Homeostatis Flashcards
Def of homeostasis
Physiological control systems maintain the internal environment within restricted limits
Why is homeostasis important for organisms
Homeostasis is important
1. Maintains optimum conditions for enzyme action and cellular function
Examples of physiological factors controlled by homeostasis
- Core body temperature
- Metabolic waste concentrations (urea + CO2)
- Blood pH
- Concentration of glucose in blood
- Water potential of the blood
- Concentration of respiratory gases in blood
What is a hormone
Chemical substance released by endocrine glad that is carried by the blood to stimulate an effect on target organ
Compare endothermic and ectotherms
Endotherms
- warm blooded
- heat from the inside
Ectotherms
- cold blooded creatures
- heat themselves by environmental conditions
Where does body heat energy come from in endotherms
Externally
- mammals absorb solar radiation directly, or indirectly by radiation, conduction or convection from their environment
Internally
- as by product of metabolic rate, respiration
Outline the role of hypothalamus in thermoregulation
Thermoregulation centre in hypothalamus initiates switching on/off heat loss/ conservation mechanism
(Two centres: hot control + cold control)
Thermoreceptors (heat sensitive neurones) monitor temperature
What is negative feedback
When a change occurs in body it responds in such a way as to reverse the direction of change
Mechanism for negative feedback
1) sensory receptor detects change (stimulus)
2) an integrating centre receives input from sensors and coordinates the response
3) effector carry out corrective actions to bring about a response
4) returning conditions to normal is negative feedback
Annotate diagram on the control of body temperature
See notes
Advantages and disadvantages of being ectotherm (cold blooded)
ADV:
- less food needed
- greater proportion of food energy for growth
DISADV:
- less active in cooler temperatures as need to warm up before can be active
Advantages and disadvantages of being an endotherm (warm blooded)
ADV:
- can be active in cooler conditions
- enzymes can work efficiently all the time
- can inhabit at cooler regions
DISADV:
- significant proportion of food intake used to generate heat
- less food energy available for growth
Types of peptide hormones and steroid hormones
PEPTIDE
- adrenaline
- insulin
-glucagon
STEROID
- oestrogen
- Progesterone
What is the normal blood concentration of glucose
90mg/100cm3
Symptoms of too low sugar levels
Respiration slows which reduces formation of ATP
Stops cellular processes
Brain cells die leading to fainting then death
Symptoms of glucose levels in blood being too high
The blood water potential drops leading to cells losing water causing organ damage and failure leading to death in serve cases
What is the role of the pancreas
In exocrine system (enzymes)
- produces enzymes in pancreatic duct for digestion
In endocrine system (hormones)
- islets of langerhans secrete hormones insulin & glucagon directly to blood stream to regulate glucose levels
What happens to glucose in muscle/adipose and liver tissue
In Muscle/adipose tissue
- increase uptake due to increase glucose channels
M —> glycogen. A —> Fat
In liver tissue
- increase uptake increased diffusion
Converted glycogen or respired
Process of lowering blood glucose levels in muscle or adipose cells
1) insulin binds to receptors
2) binding causes chemical signal inside cell
3) chemical signal effects vesicle causing it to fuse with membrane and release glucose carrier proteins onto membrane
4) increase the number of glucose carrier proteins
5) facilitated diffusion of glucose into cell increases
6) enzymes activated to turn glucose —> glycogen (muscle cell) or fat (adipose cell)
Annotate insulin effect on muscle/ adipose cell diagram
Include
- insulin binding to receptors
-vesicle with glucose carrier proteins
- glucose carrier proteins onto membrane
- enzymes with glucose Turing to fat or glycogen
Process of lowering blood glucose levels in liver cells
1) insulin binds to receptors proteins
2) chemical signal activates enzyme - phosphorylase
3) this reacts glucose with phosphate (phosphorylises)
4) this maintains conc gradient increasing uptake of glucose by diffusion
5) other enzymes stimulated which causes glycolysis and glycogenesis to occur
Outline glucagon’s role in increasing blood glucose levels
- activation of enzymes in the liver
Which increases glycogen breakdown (glycogenolysis)
Glucose synthesised from lactate and amino acids (gluconeogenesis)
Def of glycogenolysis
The process of glycogen breakdown into glucose
Def of gluconeogenesis
The process of glucose being synthesised from lactate and amino acids
What is the role of adrenaline in increasing blood glucose levels
Adrenaline affects the liver
- uses a second messenger cAMP
- increases glycogen breakdown (glycogenolysis)
- also inhibits enzyme glycogen synthase preventing production on glycogen so more glucose available
What is secondary messenger system
Used by many hormones
It works to use 1 hormone molecule
- to produce many cAMP molecules
- and large amounts of enzymes
To causes response
Annotate summary of glucose control
See notes
Too low
1. Alpha cells detect fall, glucagon secretion, in liver glycogen breakdown and synthesis of glucose
Too high
Beta cells detect rise, insulin secretion, increased uptake of glucose by adipose cells, muscle cells and liver tissue
Information of the 1 diabetes
1) T-cells attack beta cells in pancreas decreasing insulin secreted
2) liver doesn’t store glycogen
- cannot replace glucose quickly
- neurones can only respire glucose to levels falls = coma
3) cells don’t take up glucose after meal
- glucose can rise too high affecting brain cells
4) treated with insulin
- injected or digested if taken orally
Info on type 2 diabetes
- associated with obesity/ unbalanced diets
- receptors stops responding to insulin
Beta-cells produce more
If beta cells become damaged type 1 diabetes can develop - can’t be treated with insulin
Function of the renal artery
Carry blood from abdominal aorta to kidneys
Function of renal veins
Drains blood from the kidney into inferior vena cava
Label the diagram of kidney
Include
- outer area = cortex
- outer layer = renal capsule
- inner part = medulla
- nephron
- renal vein
- renal artery
- renal pelvis
- ureter
Label structure of nephron ( in kidney)
Include
- efferent arteriole
- afferent arteriole
- bowman’s capsule
- glomerulus
- distal tubule
- collecting duct
- loops of Henle (ascending & descending)
- peritubular capillaries
- proximal tubule
Role of efferent arteriole in nephron of kidney
Tiny artery that carries blood out of glomerulus
Role of afferent arteriole in nephron of kidney
Tiny artery carries blood to nephron & into glomerulus
Role of bowman’s capsule in nephron of kidney
End of tubules that surround the glomerulus
Role of glomerulus in nephron of kidney
Network of capillaries that is the site of ultrafiltration
Role of distal tubule in nephron of kidney
Role of collecting duct in nephron of kidney
Collects urine made by nephron and channels it into the minor calyx
Role of the loop of Henle in nephron of kidney
Role of peritubular capillaries in nephron of kidney
Capillaries that surround the tubules and exchange water and solutes within it
Role of proximal tubule in nephron of kidney
Function of
