co-ordination and response in humans

Question 1

what is the central nervous system and what is it made of?

Answer 1

the brain and spinal cord make up the cns where internal stimuli (blood water potential, body temperature, etc) and external stimuli (pain, touch, light, etc) are sent to for processing. relay neurons (interneurones) are found throughout the cns

Question 2

what is the peripheral nervous system and what is it made of?

Answer 2

sensory neurones transmit nerve impulses from receptors like the skin and eyes to the cns.
motors neurones transmit nerve impulses from the cns to effectors like glands and muscles

Question 3

what is the basic functional unit of the nervous system?

Answer 3

neurone (a highly specialised cell adapted to transmit electrical nerve impulses quickly throughout the body)

Question 4

describe the sensory neurone (part of?, transmits nerve impulses…?, found in the…?, axon vs dendron length, cell body is…?)

Answer 4

the sensory neurone is part of the pns. it transmits nerve impulses from the receptors to cns. it is found in the dorsal root of the spinal cord. it has a longer axon. it’s cell body is round and protruding.

Question 5

describe the motor neurone (part of?, transmits nerve impulses…?, found in the…?, axon vs dendron length, cell body is…?)

Answer 5

it is part of the pns. it transmits nerve impulses from the cns to effectors. it is found in the ventral root of the spinal cord. it has a longer dendron. it’s cell body is irregularly shaped.

Question 6

describe the relay neurone (part of?, transmits nerve impulses…?, found in the…?, axon vs dendron length, cell body is…?)

Answer 6

it is part of the cns. it transmits nerve impulses within the cns. it is found in the gray matter of the cns. they are comparable. it’s cell body is irregularly shaped.

Question 7

what is a reflex action?

Answer 7

a reflex action is an immediate response to a specific stimulus without conscious control.

Question 8

what are some examples of a reflex action?

Answer 8

knee-jerk reflex
pupil reflex
withdrawal reflex

Question 9

explain reflex actions?

Answer 9

nerve impulses are transmitted through the reflex arc very quickly. a reflex arc is the shortest pathway for nerve impulses to travel from receptor to effector. responses are specific and appropriate to the stimulus. (eg, see food=salivate, feel pain=scream, dust in eye=blink). the brain does not need to actively process the information then send out nerve impulses for the action to occur.

Question 10

what is the reflex arc?

Answer 10

the shortest pathway for nerve impulses to travel from receptor to effector is the reflex arc, and is an important reason why reflex occur so quickly.

Question 11

what is the patella reflex?

Answer 11

doctors use this as a quick test of spinal health as it is non-invasive and easy to do
steps:
1) stimulus: tap on the patella tendon
2) stretch receptors detect the stimulus
3) sensory neurone transmits nerve impulse from the receptor to the spinal cord
4a) relay neurone transmits nerve impulse to the brain
4b) motor neurone transmits nerve impulse out of the spinal cord to the effector muscle
5) muscle is stimulated to contract
6) response: lower leg jerks forward

Question 12

why is the patella reflex a reflex action?

Answer 12

this is because the action occurs independent of the brain. at the spinal cord, separate nerve impulses travel concurrently through the relay neurone and motor neurone. relay neurones transmit the nerve impulses to the brain for the person to be aware of the stimulus and response, while the motor neurone stimulates the effector to bring about a response.

Question 13

what do the eyes do?

Answer 13

the eyes convert light energy into electrical impulses that the brain can recognise and process, allowing the body to interact with the external environment safely.

Question 14

what does the retina contain?

Answer 14

the retina contains receptors that absorb light energy and generates nerve impulses to be transmitted through the sensory neurones.

Question 15

what are the lens accommodations?

Answer 15

suspensory ligaments, ciliary muscles, lens

Question 16

explain the pupil reflex

Answer 16

when ambient light intensity changes, the eyes must quickly respond to increase or decrease the amount of light that can enter the eye
in bright light:
radial muscles are relaxed, circular muscles contracted
in dim light:
radial muscles contracted, circular muscles relaxed
-the radial and circular muscles of the iris work antagonistically to increase or decrease the pupil diameter
-the pupil constricts in bright light to reduce the amount of light entering the eye, protecting the retina from overstimulation
-the pupil dilates in dim light to increase the amount of light entering the eye, enhancing dim light vision

Question 17

explain lens accommodation

Answer 17

light is refracted as it passes through the many surfaces of the eye until it reaches the light-sensitive cell of the retina. if incoming light rays cannot be focused sufficiently onto the retina, where the focal point occurs before or after the retina, the image formed will be blurry.
the ciliary muscles and suspensory ligaments work together to change the shape of the lens, which increases or decreases the extent to which light rays are are refracted. this fine adjustment allows the focal point to land directly on the retina for a clear image to form
distant objects reflect parallel light rays:
ciliary muscles relax, suspensory ligamens pulled taut, lens pulled into a thinner and less convex shape
near objects reflect diverging light rays:
ciliary muscles contract, suspensory ligaments slacken, lens become thicker and more convex
-a thinner and less convex lens refracts light to a smaller extent while a thicker and more convex lens refracts light to a greater extent

Question 18

what does the endocrine system do?

Answer 18

it functions to regulate many of the processes in the human body and keep the body safe throughout the interactions with the external environment.

Question 19

what are hormones?

Answer 19

they are chemical messengers secreted in small amounts by endocrine glands. they are secreted into the bloodstream in small amounts to target specific organs and will be destroyed in the liver when the desired function is complete. on top of serving as an associated organ in the digestive system producing enzymes, the pancreas is also an endocrine gland for regulating blood glucose concentrations.

Question 20

what organs are involved in maintaining healthy levels of glucose and how do glucose level affect our body?

Answer 20

the pancreas, liver, and muscles are all involved in maintaining healthy levels of glucose in the bloodstream. cells would be deprived of energy if they do not receive sufficient glucose to undergo respiration, resulting in tissue death and organ failure. on the other hand, having too much glucose affects the normal functioning of cells, which may also result in tissue death and organ failure.

Question 21

what happens when glucose levels are below the norm?

Answer 21

liver cells become less permeable to blood glucose, decreased rate of absorption of blood glucose, greater rate of glycogen broken down into glucose and released, fats are also broken down into glucose, glucose is synthesised from noon-carbohydrate sources

upon detecting a drop in blood glucose concentration below the norm, the islets of langerhans of the pancreas increase insulin secretion into the bloodstream. when the blood glucose concentration decreases back to the norm, the pancreas decreases its rate of insulin secretion, and any existing blood insulin is brought to the liver to be destroyed and excreted

Question 22

what happens when blood glucose levels are above the norm?

Answer 22

liver and muscle cells become permeable in blood glucose, greater rate of absorption of blood glucose, greater rate of glucose being converted to glycogen, some excess glucose is also converted to fats

when the blood glucose concentration increases above the norm, the islets of langerhans of the pnacreas increase glucagon secretion into the bloodstream. once blood glucose concentration increases back to the norm, the pancreas decreases its rate of glucagon secretion, and any existing blood glucagon is brought to the liver to be destroyed and excreted

Question 23

what is diabetes mellitus?

Answer 23

chronically elevated blood glucose concentration is an indication of diabetes where the pancreas cannot produce sufficient insulin (type 1) or target cells no longer respond adequately to insulin (type II). left untreated, diabetes could cause liver and kidney failure, and even the loss of limbs due to cells not receiving enough glucose for respiration. people suffering from diabetes need to manage their diet, have daily insulin injections, and lead healthier lives to reduce the impact of the disease.

Question 24

what do the nervous and endocrine system form together?

Answer 24

they form the major control centres for communication and regulation in the body.

Question 25

what are the similarities between the nervous and endocrine system?

Answer 25

allow organs in different organ systems to communicate with each other, react to external and internal stimuli, help maintain and regulate internal conditions (blood glucose concentration, body temperature, blood water potential, etc)

Question 26

what are the differences between the nervous and endocrine system?

Answer 26

nature of signal
-NS: electrical nerve impulses. ES: chemical hormones
speed of signal conduction
-NS: relatively faster, ES: relatively slower
mode of transmission
-NS: through neurones, ES: through the bloodstream
area of effect
-ES: localised-within the reflex arc, ES: systemic-throughout the body