B3 Flashcards
What are the 3 main stages to a nervous response?
Stimulus-a change in environment
Receptors- a group of cells that detect the stimulus
Effectors- muscles or glands that respond
What are the steps involved in a nervous reaction?
Stimulus->receptor cells->sensory neurone-.spinal cord->brain->spinal cord->motor neurone->effectors->response
What are the 3 main types of neurones?
Sensory neurones - carry electrical impulses fom receptor cells to the CNS.(dendron transmits the impulse to cell body)
Relay neurones- carry electrical impuses from sensory neurones to motor neurones(only in CNS)
motor neurones- carry eletrical impulses from CNS to effectors(axon transmits impulse away from cell body)
What are reflex actions?
They are automatic actionsthat are involuntary. They are faster as thy dont travel to brain
Reflex arc
Stimulus->Receptor cells->Sensory neurone->spinal cord->Motor neurone->response
reflex action examples?
burning hand-> bicep contracts so hand pulls away
snad in eyes-> eyelids muscles contact making you blink
Main structures of the eye?
Cornea-. trnasparent coating at front of the eye that protectseye and refracts light from entering.
Pupil- a centralhole in iris that allows light to enter the eye
iris-> a coloured ring of muscle tissue that alters pupil size by contracting and relaxing.
Lens-a transparent biconvex lens that focuses light clearly on the retina
Ciliary body-ring of muscle tissue that alters hape of lens
How are images formed?
Cornea refracts incoming light rays. Light passes through pupil and is refracted by lens creating image on retina. Photoreceptors in retina produce nervous impulse when exposedto light, image travels down optic nerve to brains creating visual image.
How does eye focus on near and far objects?
- When ciliary muscle contracts, lens become more convex(fatter) you can focus on nearby objects
- When cilialy muscles relax, lens becomes less convex(thinner), you can focus on distant objects
What causes short sightedness, how can it be corrected?
- Shot sightedness is caused by lens being too strong or eyeball being too long. This makes light rays meet infront of retina, image is blury
- Can be corrected with concave lens, bends light rays before they enter eye
What causes long sightedness, how can it be corrected?
- Long sihgtedness caused by persons lens being too weak, or eyeball too short, light rays meet behind retina so image is blury
- Convex lens bends light invanrds before it meets eye
What are 2 typesof photoreceptors?
Rods- Respond to light, black and white, allows vision in low light levels
Cones- Respond to colours. Diferent cone cells repsond to R,G,B light
Whats an advantage of having a brain?
Having a central control centre means neuronal communcations are much faster than if they were spread around the body.
-Function of brain is process info and produce coordinated respone
What are 5 main areas of the brain and functions.
Medulla- controls automatic actions, breathing and heart rate
Cerebrum- controls balance, posture and involuntary actions
Cerebellum- controls complex behaviour: learning, memory, personality and consious thought
Hypothalamus- regualtes temperature and water balance.
Pituitary gland- stores and releases hormones that regulate many body functions
How can you investigate brain function?
Hint; scan
Ct Scans-> Use x-rays to create 3D imaes of body, it cant be used regularly as its radiation increaea risk of cancer.
MRI Scans->Use powerful magnets to identify braiin abnormalities. Fmri produces real time images
What are effects of dmage to PNS?
- inability to detect pain
- numbness
- loss of cordination
How is PNS damage treated?
While it can regenate, it has a limited ability to do so, severe nerve damage can be treated through surgery
What are effetcs of CNS damage?
Loss of control of body systems
Partial or complete paralysis
Memory loss or processing difficulties
Why is CNS not able to be treated?
CNS cannot regenerate and it is extremely hard to do surgery:
- Spinal cord is so small that identifying and repairing an indidual nevre fibre, without damaging others is too hard
- Spinal injuries often lead to paralysis
Treatments for CNS brain damage?
radiotherapy- used treat a brain tumor
surgery- remove damaged brain tissue
deep brain stimulation- inserting an electron to stimulate brain
What are hormones and how do they travel?
Hormones are chemical messengers that are secreted into the blood and made in endocrine glands. The blood transports the hormones in plasma around the body.
What are the roles of hormones?
Hormones regulate functions of many cells and organs. Hormonal control body processes that require constant adjustment. Keepng conditionsin your body constant is called homeostasis.
What is the endocrine system?
It is all the endocrine glands and hormones they produce.
Compare messaging with nerves and hormones?
Hormones- slower, in blood, long acting and larger are. HBGT
Nerves- faster, electrical impulse along axon of neurone, short acting, small precise area.
What is thyroxine?
A hormone released by throid gland, located in neck. It plays important role in regulating body’s metabolic rate.
What is adrenaline?
Hormone secreted by adrenal gland in times of stress to prepare body for fight or flight situation.