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Question 1

How many layers of smooth muscles do arteriole walls have?

Answer 1

Arterioles usually contain only one to two layers of smooth muscle in their walls

Question 2

Where is the primary site of vascular resistance?

Answer 2

Arterioles

Question 3

Where does the greatest change in in blood pressure and velocity of blood flow occur?

Answer 3

at the transition point between arterioles and capillaries

Question 4

Describe the range of permeability profiles of the capillary beds

Answer 4

Blood-brain barrier: only gases and water can freely diffuse across the specialised endothelial layer in the brain

Sinusoidal: In liver- red blood cells can move in and out of the circulation

Fensetrations: In kidney- allow rapid water, small protein and molecule movement in and out of tissues

Question 5

Describe the three layers of venule walls

Answer 5

An inner endothelium composed of squamous endothelial cells that act as a permeable membrane

a middle layer of muscle and elastic tissue ( poorly developed to have thinner walls that arterioles)

an outer layer of fibrous connective tissue

Question 6

why is the porosity of venules particularly important in the anterior pituitary?

Answer 6

short portal venules between the neural and anterior pituitary lobes provide an avenue for rapid hormonal exchange via the blood.

Question 7

What are high endothelial venules?

Answer 7

a special type of venule where the endothelium is made up of simple cuboidal cells

Question 8

Which veins carry oxygenated blood to the heart?

Answer 8

pulmonary and umbilical veins

Question 9

What is the role of valves in veins?

Answer 9

to prevent backflow, ensure unidirectional flow

important in the control of blood pressure as changes in the muscular tone of veins change central blood volume and thus blood pressure

Question 10

what are the portal venous systems? Give examples

Answer 10

wo capillary beds are joined together by a series of veins or venules

hepatic portal vein and the hypophyseal-hypothalamic portal system in the hypothalamus and anterior pituitary

Question 11

name the two sensors in the body and what they measure

Answer 11

skin and hypothalamus, which measure the external body temperature and the internal (core) body temperature, respectively

Question 12

If the pH of blood falls below 7.35, then this is called….

Answer 12

acidosis

Question 13

if pH increases above 7.45, then this is called…

Answer 13

alkalosis

Question 14

Signs and symptoms to acidosis

Answer 14

headaches, confusion, feeling tired, tremors, and coma

Question 15

What are the two types of acidosis

Answer 15

metabolic acidosis= increased production of metabolic acids, such as lactic acid or an inability to excrete acid via the kidneys

respiratory acidosis= an excessive buildup of carbon dioxide due to hypoventilation

Question 16

What mainly determines the movement of water between compartments and across cell membranes

Answer 16

differences in hydrostatic and osmotic pressures on either side of these barriers

Question 17

How are hydrostatic forces created?

Answer 17

by the pumping action of the heart

Question 18

How are osmotic pressures created?

Answer 18

by the concentration of solute particles

Question 19

how can osmotic pressure be measured?

Answer 19

from the number (concentration) of solute molecules present in a solution.

Question 20

where is an increase in plasma osmolality detected?

Answer 20

hypothalamus

Question 21

What is the protective mechanism used by the hypothalamus when there is a rise in plasma osmolality? Why is this important?

Answer 21

the sensation of thirst is quenched, preventing excessive consumption and encourages frequent small drinks until fluid balance is restored

if water is consumed too quickly (or if there is blockage of urine production) body fluids become diluted and there is a reduction of sodium concentration in the extracellular fluid that causes a shift in osmotic pressure making cells and tissues swell= oedema

Question 22

What four categories can tissues be divided into?

Answer 22

 epithelial tissue
 connective tissues (includes blood, cartilage, bone, teeth and fat)
 muscle tissue
 nerve tissue

Question 23

Describe the functions of epithelial tissue layers?

Answer 23

Protection: deeper layers of tissue from injury or infection, skin protects underlying tissues from sunlight, heat, cold, abrasion

Absorption/secretion: Nutrients from gut, secretion of enzymes for digestion

Selective diffusion: Transfer of gases, nutrients & waste products between blood and surrounding tissues

Question 24

Name some roles of membrane transport systems

Answer 24

• Maintenance of intracellular pH
• Maintenance of intracellular ionic composition
• Regulation of cell volume
• Uptake and concentration of metabolic fuels and building blocks
• Extrusion of waste products of metabolism and toxic substances
- in some cases drugs
• Generation of ionic gradients necessary for the electrical excitability of nerve
and muscle

Question 25

Define passive transport

Answer 25

Non-polar molecules are able to enter and, therefore, diffuse across the hydrophobic domain of lipid bilayers

Question 26

Define permeability coefficients

Answer 26

the speed at which any substance transverses a lipid bilayer

Question 27

What are the models for facilitated transport?

Answer 27

``` protein pores (also known as channels), ping-pong proteins (carriers) and flip-flop proteins (unlikely thermodynamically) ```

Question 28

Whether the transport of an ion or molecule can occur spontaneously (passive transport) or requires energy (active transport) is determined by ....

Answer 28

the free energy change of the transported species

Question 29

what is secondary active transport?

Answer 29

the transport of one substance is linked to the concentration gradient for another substance via a co- transporter

Question 30

Name some examples of cotransporters

Answer 30

Na+ glucose co-transport in the small intestine and kidney (symport). Entry of sodium provides the energy for the entry of glucose • Na+/Ca2+ exchange - Inward flow of sodium down its concentration gradient drives outward flow of Ca2+ up its concentration gradient (antiport) •Na+/H+- exchange - Inward flow of sodium down its concentration gradient leads to cell alkalization by removing

Question 31

How does thiazides work?

Answer 31

Thiazides block the action of the sodium-chloride co-transporter (NCCT) resulting in sodium retention (and hence water) in the collectingduct

Question 32

how does ADH work?

Answer 32

Anti-diuretic hormone (ADH - also known as (arginine)-vasopressin [AVP]) acts on aquaporins to allow water to quickly back into the body

Question 33

How does aldosterone work?

Answer 33

Aldosterone is a mineralocorticoid hormone produced by the adrenal cortex that acts as a nuclear transcription factor when it binds to the mineralocorticoid receptor. In the cortical collecting duct, aldosterone thus stimulates the synthesis of ROMK, the epithelial sodium channel complex (ENaC) and the Na-K-ATPase (Na pump)

Question 34

how does Amiloride work?

Answer 34

Amiloride blocks the action of the ENaC. Na+ stays in the duct and water stays with it and is passed in the urine, thus lowering water retention.

Question 35

how does spironolactone work?

Answer 35

it antagonises the actions of aldosterone at the mineralocorticoid receptor, thereby preventing these channels and transporters that move Na+ from the collecting duct into blood from being produced. Na+ stays in the duct and water stays with it and is passed in the urine, thus lowering water retention.