'Steady state', Diabetes (5) Flashcards
(32 cards)
Define homeostasis -2 marks
+ what facilitates it?
The maintenance of a constant internal environment within set and narrow limits using control mechanisms which operate in response to a changing internal and external environment.
Negative feedback.
How are changes in the body reversed (3 marks)
Changes in the body/internal environment (tissue fluid, derived from blood plasma) are detected by sensors or sensory receptors, or changes in the external environment are detected by
The stimulus is sent to the control centre and then an effector to reverse the change and bring it back to the normal.
The organism must give a response either physiologically or behaviourally.
Changing internal or external environment changes variable - VARIABLE - value of variable detected - SENSOR - CONTROL CENTRE (knows ideal value/set point) - EFFECTOR - brings variable back to set point - VARIABLE
All endocrine glands are controlled by the hypothalamus (nervous tissue) by the pituitary gland (endocrine tissue).
Name factors that must be maintained constant in the internal environment
- core temperature
- blood- pressure, glucose concentration, pH, urea and mineral ion concentrations
- CO2
- H2O
what is the endocrine system
A system made of endocrine glands, i.e. producers of hormones/chemical signals; they secrete them directly into the blood; ductless.
what is an exocrine gland
One that has a duct or tube which secretes its chemicals into a lumen or an extracellular area eg. a sweat gland
briefly describe the CONTROL CENTRE of the human body
the hypothalamus, in the brain, made of nervous tissue, regulates all homeostatic mechanisms via
- autonomic/involuntary NS
- endocrine system
It receives signals from sensors/receptors all over the body, and communicates to effectors to carry out an appropriate response by cell signalling.
which part of the nervous system innervates glands
The autonomic system in the peripheral NS
- Sympathetic + Parasympathetic sub-divisions respectively:*
- fight or flight*
- homeostasis and body at rest*
From the following examples of exocrine glands, name where they secrete and what they secrete
- PANCREAS
- STOMACH
- GALL BLADDER
PANCREAS: Lumen of Duodenum; Digestive enzymes- lipases, amylases, proteases
STOMACH: Stomach; Pepsin, HCl
GALL BLADDER: Duodenum; Bile
what are the two types of hormone and what are they made of
NON-STEROID HORMONES - amino acid based, water soluble
made of protein, peptides or derivatives of amino acids
STEROID HORMONES - synthesised from cholesterol, lipid soluble
name three non-steroid hormones and three steroid hormones
Insulin + adrenaline, glucagon
Cortisone, oestrogen, adrenal corticoids
What is the difference between the ways in which steroid and non-steroid hormones interact with a target cell
Non-steroid hormones are hydrophilic/water soluble and cannot pass through the phospholipid bilayer.
They bind to a specific, complementary CSM receptor, and initiate a response within the cell (first messenger).
Steroid hormones are hydrophobic/lipid-soluble and can cross the phospholipid bilayer, so enter the cell. They affect the transcription of specific genes in the nucleus.
what is the role of cyclic AMP in cell-signalling by hormones
cAMP is a second messenger inside the target cell of water-soluble hormones which cannot enter the cell.
The intra-cellular enzyme Adenyl cyclase converts ATP to cAMP.
explain the actions of FIRST MESSENGER and SECOND MESSENGER in cell signalling
- An endocrine gland releases a water-soluble hormone, the first messenger, into the blood
- It binds to a specific, complementary receptor molecule on the P bilayer of the target cell.
- The hormone-receptor complex activates a G-protein, which activates adenylate cyclase.
- It converts ATP into cyclic AMP, the second messenger
what controls the release of hormones from the adrenal cortex and which type of hormones does it produce
The release is controlled by the PITUITARY GLAND (hypothalamus)
It produces STEROID hormones, involved with long-term stress, and two types of them:
- GLUCOCORTICOIDS*
- MINERALOCORTICOIDS - regulate Na+/K+ content of blood*
Name specific mineralocorticoids + glucocorticoids and give their function
glucocorticoid: CORTISOL
promotes gluconeogenesis
mineralocorticoid: ALDOSTERONE
increases Na+ content of the blood + blood pressure
which two hormones are released from the adrenal medulla
ADRENALINE + NORADRENALINE
-have receptors on a variety of tissues
-short-term stress response
Give the 9 effects of adrenaline & noradrenaline
- increase heart rate
- dilation of pupils - allow more capture of light (evade predators)
- increase blood to brain (mental awareness)
- increase glycogenolysis in liver
- increase stroke volume i.e. pressure at which the heart pumps/vol. in one pump
- stimulation of erector pili muscle of body hair (increase body size)
- constriction of vessels in non-essential organs to increase blood pressure
- relaxation of smooth muscle in bronchioles
- decreases blood flow to digestive organs
affects of INSULIN
- accelerated uptake of glucose into cells from blood
- accelerated conversion of glucose into glycogen (glycogenesis)
- decreased glucose breakdown/ decreased metabolic rate inside cell
- increased lipid formation from glucose
which dysfunction causes DIABETES TYPE 1
ß - cells do not produce & secrete insulin
thought to be an autoimmune disease where immune system attacks own ß - cells
who is affected by the two types of diabetes
TYPE 1
Children, continues into adulthood.
TYPE 2 = 90% of diabetics
Develops with age- usually people over 40, but increasingly children at risk of obesity.
How is TYPE 2 DIABETES treated
DRUGS:
- stimulate insulin production
- slow down absorption of glucose from small intestine
- (may need to inject insulin)
- regulate carbohydrate intake in diet (in particular, refined)
- increase exercise levels
- lose weight
how can a type 1 diabetic
- Regular injections of insulin into adipose tissue (cannot be taken orally bc protein)
- Regular testing of blood glucose levels- pricking finger + blood glucose monitor- determines quantity of insulin injected
what happens when injecting the wrong quantity of insulin
too MUCH = hyperglycaemia
too little = hypoglycaemia
`what are contributory factors to DIABETES TYPE 2
- diet -excessive over-eating/refined carbohydrates eg. starched
- physical inactivity
- obesity -excess body weight- fat cells metabolise glu v. slowly
- genetic factors eg. higher frequency in asian/afro-caribbean communities
