Unit 3 study guide

Neurotransmitters

Chemicals that transmit information from one neuron to another.. Examples are Dopamine and Serotonin.

Neuromodulators

chemicals released in the nervous system that influence the sensitivity of the receiving neuron to neurotransmitters

Neurohormones

produced and released by neurons in the brain, rather than by the endocrine glands, and delivered to organs and tissues through the bloodstream

Average Brain Size is…

1.3 to 1.4 kg. . . 1200 to 1400 cm volume

Brain size correlation to intelligence

Weak correlation it depends more on the neural connections not the size of the brain.

Forebrain at 4 weeks (prosencephalon)

Front Brain

midbrain at 4 weeks (mesencephalon)

Middle Brain

hindbrain at 4 weeks (rhombencephalon)

Back Brain

Fore brain (adult) develops into…

the Cerebrum, Thalamus, and Hypothalamus.

Midbrain (adult) develops into….

nothing (unchanged)

Hind brain (adult) develops into…

The PONS, Medulla, and Cerebellum.

Cerebrum

Area of the brain responsible for all voluntary activities of the body and thinking

Diecephalon

thalamus and hypothalamus

brain stem

PONS, Medulla, and mid brain

Cerebellum

coordination and balance

Fissures

deep grooves on the cerebellum

Sucli

shallow grooves on the cerebellum

Gyri

Raised ridges on the brain

corpus callosum

Connects the left & right hemispheres and allows communication between them. shaped like a C

medulla oblongata

Part of the brainstem that controls vital life-sustaining functions such as heartbeat, breathing, blood pressure, and digestion.

Pons

the part of the brainstem that links the medulla oblongata and the cerebelum.Also regulates essential unconscious processes including sleep cycles, respiration, swallowing, and bladder control

How many ventricles are in the brain?

4- 2 Lateral, 3rd is in the thalamus, 4th is in the brainstem

CSF

cerebrospinal fluid, provides cushion to the brain.

basal nuclei

Controls movement and coordination- start/stop.

Meninges

three protective membranes that surround the brain and spinal cord

dura mater

tough outer layer of the meninges

Arachnoid Mater

Middle "spider-like"

pia mater

thin, delicate inner membrane of the meninges

Lobes of the brain

frontal, parietal, occipital, temporal

frontal lobe

associated with descions, reasoning, planning, parts of speech, movement, emotions, and problem solving

parietal lobe

receives sensory input for touch and body position

temporal lobe

A region of the cerebral cortex responsible for hearing and language.

occipital lobe

A region of the cerebral cortex that processes visual information

Pituatry gland is connected to…

hypothalamus

central suclus

Separates frontal lobe from parietal lobe- Anterior (motor) Posterior (Sensory)

Whole Brain thinking

Using both the logical left side and the emotional right side of the brain together for best results

Association fibers

same hemisphere

commissural fibers

connect one hemisphere to the other

Hypothalamus

a neural structure lying below the thalamus; directs eating, drinking, body temperature; helps govern the endocrine system via the pituitary gland, and is linked to emotion

Thalamus

the brain's sensory control center, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla

Diecephalon

thalamus and hypothalamus

pineal gland

produces melatonin & controlled by light (near the center of the brain)

Mid Brain Function

controls arousal, visual and auditory reflexes, and voluntary movement

Alertness structure

Reticular formation (a diffuse, net-like network of over 100 interconnected neural nuclei spanning the core of the brainstem, from the medulla oblongata through the pons to the midbrain)

Memory (Lymbic)

Hippocampus

Brain waves

patterns of neuron electrical activity

beta waves

awake and alert (smaller and faster)

theta waves

brain waves indicating the early stages of sleep

delta waves

the large, slow brain waves associated with deep sleep

Seizure

Abnormal electrical activity in the brain

Epilepsy

chronic brain disorder characterized by recurrent seizure activity

sensory homunculus

Functional map of the primary sensory cortex

stroop effect

the tendency to read the words instead of saying the color of ink

Neuroplasticity

the ability within the brain to constantly change both the structure and function of many cells in response to experience or trauma

Skeletal Muscle

Type of striated muscle responsible for voluntary movements, attached to bones.

Cardiac Muscle

Type of involuntary striated muscle found only in the heart, responsible for pumping blood.

Smooth Muscle

Type of involuntary muscle that is not striated, found in the walls of hollow organs and structures, such as the intestines and blood vessels.

Functions of skeletal muscles

Produce movement, Maintain posture, Support soft tissues, Guard body openings, Maintain body temperature, Store nutrient reserves

Tendons

Muscle —> bone

Ligaments

Bone —> Bone

Epimysium

whole muscle

Perimysium

fascicle (bundle of fibers)

Endomysium

individual muscle fiber

Connective tissue function

support, protect, carry blood vessels/nerves

Muscle Fiber

A single muscle cell (long, multinucleated)

Sarcolemma

cell membrane

Sarcoplasm

cytoplasm

Sarcoplasmic reticulum (SR)

stores Ca²⁺

Myofilaments

protein filaments

Thick filament

myosin

Thin Filament

Actin

Myosin

Motor Protein

Actin

track protein

Myosin head

Bonds to actin

Tropomyosin

blocks binding sites

Troponin

moves tropomyosin

Sarcomere

contractile unit for muscle

T-tubule

carries signal inward

Triad

T-tubule + 2 SR

What Are Myofilaments Made Of?

Proten

thousands to millions of fibers

Muscles

hundreds–thousands of myofibrils

Fiber

thousands of sarcomeres

Myofibril

Triad Function

Releases calcium → triggers contraction

What Happens During Contraction? ( A band)

stays same

What Happens During Contraction? (I band)

Shortens

What Happens During Contraction? (H zone)

Disappears

What Happens During Contraction? (Z discs)

Moves closer

Sliding Filament Theory

Myosin pulls actin → sarcomeres shorten → muscle contracts

Neuromuscular Junction (NMJ)

• Nerve releases acetylcholine (ACh)

• ACh binds receptors

• Na⁺ enters → action potential

• Muscle contracts

Motor neuron

Key parts:

• Synaptic cleft

• Vesicles

• ACh

• Receptors

• Na⁺ channels

• Ca²⁺ channels

• Acetylcholinesterase (breaks ACh)

Excitation

1. Nerve signal

2. ACh release

3. Muscle action potential

Contraction

Ca²⁺ released
5. Binds troponin
6. Myosin binds actin
7. Power stroke

Contraction Cycle

• ATP binds → myosin releases

• ATP → ADP + P → energy

• Myosin pulls actin

• Ca²⁺ allows binding

Muscle Twitch Phases

• Latent = delay

• Contraction = tension rises

• Relaxation = tension falls

Motor Unit

1 neuron + many fibers

Small units

Fine control

Large units

Strength

Muscle Tone

Constant low-level contraction

Force of Contraction Depends On

• Fiber recruitment

• Fiber size

• Stimulation frequency

• Stretch level