Comparative Anatomy- Final Exam

Ovaries are paired, except in…?

• hagfish, birds, and bats- only have 1

  • birds and bats- decreased mass for flight

What are oocytes?

• produce eggs

• develop inside a follicle

• egg = ovum

  • = yolk → made of egg cell and lipids

• eggs released into coelom

  • process = ovulation

When do ovaries regress?

after breeding (except in placental mammals)

Describe oviducts.

• muscular and glandular

• ostium = opening (where egg goes in)

• infundibulum = funnel

• end at cloaca in most

Describe the shark oviducts.

• produce large ovum

• single ostium

• 1. shell gland

  • produce albumin = “egg white” → protein plus water

  • secretes leathery shell for egg layers

    • laying eggs = oviparity

• 2. uterus

  • for offspring to develop

    • get nutrients from yolk OR uterine lining

  • few viviparous species

    • viviparous = give birth to live young

Describe bony fish oviducts.

• ovarian cavity continuous with oviduct (so eggs not released into coelom)

• carried directly to genital pore

• no cloaca

Describe amphibian oviducts.

• some have glandular oviducts

• secrete jelly around eggs

  • prevents desiccation

• ovisacs

  • = caudal expansion of oviduct to store eggs

  • function: hold eggs until environmental conditions are right (water and temp)

Describe the bird oviduct.

• one functional ovary and oviduct

• regionalized for producing shelled egg

• magnum = secretes albumin

• uterus/shelled gland = secretes egg shell and pigment added

What is spermathecae?

• folds in lining of oviduct or cloacal lining

• sperm storage

• seen in salamanders, turtles, squamates, birds

Describe monotremata reproduction.

• platypus and echidna

• only oviparous mammals

• lack nipples

• have cloaca

• one ovary and oviduct → 2 uteri

• eggs retained in uterus

• eggs incubated briefly outside

Describe theria reproduction.

• marsupials and placentals

• true nipples

• viviparity

• all have placenta to nourish embryo

• marsupials

  • embryo has short internal development and long external development in pouch

• placentals

  • embryo has much longer internal development

• reproductive tracts

  • oviduct- short and lined with cilia

  • uterus

    • highly vascularized lining = endometrium

      • egg implants here

    • muscular wall = myometrium

      • gives contractions for child birth

  • vagina

    • unpaired, terminal opening

    • opens into

      • a. urogenital sinus (which also receives urethra)- most common

      • b. vestibule of vulva

        • primates

        • urethra separate from vagina

      • cervix = muscular opening between vagina and uterus

What are the types of uteri in therians?

• 1. duplex

  • 2 separate reproductive tracts

  • marsupials

• most have two uterine horns that fuse distally

• 2. bipartite

  • slight partition

  • rabbits and hamsters

• 3. bicornuate

  • horns connected but with no partitions

  • ungulates, carnivores

• 4. simplex

  • complete fusion of uterine horns into single uterus

  • primates and armadillos

What is the functional unit of the nervous system?

neuron

What is the type of signal, signal speed, and travel route for the nervous system and endocrine system?

Which body system coordinates body functions with endocrine system?

nervous system

What are the parts of the central nervous system?

brain and spinal cord

What are the parts of the peripheral nervous system?

cranial nerves, spinal nerves, autonomic nerves

Describe the parts of the neuron.

• 1. cell body

  • nucleus and organelles

• 2. dendrites- many receivers

  • conduct signals toward cell body

• 3. axon

  • conduct signals away from cell body

    • axon hillock → terminal branches

• 4. schwann cells

  • insulating cells around axon

  • make myelin: layers of lipids that impede nerve impulses

  • nodes of ranvier: areas of exposed axon

  • saltatory conduction: nerve impulses move faster because they jump from node to node

  • “nerve fiber” = usually a myelinated axon

• 5. synapse

  • gap between neurons where nerve impulse is transferred

  • neurotransmitters: chemicals that carry nerve impulse across a synapse

What is a nerve?

1 or more nerve fibers wrapped in fibrous sheath and supplied by blood vessels

What 3 things are needed for the nerve circuit?

1. sensory input

2. integration

3. motor output

What are the steps of the nerve circuit?

• 1. sensory input

  • collect info from sensory receptors

  • conduct signals to integration centers

    • sensory/afferent neurons

  • sensory info types:

    • a. external (ex: tactile info, temp, vision, auditory)

    • b. internal (ex: osmotic pressure of blood, body temp)

• 2. integration

  • signal info processed

  • appropriate response needs to be determined

  • done by interneurons

• 3. motor output

  • conduct response signal to effector cells for response (ex: muscle contracts)

    • ex of simple reflective response in spinal cord

  • most integration happens in brain

What nerves are part of the peripheral nervous system?

1. somatic

2. visceral

Describe somatic nerves

• voluntary actions

  • skeletal muscle

• a. sensory nerves (afferent)

  • carry signals TO CNS

• b. motor nerves (efferent)

  • carry signals from cns to effector cells

• c. mixed nerves

  • contain both sensory and motor fibers

  • common in verts

Describe visceral nerves and the autonomic nervous system

• involuntary actions

• signals to:

  • organs

  • glands

  • smooth muscle

  • etc.

• mostly involves motor neurons

• = autonomic nervous system

  • a. sympathetic division

    • energy expenditure and arousal

  • b. parasympathetic division

    • energy and self maintenance

  • para and sym connect to one organ = antagonistic effects

  • examples of autonomic system

    • 1. heart rate

      • sympathetic- increased rate

      • para- decreased rate

    • 2. stomach and intestines

      • sym- decreased digestive activity

      • para- increased digestive activity

What is the difference between the sympathetic and parasympathetic nervous systems?

• sympathetic: get ready for action- lots of oxygen and shut off digestion in short term

• parasympathetic: maintain body function and energy- slow heart rate and stimulate digestion

What is the function of the central nervous system?

integration and processing

What does the spinal cord use?

• receives sensory signal → motor response signal

  • simple, reflective responses

  • pathway for signals to travel to and from the brain

What does the brain do?

• complex integration and processing

• ex: homeostasis, learning, memory

• sensory info from spinal cord or directly from cranial nerves

What is the meninges?

connective tissue that covers brain and spinal cord

Describe the fish meninges.

• 1 layer = primitive meninx

• vascularized membrane

Describe the amphibian and reptile meninges.

• 2 layers

  • a. leptomeninx

    • inner vascularized membrane

  • b. dura mater

    • tough outer membrane

Describe the meninges of the birds and mammals.

• 3 layers

• a. pia mater

  • inner vascularized

• b. arachnoid

  • middle- connective tissue

  • subarachnoid space: between layers and fills up with cerebrospinal fluid (CSF)

• c. dura mater

  • tough outer layer

Describe the basic spinal cord structure.

• occupied vertebral canal

• neurocoel: internal cavity filled with CSF

• cerebrospinal fluid

• white matter = contains myelinated axons

• gray matter = unmyelinated axons and cell bodies

• ganglion = group of cell bodies (outside of CNS)

• interneurons: conduct signals to and from brain

  • bundles of interneuron nerve fibers = tracts

    • ascending tract = carries to brain

    • descending tract = carry impulses down from brain

• most vertebrates

  • 2 spinal cord enlargements

    • cervical

    • lumbar

What is the function of CSF?

1. protective cushioning (or shock absorption)

2. remove waste products and pH buffer

3. buoyancy of brain

What is the amniote spinal cord pattern?

• dorsal root = contains sensory nerve fibers and ganglia

• ventral root = contains motor neuron fibers

• 2 roots fuse distally to become spinal nerve

Why do most vertebrates have spinal cord enlargements?

lots of nerves to innervate pectoral and pelvic appendages

Describe the cross section of the agnathan spinal cord.

• no blood vessels in brain

• only have gray matter (no myelin until jawed fish)

Describe the spinal cord cross section in other verts

• round or square

• X or H shaped gray matter

  • tetrapods- folded surface

What are some variations in the dorsal and ventral roots of the spinal cord

• don’t fuse in lampreys = separate spinal nerves

• non-amniotes may also have motor neurons in dorsal root

Describe the jawed fish spinal cord.

• urophysis = caudal swelling of spinal cord with endocrine function

  • contain neurosecretory neurons = neurons in the CNS that produce neurohormones and secrete them into the blood

  • urophysis produces urotensins: raise blood pressure

Describe spinal nerves.

• 1 pair per segment or vertebra

• emerge through intervertebral foramina

• cauda equina

  • long caudal spinal nerves

  • go through vertebral canal before exiting foramen

  • occur because spinal cord grows slower than vertebral column

  • occurs in mammals, frogs, and a few fish

• rami: division of spinal nerve close to roots

  • a. dorsal ramus: connects to muscles and skin of back

  • b. ventral ramus: goes to lateral-ventral muscles and skin

• plexus

  • 2 or more nerves unite into common trunk then redistributed

  • 2 major- at paired appendages

Describe the rami of mammals.

• rami communicantes

  • connect to sympathetic trunk = part of ANS

  • signals with visceral function

Describe early development of the brain.

• 3 parts

• 1. prosencephalon = forebrain

  • sensory processing, endocrine function and higher integration

• 2. mesencephalon = midbrain

  • sensory processing (visual and auditory)

• 3. rhombencephalon = hindbrain

  • coordination of movement and autonomic functions

Describe later development of the brain.

• 3 parts → 5 parts

• prosencephalon = forebrain

  • 1. telencephalon and 2. diencephalon

• 3. mesencephalon

• rhombencephalon

  • 4. metencephalon and 5. myelencephalon

Describe the internal development of the brain

• forms from neural tube

  • sheet of ectoderm that folds up

• 4 cavities remain (=ventricles)

  • ventricles 1 and 2 = lateral ventricles

    • in right and left half of telencephalon

  • ventricle 3 in diencephalon

  • ventricle 4 in metencephalon and myelencephalon

  • aqueduct of sylvius = passageway between 3rd and 4th ventricles

Describe the internal structure of the brain

• choroid plexuses: projections of pia mater and cells lining ventricles

  • mostly in 3rd and 4th ventricles

  • produce CSF

    • minimal to no lymphatic vessels in brain

    • collects excess water from brain

    • diffuses into venous system

    • mammals

      • collects in subdural venous sinuses

• nucleus (nuclei): groups of cell bodies in CNS

• neuroglia (or glial) cells: interstitial cells that have a supportive function

What are the parts of the myelencephalon?

• medulla oblongata

Describe the medulla oblongata.

• coordinates involuntary actions (ex: heart rate, respiration, blood pressure)

• little size variation- why?

  • all groups need same functions

    • one exception: vagal lobe

      • large nucleus off medulla, found in bottom feeding fish (ex: catfish, carp, sucker)

      • receive signals from numerous chemoreceptors

Describe the cerebellum.

• coordinates movement of skeletal muscles and equilibrium

  • equilibrium: sensory input from semicircular canals

• variation- size correlated with complexity of movements

  • larges in mammals and birds

    • complex movement on land and flying

Describe the pons

• pons = fiber tracts between cerebellum and cerebrum

  • carries motor signals

  • connect to pyramids of medulla = fiber tracts from pons through medulla to spinal cord and carries motor signals

What are the parts of the metencephalon?

• cerebellum

• ventral side (birds and mammals only)

  • pons

What are the parts of the mesencephalon?

• optic lobes

• auditory lobs

Describe the mesencephalon.

• 1. optic lobes

  • visual input

  • largest in lampreys and birds

    • rely heavily on vision for foraging

• 2. auditory lobes

  • input from ear

  • well developed in most amniotes

• both 1 and 2 process basic reflexes and relay signals to cerebral hemispheres

• amniotes

  • brainstem = brain minus cerebral hemispheres and cerebellum

  • 2 sets of lobes (optic and auditory) = corpora quadrigemina

• ventral side

  • tegmentum = basal plate

    • deep layer (not visible)

    • cerebral peduncles = bulges

      • = additional fiber tracts that communicate between telencephalon and hindbrain- spinal cord and carry motor signals

      • in most amniotes

What are the parts of the diencephalon?

• epithalamus

• thalamus

• hypothalamus

Describe the epithalamus.

• pineal organ

  • = photoreceptor in agnatha

  • = endocrine role in jawed verts

  • function: regulates biological rhythms

• habenulae = nuclei receiving olfactory fibers and tracts from forebrain

  • reflex responses to olfactory stimuli

  • large in olfactory foragers

    • ex: well developed in sharks

    • absent in aquatic mammals (can’t smell in water)

Describe the thalamus.

• important relay center of brain

• all ascending fibers synapse here and sent to telencephalon

• intermediate mass = nuclei bulge into 3rd ventricle

  • mammals only

• ventral side

  • hypothalamus

Describe the hypothalamus.

• optic chiasma = where optic nerves cross

• infundibulum = ventral projection that holds the pituitary gland

• pituitary gland = endocrine gland

• hypothalamic nuclei: center for homeostasis

  • osmotic monitoring

  • regulates appetite and temperature

  • some autonomic control

• contains neurosecretory neurons

  • produce neurohormones that control pituitary gland and gonads

What are the parts of the telencephalon?

• olfactory bulb and tract

• 2 cerebral hemispheres = cerebrum

Describe the olfactory bulb.

• receives nerves from the cells lining olfactory epithelium

• variation:

  • poorly developed in birds and some mammals (especially true of bats and some primates)

  • well developed in lower vertebrates

  • development is related to importance in foraging and communication

What are ventricles in the brain?

open area with CSF

Describe the fish cerebrum.

• 1. primitive pallium

  • process sensory input

    • olfactory cues directly from olfactory tract

    • other sensory info relayed up from thalamus

• 2. globus pallidis (aka subpallium)

  • process motor signals

Describe the amphibian cerebrum.

• additional nuclei overall

• globus pallidis expands- why?

  • because now have appendages and more muscles for walking on land- requires more processing capability

• non-amniotes → large olfactory bulbs and large part of cerebrum devoted to olfaction (“olfactory brains”)

Describe the cerebrum of reptiles and birds.

• major expansion

• new error = dorsoventricular ridge forms

• receives and processes sensory info from thalamus

  • some direct processing and motor signals sent out to body but other info sent to globus pallidus

Describe the cerebrum of birds and mammals.

• major expansion

• flexure: forebrain becomes angles to rest of brain

• cerebrum covers diencephalon and mesencephalon

• otherwise, bird brains are similar to reptiles

Describe the cerebrum of mammals.

• reorganization of pallium into neocortex on outside

• other changes?

  • surface folded

    • ridge = gyrus

    • grooves = sulcus

    • why? increased surface area of neurons

    • lacking in monotremes, marsupials and some rodents

• internal structural changes

  • internal capsule: fiber tract to brainstem

  • corpus callosum: fiber tract between hemispheres

    • where epilepsy comes from

  • basal ganglia

    • = globus pallidus + 3 new nuclei

      • caudate nucleus, putamen, and amygdoloid nucleus

    • processing of motor signals

    • relay motor signals

      • neocortex < - > thalamus

    • parkinson’s disease

• neocortex

  • divided into 4 lobes:

  • major processing functions

    • sensory

      • temporal → auditory and olfaction

      • occipital → vision

      • parietal → touch

    • voluntary motor activity → frontal lobe

    • problem solving → frontal and parietal

    • memory → frontal and temporal

    • frontal → control over social behavior, personality

  • hippocampus

    • inner temporal lobe

    • spatial and short term memory

    • navigation

    • alzheimer’s disease

    • other verts also have hippocampus but not in neocortex

      • bird hippocampus- chickity bird does seed cacheing

        • in fall, hippocampus grows by 1/3

What is a lobotomy? Who was the first to do it on humans?

• procedure that destroys part of the neocortex to alter behavior

• treat severe human psychiatric problems

• Gottlieb Burkhardt (1st to use it on humans)- europe

What is a leucotomy?

• antonio egas moniz- europe

• destroyed neocortex and parts of thalamus

• won nobel prize

Who found the ice pick lobotomy? What is it?

• uses ice pick

• frontal lobotomy: destroys frontal lobe or prefrontal cortex

  • cognition, personality, decisions

What are the sensory cranial nerves (PNS)?

• #0- terminal

• #1- olfactory

• VN- vomeronasal

• #2- optic

• epiphyseal (e)

• profundus (p)

• ALL- anterior lateral line

• PLL- posterior lateral line

• #8- vestibulocochlear

Describe the terminal cranial nerve.

• #0

• sensory

• in gnathostomes (jawed vertebrates)

• goes between olfactory mucosa → forebrain

• pher0mone receptors

  • mating and reproductive behavior

Describe the olfactory nerve.

• #1

• sensory

• goes from olfactory epithelium → bulb

Describe the vomeronasal nerve.

• sensory

• cranial nerve (PNS)

• goes from vomeronasal organ → olfactory bulb

• VN organ = accessory chemoreceptor (for pheromone detection)

• isolated in nasal cavity

• not in humans

• some mammals, amphibians, squamates

  • flenmen behavior (mammals)

  • forked tongue in squamates

Describe the optic nerve.

• sensory

• retina → chiasma

• fibers cross to opposite sides of brain = 2 separate images

  • produces monocular vision (eyes don’t overlap)

• some mammals- only some fibers cross and continue to opposite sides = 1 image and binocular vision

  • eyes must overlap

• birds- also have binocular vision → visual signs relayed throughout brain

Describe the epiphyseal nerve.

• sensory

• pineal organ or parapineal connected → habenulae

• lamprey and some bony fish

  • lampreys - photoreceptor

• some frogs, toads, and lizards: parapineal organ (also a photoreceptor)

Describe the profundus nerve.

• extends to skin of snout- head

• separate nerve

  • some jawed fishes

• fuses with trigeminal in other vertebrates (is the ophthalmic of trigeminal)

Describe the anterior lateral line and posterior lateral line.

• sensory nerves

• connect lateral line to hindbrain

• lateral line detects motion in water

• merge with cranial nerve #7,9,10

• aquatic non-amniotes

Describe the vestibulocochlear nerve.

• sensory

• connects medulla oblongata → inner ear

• 2 major branches

  • a. vestibular- goes to semicircular canals

  • b. cochlear- goes to organ of the inner ear that converts vibrations to nerve impulses

    • fish = lagena

    • tetrapods = cochlea

What are the motor cranial nerves?

• #3- oculomotor

• #4- trochlear

• #6- abducens

• #11- spinal accessory

• #12- hypoglossal

Describe the oculomotor, trochlear, and abducens nerves.

• motor nerves

• connect eye muscles → mid and hindbrain

• oculomotor- autonomic connections for vision

  • controls iris and size of pupil

Describe the spinal accessory nerve.

• motor

• only in tetrapods

• connects hindbrain to pharynx and soft palate, as well as superficial neck and shoulder muscles in mammals only

Describe the hypoglossal nerve.

• motor

• only in tetrapods

• = spinal nerve locked in cranium

  • during development, spinal nerves have a dorsal and ventral root (lacking in cranial nerves)

• goes to muscle of tongue

What are mixed nerves? Which nerves fall under this category?

• contain sensory and motor fibers and may contain visceral fibers of autonomic nervous system

• all mixed nerves emerge from hindbrain

• #5 (trigeminal), #7 (facial), #9 (glossopharyngeal), #10 (vagus) = branchiomeric

  • only in fish

  • go to branchial arches and jaws

    • ventilating gills and feeding

Describe the trigeminal nerve.

• mixed nerve

• sensory-tactile reception

  • skin of head and teeth

  • covers linings of oral and nasal cavities

  • anterior tongue

• motor- muscles of jaws

Describe the facial nerve.

• mixed nerve

• sensory

  • taste receptors

    • fish- pharynx

    • tetrapods- anterior tongue

• motor

  • muscles of hyoid arch

  • in all vertebrates

  • tetrapods- face muscles

Describe the glossopharyngeal nerve.

• mixed nerve

• fish- sensory and motor

  • 3rd pharyngeal arch

• tetrapods

  • many fibers lost along with gills

  • motor- neck muscle

  • sensory- posterior tongue

    • taste, touch, temp

  • also have visceral fibers to one salivary gland

Describe the vagus nerve.

• mixed nerve

• fish- sensory and motor

  • pharyngeal arches

• tetrapods- motor

  • neck muscles- swallowing

• all vertebrates

  • sensory- oral cavity

    • taste and touch

  • also have visceral factors to heart and many of our visceral organs

What are the nerves that are involved with the tongue?

• 4 major nerves

• motor → hypoglossal

• sensory

  • touch → trigeminal (anterior), glossopharyngeal (posterior)

  • taste → facial (anterior), glossopharyngeal (posterior)

  • visceral salivary glands → facial and glossopharyngeal

What nerves comprise the autonomic nervous system?

• entirely visceral motor neurons

  • sensory fibers may share a common pathway

What are the two components of the autonomic nervous system?

• a. sympathetic

  • branches spinal cord and spinal nerves

  • diagram: black nerves = sympathetic, red nerves = parasympathetic

• b. parasympathetic

  • branches from brain and spinal cord (sacral)

What neurons are needed to reach effector cells?

• a. preganglionic neuron

  • CNS → autonomic ganglion

• b. postganglionic neuron

  • autonomic ganglion → effector cell

• some go through rami communicantes: connects spinal nerves to sympathetic trunk

What are the three types of ganglia present in the ANS?

• a. sympathetic

  • sympathetic trunk near spinal cord

• b. collateral

  • near head or abdominal aorta

• c. terminal

  • in visceral organ

Are effector cells innervated by sympathetic or parasympathetic nerves?

• most effector cells are innervated by both

• exception: skin only has sympathetic

What is the endocrine system?

• glands that produce chemicals that influence specific target cells

• gland: tissue producing a secretion

• hormones: chemical messengers of endocrine system

  • travel through blood

• hormones only bind with cells with specific receptors

  • except general metabolic hormones

    • influence all cells

    • ex: insulin

• tropic hormones: stimulate other endocrine glands

What are the major endocrine glands?

brain:

1. hypothalamus

2. pituitary

3. pineal

around body:

4. adrenal

5. gonads

6. thyroid

7. parathyroid

8. pancreas

What do glands do?

diffuse endocrine tissue

What hormone does the stomach produce?

gastrin: stimulates cells to produce acid

Describe the hypothalamus gland.

• = intermediary for endocrine and nervous systems

• works closely with pituitary gland

• receives info from brain

• initiates hormone production

• hormones either:

  • 1. stored in pituitary

  • 2. activate pituitary

    • to produce other hormones

• pituitary

• production and movement of neurohormones

What parts is the pituitary divided into?

• a. neurohypophysis

• b. adenohypophysis

What are neurohormones?

hormones produced in CNS

Describe production and movement of neurohormones in the hypothalamus.

• neurosecretory hormone

  • neurohormones made at cell body

  • cell body → axon

  • axon terminal → blood sinusoid

  • sinusoid → circulation

  • axon terminal and sinusoid come together = neurohemal organs