Exam 3 Part B

Nervous System (NS)

the fast-acting internal system of communication involving sensory receptors, networks of nerve cells, and connections to muscles and glands that respond to nerve signals

Cnidaria

their nervous system is diffused -> aka a nerve net

-ex: hydra

Platyhelminthes

1. pair of ganglia (a group of cell bodies) = the brain

2. 2 nerve cords joined by cross connections

3. cephalization

4. bilateral symmetry

-ex: planaria

Cephalization

formation of a head region

Bilateral Symmetry

an organism in which one plane divides the body into 2 halves that are mirror images of e/o

Peripheral Nervous System (PNS)

1. sends info to CNS

2. transmits messages from CNS to effectors

Annelids

1. pair of ganglia (brain) (above pharynx)

2. pair of connectives (arond pharynx)

3. ventral nerve cord with ganglia in ea. segment

4. lateral branching nerves

-ex: earthworm

Arthropods

1. pair of ganglia (brain) (above esophagus)

2. pair of connectives

3. double ventral nerve cord with abdominal ganglia

4. lateral branching nerves

-ex: insect

Vertebrates

1. brain -> cranial nerves

2. spinal cord -> spinal nerves

Human Nervous System

1. CNS (brain & SC)

2. PNS (cranial & spinal nerves)

a. Somatic NS (skin + eyes)

i. sensory (afferent)

ii. motor (efferent)

b. Visceral NS (int. organs)

i. sensory

ii. motor/autonomic NS

-parasympathic NS

-sympathetic NS

Sympathetic NS

fight or flight; arousal & energy generation

Parasympathetic NS

rest & digest; calm; return to self-maintainance function

How does the NS coordinate activities in the animal body?

it processes information and determines an appropriate response

Stiimulus & NS

1. stimulus goes to receptor on sensory (afferent) neuron

2. stimulus crosses synapse to one of many interneurons

3. stimulus crosses synapse to motor (efferent) neuron

4. stimulus crosses synapse to effector (muscle or glands)

5. response

Reflex Action

super fast response to certain stimuli

-ex: placing your hand on a hot stove

Complex Neural Pathways

involve transmission of impulses to and from the brain

Forebrain

activities that include processing of olfactory input, regulation of sleep, learning, and any complex processing

Midbrain

coordinates routing of sensory input

-connects the forebrain and the hindbrain

Hindbrain

controls involuntary activities, such as blood circulation, and coordinates motor activities, such as locomotion

Cerebrum

-controls skeletal muscle contraction

-center for learning, emotion, memory, & perception

-divided into R & L cerebral hemispheres

Cerebral Cortex

-outer layer of the cerebrum

-perception, voluntary movement, and learning

-contralateral organization

Corpus Callosum

a thick band of axons that enables the R & L cerebral hemispheres to communicate

Thalamus

the main relay center thru which sensory info passes to the cerebrum

Hypothalamus

regulates homeostasis and basic suvival behaviors

Suprachiasmatic Nucleus (SCN)

group of neurons in the hypothalamus that acts as the pacemaker for circadian rythms

Posterior Pituitary

stores & releases hormones

Pons and Medulla Oblongata

contains pathways for information traveling btwn the PNS and the cerebrum

Medulla Oblongata

the "vital center" of the brain

-breathing & heart rate

Cerebellum

helps coordinate motor functions

Brainstem

includes the midbrain, pons, and medulla oblongata

Frontal Lobe

a. prefrontal cortex - decision making & planning

b. motor cortex - control of skeletal muscles

Broca's Area

speech formation

Parietal Lobe

a. somatosensory cortex - sense of touch

b. sensory association cortex - integration of sensory info

Occipital Lobe

a. visual association cortex - combining images & object recog.

b. visual cortex - processing visual stimuli & pattern recog.

Wernicke's Area

language comprehension

Temporal Lobe

a. auditory cortex - hearing

Receptor

specialized peripheral ending of an afferent neuron, or seperate cell intimately associated with it, that detects changes in some aspect of the environment

Classification of Receptors

receptors are classififed based upon the stimuli they respond to

Types of Mechanoreceptors

a. touch and pressure receptors in the skin

-gentle pressure, strong pressure, or gentle vibrations

b. stretch receptors in muscles and tendons

c. haor cells in the ear

Muscle Spindles

provides feedback about the amount and rate of muscle stretch

Golgi Tendon Organs

signal the force that develops in the tendon on muscle contraction

Photoreceptors

respond to light

Chemoreceptors

respond to chemicals

a. taste receptors (taste buds (modified epithelial cells))

b. olfactory receptors (located in olfactory epithelium)

Thermoreceptors

respond to warm and cold

-free nerve endings in the skin

Nociceptors (pain receptors)

respond to excess heat, P, or specific chems

-free nerve endings in the skin

-ex: harmful stimuli that could cause tissue damage

What is within the cochlea?

the organ of corti which contains hair cells

Cupula

structure within the semicircular canals that detects rotational head movement

Rods

detect black, white, and shades of gray (dim light)

Cones

detect color, bright light, and fine detail

Fovea

highly concentrated areas of cones

-site of greatest detail in vision

Optic Disk

aka the blindspot; no photoreceptors present

Motor Mechanisms

-motor neurons of somatic NS -> voluntary muscle (skeletal muscle)

-motor neurons of visceral NS (autonomic NS) -> involuntary muscle (smooth & cardiac muscle) and glands

Types of Effectors

1. Muscles (skeletal, smooth, and cardiac)

2. Glands (oil & digestive)

What stimulates the muscle?

the nervous system stimulates the muscle (this generates a force)

What part of the nervous system stimulates the muscle?

motor neuron but depends on the type of muscle

What are muscles composed of?

muscle fibers or cells that produce myofibrils

Sarcomere

contractile unit of muscle

What happens to sarcomere when the muscle contracts?

myosin globular heads pull the thin (actin) filaments inwards

Sliding-Filament Theory

1. ATP binds → myosin head detaches (low-E)

2. ATP hydrolysis (ADP + Pi) → myosin head = high-E

3. Myosin binds actin → cross-bridge forms

4. ADP + Pi released → thin filament moves twd the center of the sarcomere

Flexion

biceps contracting; triceps relaxing

Extension

biceps relaxing; triceps contracting

Endoskeleton

internal skeleton

How many bones in an adult human?

206

Glands

groups of cells specialized to secrete a substance released from the cells

-ex: oil glands in the skin; glands in the small intestine that release digestive secretions