Bio 112 Exam 2

4 Types of Tissues

1. Connective Tissue: plays a role in support

2. Nervous Tissue: controls and coordinates body function

3. Muscle Tissue: functions in movement

4. Epithelial Tissue: covers the outside of the body, lines organ surfaces, form glands

Types of connective tissue and where they’re found

1. Loose CT: adipose/fat, reticular connective tissue

2. Dense CT: tendons, ligaments

3. Supportive CT: bone, cartilage

4. Fluid CT: blood, lymph

Where is nerve tissue found?

Brain, spinal cord, nerves throughout the body

Types of muscle tissue and where they’re found

1. Skeletal muscle: bladder, rectum

2. Cardiac muscle: Heart

3. Smooth muscle: Blood vessels, walls of digestive tract

Where is Epithelial tissue found?

Skin, lines organ surfaces, form glands

Why is epithelial tissue important for homeostasis?

• Control exchange of materials across its surface 

• Membrane proteins regulate the transport of molecules and ions

• Homeostasis depends on this regulation of transport

What is the polarity of Epithelial tissue and its importance?

• Apical side (faces outer environment)

  • Lines organs and secretes mucus

• Basolateral side (faces the inside)

  • attaches epithelial tissue to basal lamina

What are the differences between cells, tissues, organs, organ systems?

Cells have similar functions and are organized into tissues, Tissues are organized into specialized structures called organs, organs are part of a larger unit called organ system.

Are organs made up of one type of tissue?

No, organs are made up of many types of tissue.

How does body size affect an animal’s physiology?

As an organisms size increases, its mass-specific metabolic rate must decrease.

What is the cell surface volume ratio?

Controls the rate at which nutrients enter/exit the cell and rate at which they are used. Most optimal is HIGH surface area and LOW volume.

What is the consequence of rapid volume increase more than surface area?

The Basal Metabolic Rate decreases because it is inversely proportional to the mass of an animal.

What does surface area control?

Diffusion rate

What does volume control?

Metabolic rate

What are 3 ways for a structure to have a high surface area volume ratio?

1. Flattening (I.e. fish gills)

2. Folding (I.e. small intestine)

3. Branching (I.e. blood vessels)

What is homeostasis?

Maintaining the internal environmental parameters; keeping things constant

What tissue type is important for homeostasis?

Epithelial Tissue

How do homeostatic systems function?

Homeostasis is reliant on Negative feedback.

• Sensor

  • Structure that detects some aspect of the external or internal environment and sends that information to the integrator

• Integrator

  • Component of the nervous system that evaluates incoming sensory information and determines potential responses

• Effector

  • Any structure that helps return to the desired normal condition, set point, via signals from the integrator

What are the 4 mechanisms of heat exchange?

1. Conduction

   • Direct transfer of heat between two physical bodies in contact

   • I.e. Turtle basking on a rock, heat transfers from rock to turtle

2. Convection

   • Heat exchanged between a solid and liquid or gas, rather than two solids

   • I.e. heat transfer occurs from water to the turtle 

3. Radiation

   • Exchange but no physical contact

   • I.e. Sun radiates heat unto the turtle

4. Evaporation

   • occurs when liquid turns into gas

   • I.e. water evaporates off of the turtle shell

Homeotherm vs Heterotherm

Homeotherms - Keep body temperature constant

Heterotherms - Tolerate changes in body temp

Endotherm vs Ectotherm

Endotherm - produces own heat

Ectotherm - relies on heat from the environment

What is the difference between the CNS and the PNS?

• Central nervous system - Brain and Spinal Cord

• Peripheral nervous system - All of the components of the nervous system outside the CNS are part of the PNS

  • Sensory cells in PNS sense stimulus, send to neurons in PNS, when activated send signal to CNS to interneurons, interneurons tell motor neurons to activate effectors/ glands/ muscles

What are the 3 types of neurons?

1. Sensory neurons (In PNS)

   • transmit information to the brain and spinal cord

2. Interneurons (In CNS)

   • makes connections between the sensory neurons and motor neurons

3. Motor Neurons (In CNS)

   • nerve cells that send signals to effector (response) cells in glands or muscles

What are the 3 parts of a neuron?

1. Dendrite

   • Receives the chemical signals

2. Soma/Cell Body

   • Integrates the electrical signal 

3. Axon

   • Propagates the electrical signal (passes it on)

How do neurons communicate?

Electrical signaling

What is a synapse?

The place where 2 neurons communicate and connect with each other without touching.

How is a membrane potential created?

By the difference in charge between the ions located on the outside and inside of the cell membrane. The membrane potential inside of a cell will be negative.

What is the unit of the membrane potential?

mV

What is the resting membrane potential neurons?

-65 mV to -80 mV

Where are the potassium and sodium concentrations highest?

Potassium concentration is higher INSIDE the cell and sodium concentration is higher OUTSIDE the cell.

What are the 2 mechanisms to maintain membrane potential?

1. K+ Leak Channels

2. Na+/K+ ATPase Pump

   • 3 sodium goes out and 2 potassium goes in

How does the change in ion flow affect the membrane potential?

Ion flow in and out of the membrane changes the membrane potential.

Depolarization vs Hyperpolarization

• Depolarization - less negative, more positive than resting membrane potential

• Hyperpolarization - more negative than resting membrane potential

What are the 3 phase to the action potential?

1.  Depolarization

   • Membrane potential becomes less negative and moves toward a positive charge/value

   • Na+ enters the cell

2. Repolarization

   • Changes the membrane back to a negative charge

   • K+ leaves the cell

3. Hyperpolarization

   • Membrane potential becomes more negative than resting potential

   • Momentary, then returns back to resting potential

What does it mean that action potential is an “All or Nothing” event?

MUST PASS THRESHOLD in order to fire an action potential

How do voltage-gated channels function?

Voltage-gated channels are channels in the plasma membrane that open and close in response to changes in voltage

What is a role of myelin in action potential propagation?

Myelin acts as electrical insulation preventing the ions from leaking out as it spreads down the axon.

What cells produce myelin in the CNS?

Oligodendrocytes

What cells produce myelin in the PNS?

Schwann cells

What is the node of Ranvier?

The sections of exposed axon between segments of myelin sheath that contains dense areas of voltage-gated Na+ channels. (concentrator)

How does action potential induce the release of a neurotransmitter?

1. Action Potential arrives near the synaptic cleft.

2. Voltage-gated Ca²⁺ channels open. Ca²⁺ enters presynaptic
   cells.

3. Synaptic vesicles fuse with presynaptic membrane, then
   release neurotransmitter.

4. Ion channels in the postsynaptic membrane open when neurotransmitter binds; flow of ions causes change in postsynaptic cell potential.

5. Ion channels in the postsynaptic membrane then close as neurotransmitter is broken down or taken back up by presynaptic cell.

What type of vesicles store neurotransmitters?

synaptic vesicles

Presynaptic cell vs Postsynaptic cell

• Presynaptic - sending cell

• Postsynaptic - receiving cell

What ions and channels induce synaptic vesicle fusion?

Ca²⁺

How do neurotransmitters affect the postsynaptic cell?

Neurotransmitters act as ligands that bind to ligand-gated channels on the postsynaptic membrane causing the flow of ions along the electrochemical gradient. This causes a change in the post-synaptic membrane potential.

Excitatory Postsynaptic Potential (EPSP) vs Inhibitory Postsynaptic Potential (IPSP)

• Excitatory postsynaptic potentials (EPSP) - causes the membrane to depolarize, increasing the likelihood of an action potential

• Inhibitory postsynaptic potentials (IPSP)  - causes the membrane to be hyperpolarized, decreasing the likelihood for an action potential

What are the 2 major divisions of the PNS?

1. Somatic system - controls conscious movement (voluntary movement)

2. Autonomic system - controls internal processes; unconscious movement (involuntary movement)

What are the 2 divisions of the Autonomic Nervous System?

1. Parasympathetic - promotes relaxation or digestion 

2. Sympathetic - prepares organs for stressful situations; “fight or flight”

What are the 4 structures of the brain?

1. Cerebrum - responsible for conscious thought and memory

2. Cerebellum - responsible for coordination of complex motor patterns

3. Diencephalon - responsible for information relay and control of homeostasis

4. The Brain Stem - responsible for information relay; autonomic control of the heart, lungs, and digestive system

What are the 3 processes in the sensory system?

1. Transduction - convert stimulus to action potential 

2. Amplification - amplify signal 

3. Transmission - transmit signal to brain

What are the 7 types of sensory receptor cells?

1. Nociceptors

   • Stimulated when there is a harmful stimulus. (I.e. tissue injury)

2. Thermoreceptors

   • Detect change temperature

3. Mechanoreceptors

   • Respond to distortion caused by pressure changes

4. Chemoreceptors

   • Perceive presence of specific molecules

5. Photoreceptors

   • Respond to wavelengths of light

6. Electrorecptors (uncommon)

   • Detects electrical fields

7. Megnetoreceptors (uncommon)

   • Detects magnetic fields

What the common sensory stimuli?

1. Smell

2. Sound

3. Sight

4. Pressure

5. Temperature changes

How do sensory stimuli affect action potential?

Sensory stimuli change the membrane potential of sensory receptor, resulting in a change of the firing rate of action potential sent to the brain.

Are receptor cells specific?

Yes, receptor cells are highly specific in that each sensory neurons sends its signal to specific area of the brain.

What is the Mechanoreception sensory system?

Pressure sensing systems used for hearing, physical pressure on the skin, the movement of muscles, and stretching of blood vessels.

How do hair cells transduce pressure changes into sensory neuron firing?

1. When there is a stimulus, pressure wave, the stereocilia bend

2. The potassium channels open

3. The Membrane depolarizes because there was more potassium outside of the cell

4. Then calcium flows inside the neurotransmitter

5. This induces the fusion of vesicles

6. Then the neurotransmitter is released

What is the Importance of stereocilia and the kind of channels on them?

Stereocilia are projections that are connected to each other via Potassium Channels. Ions flow into the cell through the potassium channels.

What happens if hair cell bending hyperpolarizes the membrane?

If hyperpolarization occurs, less neurotransmitters are released and leads to inhibition of postsynpatic sensory neurons.

What’re the 3 main parts of the mammalian ear structure?

1. Outer Ear

2. Middle Ear

3. Inner Ear

How do changes in air pressure lead to bending of hair cells in the cochlea?

The fluid in the cochlea is disrupted by the mechanical vibrations which cause the hair cells to bend.

What is the path of sound in the ear and functions of structures?

1. The outer ear collects pressure waves and funnels them into the ear canal where they strike the tympanic membrane

2. The tympanic membrane vibrates and passes the vibrations into the ear ossicles

3. The stapes, last ossicle, vibrates against the oval window

4. The oval window generates waves in the fluid inside the cochlea

5. The hair cells sense the pressure waves in the fluid

What structures of the ear amplify sound?

The 3 ossicles amplify the vibrations of the tympanic membrane

What structure allows hair cells to be sensitive to different frequencies?

The Basilar Membrane

Where are hair cells located in the cochlea?

The middle chamber, sandwiched between the tectorial and basilar membrane.

What is the Lateral Line System?

A series of canals in fish and larval amphibians that contains hair cells which detect pressure changes underwater.

What is the Photoreceptor Sensory System?

The organs involved in sensing light changes that range from simple-light sensitive eyespots to sophisticated, image-forming eyes. The sensory ability correlates with the environment it lives and its mode of life.

What is the structure of the insect’s compound eye?

Composed of hundreds or thousands of light - sensing columns called ommatidia. Each ommatidia has a lens that focuses light onto a small number of receptor cells.

What are the 6 major structures of the vertebrate eye and function?

1. Sclera - the tough outermost layer; “white of the eye”

2. Cornea - a transparent sheet of connective tissue formed by the front of the sclera

3. Iris - round muscle that can contract or expand to control the amount of light entering the eye 

4. Pupil - hole in the center of the iris 

5. Lens - a curved clear structure that focuses light with the cornea

6. Retina - the area in the back of the eye that receives light focused by the lens and cornea

What are the 3 different layers in the retina?

1. Photoreceptors - form a layer at the back of the retina 

2. Bipolar cells - intermediate layer of connecting neurons 

3. Ganglion cells- form the front or innermost layer of the retina and whose axons project to the brain via the optic nerve 

What is the name of the photoreceptor cells in the retina?

Rods and Cones

What is the difference between rods and cones in term of light detection?

• Rods - sensitive to dim lights and not color

• Cones - stimulated by different wavelengths of light (colors)

What is the Rhodospin complex? The effect of light on retinal and ospin?

The Rhodospin is a transmembrane protein complex of pigment (Retinal) and Opsin (protein). The complex is activated when light changes the shape of retinal and activates the Opsin.

Explain the signaling pathway(PDE and cGMP) in rods stimulated by light

1. Rhodspin is activated when light causes retinal to change shape

2. Activates membrane protein transducin, which activates Phosphodiesterase (PDE)

3. PDE breaks down cyclic guanosine monophosphate (cGMP) to guanosine monophosphate (GMP)

4. cGMP sodium gated channels close

5. Na⁺ decreases, then neurotransmitter release decreases

How is color vision possible?

There are 3 types of cones, each with a different type of opsin that responds to distinct wavelengths of light. The brain senses the color by integrating the signals from all three opsins.

• Short - blue light

• Medium - green light

• Long - Red light

What is Chemoreception?

The result of a molecule binding to the chemoreceptor and transducing electrical signals in the body.

What are taste cells? Where are they found?

Taste cells are taste-sensing chemoreceptors that synapse to sensory neurons and are found in taste buds in groups of 100. The taste buds are scattered around the mouth and throat, but mostly on the tongue.

What are Olfactory Receptors connected to?

Each Olfactory neurons has one type of receptor, and neurons with the same receptors all project to the same Glomerulus in the Olfactory bulb.

What are some other sensory systems found in animals?

• Thermoreception - detects change in temperature

• Electroreception - detection in electrical fields 

• Magnetoreception - detection in magnetic fields