Unit 2 Homeostasis Flashcards
label a nephron (distal convoluted tubules, loop of Henle, proximal convoluted
tubules and the collecting duct).
Check onenote
Define and describe negative feedback
Negative feedback systems maintain homeostasis by producing a response that is the opposite of the original change.
Negative feedback decrease the original stimulus
define and describe homeostasis
Homeostasis refers to the body’s maintenance of internal environments within tolerance limits despite stimuli from the external environment
What is osmotic pressure
Osmotic pressure refers to the tendency of a solution to take in the pure solvent
Simply put, Osmotic pressure is determined by the concentration of substances dissolved in the water of the blood plasma.
distinguish between excretion and elimination
Excretion - removal of products of metabolism
Eliminations - removal of undigested food
define and describe a positive feedback
Positive feedback has no role in homeostasis. When it occurs, the response to a stimulus reinforces and intensifies the stimulus
how does a positive feedback reinforce a stimulus
The intensified stimulus results in an even greater response, it does this through the nervous and endocrine system
Give examples of positive feedback
Childbirth
Blood clotting
give examples of negative feedback
Thermoregulation
Blood glucose regulation
Gas concentration regulation
Bodily fluids regulation
recall the basic process of aerobic respiration
A chemical process in which oxygen is used to make energy from carbohydrates.
Formula;
C6H12O6 + 6O2 → 6CO2 + 6H2O
How is carbon dioxide carried in the blood plasma
Carbon dioxide is carried in the blood plasma as hydrogen ions
What do the following terms mean;
Neo
Genesis
Lysis
Lipo
– Neo = New
– Genesis = Creation
– Lysis = Breakdown of cell
– Lipo = fat
Define thermoregulation
Thermoregulation refers to the regulation of body temperature; the balance of heat gain and heat loss in order to maintain a constant internal body temperature independent of the environmental temperature
Describe the components of the stimulus-response feedback model
○ The STIMULUS is the change in the environment that causes the system to operate
○ The RECEPTOR detects the change
○ The MODULATOR is a control centre responsible for processing information received from the receptor and for sending information to the effector
○ The EFFECTOR carries our a response counteracting or enhancing the effect of the stimulus
○ FEEDBACK is achieved because the original stimulus has changed by the response
How does the body react to an INCREASE in body temp
Stimulus - Increase in body temperature
Receptor - peripheral thermoreceptors are stimulated sending info to the hypothalamus
Modulator - The hypothalamus responds through the effector
Effector -
*Vasodilation of skin areterioles occur
* Sweating occurs
* Behavioural response occurs
* In the long term, can be a decrease in metabolic rate
Response -
* Vasodilation causes an increase in blood flow through the skin, with the surface temperature rising causing heat loss through convection
*Sweat evaporates having a cooling effect
*Decrease in metabolic rate causes less heat to be produced in the body
Feedback - body temperature decreases
how does the body react to a DECREASE in body temp
Stimulus
-decrease in body temp
Receptor
- peripheral thermoreceptors are stimulated sending info to the hypothalamus
Modulator
- Hypothalamus activates the effectors
Effector
* Skeletal muscles cause shivering
* Vasoconstriction of skin blood vessels
* Adrenal medulla secretes adrenaline and noradrenaline increases cellular metabolism
* Pituitary gland releases TSH which causes the thyroid to release thyroxine into the blood
* Behavioural change
Response
* Shivering increases heat production
* Vasoconstriction causes a reduction in heat loss
* Increased metabolism causes the body to produce more heat
* Thyroxine increases metabolic rate, which increases the heat produced
Feedback - body temperature increases
how does the body react to an INCREASE in blood glucose
Stimulus
- Increase in blood glucose
Receptor
- chemoreceptor detects increase in blood sugar sending information to the hypothalamus
Modulator
- Hypothalamus activates the liver, adrenal glands and pancreas
Effector
* Pancreas secretes insulin and glucagon through alpha and beta cells. Insulin causes a decrease in blood glucose levels
* Liver converts glucose to glycogen for storage through the process of glycogenesis
Response
* Insulin causes a decrease in blood glucose levels
* Liver causes the glucose to be used for storage
Feedback
- Decrease in blood glucose
how does the body react to an DECREASE in blood glucose
Stimulus
- Decrease in blood glucose
Receptor
- chemoreceptors detect decrease in blood sugar sending information to the hypothalamus
Modulator
- Hypothalamus activates the liver, adrenal glands and pancreas
Effector
* Pancreas secretes glucagon through alpha cells. Glucagon causes an increase in blood glucose levels
* Liver converts glycogen to glucose for use through the process of glycogenolysis
Response
* Glucagon causes a decrease in blood glucose levels
* Liver causes the glucose to release into the blood
Feedback
- Decrease in blood glucose
how does the body react to an INCREASE in bodily fluids
Stimulus
- increase in bodily fluids
Receptor
- Osmoreceptors in the thirst centre of the hypothalamus detect an increase in plasma volume and decrease in osmotic concentration of extracellular fluid
Modulator
- The thirst centre of the hypothalamus is stimulated making the person feel overly hydrated
Effector
- The kidneys begin with excretion being excreted as urine
- Adrenal glands release aldosterone to maintain sodium levels within the body
Response
- Kidneys excrete at a faster rate and release excrete large volumes of water
- Aldosterone maintains the sodium levels in the body
Feedback
- Decrease in bodily fluids
how does the body react to an DECREASE in bodily fluids
Stimulus
- Decrease in bodily fluids
Receptor
- osmoreceptors in thirst centre of hypothalamus detect the increased osmotic pressure of blood
Modulator
- the hypothalamus stimulates the posterior lobe of the pituitary gland and the thirst centre is stimulated
Effector
- Posterior lobe of pituitary gland releases ADH which is carried to nephron tubules
- Thirst centre makes the person feel thirsty to trigger a behavioural response
Response
- ADH increases the permeability to water of the distal convoluted tubules and the collect ducts - meaning more water is reabsorbed into the blood plasma
- Water is consumed replenishing thirst
Feedback
- Increase in bodily fluids
how does the body react to an INCREASE in gas concentrations (comeback to this card)
Stimulus
- Increase in CO2 concentration
Receptor
- Central chemoreceptors in medulla oblongata
Modulator
- Respiratory centre in the medulla oblongata sends nerve impulses to diaphragm and intercostal muscles
Effector
- Diaphragm and intercostal muscles have an increased rate and depth of breathing
Response
- Decrease in Co2
Feedback
- Decrease in breathing rate
Distinguish between physiological and behavioural activities
Physiological activites - Nervous or Endocrine mechanisms - body does it subconsciously
Behavioural activities - conscious decisions to maintain homeostasis
Name the four main components of homeostasis
Thermoregulation
Blood glucose
Gas concentrations
Bodily Fluids
what are disruptions to homeostasis
Disruptions to homeostasis are;
Hormonal - Insulin & Thyroxine
Behavioural - Drugs, Exercise, Eating Habits
Disease - Emphysema, Fever, Hypertension
What are important aspects of the internal environment
- Core body temperature
- pH and concentrations of dissolved substances in the body fluids
- Concentration of glucose in the blood
- Concentration of oxygen and carbon dioxide in the blood and other body fluids
- Blood pressure
- Concentration of metabolic wastes
define and describe feedback systems
A FEEDBACK SYSTEM is a circular situation in which the body responds to a change, or stimulus, with the response altering the original stimulus and thus providing feedback.
define glycogenolysis
the process of converting glycogen back to glucose
define gluconeogenesis
the process of producing glucose molecules from lipids and amino acids
define glycogenesis
the process whereby glucose molecules are chemically combined in long chains to form glycogen molecules
define lipogenesis
the production of lipids
define lipolysis
the breakdown of lipids in the body
what are the normal levels of the main components of homeostasis
Body Temp - 36.8C
Blood Glucose concentration - 4-6 millimoles per litre
Bodily fluids - 45-60%
What do alpha and beta cells secrete
Alpha cells - secrete glucagon
Beta cells - secrete insulin
how does insulin cause a decrease in blood glucose levels
○ Accelerating the transport of glucose from the blood into body cells, especially those of the skeletal muscle
○ Accelerating the conversion of glucose into glycogen in the liver and skeletal muscles
○ Stimulating the conversion of glucose into protein
○ Stimulating the conversion of glucose into fat in adipose tissues, or fat storage tissue, a process known as lipogenesis
how does glucagon cause an increase in blood glucose levels
○ Stimulating glycogenesis
○ Stimulating gluconeogenesis - this involves the breakdown of lipids through lipolysis
○ Having a mild stimulating effect on protein breakdown
distinguish between aortic body and carotid body
Aortic body - the group of cells within the walls of the aortic arch that are sensitive to changes in the concentrations of oxygen and carbon dioxide in the blood and its pH
Carotid body - the group of cells within the walls of the carotid arteries that are sensitive to changes in the concentration of oxygen and carbon dioxide in the blood and its pH
distinguish between vasodilation and vasoconstriction
Vasodilation - increase in heat loss - widening of blood vessels
Vasoconstriction - reduction in heat loss - shortening of blood vessels
define and describe the four methods of heat transfer
Conduction: The transfer of heat through a material or between materials in direct contact with each other, due to a temperature difference.
Convection: The transfer of heat through a fluid (liquid or gas) by the movement of the fluid itself, due to a temperature difference.
Radiation: The transfer of heat through electromagnetic waves, which can travel through a vacuum and do not require a medium.
Evaporation: The transfer of heat through the process of changing a liquid to a gas, which requires energy and removes heat from the surroundings.
