Homeostasis, Nervous system

Question 1

What is homeostasis?

Answer 1

The dynamic constancy of the internal environment despite constant changes in the external environment.

Question 2

Set point

Answer 2

The optimum value that you want to maintain

Question 3

Controlled variable

Answer 3

The aspect you want to maintain

Question 4

What is the feedback mechanism

Answer 4

Detect change in sensor cells/receptors. Signal to integrating centre. Signal back in response to an effector. Action to change the variable. Change is detected and feed back.

Question 5

What is negative feedback

Answer 5

Where deviation away from the set point value causes a return to the optimum.

Question 6

What is positive feedback?

Answer 6

Where deviation away from the set point value causes a further deviation.

Question 7

What is the process when the blood pressure changes?

Answer 7

1) Baroreceptor found in Carotid artery and aorta.
2) Signals through Glossopharyngeal nerve to Medulla oblongata
3) Impulses back through the autonomic nerve system
4) Vasoconstriction or vasodilution

Question 8

What is the process when the temperature changes.

Answer 8

1) Thermorecpetors in skin and in hypothalamus.
2) Integrator- Hypothalamus activates effectors
3) Effectors for warming up occur

Question 9

Give examples of effectors for warming up

Answer 9

Pili muscles contract so hair can rise, vasoconstriction and skeletal muscle contacts (shivering).

Question 10

Give examples of positive feedbacks

Answer 10

Action potential in nerves, ovulation, in birth labour, lactation (baby milk) and blood clotting.

Question 11

How does positive feedback end?

Answer 11

It can be self-terminating E.g baby stops suckling, baby is born. Or other feedback loops can activate them to shut them down.

Question 12

Peripheral Nervous system

Answer 12

Composed of the somatic and autonomic nerves (voluntary and involuntary)

Question 13

CNS

Answer 13

Is composed of the Brain and the spinal cord. (The body’s master control unit)

Question 14

What sets of neurones are found in the Autonomic system?

Answer 14

Preganglionic neurons and postganglionic neurons.

Question 15

Where is the preganglionic neurons found?

Answer 15

Starting from the spinal cord.

Question 16

Where is the postganglionic neurons found?

Answer 16

Outside the CNS, after passing the ganglion. (2nd part, like motor neurone)

Question 17

What is a ganglion?

Answer 17

A nerve cluster or group of nerve cell bodies located in the autonomic nervous system and sensory system.

Question 18

What is Autonomic Nervous System?

Answer 18

Involuntary bodily processes.

Question 19

What is the Sympathetic system?

Answer 19

Part of the Autonomic nervous system. When stressed and release adrenaline/ epinephrine. Makes an excitatory reaction. Speeds up

Question 20

What is Parasympathetic system

Answer 20

In the Autonomic NS, more active in calm states and slow things down.

Question 21

Give the order in which the vertebrae is ordered top to bottom: lumbar, sacral, cervical, thoracic.

Answer 21

Cervical, thoracic, lumbar, sacral, coccygeal.

Question 22

What is cranial neurons?

Answer 22

Nerves coming out of the brain and brain stem

Question 23

What are peripheral neurons?

Answer 23

Nerves coming out of the spinal cord (cervical to coccygeal).

Question 24

Where does the sympathetic neurons outflow from?

Answer 24

Come out from the Thoracic and Lumbar in the vertebrae.

Question 25

Where does the parasympathetic outflow from

Answer 25

From the cranial (brain) and sacral.

Question 26

What length is the preganglionic fibre in para and sympa

Answer 26

Sympa= Short
Para = long

Question 27

What neurotransmitter is released in the ganglion in para and sympa?

Answer 27

Acetylcholine

Question 28

What is a neuroeffector transmitter?

Answer 28

A transmitter that acts on the effector and gets released from a motor neurone.

Question 29

What neuroeffector transmitter does sympa and para have?

Answer 29

Sympa secrete Noradrenaline (alpha or Beta). Para secrete acetlycholine.

Question 30

What does Noradrenaline do?

Answer 30

Increases the heart rate and sweat and decreases digestion, vasoconstriction.

Question 31

What does acetylcholine do?

Answer 31

Decreases the heart rate and sweat. Increases digestion and vasodilation.

Question 32

What is the endocrine system?

Answer 32

The hormone system

Question 33

What are steroids?

Answer 33

A hormone that is made of lipids. So it can pass through the membrane and bind to receptors in the nucleus to change gene expression

Question 34

What can hormones be made of?

Answer 34

Protein or lipids (steroid)

Question 35

What is Cortisol?

Answer 35

A steroid hormone that is released when stressed and controls the glucose blood levels.

Question 36

How is cortisol released?

Answer 36

CRH is released and this causes ACTH to be released. Then cortisol is released. An increase in cortisol results in decrease in CRH secretion. NEGATIVE FEEDBACK

Question 37

Give an example of a Positive feedback?

Answer 37

1) Baby suckles at the mother nipple.
2) Signals go to the brain
3) Oxytocin is released into the blood
4) Oxytocin contracts the ducts in the breasts, increasing pressure and releasing milk
5) The more suckling, the more oxytocin is released.
6) No suckling stops further secretion of oxytocin.

Question 38

Give the equation linking pH and H+ ions?

Answer 38

pH= -log10 [H+]
[H+] = 10^-pH

Question 39

What is the pH buffer system

Answer 39

CO2 + H20 = H2CO3 = H+ + HCO3-