Principles Flashcards
What is meant by the term tissue?
A group of cells with a similar structure and function
What is meant by the term organ?
Made up of two or more types of primary tissue that function together to perform particular functions
What is mean by the term ‘body system’?
A group of organs that perform related functions and work to achieve common goals
Define the term ‘homeostasis?
The maintenance of steady states within our bodies by coordinated physiological mechanisms. Essential for survival.
What is a feedforward control system?
Responses made in anticipation of change.
Usually act in combination with negative feedback.
What is a feedback control system?
Responses made after change
What is the two types of feedback system?
Negative
Positive
What is the main type of homeostatic control?
Negative feedbac=promote stability through closed loop
Give an example of negative feedback
Control of blood pressure
What are the stages of a negative feedback system?
- Deviation on controlled variable from the norm
- Sensor
- Control Centre
- Effector
- Compensatory response
- Restoration of controlled variable to normal
- Negative feedback shut off the system responsible for the response
What is positive feedback?
Amplifies initial change
Give an example of positve feedback
Uterine contractions during labor become stronger until the birth of a baby
What are the consequences of a disruption in homeostasis?
Disease and death
Why is cholesterol important in a membrane?
Provides fluidity and stablitliy
What are the three types of proteins in a membrane?
Integral, transmembrane and peripheral
What is an intergral protein?
One embedded in the membrane ie receptor
What is a transmembrane protein?
One that is across the membrane eg channels
What is a peripheral protein
One that is not actually part of the membrane eg enzymes
What is the glycocalyx?
The combination of glycoproteins and glycolipids
Name examples of cell adhesion molecules?
cadherins
integrins
What do carbohydrates on the cell membrane do?
Act as self identity markers- identifies self and interacts with other cells
What is a desmosome?
Adhering junction that anchors cells together
What is a tight junction>
Lateral edges of epithelial cells near their lumenal (apical) membranes
What is a gap junction
communicating junctions that allow the movement of charged ions and small molecules between two adjacent cells
What is Fick’s law of diffusion?
Several factors infuence the rate of diffusion:
1. magnitude of the concentration gradient
2.surface area of the membrane
3 lipid solubilty
4. molecular weight
5.distance
What are aquaporins?
Water channels
What is osmolarity?
The concentration of osmotically active particles in a solution
What is tonicity?
the effect a solution has on a cell volumes eg iso, hypo or hypertonic
What osmolaroty are body fluids?
around about 300 mOsm
What is the difference between facilitated diffusion and active transport?
Facilitate diffusion uses a carrier to transfer from high to low conc (not energy requiring) where as active transport requires a transporter to transfer from a low to high conc.
How many sodiums are transported out of the cells in the sodium potassium pump>
three
How many potassiums enter the cell in the sodium potassium pump?
two
Name the two types of secondary active transport?
Symport
Antiport
What is symport?
The solute moves in same direction as the sodium
What is antiport?
The solute mover in opposite directions to sodium
What are the three important aspects of carrier mediated transport?
Specificity
Saturation
Competition
What is a membrane potential?
Separation of opposite charges across the membrane
What is the sodium concentration outwith the cell?
150 mM
What is the intracellular sodium conc
15 mM
What is the extracellular potassium conc
5mM
what is the intracellular potassium conc
150mM
What is the extracellular A- conc
0
What is the intracelullar A- conc
65mM
What is the extracellular chloride conc?
110mM
What is the intracellular conc of chlorine?
7nM
What is the relative permeability of sodium?
1
What is the relative permeabilty of potassium?
100
What is the membrane potential at Ek?
-90mV
What is the Nernst equation?
Ek= 61log(ion outside the cell/ion inside the cell)
What is the value of Ena?
+61mV
What is the resting membrane potential?
-70mV
What is the resting membrane potential using goldman-hodgkin-katz equation?
-83mV
What hormone regulate glucose during starvation?
Cortisol (adrenal) Growth hormone (pituitary)
What hormone regulate glucose in emergencies?
Adrenaline (adrenal gland)
What hormone regulate glucose normally?
Glucagon and insulin (pancreas)
Which cells release glucagon?
alpha cells in islets of langerhans
Which cells release insulin?
beta cells of islets of langerhans
WHat three things does insulin do?
Stimilates uptake if glucose into cells.
Activates liver enzymes to convert glucose to glycogen.
Promotes incorporation of amino acids into protein in muscle and promotes lipogenesis.
How does insulin promote glucose uptake?
causes the insertion of GLUT 4 proteins into cell membrane
What causes insulin production to increase?
Increased glucose
increased amino acids
increased parasympathetic stimulation
increase glucagon
What causes inhibiting insulin
decreased glucose
increase sympathetic drive
What happens in diabetes?
Glucose very high but cells cant use. Use lipolysis to generate energy/ Increases acetyl coA. Cant use excess so forms ketones. Metabolic acidosis and compensatory hyperventilation.
What is the difference between type 1 and type 2 diabetes?
- No insulin produced
2. Enough insulin- cells no longer sensitive to insulin
What are the actions of glucagon?
Increase liver glycogenolysis.
Inhibit glycogen synthesis.
Promote liver gluconeogenesis.
Promotes lipolysis.
What is the effect of growth hormone durign starvation state?
Decreases glucose uptake in cells.
Mobilises glucose from the liver
Promotes lipolysis.
What is normothermia?
Normal core body temperature
What is basal metabolic rate?
minimum energy required to sustain vital body functions
what activates the posterior hypothalmic centre
cold
what activates the anterior hypothalamic centre?
warmth
What is an endogenou pyrogen?
Released by macrophages in repose to infectio or inflammation- stimulate prostaglandidn release in the hypothalmus
WHat do protstaglandins do?
Initiate ‘cold response’ to heat the body which results in fever ie resets the normal hypothalamic thermic set point