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PIA BIOLOGY ISA
8
Isabel Ponti 4C
BIOLOGY'S PIA PRESENTATION
The Nervous System
Nervous System
The nervous system acts as
the communication network
consisting of all of the body's
nerve cells. It takes
information from the world
around us along with
information from diferent
body systems and allows us
to make quick decisions.
Central Nervous System
The central nervous system consists of the brain and the spinal cord and
forms the body's decision maker.
Central Nervous System
Brain
The Brain is an organ of soft nervous tissue. It is located in the skull. The brain is the coordinating center of our senses and intellectual and nervous activity.
Spinal Cord
The spinal cord is a cylindrical bundle of nerve fibers. It is enclosed in the spine and connects nearly all parts of the body to the brain forming the central nervous system.
Peripheral Nervous System
The peripheral nervous system is made up of the sensory and motor neurons that connect the central nervous system to the rest of the body. It gathers information and transmits information from the Central Nervous system to the rest of the body.
What is a Synapse?
Synapse
Is a junction where neurons communicate with one another. Information is passed down the axon of the neuron as an electrical impulse known as action potential. Once the action potential reaches the end of the axon it needs to be transferred to another neuron or tissue. It must cross over the synaptic gap between the presynaptic neuron and post-synaptic neuron. At the end of the neuron (in the axon terminal) are the synaptic vesicles, which contain chemical messengers, known as neurotransmitters. When the electrical impulse (action potential) reaches these synaptic vesicles, they release their contents of neurotransmitters. Neurotransmitters then carry the signal across the synaptic gap. They bind to receptor sites on the post-synaptic cell, thereby completing the process of synaptic transmission.
How does an impulse travel through the neuron?
First, there are more negative electrical charges inside than outside of it. The chemical part leads to Na+ getting in. As a result, there are more positive charges inside. As the impulse passes, K+ flows out and, again, there are more negative charges.
Bones and Muscles
Bones and muscles
Bones and muscles are connected by tough, inelastic tendons . The muscles pull the bones at joints and that's how movemenat is made. Muscles can only pull or contract , not push so an antagonistic muscle is needed to return everything to its original position.
Structure of bones:
Bones
Their function is to protect the organs of the body , keep the structure of the body to move (along with the muscles). The bones are made up of osteocytes and it's divided between the compact bone ( the outside layer) and the spongy bone that keeps the bone narrow that contains the read blood cells , the inmune cells and the yellow marrow (fat). It's main components are the fiber and calcium.
Structure of muscles
Muscles
Their main function is movement along with bones. The muscle is made up of the sarcolema (cell membrance), the sarcoplasm (cytoplasm), the sarcoplasmic rectlum (stores calciu) and they form the sarcomere (the simplest unit to a muscle contraction)
Simple reflecx arc
Simple reflex arc
In a reflex arc, the receptor is stimulated and an impulse is sent through a sensory neurone to central nervous system (the spinal cord takes care of reflexes below the neck). Then, an impulse is sent through a motor neurone to an effector which gives the response. It's an automatic reaction, you can't control it.
Order of events after the knee is tapped
Reaction of the skin to cold water:
Skin
P- Hypodermis (fatty tissue)
Q- Sebaceous gland
R- Hair
S- Arteriole
T- Capillaries
U- Sweat gland
V- Nerve ending
response of skin to cold weather
name of part
letter from Fig 3.1
stands upright to trap air
hair
R
constricts to reduce blood flow to skin
arterioles
S
stops producing sweat
sweat glands
U
Skin chart
Exercise 1
When sweat is secreted, it evaporates and takes heat from the body. vasodilatation consists on the widening of blood vessels so that more blood flows and more heat is exchanged with the surroundings. They are both mechanisms against overheating
3
It is a motor neurone because it has all the components of cell body, nucleus, dendrites, axon and sheath. Moreover , it has its cell body at the top of the cell, while sensory neurones have it in the middle of the cell