Homeostasis controlling body temp and blood glucose

Question 1

Explain what homeostasis is
○ Define homeostasis
○ Define ‘tolerance limits’

Answer 1

The maintenance of a constant internal environment, at steady state, despite fluctuations in the external environment. (i.e. within tolerance limit: limit to which factors balance, beyond which body malfunctions)

Question 2

What internal aspects of body must be regulated?

Answer 2

Body works best in narrow range of conditions:
-core body temp
-pH and concentrations of dissolved solutes in blood/body fluids
-conc of oxygen and CO2 in blood/body fluids
-conc of glucose in blood
-blood pressure
-conc. of metabolic wastes

Question 3

Define feedback system

Answer 3

circular situation in which body responds to change/stimulus, with the response altering the original stimulus

Question 4

Describe the stimulus-response model of homeostatic control, including definitions of each part (stimulus, receptor etc)

Answer 4

Stimulus-change in internal/external environment
Receptor-cell/nerve ending detects change
Modulator-receives message and coordinates the response
Effector-muscle/gland that causes response
Response-course of action (change in response to stimulus)
Feedback-how stimulus changes

Question 5

Explain the meaning of the term negative feedback and positive feedback

Answer 5

negative-feedback is opposite of initial stimulus (most common)
positive-feedback increase initial stimulus (blood clotting, oxytocin giving birth)

Question 6

Define set point

Answer 6

in feedback system, the level to which variable is to be maintained (by negative feedback)
and the point to which conditions fluctuate (dynamic eqm)

Question 7

Define thermoregulation. What hormone regulates body temp?

Answer 7

regulation of body temp; balance of heat gain and loss in order to maintain a constant internal body temp independent of environmental temp
-thyroxin will increase metabolism

Question 8

What is our optimum body temp? How is it constant

Answer 8

constant at 36.8
equal gain and loss of heat

Question 9

Ways to input heat

Answer 9

Via body processes such as metabolism, respiration of liver and muscle cells, or gained from surroundings by conduction and radiation

Question 10

Ways to output heat

Answer 10

radiation, conduction, convection to surroundings as well as evaporation of water from skin and lungs, warm air breathed out, warm urine and faeces out

Question 11

Describe the role played by the skin in thermoregulation
Define factors causing this regulation on skin

Answer 11

Large surface area and location of skin between internal and external environment=very important organ in body temperature regulation. Heat can be lost via:
radiation- emission of electromagnetic radiation
convection- moving air removes heat that is radiated
conduction-direct transfer of heat by contact
evaporation

Question 12

How does heat production occur

Answer 12

increase metabolic rate due to muscular activity/exercise, stress (hormones from activities of autonomic division of nerv.system) and rising body temperature (biochem reactions increase)

Question 13

Define metabolic rate
What factors effect rate?

Answer 13

the rate at which energy is released by the breakdown of food
effected by exercise, stress, and body temperature

Question 14

Function and location of peripheral thermoreceptors

Answer 14

in skin and mucous membranes
detect temp change in external environment and send information to hypothalamus

Question 15

Function and location of central thermoreceptors

Answer 15

detect internal temperature change
Additional in spinal cord and abdominal organs that aid in internal temperature detection, sending info to hypothalamus

Question 16

Differentiate the role of hot and cold receptors in the body

Answer 16

hot-when stimulated, mechanisms operate to reduce heat production
cold-stimulated, hypothalamus receives information and initiates heat conservation and heat production mechanisms

Question 17

Describe the physiological mechanism in the blood vessels that operates to respond to lowered internal or external temperature in order to maintain homeostasis

Answer 17

Stimulus-decrease in temp=change in external environment
Receptor-central thermoreceptors in hypothalamus
Moderator-hypothalamus stimulates sympathetic nerves
Effector-smooth muscles in arteries
Response- contract and reduce
Feedback-decrease blood flow, less heat loss through radiation =increase core temperature

Question 18

How is heat regulated via sweating. Explain in detail (increase heat loss) and not via srmerf

Answer 18

occurs when temperature is above 28 degrees
sweating is stimulated by sympathetic nerves active secretion of fluid by sweat glands in skin that cause body cooling due to evaporation of hot liquid

Question 19

How is heat regulated via shivering. Explain in detail
(increase heat production) not the srmerf

Answer 19

continuous contraction/relaxation of skeletal muscles
due to no work being done. energy produced by muscles is released as heat, warming the body

Question 20

Describe the physiological mechanism in the blood vessels that operates to respond to raised internal or external temperature in order to maintain homeostasis

Answer 20

Stimulus-increase in temp=change in external environment
Receptor-central thermoreceptors in hypothalamus
Moderator-hypothalamus stimulates sympathetic nerves
Effector-smooth muscles in arteries
Response- relax and dilate
Feedback-increase blood flow, greater heat loss through radiation =decrease core temperature

Question 21

Describe the physiological mechanism of the thyroid gland that operates to respond to lowered internal or external temperature due to change in metabolic rate in order to maintain homeostasis

Answer 21

Stimulus-low metabolism due to low thyroxine=internal change that causes fall in internal temperature
Receptor-central thermoreceptors in hypothalamus=releasing factors
Moderator-hypothalamus stimulates anterior lobe of pituitary to release TSH
Effector-thyroid gland
Response- increase thyroxine production and secretion into blood
Feedback-increased metabolism therefore increased internal temperature

Question 22

Describe the physiological mechanism of the skeletal muscles that operates to respond to decrease internal or external temperature in order to maintain homeostasis

Answer 22

Stimulus-decrease core temp-change in external environment
Receptor-central thermoreceptors in hypothalamus
Moderator-hypothalamus stimulates sympathetic nerves
Effector-skeletal muscle
Response- increase heat production from rhythmic muscle tremors
Feedback-increase core temperature

Question 23

Describe the physiological mechanism of the sweat glands that operates to respond to raised internal or external temperature in order to maintain homeostasis

Answer 23

Stimulus-increase in temp of external environment
Receptor-peripheral thermoreceptors in skin detect change
Moderator-hypothalamus stimulates
Effector-sweat glands in skin release sweat
Response- evaporation occurs removing heat from skin
Feedback- decrease core temp

Question 24

Describe the behavioural mechanism of the body that operates to respond to raised internal or external temperature in order to maintain homeostasis

Answer 24

Stimulus- change in external environment temperature
Receptor-peripheral thermoreceptors in skin detect
Moderator-cerebral cortex conscious part of brain
Effector-skeletal muscle
Response- turn on heater/add layers/reduce SA
Feedback- increased core temp

Question 25

Difference between heat stroke and heat exhaustion

Answer 25

heat exhaustion more frequent as result of extreme sweating or vasodilation to lose heat

Question 26

Explain why glucose is so important to cells and how it plays it’s role?
Add related equation for cell respiration

Answer 26

Glucose is the cells source of energy for activities. Energy is released from these molecules during cellular respiration
C6H12O6 + 602 —> 6CO2 + 6H2O

Question 27

Describe glycogen. What is it’s relationship with glucose

Answer 27

Glycogen is a long chain of glucose molecules chemically combined. Glucose is stored as glycogen in liver and skeletal muscles.

Question 28

Describe glycogenesis, glycogenolysis and gluconeogenesis

Answer 28

Glycogenesis- formation of glycogen from glucose and other carbs
Gluconeogenesis-creation of new glucose through conversion of fats/proteins
Glycogenolysis- break down/apart of glycogen to glucose

Question 29

What role does islets of langerhaans play in blood glucose homeostasis
(memorise diagrams and write down)

Answer 29

contain chemoreceptors to detect change in blood glucose
-alpha cells:glucagon
-beta cells:insulin

Question 30

List the effects of insulin on cells. What role does insulin play in blood glucose homeostasis
(memorise diagrams and write down)

Answer 30

From beta cells-decrease blood glucose by:
-accelerating transport of glucose from bloods into body cells (skeletal muscles)
-accelerating glycogenesis in liver/skeletal muscles
-stimulating protein synthesis (from glucose to protein)
-stimulating lipogenesis/fat storage

Question 31

What role does glucagon, secreted by pancreas, play in blood glucose homeostasis
(memorise diagrams and write down)

Answer 31

from alpha cells-increase blood glucose levels by:
-stimulate glycogenolysis
-stimulate gluconeogenesis in the liver (new glucose molecules formed form amino acids and fats (broken down/lipolysis)
-inducing protein breakdown

Question 32

What role does adrenal cortex play in blood glucose homeostasis
(memorise diagrams and write down)

Answer 32

-ACTH stimulates release of glucocorticoids (cortisol)
.ensure that enough energy provided to the cells therefore stimulating glycogenolysis in liver
-increase amino acid transportation to liver
-allows muscle cells to shift from using glucose to fatty acids for their metabolic energy
and releases aldosterone (other flashcard)

Question 33

What role does adrenal medulla play in blood glucose homeostasis
(memorise diagrams and write)

Answer 33

-release adrenaline and noradrenaline
-increase blood glucose levels by glycogenolysis
-stimulates production of lactic acid from glycogen in muscles used to make glucose in the liver

Question 34

SRMERF for high blood glucose levels

Answer 34

S – High concentration of glucose in blood
R – Chemoreceptors called beta cells in islets of Langerhans are stimulated
M –beta cells in Islets of Langerhans
E – Beta cells secrete insulin
R – Increased uptake of glucose into the cells, storage of glucose as glycogen in liver and skeletal muscles, promotes fat storage and protein synthesis
F – Decrease in glucose concentration in the blood

Question 35

SRMERF for low blood glucose levels

Answer 35

S – Low concentration of glucose in blood
R – Chemoreceptors called alpha cells in islets of Langerhans are stimulated
M –Alpha cells
E – Alpha cells in the Islets of Langerhans secrete glucagon
R – Glycogenolysis occurs in liver and muscles, gluconeogenesis occurs, lipolysis and some breakdown of protein occurs.
F – Increase in glucose concentration in the blood

Question 36

Describe the physiological mechanism of the adrenal gland that operates to respond to lowered internal or external temperature due to change in metabolic rate in order to maintain homeostasis

Answer 36

Stimulus- low metabolism=low adrenaline/noradrenaline=internal change
Receptor- central thermoreceptors in hypothalamus=releasing factors
Moderator-hypothalamus stimulates adrenal medulla to release adrenaline and noradrenaline into blood
Effector-adrenal medulla
Response-increase in cellular metabolism=increase heat production
Feedback-increase metabolism=increase in core temperature

Question 37

Describe possible factors that may affect the rate of evaporation of sweat

Answer 37

Humidity will effect an individuals ability to sweat. High humidity, large water vapour conc in air, will lower evaporation rate.

Question 38

Describe the role of the pancreas in the regulation of blood sugar (summed version of function of adrenal glands, insulin, Langerhans, etc)

Answer 38

Regulation of blood glucose by production of insulin and glucagon
contains clusters called islets of Langerhans which are made up of alpha and beta cells. Alpha cells secrete glucagon, which causes an increase in blood glucose levels. Beta cells secrete insulin which causes a decrease in blood glucose levels.

Question 39

Briefly describe how are blood sugar levels maintained

Answer 39

by controlling the uptake of sugar by cells and its consequent storage and release

Question 40

Distinguish between type 1 and 2 diabetes

Answer 40

Type 1
Autoimmune disease/destroyed beta cells/no longer function which means No insulin is produced to store glucose away
Type 2
Pancreas still produces insulin, yet cells do not respond to insulin
Insulin resistance caused from obesity/insufficient exercise/diet high in fats/sugar/too much alcohol leads to high blood glucose levels.

Question 41

Distinguish between hyper and hypoglycaemia

Answer 41

Hypo-deficiency of glucose in the bloodstream.
Hyper-abnormally high level of glucose in the blood

Question 42

Explain how and why diabetes sufferers can become hyperglycaemic

Answer 42

Individuals with diabetes have abnormally high blood glucose levels. This is due to produces insufficient insulin, therefore unable to decrease blood glucose levels.

Question 43

Why do glucose levels need to be increased by adrenal glands in time of stress/fight or fight

Answer 43

glucose breaks down to create energy. Hormones are released to make sure enough glucose is prevalent for a response.

Question 44

How does hypothyroidism and hypoglycemia relate to unexplained weight gain, fatigue, and an intolerance to the cold temperatures

Answer 44

Unexplained weight gain
body cells not responding to insulin
Glucose remains in the blood, converted into fat causing a decrease in cellular respiration

Fatigue
Thyroxine regulates metabolic rate
Without a thyroid gland, the basal metabolic rate decreases and the patient has less energy

An intolerance to cold temperatures
Heat energy is released from some of the chemical reactions stimulated by thyroxine
The decrease in thyroxine / basal metabolic rate result in a reduction of body heat