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Biology 2020 > The Nervous System > Flashcards

The Nervous System Flashcards

1
Q

Relationship between receptors, the central nervous system and the effectors.

A

Stimuli—>central nervous system—-> effectors

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2
Q

What is reflex arc

A

A reflex arc is the shortest pathway by which nerve impulses travel from the receptor to the effector in a reflex action.

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3
Q

Function of sensory neurones

A

Transmits nerves impulses from the sense organs to the central nervous system.

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4
Q

Function of relay neurone

A

Transmits never implises from the sensory neurone to the motor neurone

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5
Q

Function of motor neurone

A

Transmits nerve impulses from the central nervous system to the effectors.

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6
Q

Reflex centres

A
  • Cranial reflexes—> controller by the brain( unconsciously)

- Spinal reflexes—> controlled by the spinal cord

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7
Q

What happens when you touch a hot object?

A
  1. The heat on the object stimulates the thermal receptors in your skin. Electrical impulses are produced.
  2. The electrical impulses travel along the sensory neurone to the spinal cord.
  3. In the spinal cord, the electrical impulses are transmitted first across a synapse to a relay neurone, then across another synapse to the motor neurone.
  4. The motor neurone transmits the electrical impulses from the spinal cord to the muscle tissues in the affected arm.
  5. The biceps muscle contract and causes the hand to withdraw suddenly.
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8
Q

Function of iris

A

Structure: a circular sheet of muscles
Functions:
1. It contains a pigment that gives the eye its colour
2. It controls the amount of light entering the eye with the circular muscles and radial muscles

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9
Q

Function of conjunctiva

A

Structure: a thin transparent membrane covering the sclera
Function:
1. It secretes mucus to keep the eyeball moist.

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10
Q

Sclera or sclerotic coat

A

Structure: A tough white outer covering of the eyeball
Function:
1. Protects the eyeball from mechanical injuries.

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11
Q

Pupil

A

Structure: A hole in the Centre of the iris
Function: allows light to enter the eye.

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12
Q

Eyelashes

A

Function: shield the eye from dust particles

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13
Q

Eyelids

A

Functions:
1. Protects the cornea from mechanical injuries.
2.

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14
Q

Tear gland

A
  1. Secretes tears—> wash away dust
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15
Q

Ciliary body

A
  1. Contains ciliary muscles which control the curvature/thickness of the lens
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16
Q

Suspensory ligament

A
  1. A connective tissue that connects the edge of the lens to the ciliary body
17
Q

Cornea

A
  1. Refracts light into the eye
18
Q

Aqueous chamber

A

The space between the lens and the cornea—>filled with aqueous humour

  1. Keeps the front of the eyeball firm
  2. Helps to refract light into the pupil
19
Q

Lens

A

1.focuses light onto the retina

20
Q

Choroid

A
  1. It is pigmented black to prevent internal reflection of light
  2. It contains blood vessels that transport oxygen and nutrients to the eyeball and remove excretory products from the eye
21
Q

Vitreous chamber

A

The space behind the lens—>filled with vitreous humour

  1. Keeps eyeball firm
  2. Helps refract light onto the retina
22
Q

Yellow spot/fovea

A

Contains the greatest concentration of cones but no rods

1. Where images are normally focused

23
Q

Optic nerve

A
  1. Transmits nerve impulses to the brain when photoreceptors in the retina are simulated
24
Q

Blind spot

A

Not sensitive to light

25
Q

Retina

A

Contains photoreceptors—> connected to the nerve endings from the optic nerve

26
Q

Function of cones and rods

A

Cones: Enable is to see colors in bright light
Rods: more sensitive than cones —> enable us to see in dim light but only in black and white

27
Q

Pupil reflex in bright light

A

BCCRRPC

  1. The circular muscles of the iris contract
  2. The radial muscles of the iris relax
  3. The pupil constricts—> reducing the amount of light entering the eye.
28
Q

Pupil reflex in dim light

A

DRCCRPD

  1. The radial muscles of the iris contract
  2. The circular muscles of the iris relax
  3. The pupil dilates—>increasing the amount of light entering the eye.
29
Q

Focusing on a distant object

A

DOCRPSL

  1. The ciliary muscles relax, pulling on the suspensory ligaments.
  2. Suspensory ligaments become taut, pulling on the edge of the lens.
  3. Lens becomes thinner and less convex, increasing its focal length.
  4. Light rays from the distant object are sharply focused on the yellow spot.
  5. Cones in the yellow spot are stimulated.
  6. Electrical impulses produced are transmitted by optic nerve to the brain—> interprets the impulses, allowing the person to see the distant object.
30
Q

Focusing on near object

A

NOCC

  1. Ciliary muscles contract, relaxing their pull on the suspensory ligaments.
  2. Suspensory ligaments slacken, relaxing their pull on the lens.
  3. The lens becomes thicker and more convex, decreasing its focal length.
  4. Light rays from the near object are sharply focused on the yellow spot.
  5. Cones in the yellow spot are stimulated.
  6. Electrical impulses are produced and transmitted by the optic nerve to the brain—>interprets the impulses, allowing the person to see the near object.
31
Q

Definition of hormone

A

It is a chemical substance, produced by a gland, carried by the blood, which alters the activity of one or more specific target organs and is then destroyed by the liver.

32
Q

What is an endocrine gland?

A

The hormone produced by an endocrine gland directly enters the bloodstream.
The islets of Langerhans secrete hormones insulin and glucagon directly into the bloodstream.

33
Q

Effects of adrenaline

A

1.

34
Q

Signs of diabetes mellitus

A
  • persistently high blood glucose level
  • presence of glucose in the urine after a meal
  • healing of wounds is slow and difficult
35
Q

Effects of glucagon

A

The target of glucagon is the liver

  1. Stimulates the liver cells to convert glycogen into glucose
  2. Stimulating the conversion of fats and amino acids into glucose

Biology 2020 (13 decks)

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