Unit 10: Humanbody + Homeostasis

Homeostasis

body keeps internal conditions stable, in balance

Negative feedback

Body responds to reverse changes

Positive Feedback

Body increases change, moving it further away from normal

Insulin

A hormone produced by the pancreas that reduces blood sugar, turning glucose into glycogen

Glucagon

A hormone produced by the pancreas that raises blood sugar levels, by breaking glycogen back into sugar, and releasing it into the bloodstream.

Respiratory System

To supply 02 and remove CO2 from the body

Respiratory Structures

Lungs, alveoli, diaphragm, trachea, nose/moth

Alveoli

Cluster of air sacs where gas exchange occurs. Is 1 cell thick which allows diffusion of gas, as 02 enters and CO2 leaves

Capillaries

Thinnest blood vessel in the body and 1 cell thick, that connect arteries to veins and are main sites of exchange.

Circulatory System

To transport oxygen, nutrients, hormones, and waste throughout the body via blood

Pulmonary vein → only vein to carry oxygen rich blood

Aorta (artery) →Largest blood vessel in human body

Vena cava

1. Interior v.c →enters heart from below

2. Superior v.c →enters heart from above

Pulmonary Artery → only artery that carries 02 poor blood

Hemoglobin

A protein found in red blood cells that is responsible for carrying 02 and CO2 throughout the body by binding to them

Arteries

Blood vessel that carries blood away from the heart, are 1 cell thick

Veins

Blood vessel that carries blood towards the heart, are thick and with valves to prevent back flow.

Blood pressure

The force of blood pushing against walls of blood vessels

Systolic pressure

the pressure of arteries when the heart contracts and pushes blood into body (higher number: 80-120)

Diastolic pressure

The pressure in your arteries when your heart is at rest between beats (Lower number: 60-80)

Causes for high blood pressure

Narrow veins, thick blood, high blood amount in system

Human Nervous System

To send, receive, and process messages between the brain, spinal cord, and the rest of the body - allowing you to sense, move and react.

Central Nervous System(CNS)

Made of brain and spinal cord to process info and make decisions

Peripheral Nervous System (PNS)

Motor and sensor nerves outside the brain

• Motor neurons: muscle movement and gland activity

• Sensory neurons: sensation (touch, pain, temp, ect)

Neurons

A specialized cell that carries electrical signals (tiny burst of electricity from external factors) to help the body sense, move, and respond.

Dendrites→receives signals

Nucleus → contains DNA

Myelin Sheath →Insulates axon and speeds up signals

Axon →Action potential travels down

Axon terminal →Releases neurotransmitters to transmit signals at the synapse, onto the next cell.

Stimulus→Dendrites→Cell body→Axon→ Axon terminal→Synapse→Next neuron

Neurotransmitters

A chemical substance that is released at the axon terminal by the arrival of action potential, and diffuse across into the synapse, causing the transfer of action potential onto the next neuron.

Excitatory neurotransmitters

Chemical messenger that makes the next neuron more likely to send down electrical signal

Inhibitory neurotransmitter

Chemical messenger that makes the next neuron less likely to send an electrical signal

How do neurons communicate?

1. Action potential reaches axon terminal

2. Action potential causes vesicles to move towards the membrane and release neurotransmitters into the synapse

3. Neurotransmitters travel onto the other neurons dendrites, binding to receptor proteins

4. New electrical signal(action potential) is sent down the post-synaptic neuron

5. Afterwards, unused neurotransmitters are broken down or reabsorbed.

Cocaine

Blocks dopamine(type of transmitter) from being reabsorbed

Meth

Blocks dopamine re-absorption and release large amounts of dopamine

Nicotine

Binds to receptors of neurons and causes dopamine release

→also binds to cell body receptors, increasing speed of action potential, meaning more dopamine releases

How a brain develops

Dendrite connections grow between neurons

• The more often certain neurons communicate, the stronger their communications become

• New protein receptors will form on dendrite to increase signaling

Myelin

A fatty coating that wraps around the axon

→When learning, myelin recognizes the repeated signals, making signals travel faster down the axon.

→Weak connections between neurons are pruned as axons and dendrites die and decay