Coordination and Response Flashcards
Describe the human nervous system
Made up of CNS (central nervous system - brain and spinal cord) and PNS (peripheral nervous system - cranial and spinal nerves)
Distinguish between voluntary and involuntary
actions
- Voluntary actions: we choose to make and the decisions to make them occur in brains
- Involuntary: happens unconsciously without us having to think about them (blinking, breathing, beating of heart)
Sequence of event
stimulus -> receptor (detect the changes) -> coordinator (decides what to do) -> effector -> response
Describe a simple reflex arc
In a reflex arc, nerve impulses are transmitted to the spinal cord by the sensory neurone. Inside the grey matter of the spinal cord, the impulses are passed onto relay neurons. The impulses leave the spinal cord along motor neurons to go to effector.
Types of neurones
- Sensory: transmit impulses from sense organs to the brain and spinal cord
- Relay: that carry message from 1 part of the CNS to another
- Motor: neurons transmit impulses away from the brain and spinal cord to effector organs (muscles and glands)
- There’s a gap between 2 neurones called synapse where chemical transmitter substances are released to pass the impulse to the next neurone
- Myelin: an insulation helps speed up the impulses
Describe the action of antagonistic muscles to
include the biceps and triceps at the elbow joint
- Muscles are attached to bones by tendons
- Bones held together at a joint by ligaments
- When biceps contract, triceps relax and vice versa
- Antagonistic = to work against
Define sense organs
groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals
Describe the structure and function of the eye,
including accommodation and pupil reflex
- Pupil reflex:
+ In dim light: circular muscles relax, radial muscles contract => pupil dilates
+ In bright light: circular muscles contract, radial muscles relax => pupil constricts - Accomodation
+ Distant object: ciliary muscles relax, suspensory ligaments tighten => lens pulled into an elliptical shape
+ Near object: ciliary muscles contract, suspensory ligaments loosen => lens become spherical
Distinguish between rods and cones, in terms
of function and distribution
- Rod cells are distributed in the periphery of the retina. Responds to low intensity
- Cones are in the central of retina. Responds to high intensity. Fovea is made entirely of cones
Define a hormone
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
State the role of the hormone adrenaline
o Heart: increase in heart rate so that more oxygen and glucose are delivered to muscles for respiration
o Eye: pupil dilates so that more light reaches the retina
o Trachea: dilates so more airflow to lungs
o Brain + muscles: blood vessels dilate so that more blood flows to these organs
o Digestive system + other organs: blood vessels constrict so less blood flows here
o Liver: breaks down glycogen into glucose so that more glucose diffuses into blood for respiration
Compare nervous and hormonal control systems
- Nervous system: \+ Structure: nerves \+ Form of info: electrical impulses \+ Pathways: along neurones \+ Speed: fast \+ Duration of effect: short \+ Target area: small \+ Response: muscle contraction or secretion by glands - Endocrine: \+ Structure: glands \+ Form of info: hormones \+ Pathways: in blood \+ Speed: slow \+ Duration of effect: long \+ Target area: whole tissue/organ \+ Response: many responses
Discuss the use of hormones in food
production
- Bovine somatotropin (BST) is a hormone used to increase milk production in cattle
- Concerns:
+ Animal welfare concerns as some cows treated with BST become infertile
+ Large quantites can be worrying
Define geotropism
a response in which a plant grows towards or away from gravity.
- Positively geotropic: grows in the same direction as gravity (roots)
- Negatively geotropic: grow in the opposite direction of gravity (shoots)
Define phototropism
a response in which a plant grows towards or
away from the direction from which light is coming
- Positively phototropic: shoot
- Negatively phototropic: roots
Auxin
- Auxins are plant growth substances, produced by the shoot and root tips of growing plants.
Auxin in geotropism
- Auxins in the root builds up on the lower side → slow down the cell growth by inhibiting cell elongation → cells on upper side elongate more → root bends downward
- Auxins in the shoot builds up on the lower side → stimulates cell to elongate → grow more on lower side → bend upwards
Differences between sensory and motor neurones
Sensory: - Cell body: Near end of neurone, just outside the spinal cord - Dendrites: Present at end of neurone - Axon: Very short - Dendron: Very long Motor: - Cell body: At start of neurone, indise the grey matter of the spinal cord - Dendrites: Attached to cell body - Axon: Very long - Dendron: None
Auxins in phototropism
- If a shoot is exposed to light from one side
- More auxins are moving in the shaded side (from the tip of the shoot) -> stimulates cells to elongate
- Shoot bends toward the light.
- This is called positive phototropism.
- If a root is exposed to light in the absence of gravity
- More auxins are moving in the shaded side (from the tip of the root)
- Root bends away from the light because it is not sensitive to light
- This is called negative phototropism.
Define homeostasis
the maintenance of a constant internal environment
Define negative feedback
acts to ensure that the actual temp is as close to the pre-set temp as possible
What regulates the body temp and where can it be found
Hypothalamus found below the brain
Controlling temp: in the heat
- Arterioles undergo vasodilation - increases blood flow through capillaries so more heat can be lost through radiation and convection
- Sweat glands produce sweat => sweat on skin evaporates to cool the body
- Hair lies flat => less air is trapped => heat lost through convection
Controlling temp: in the cold
- Arterioles undergo vasoconstriction
- Sweat glands stop producing sweat
- Hair stands up to trap air to reduce heat loss
- Shivering by the muscles so releasing heat from respiration=> blood flows through muscles and is warmed
