Unit 1: Nervous System Flashcards
What is a feedback system?
The way your body detects one of its systems has deviated from it’s “set point” (normal). Can be negative or positive
What is homeostasis?
The steps your body takes to maintain a constant internet all environment despite changes in the external environment
Your body strives to keep many internal conditions within a range of normal values
What are the components of a feedback system?
Sensor - detects a change
(Nerve signals control centre)
Control centre - compared the change to the “set point”
(Nerve signals effector)
Effector - responds, adjusting the system back to the “set point”
Example of positive feed back system…
Childbirth
Sensor - cervix pressure sensors
Control center - brain
Effector - pituitary gland releases oxytocin which makes the uterus contract and pushes baby’s head onto the cervix
What is a positive feedback loop?
The change in internal conditions that cause it to keep changing, less common in the body
What is a negative feedback loop?
Once normal is reached, this is detected and the signal to change is stopped, more common in the body
Example of negative feedback system…
Body temperature
Sensor - brain temperature sensors
Control center - brain
Effector - blood vessels dilate and sweat glands are activated to lower body temperature
What is the central nervous system?
The control center in the maintenance of homeostasis…
- the brain
- the spinal cord
What is myelinated tissue?
“White matter” that conducts impulses quickly
What is unmyleinated tissue?
“Grey matter” that conducts impulses slowly
What is the brain composed of?
- myelinated tissue (white matter) on the inside
- unmyelinated tissue (grey matter) on the outside
What is the spinal cord composed of?
- myelinated on the outside
- unmyelinated on the inside
What are meninges?
The entire CNS is covered by meninges, a triple layer of tough elastic membranes
What are the names of the layers of the meninges?
Outer layer = dura Mayer
Middle layer = arachnoid
Inner layer = periosteal (pia)
What do the meninges do?
- creates a blood brain barrier that only allows certain substances from the blood to enter the brain (positive or negative) such as glucose, oxygen; caffeine, alcohol (flaw), while keeping others out, toxins and infections
- acts as a shock absorber due to the presence of cerebrospinal fluid between each layer
What does the cerebrospinal fluid do?
Acts as a shock absorber between each layer of meninge, provides cushion between the brain and the cranium (skull)
What does the brain contain?
Over 100 billion nerve cells, each having 10 000 connections to other nerve cells
What is the brain protected by?
The cranium (skull)
How are sutures beneficial?
The craniums large size, each at birth, is compensated for by sutures in the cranium, which allow it to compress in the birth canal (some sutures don’t full close until the age of 6, creating soft spots on the head)
What is the cerebellum?
- “little brain”
- co ordination and proprioception (balance)
What is the medulla oblongata?
Automatic regulation of breathing, heart rate, coughing, etc…
What is the pons?
Relay center between many brain areas (receive signals, sends signals)
What is the midbrain?
Processes information from eyes, nosed ears and controls muscles
What is the thalamus?
Relay center between many brain areas
What is the hypothalamus?
Controls basic drives (hunger, thirst, emotions, etc..)
What is the ventricle?
Stores and produces cerebrospinal fluid
What is the corpus callosum?
Links the right side of the brain to the left side
What is the right side responsible for?
Intuitive thinking, artistic ability
What is the left side responsible for?
Sequential thinking, language, math
What is the cerebral cortex?
4 lobes on each side of the brain, outer layer of the brain