels down the MOTOR neurone to the EFFECTOR in response
Why are reflex actions are automatic and rapid?
Reflex actions are automatic and rapid; they do not involve the conscious part of the brain.
What is the method for Required Practical 7: Reaction Time?
- Person sits with their dominant arm resting on a table with upright posture
- Hold a ruler vertically between their thumb and index finger, with the 0 cm mark at their fingers.
- Drop the ruler without warning and let them catch it as quickly as possible.
- Record the measurement on the ruler that is level with the top of test subjects thumb (distance ruler falls = reaction time).
- Repeat the test at least 5 times and calculate a mean.
- Test different conditions, e.g.:
-With or without caffeine (after a set time for it to take effect).
-With or without distractions (like loud noises). - Compare results to see how the factor affects reaction time.
What are the variables for Required Practical 7: Reaction Time?
What is the ENDOCRINE SYSTEM?
The ENDOCRINE SYSTEM consists of a number of glands that secretes hormones {which are chemicals that control the body} directly into the bloodstream
What are the key differences between the ENDOCRINE SYSTEM and CNS?
- CNS - uses electrical impulses through neurones
ES - uses hormones which are chemicals - CNS - signalling is extremely fast
ES - slower effect but more long lasting
Where is the PANCREAS and what does it release hormones?
Found lower stomach
Pancreas
-Insulin – Lowers blood sugar levels.
-Glucagon – Raises blood sugar levels.
Where is the OVARIES and what does it release hormones?
Found in lower area
Ovaries (In females)
-Oestrogen – Regulates the menstrual cycle and is involved in female sexual development.
-Progesterone – Helps maintain pregnancy and regulates the menstrual cycle.
Where is the TESTES and what does it release hormones?
Found in lower area
Testes (In males)
-Testosterone – Controls sperm production and male sexual characteristics.
Where is the THRYOID and what does it release hormones?
(Located in the neck)
Thyroxine – Controls the rate of metabolism and helps regulate growth and development.
Where is the ADRENAL GLANDS and what does it release hormones?
(Located on top of the kidneys)
Adrenaline – Prepares the body for “fight or flight” response (increases heart rate, dilates airways).
Why is the PITUITARY GLAND known as the “Master Gland”?
Pituitary Gland (Located at the base of the brain)
FSH (Follicle Stimulating Hormone) – Regulates the menstrual cycle.
LH (Luteinising Hormone) – Triggers ovulation in females.
Growth Hormone – Stimulates growth and development.
ADH (Antidiuretic Hormone) – Controls water balance by affecting the kidneys.
These hormones in turn act on other glands to stimulate other hormones to be released to bring about effects
What does INSULIN do?
INSULIN:
-When the concentration of glucose in blood increases, this is sensed by the pancreas which secretes INSULIN
-INSULIN travels all around the body and triggers body cells to take up glucose from the blood.
-INSULIN also triggers liver and muscle cells to store excess glucose AS A STORAGE MOLECULE CALLED GLYCOGEN
What is diabetes?
When the control of blood glucose control does not work effectively
What is type 1 diabetes and how is it treated?
When the pancreas doesn’t produce enough insulin.
TREATMENT- to monitor blood glucose concentration the inject insulin if concentration rises too high after a meal
What is type 2 diabetes and how is it treated?
When the body stops responding to the insulin produced by the pancreas.
TREATMENT- Diet/exercise
What happens if blood glucose concentration falls?
-Pancreas releases GLUCAGON into the bloodstream.
-GLUCAGON triggers liver cells to convert glycogen BACK to glucose that is released into the blood.
During puberty, what do reproductive hormones do?
During puberty, what do reproductive hormones cause secondary sexual characteristics to form e.g pubic hair
