Indroduction to nervous and endocrine systems

Question 1

what does the nervous system consist of?

Answer 1

The central nervous system and peripheral nervous system

Question 2

What does the CNS consist of?

Answer 2

• Brain and spinal cord
• voluntary and involuntary control
• behaviour

Question 3

What does the PNS consist of?

Answer 3

Connects CNS to limbs and organs

Divided into:
ANS - parasympathetic, sympathetic and enteric NS (involuntary)

SNS - voluntary motor control eg. muscle movements

Question 4

What is an example of the SNS mediating involuntary control?

Answer 4

reflex arcs

Question 5

What does connection of dendrite and axon terminal form?

Answer 5

synapse

Question 6

what do oligodendrocytes form?

Answer 6

Myelin - this causes the signal to be quicker (creates protective sheaths around nerve fibres)

Question 7

what is the function of the cell body of a neuron?

Answer 7

contains genetic information, maintains the neuron’s structure, and provides energy to drive activities.

Question 8

what is the function of the dendrites of a neuron?

Answer 8

receive input from many other neurons and carry those signals to the cell body

Question 9

what is the function of astrocytes

Answer 9

clearing excess neurotransmitters, stabilizing and regulating the blood-brain barrier, and promoting synapse formation.

Question 10

what is the function of the axon?

Answer 10

directs electrical impulses or action potentials away from the cell body or soma of a neuron towards another cell

Question 11

what are axon terminals?

Answer 11

It is responsible for releasing neurotransmitters and is in close proximity to but not touching other nerves or effector cells, such as muscles.

Question 12

What happens to synaptic vesicles at the axon terminal?

Answer 12

they are filled with neurotransmitters which are released into the synapse and binds with receptors

Question 13

What does the blood brain barrier prevent?

Answer 13

Toxic chemicals from getting to the brain
- Prevents 98% of drugs from passing

Question 14

What do endocrine glands do?

Answer 14

Secrete hormones into the bloodstream
- target cells express hormone receptors

Question 15

what are different types of hormones?

Answer 15

Peptide
Steroid
Amine

Question 16

What is an examples of a peptide hormone?

Answer 16

Insulin, glucagon (hydrophilic - can’t cross membranes so are released by exocytosis)

Question 17

What are examples of steroid hormones?

Answer 17

oestrogen, testosterone (hydrophobic so is able to pass through membranes - typically found inside the cell)

Question 18

what is homeostasis?

Answer 18

the ability of the body or a cell to seek and maintain a condition of equilibrium or stability within its internal environment when dealing with external changes

Question 19

what happens when the body temperature increases?

Answer 19

• Blood vessels dilate
• capillaries become flushed with warm blood
• Heat radiates from skin surface
• Sweat glands activated, secrete perspiration to help cool the body

Question 20

what happens when body temperature decreases?

Answer 20

• blood vessels constrict
• blood diverted from skin capillaries to minimise heat loss from skin
• skeletal muscle activates when more heat must be generated; shivering begins

Question 21

What happens if calcium levels drop?

Answer 21

parathyroid releases PTH which:
- increases calcium release from bones
- increase calcium uptake in intestines
- increase calcium reabsorption from urine

Question 22

what is the difference between between the nervous system and endocrine?

Answer 22

• NS is a wired system with arrangement between neurons, ES is wireless with no connection
• Neurotransmitters are released across short distances, hormones are carried long distances in the blood
• NS response is rapid and brief, ES is slow and longer lasting

Question 23

what is the axon hillock?

Answer 23

has lots of sodium channels for action potentials to fire

Question 24

what produces myelin sheets?

Answer 24

Schwann cells (PNS)
Oligodendrocytes (CNS)

Question 25

What is the node of ranvier?

Answer 25

spaces between myelin which allows the action potential to fire

Question 26

What is found at dendritic spines?

Answer 26

neurotransmitter receptors which cause depolarisation

Question 27

What are examples of neurotransmitters?

Answer 27

CNS - glutamate, GABA, serotonin, dopamine, noradrenaline PNS - noradrenaline, acetylcholine

Question 28

How does resting membrane potential develop?

Answer 28

- Membrane is more permeable to potassium than sodium ions - inside of the cell becomes negative (more potassium flowing out than sodium moving in) - resting membrane potential develops - sodium potassium pumps maintain resting potential

Question 29

how does the sodium potassium pump work?

Answer 29

There is more sodium outside the cell and more potassium inside the cell Uses energy in the form of ATP to move ions against their diffusion gradient 3 sodium ions are pumped out of the cell 2 potassium ions are pumped into the cell

Question 30

What happens if an action potential reaches the threshold

Answer 30

Voltage gated sodium channels open (depolarisation)

Question 31

what happens during depolarisation?

Answer 31

potassium ions diffuse out of the cell

Question 32

how does it get back to resting potential after hyperpolarisation?

Answer 32

active transport using sodium-potassium pumps

Question 33

what is the time when the membrane is hyperpolarised called?

Answer 33

refractory period - no action potentials can occur

Question 34

What is absolute and relative refractory periods?

Answer 34

During absolute refractory, the neuron cannot fire another action potential. Relative refractory occurs after absolute refractory. During relative refractory, it is possible for the neuron to produce another action potential, but it requires a much greater stimulus to reach the threshold.

Question 35

What is the effector neurotransmitter for sympathetic and parasympathetic ns

Answer 35

Sympathetic - NA acting on adrenoceptors Parasympathetic - acetylcholine (Ach) acting on muscarinic Ach receptors

Question 36

what is the ganglia neurotransmitter?

Answer 36

Ach for both sympathetic and parasympathetic ganglia acting on nicotinic receptors

Question 37

what is the localisation of ganglia?

Answer 37

Sympathetic- close to spinal cord Parasympathetic - close or within target organs

Question 38

what are features of the brain functions?

Answer 38

- four main cells: neurones, astrocytes, microglia ans oligodendrocytes - consciousness - behaviour - learning and memory -senses

Question 39

What are features of the spinal cord functions?

Answer 39

- cells types: neurones, astrocytes, microglia, oligodendrocytes - pathway connecting brain to PNS - Fibre tracts running to/from brain - peripheral afferent input via dorsal horn - efferent input via ventral horn

Question 40

how many vertebrae does the spinal column have?

Answer 40

31

Question 41

where does sympathetic interaction in the spinal cord occur?

Answer 41

thoracolumbar

Question 42

where does parasympathetic innervation in the spinal cord occur?

Answer 42

craniosacral

Question 43

is glutamate and GABA excitatory or inhibitory?

Answer 43

Glutamate - excitory GABA - inhibitory

Question 44

what is IC50 and EC50

Answer 44

50% of max response - inhibitory conc -excitory conc

Question 45

what does the lower the value of IC or EC50 mean?

Answer 45

the more potent the drug

Question 46

what is chemical antagonism?

Answer 46

when one drug antagonises the action of another by chemically combining with it

Question 47

what is physiological antagonism?

Answer 47

when two drugs counteract each other by producing opposing effects on different receptors

Question 48

what is pharmalogical antagonism?

Answer 48

when drugs counteract each other by acting on the same receptor type