Anatomy Lecture 1

What is anatomy

It’s the study of structures and shapes of the body and its components and those observations can be used to see sizes and relationships of parts

What do we mean by gross anatomy

By gross anatomy, we mean the large structures and everything that is easily observable

What do we mean by microscopic anatomy

We mean the structures that are too small to be seen with the naked eye such as cells and tissues that can only be viewed with a microscope.

What is physiology

It’s the study of how the body and its parts function

By observing the structure (by studying the anatomy), we can determine which functions can occur.

Ex: air sacs of lungs = very thin walls. Why? It’s because it allows them to exchange gas easily and provide oxygen to the body compared to if they had thicker walls, the oxygen would stay emprisonned.

What are the 6 levels of structural organization

1. Atoms

2. Cells

3. Tissues

4. Organs

5. Organ systems

6. Organisms

Atoms combine to form molecules which make up the cells and tissues are made from a group of similar types of cells while organs are made of different types of tissues. Organ systems consist of different organs that work tgth closely while human organisms are made of many organ system.

What is the integumentary system

• It’s the outer covering of the body, so the skin and it also includes hair, fingernails, glands…

• It waterproofs the body

• It cushions (serves as a cushion) and protects the deeper tissues from injuries

• Produces vitamin D with help of sunlight

• Excretes salts in perspiration (while sweating)

• Helps regulate the body temperature

• Physical house/primary location of cutaneous nerve receptors

What are cutaneous nerve receptors?

They are different nerve endings that are embedded to detect sensations such as touch, pressure, pain and temperature located on a specific skin layer

Define the skeletal system

• Consists of bones, cartilage, ligaments and joints

• Provides muscle attachment for movement

• It protects vital organs

• Site of blood cell formation

• Stores minerals (calcium, phosphorus (it makes the bones stronger))

The skeletal system provides a framework that the muscles use to cause movement. The blood cells are formed within the bones and it stores minerals

Define the muscular system

So basically, we have a groupment of muscles that contract, in other words, shorten to produce the movement of the bones such as the manipulation of the environment, of the facial expression, of locomotion, the maintaning of the posture.

It also produces heat

Define the nervous system

• It’s a fast acting control system

• Made of brain/ spinal cord/ nerves/ sensory receptors

• Responds to internal and external stimuli

• The sensory receptors detect changes

• Messages are sent to the central nervous system which assesses information and activates effectors (so the muscles and glands)

Define the endocrine system

• It secretes hormones which are chemical molecules into the blood

• Hormones control body functions such as growth, reproduction and use of nutrients

What are the 7 categories the endocrine glands include:

1. Pituitary gland

2. Thyroid and parathyroids

3. Adrenal glands

4. Thymus

5. Pancreas

6. Pineal gland

7. Ovaries in females and testes in males

Mnemo technique: Please Try Any Tricks, Practice Pass Okay → PTAT-PPO

Define the cardiovascular system

It includes the heart and the blood vessels where the heart pumps the blood and the blood vessels transport the blood to tissues

What does blood contain and what does it transport

• Blood contains white blood cells and chemicals that provide protection against forein invaders

• It transports: Oxygen and carbon dioxide, nutrients and hormones

Define the lymphatic system

• Contains lymphatic vessels, lymph nodes and lymphoid organs

• Complements the cardiovascular system by returning the leaked fluids back to the bloodstream

• The lymph nodes and the lymphoid organs clean the blood

• The lymphatic system also houses the white blood cells which are involved in immunity

Define the respiratory system

Components involved:

• Nasal passages, pĥarynx, larynx, trachea, bronchi and lungs

Gases are exchanged with the blood through the air sacs in the lungs which:

• Supplies the body with oxygen

• Removes carbon dioxide

Define the digestive system

Components:

• Oral cavity (the mouth), esophagus, stomach, small and large intestines, rectum and accessory organs

Role:

• Break down food

• Allows for nutrient absorption into the blood

• Eliminates indigestible material as feces

Define the urinary system

Components:

• Kidneys, ureters, urinary bladder and urethra

Role:

• Eliminates nitrogenous wastes

• Maintain acid-base balance

• Regulates water and electrolyte balance

• Helps regulate normal blood pressure

Define the reproductive system

Components in male:

• Testes, scrotum, penis, accessory glands and duct system

Role in male:

• The testes produce the sperm and the duct system carries it to the exterior

Components in females:

• Ovaries, uterus, uterine tubes, vagina

Role in females:

• Ovaries produce eggs and the uterus provides a site of development for the uterus

8 important life functions

1. Maintaining boundaries

2. Movement

3. Responsiveness/irritability

4. Digestion

5. Metabolism

6. Excretion

7. Reproduction

8. Growth

Maintaning boundaries?

Ensure there is a boundary between the inside and the outside which separates them

Movement?

There must be locomotion and the movement of substance in the body and in the cells

Responsiveness/irritability

It’s the ability to sense changes and react accordingly to it

Digestion?

Breakdown and absorption of nutrients

Metabolism?

It’s the chemical reactions within the body

• Breaking down of the complex molecules into the smaller ones

• The build of of larger molecules from smaller ones

• Produces energy (ATP)

• Regulated by hormones

Excretion?

Eliminates excreta (waste) from metabolic reactions

Waste may be removed in the form of urine, feces, sweat…

Reproduction?

It is essential on the cellular and organismal level:

• On the cellular level: New cells are used for growth and repair

• On the organismal level: It’s the reproductive system that handles it

Growth?

There must be an increase in cell size or body size and that is done through increasing the number of cells and hormones play a huge role in the process

What are the 5 major survival needs?

1. Nutrients

2. Oxygen

3. Water

4. Normal body temperature

5. Atmospheric pressure

Why are nutrients essential for our survival?

By nutrients, we include carbohydrates, proteins, lipids, vitamins and minerals

They are essential because they are used for energy and cell building

Why is oxygen required for chemical reactions?

It is made available by the cooperation between the respiratory and cardiovascular systems

It is so essential because it is required for chemical reactions

Why is water so essential to our survival?

• Water is the most abundant chemical in our body since it composes about 60-80% of our body weight

• It provides a fluid base for body secretions and excretions

Why is normal body temperature so important?

It’s because below a certain temperature (in humans generally 36-37), the chemical reactions slow down such as slowing down the heart beat (remember when meredith fell in cold water)

Above a certain temperature, chemical reactions proceed way to rapidly which will lead to enzyme denaturation and oxygen depletion which lead to brain tissue damage, heart failure and widespread multi-organ failure death

Why is atmospheric pressure so essential

It’s because it must be appropriate for gas exchanges

What is the anatomical position

• It is the standard body position used to avoid confusion

• The terminology always refer to this position regardless of the actual body position

• The position is the following:

Standing erect, feet parallel, arms hanging on each sides with palms facing forward and thumbs pointing away from the body

The directional terms

They explain the location of one body structure in relation to another

1. Superior (cranial or cephalic) = above, toward the head or upper part of a structure or of the body

2. Inferior (caudal) = away from the head or toward the lower part of a structure or the body = below

3. Anterior (ventral) = in front of, toward or at the front of the body

4. Posterior (dorsal) = toward or at the backside of the body

5. Medial = toward or at the midline of the body (inner side of)

6. Lateral = away from the midline of the body (outer side of)

7. Intermediate = between a more medial and lateral structure

8. Proximal = close to the origin or attachment of the body part

9. Distal = farther from the origin or point of attachment of body part

10. Superficial (external) = toward or at the body surface

11. Deep (internal) = away from body surface, more internal

Body planes

There exists 3 types of planes which are sections that we cut along imaginary lines

1. Sagittal section which is a plane that separates the body into 2 pieces from up to down without it being necessarily 2 equal pieces (broad term):

• There is also the midsagittal that is the section that cuts the body into 2 equal left and right parts

2. The coronal/frontal which divide the the body into anterior and posterior parts

3. The transverse/cross divides the body into superior and inferior parts

What are body cavities?

They are fluid-filled spaces inside the body that provides varying degrees of protection to organs within them

What are the 2 main groups of internal body cavities

1. Dorsal

2. Ventral

Body cavities illustrated

Dorsal body cavity separated into: spinal cavity and cranial cavity

Ventral body cavity separated into: thoracic cavity and the abdominopelvic cavity composed of pelvic cavity and abdominal cavity

Dorsal body cavity subdivisions

1- Cranial cavity (role and structure):

• It houses the brain and is protected by the skull

2- Spinal cavity (role and structure):

• It houses the spinal cord and is protected by the vertebrae

Ventral body cavity subdivisions

1. Thoracic cavity

2. Abdominopelvic cavity

Thoracic cavity structure and role

It’s the cavity superior to the diaphragm. It holds the heart, lungs and other organs. The mediastinum which is the central region in the thoracic cavity houses the heart, the trachea and other organs, while the left plural cavity holds the left lung and the right plural cavity holds the right lung.

The thoracic cavity is protected by the rib cage.

Abdominopelvic cavity structure and role

It contains the pelvic cavity and the abdominal cavity

It’s the cavity inferior to the diaphragm

• The abdominal cavity contains the stomach, the liver and other organs. It is protected by trunk muscles

• The pelvic cavity contains the reproductive organs, the bladder and the rectum and it is protected somewhat by bony pelvis

There is no physical structure that separates the abdominal cavity from the pelvic cavity

Abdominopelvic cavity subdivision

There exists:

• 4 quadrants

• 9 regions

Name 4 other body cavities

1. Oral and digestive cavities

2. Nasal cavity

3. Orbital cavities

4. Middle ear cavities

Homeostasis definition

• It’s the maintenance of a relatively stable internal condition

It is a dynamic state of equilibrium/balance which is essential for normal body functioning and to sustain life

A homeostatic imbalance leads to disease

What are the 2 main controlling systems of homeostasis

1. Nervous system

2. Endocrine system

What are the 3 components of homeostatic control mechanism

1. Receptor

2. Control center

3. Effector

Define what is a receptor in the homeostatic control mechanism

It’s some form of sensor

• It responds to changes in the environment (response to stimuli)

• It sends information to the control center on the afferent pathway

What is an afferent pathway

It’s a neural route that carries sensory information from the body’s peripheral receptors toward the central nervous system (the brain and spinal cord)

Define the control center in a homeostatic control mechanism

It’s the component that receives signal from the receptor

1. It determines a set point

2. It analyses the information it received from the receptor by comparing it to the normal set point

3. It determines an appropriate response

Define the effector on a homeostatic control mechanism

It’s the muscle/organ/gland that acts as the output device on a homeostatic control mechanism to carry out the response that restores the balance

1. It provides a means for response to the stimulus

2. The information flows from the control center to the effector on the efferent pathway

What are feedback mechanisms

They are regulatory hoops that the body uses to monitor internal conditions and keep them within a safe and stable range.

Define negative feedback

• It includes most homeostatic control mechanisms

• It shuts of original stimulus or reduces its intensity

• It works like a household thermostat

The elements of a homeostatic control system

In a logical way:

1. The stimulus produces changes in variable which causes an imbalance

2. The receptor detects a change

3. Input: Information is being sent to the control center through an Afferent pathway

4. Output: Information is sent through an Efferent pathway to the effector

5. The response from the effector feeds back to reduce the effect of stimulus and returns the variable to a homeostatic level

Examples of negative feedback

Blood sugar regulation

Regulation of the body temperature (thermoregulation)

House thermostat

What is a positive feedback

It’s rare in the human body

It increases the original stimulus to push the variable even farther so an even bigger imbalance.

The reaction occurs at a faster rate as a result and in the human body such positive feedback occurs only in blood clotting and during the birth of a baby because for the childbirth, the baby pushing against the cervix release oxytocin which causes stronger uterine contractions which would make the baby pushed harder until birth. In blood clotting, the injuried tissues release chemicals that activate platelets which attracts even more platelets to seal fastly the wound or even in breastfeeding to release even more milk until feeding stops

Whats the big difference between positive and negative feedback

In negative feedback, the body fight to reduce or reverses a change to bring a system back to a stable state. However, positive feedback amplifies or increases the change which moves the system further away from its starting point