Bio Exam 4 - Chapter 45, 48, 49, 47

excitatory vs inhibitory synapse

excitatory increase the activity of the receiving neuron, while signals sent across inhibitory synapses reduce neuron activity

spatial vs temporal summation

Spatial summation involves simultaneous signals coming from multiple presynaptic neurons being received by a single postsynaptic neuron. Temporal summation involves a single presynaptic neuron rapid-firing signals to a postsynaptic neuron

afferent neurons

sensing neurons

carry information to nervous system

efferent neurons

motor neurons

carry information to effector cells outside of Nervous system like in muscles or glands

interneurons

communicate between neurons

association neurons

types of neural networks

1. nerve net - simple, no central command center, nerves control certain parts of the organism ex. in cnidarians/anemone

2. ganglia - neurons organized into clusters ex. earthworm

3. brain - more complex, processes information

gray matter vs white matter

gray - darker because has more neuronal cell bodies; sends information through the axon

white - has more axons

spinal reflex

doesn’t go through the brain; processed in spinal cord

• conversion of afferent to efferent information in the spinal cord without participation of brain

  • ex. knee-jerk reflex

how does knee-jerk reflex work

sensory neuron receives information (the tapping from the hammer), and sends the information down the spinal nerves on the afferent pathway, connect with the interneurons which send signal to motor neuron which transmits signal down efferent pathway to the skeletal muscle which contracts

difference between central and peripheral nervous system

central: includes brain and spinal cord

peripheral: neurons that connect central nervous system to all tissues and parts of the body

examples of conscious afferents

sensory information like sight and sound that are sent to CNS

examples of unconscious afferents

physiological information like blood pressure, and deep body temperature that are sent to CNS

examples of voluntary efferents

commands to skeletal muscles sent by CNS

examples of autonomic efferents

physiological controls like heart rate and sweating sent by CNS

parts of the early embryonic “brain”

forebrain, midbrain, and hindbrain

what does the brain develop from

the dorsal hollow neural tube in the embryo (looks like the dorsal hollow nerve chord present in all chordates)

what does the forebrain develop into

1. diencephalon

   1. thalamus

   2. hypothalamus

2. telencephalon

   1. cerebrum

      1. left and right cerebral hemispheres

      2. cerebral cortex

what does the hindbrain develop into

1. medulla

2. pons

3. cerebellum

what does the midbrain develop into

midbrain has the least change and stays very small in comparison to rest of brain

spinal cord function

• conducts information to and from the brain

• integration of information from the peripheral nervous system

  • issues motor commands

brain stem function

• made up of the midbrain, pons, and medulla

  • pons: bridge between cerebrum and cerebellum

  • medulla: involved in control of physiological functions such as breathing and swallowing

• has its own peripheral nervous system

• core of brain stem called reticular activating system

  • damage below RAS can cause paralysis but sleep-wake cycle still intact

  • damage above RAS can cause coma because it interrupts pathways that keep the brain awake

what are the parts and functions of the adrenal axis

1. Hypothalamus: regulates physiological functions such as hunger, thirst, pleasure; control center for basic needs

2. Thalamus: relay station for all sensory information except for smell

3. Pituitary gland: secretes hormones regulating homeostasis, functionally connected to hypothalamus

parts of limbic system and its function

network of neuronal pathways important for motivation, instinct, emotional association with memory, and formation of long term memory

includes the parts of the forebrain:

• amygdala: fear, and fear memory; if this region is damaged then you can’t learn to be afraid of a stimulus

• hippocampus: transfers short term memory to long term memory

what are the parts of the cerebral cortex

• temporal lobe

• frontal lobe

• central sulcus (separates frontal and parietal lobe)

• parietal lobe

• occipital lobe

temporal lobe function

• receive and process auditory information

• facial recognition

  • identifying and naming objects

• understanding spoken language

• *if temporal lobe is damaged the individual would develop agnosia (difficulty identifying things)

frontal lobe function

the association cortex for higher order information processing, and associating info from senses and memory

ex. reasoning, planning, personality

what is the primary motor cortex

*present in frontal lobe

• issues motor commands throughout the body; controls muscles

• parts of the body with fine motor control such as face, hands, fingers, have larger representation on cortex (more neurons devoted to controlling them)

parietal lobe function

• integrating sensory information from various parts of the body

  • ex. visuospatial processing/body awareness

what is the primary somatosensory cortex

*below central sulcus, present on parietal lobe

• its neurons receive info from different parts of the body

• areas of body with lots of mechanoreceptors like lips, hands, fingers, have larger representation on PSC

occipital lobe function

receives and processes visual information

if occipital lobe damaged, you can see images but can’t see motion or translate visual experience into language

autonomic nervous system

part of the peripheral nervous system that controls involuntary physiological functions to maintain homeostasis

includes the sympathetic and parasympathetic nervous system

how are preganglionic neurons different in sympathetic and parasympathetic nervous system?

*send signals

sympathetic: cholinergic; acetylcholine is neurotransmitter

parasympathetic: cholinergic; acetylcholine is neurotransmitter

how are postganglionic neurons different in sympathetic and parasympathetic nervous system?

*receive signals

sympathetic: noradrenergic; norepinephrine is neurotransmitter

parasympathetic: cholinergic; acetylcholine is neurotransmitter

how is anatomy of sympathetic and parasympathetic nervous system different

sympathetic: most of the ganglion are lined up in ganglion chain

• preganglionic neurons are mostly from the thoracis and lumbar regions

parasympathetic: preganglionic neurons usually come from cranial and sacral regions

• most of the ganglion are close to the target organs

how are sympathetic and parasympathetic nervous system functions different

• sympathetic: active during fight or flight response

  • heart rate and cardiac output increased

  • blood flow to skeletal muscle increased

• parasympathetic: active when you’re relaxed/normal condition

  • digestive system activity increased

  • heart rate and blood pressure go down

what are the structural components of vertebrate eyes

• sclera: outer covering

• cornea: anterior portion modified

• iris: colored part of eye, controls size of pupil to adjust amount of light let into eye

• pupil: hole where light enters

• lens: helps eyes focus light

• blind spot: area with no photoreceptors and just blood vessels

• retina: receives image and converts to neuronal signal with neurons and photoreceptors

  • fovea: small depression on the retina that contains mostly cone cells

  • choroid: between retina and sclera; rich in blood vessels to provide nutrients

what is the aqueous humor

a liquid secreted by a ciliary body/muscle at front of eye and controls the curve of the lens

what is the vitreous humor

a clear gel that holds the shape of the eye; it doesn’t get replenished so as you get older it isn’t replaced

what is the order of flow of light through the eye

iris → pupil → retina

how does the lens change to accommodate different distances

• more rounded lens to look at things close by

• flatter lens to look at distant things

what lenses are prescribed for different sight issues

concave (hourglass shape) for near sightedness

convex lens if image lands behind retina

bifocal lens if near and farsighted

what are rods and cone cells

• rods: function in dim light, detect shape and movement; don’t see color

• cones: responsible for vision in bright light, and seeing fine details; allow color vision

what is present in the retina

photoreceptors, ganglion cells, amacrine cells, bipolar cells, horizontal cells

flow of information in the retina

photoreceptor (absorbs light and converts to electrical signal) → bipolar cell (receive signal and send to ganglion) → ganglion cell (receive and send to optic nerve)

lateral flow has horizontal cell synapsing with photoreceptor and send info to amacrine cells

why does binocular vision occur

two eyes see overlapping yet slightly different visual fields

left and right eye receive signals from both sides of the vision fields, and sort right field signal to left brain, and left field signal to right brain

flow of light/visual information out of the retina

retina → optic chiasm (where the left and right optic nerves meet) → visual cortex

what is broca’s area

• located in frontal lobe in front of primary motor cortex

• essential for speech

• if this is damaged the individual would have slow or lost speech

wernicke’s area

• located in temporal lobe

• involved in sensory aspects of language like making sense of words

• wouldn’t be able to speak sensibly or understand language if this area was damaged

angular gyrus

• located in parietal lobe

• essential for integrating spoken and written language

how do signals travel in the brain when you have to repeat a heard word

1. receive the signal in auditory cortex when you hear the word

2. wernicke’s area to understand word

3. broca’s area to make the speech

4. primary motor cortex to move lips and tongue to make sound

how do signals travel in the brain when you have to speak a written word

1. receive visual signal in eye

2. visual cortex

3. angular gyrus integrates spoken with written language

4. wernicke’s area to understand the word

5. broca’s area converts signal to speech

6. primary motor cortex moves the mouth to make sound

declarative memory

of people places and things that can be recalled and described

hippocampus is important for this

procedural memory

memory of how to perform a motor task; can’t be described

types of glial cells

- microglia cells: immune defense of central nervous system
- astrocytes: part of barrier between blood and brain
- oligodendrocytes: insulate neuronal cells in central nervous system with myelin sheath
- schwann cells: insulate neuronal cells in peripheral nervous system with myelin sheath

what are endocrine glands and how do they act on body

• an aggregation of endocrine cells

• its chemical signals are released into extracellular fluid/environment → signal communicates with blood → info carried throughout body in the blood

• called ductless glands because signal is released directly to extracellular fluid

what are exocrine glands and how do they act on body

signals carried out through ducts to the outside of body or to a body cavity

ex. sweat glands, salivary glands

what are the types of endocrine signals

1. hormones: signal enters the blood and activates cells far away from the site of release

   1. neurohormones: produced by neuroendocrine cells

   2. pheromones: released to outside of body and affects the response of animals

2. paracrine: chemicals act on target cells near the release site

3. autocrine: acts on the same cells that secrete them

what are the chemical groups of hormones

1. peptides/proteins: usually water-soluble so easily transported in the blood ex. insulin, growth hormone

2. steroid hormones: usually synthesized from cholesterol so not water-soluble but lipid-soluble → can pass easily through cell membrane; usually bound to carriers in the blood ex. corticosteroids

3. amine hormones: mostly synthesized from special amino acid called tyrosine; some are water-soluble (epinephrine), some are lipid-soluble (thyroxine)

what response does epinephrine trigger in the heart, blood vessels, and liver

• binds to heart → increased heartbeat

• binds to blood vessels → more blood sent to muscles

• binds to liver → more glucose production

differences between nervous and endocrine systems, and how are they connected

nervous system - rapid responses since chemical synapses and nerve impulses act on target cells

endocrine system - involves hormones so slower response time

connected by the pituitary gland

what parts are in the HPA axis and how does it work

hypothalamus, anterior pituitary, and adrenal gland

1. hypothalamus produces corticotropin releasing hormone

2. corticotropin acts on anterior pituitary, which produces adrenal corticotropin hormone

3. adrenal corticotropin acts on adrenal gland to produce glucocorticoid

   1. short loop negative feedback: too much tropic hormone produced makes hypothalamus stop releasing

   2. long loop negative feedback: too much of the hormone makes anterior pituitary and hypothalamus stop production

what is the posterior pituitary and function

contains axons from hypothalamic neurons

releases neurohormones produced by the hypothalamus like oxytocin and vasopressin/ADH

what is the anterior pituitary and function

contains endocrine cells controlled by neurohormones from the hypothalamus

produces hormones

what hormones are produced in the anterior pituitary

• tropic hormones

  • thyrotropin (thyroid stimulating)

  • luteinizing hormone

  • follicle stimulating hormone

  • corticotropic hormone

• growth hormones

• endorphins (make pain tolerance higher)

  • morphine

what is the function of hypothalamus

1. receives information about body and environment through many receptors

   1. maintains homeostasis by regulating

2. releases neurohormones to anterior pituitary via portal blood vessels

3. produces and secretes two neurohormones into the posterior pituitary

what hormones are produced in adrenal gland

• adrenal cortex: produces cortisol/corticosteroids

  • affects blood glucose level and immune function

• adrenal medulla: produces epinephrine and norepinephrin

  • produced during fight or flight response or in response to stressful stimulus

what is the cycle of blood flow

1. right atrium receives oxygen poor blood from superior and inferior vena cava

2. right ventricle contracts

3. blood goes to pulmonary artery which sends to

4. lung

5. pulmonary veins bring oxygen rich blood back to heart

6. left atrium receives oxygenated blood

7. left ventricle contracts and takes blood to

8. aorta which delivers oxygenated blood throughout the body

9. oxygen poor blood comes back into heart from superior and inferior vena cava

what is the systemic and pulmonary circuit

• left pump of heart delivers body throughout the body with the systemic circuit

  • left side has thicker cardiac muscle wall because it pumps more

• right pump delivers blood to the lungs through the pulmonary circuit

what are the major valves in the heart and functions

• atrioventricular valve: has a left and right valve, between the atria and ventricles, and opens from atrium towards ventricle so blood goes only in that direction to prevent backflow

  • right AV valve is tricuspid

  • left AV valve is bicuspid

• pulmonary valve: prevents backflow of blood into right ventricle, directs blood to lungs

• aortic valve: prevents backflow of blood into left ventricle, directs blood to aorta

what are the stages of the cardiac cycle

• systole - when ventricles contract and blood goes into arteries from atria to muscle

• diastole - when ventricles relax

what makes lub dup sound in heart

lub - ventricles contract and atrioventricular valves close, causing pressure to build in ventricles (systole)

dup - the pulmonary and aortic valve open allowing blood in, pressure in ventricles lowers so it relaxes, and now pressure in pulmonary and aortic valves is higher so the valves close which makes the dup sound (end of systole)

what is blood pressure and why does it get high

pressure that blood is pushing onto the vessel walls

*if arteries harden, then they can’t be flexible to accommodate more blood rushing which causes high blood pressure

sinoatrial node

primary pacemaker present on the wall of right atrium at junction between it and superior vena cava

• pacemakers are modified cardiac muscle cells that initiate action potentials without stimulation from nervous system

how does action potential/signal travel through the heart during a heartbeat

1. starts at Sinoatrial node which generates action potential

2. atria contract

3. slight delay before Atrioventricular node continues the signal

4. bundle of His (modified cardiac muscle fibers)

5. purkinje fibers

6. ventricles contract

what does blood plasma contain

*the fluid portion of blood, contains:

• water

• salt (buffer that regulates blood pH)

• nutrients like glucose, vitamins, waste products

• hormones

• proteins, immune response elements

what are the cellular components of blood

• red blood cells (erythrocytes) - biconcave and don’t have nucleus when mature; packed with hemoglobin; main function is carrying oxygen

• white blood cells (leukocytes) - colorless; involved in inflammation and immune response

• platelets - cellular fragments essential for blood clotting; bone marrow produce megakaryocytes which break down into platelets; short lifespan

what is hematocrit

volume of packed blood cells/volume of blood x 100%

• measures percentage of red blood cells in your blood

• generally higher hematocrit in men

what is the process of forming a blood clot

1. an injury to blood vessel lining causes collagen fibers to be exposed

2. platelets are activated and become sticky, adhere to fibers and activate other platelets

3. prothrombin circulating blood plasma is converted to thrombin

4. thrombin acts on fibrinogen circulating in plasma to form fibrin

5. fibrin threads form meshwork that seals wound until vessel wall heals

what are the tissue layers of blood vessels

• endothelium - innermost, thin

• muscular layer - middle layer of smooth muscle

• connective tissue - outer layer with elastic and collagen fibers

elastin layers in between those