Reflexes and receptors Pt 2

Question 1

Explain the role played by reflexes in coordination of the body. Define the term reflex

Answer 1

rapid, automatic response to a change in the external or internal environment

Question 2

Describe the four important properties of reflex arcs

Answer 2

-require a stimulus to trigger reflex (non-spontanuous)
-involuntary (no conscious thought
-rapid w/only small number of neurons involved
-stereotyped (occurs in same way each time)

Question 3

What coordinates reflexes? what is meant by spinal reflexes

Answer 3

mainly spinal cord
-reflexes carried out by spinal cord. message is not sent to brain until after a response has been carried out=involuntary

Question 3

Draw the reflex arc and describe the process
What does this arc prevent and aid

Answer 3

1. receptor detects stimulus+ reacts to a change in internal/external environment by initiating a nerve impulse in sensory neuron via dorsal root and ganglion
2. sensory neuron conducts impulse from receptor to spinal cord which later sends message to brain
3. information processed in CNS
4. message is passed by 1 interneuron straight to motor neuron or many interneurons direct to motor neuron
5. at least one synapse between a sensory or motor neuron and interneuron
6. motor neuron carries impulse to effector through ventral root
7. effector (muscle or glands) receives nerve impulse and carries out muscle movement via neuromuscular junction/across a motor end plate

protective mechanism against further damage and repetition of harmful action

Question 4

examples of reflexs

Answer 4

withdrawing hand from painful stimulus, blinking when something touches cornea of eye, sneezing or coughing when something irritates trachea or nose, catching ball, braking car

Question 5

Define innate/protective reflex and examples

Answer 5

a response to a stimulus that is acquired genetically therefore since birth
-suckling, chewing, following movements with eyes

Question 6

Define acquired reflex and examples

Answer 6

a response to a stimulus that has been learnt through practice
-catching a ball, slamming on brakes in car, adjusting muscles to ride and balance on bike

Question 7

What are the receptor types

Answer 7

pain receptor, osmoreceptor, thermoreceptor, chemoreceptor, touch receptor

Question 8

Describe the role of thermoreceptors, their location and the stimuli they detect

Answer 8

respond to heat/cold
-peripheral thermoreceptors in skin: nerve endings inform brain of changes to outer body temp
-hypothalamus: monitors core temp, detect temp of blood flowing through brain and regulate body temp

Question 9

Describe the role of osmoreceptors, their location and the stimuli they detect

Answer 9

sensitive to small changes in osmotic pressure of body fluids
-in hypothalamus
-stimulate hypothalamus so that the body’s water content is maintained within very narrow limits

Question 10

Describe the role of chemoreceptors, their location and the stimuli they detect

Answer 10

sensitive to particular change in particular chemicals.
-in nose and mouth making us sensitive to smells and tastes
peripheral: (aortic/carotid bodies) within walls of aorta and carotid arteries sensitive to CO2, O2, H ions change in blood plasma
central: in medulla oblongata sensitive to conc of CO2 in blood and H ions in CSF
e.g. in blood vessels sensitive to pH of blood and conc of O2 and CO2=regulation of heart beat and breathing

Question 11

Describe the role of pain receptors, their location and the stimuli they detect.

Answer 11

stimulated by damage to tissue(cut, bump, bruise)
-in skin and mucous membranes
-warns body of damage in order for body to take action and prevent further damage and reoccurrence

Question 12

Define touch receptor, location, and their function

Answer 12

receptor sensitive to touch
-found in surface of skin or deeper

Question 13

Define receptor

Answer 13

structure able to detect change in the body’s internal or external environment

Question 14

Stimulus and way of prevention made by sneezing

Answer 14

stim: irritation to walls of nasal cavity
prevention: forceful air expulsion from lungs removes mucous, foreign particles and gases

Question 15

Stimulus and way of prevention made by coughing

Answer 15

stim: irritation in lower respiratory tract bronchi and bronchioles
prevention: air forced from lungs drives mucus and foreign matter up trachea toward throat

Question 16

Stimulus and way of prevention made by vomiting

Answer 16

stim: psychological, excessive stretching of stomach, bacterial toxins
prevention: muscles of abdomen and diaphragm contract and stomach expels contents

Question 17

Stimulus and way of prevention made by diarrhoea

Answer 17

stim: small/large intestine irritation by bacteria viruses
prevention: increase muscle wall contractions for irritant removal